Pianotech

Original Message------

I believe I've seen reference to this before.

I'm interested in what a Steinway B sound board assembly might weigh.

Would some of those out there who build bellys be able to provide this info?

Weight of panel with ribs?

Weight of panel with ribs and bridges?

I've never weighed them but I do notice after I'm done some feel heavier than others

I'd like to start keeping track

Thank you list

Fenton Murray, RPT

Sent from my iPhone

Original Message------

Typical and original S&SB S/B assemblies, without bridges, weigh approx. 17 lbs. give or take. Large "A" boards are similar. Bridges add about 6 lbs. more. Variations in weight from one old board to another (which aren't dramatic) are due to overall panel thickness, degree of edges thinning, and rib dimensions.

A S&S "D" board without bridges can weigh as much as 25 lbs.

These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of downbearing.

Thank you Nick!
Great helpful info.
I weighed my ton of bricks today and it tipped the scales at 16.3 pounds.
Nice!
with the base cut off shortening the four longest ribs there's likely the other .7
that in the elimination  of the coupling device on the three long ribs, which I could still easily add back to the assembly
this is a maple bar that couples three ribs
would you comment on its function ?mass loading or simply coupling the ribs to help them share the load?
incidentally I have choked the tone before, I used to add a degree and a half of down bearing which I got from somebody way before the Internet
now I'm in the neighborhood of a third of a degree to 1° in the treble.
this of course requires more exact woodworking on the bridge top
thanks again Nick
Fenton

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton
------------------------------

Original Message:
Sent: 05-03-2020 15:08
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

Original Message------

Typical and original S&SB S/B assemblies, without bridges, weigh approx. 17 lbs. give or take. Large "A" boards are similar. Bridges add about 6 lbs. more. Variations in weight from one old board to another (which aren't dramatic) are due to overall panel thickness, degree of edges thinning, and rib dimensions.

A S&S "D" board without bridges can weigh as much as 25 lbs.

These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of downbearing.

Original Message------

Thank you Nick!
Great helpful info.
I weighed my ton of bricks today and it tipped the scales at 16.3 pounds.
Nice!
with the base cut off shortening the four longest ribs there's likely the other .7
that in the elimination  of the coupling device on the three long ribs, which I could still easily add back to the assembly
this is a maple bar that couples three ribs
would you comment on its function ?mass loading or simply coupling the ribs to help them share the load?
incidentally I have choked the tone before, I used to add a degree and a half of down bearing which I got from somebody way before the Internet
now I'm in the neighborhood of a third of a degree to 1° in the treble.
this of course requires more exact woodworking on the bridge top
thanks again Nick
Fenton

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton
------------------------------

Yes Nick,
I added a cut off bar
Which shortened 456 and seven Bringing them down to somewhere around 35 1/2 to 37 1/2 inches
As to measuring down bearing before stringing
The amount of preloading affects all measurements
I wedge the board down quite a bit at the struts before I pull my string and measure down Bearing
😊

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton
------------------------------

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

The problem with copying the original Steinway board is that no two boards are alike. Some are well made, some are horrible. Most are too heavy, even when they were diaphragmatic, the weight was reduced incorrectly especially from the top treble. 
The rib scales are always uneven and to copy those dimensions is a missed opportunity for improved soundboard performance. Ribs add stiffness to the panel and thus a stiffness curve is created. Smoothing out these curves has been beneficial.

The cut off bar in most cases is a bad idea. What's the point of getting a bigger piano if you just reduce the size of the board? The chladni tests I have done show that acoustically, that area is important.  Further tests show that there really isn't much downward force in that corner anyway.  Based on the many boards i have studied that were over 50 years old with still plenty of crown, i'm content with the longest rib being 45". Over that, I may add a cut off bar, but it would be a small one. Also adding a cut off bar and determining its size or location willy nilly is not a good engineering approach because by altering 3 ribs you also change the whole stiffness curve of the entire scale, which should be based on smoothness/evenness so that a collective strength is built into the structure.  Also when you change a ribs length, you also change the position of the driving point, which should be lined up under the bridge. Location of Driving points are critical towards making a board better than the original because massed produced instruments skip that important step. After becoming aware of driving points I found three pianos so far that had them aligned- Richard Gertz MH, an early Weber, and a Stieff upright. Once the driving points of the ribs are aligned ( by adjusting the scalloping length and thickness), the panel too has to be adjusted because once the panel is glued on, it will alter the locations. This is the real reason to change the thickness of the panel in all the key areas, otherwise its a guess. After all of these procedures are done, I have removed only the unnecessary parts of the soundboard and left the structural integrity in tact. My boards usually come out at five pounds lighter.

-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
------------------------------

Original Message:
Sent: 05-04-2020 09:17
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

( by adjusting the scalloping length and thickness)  Interesting. Math? 
Original Message:
Sent: 05-04-2020 12:27
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

The problem with copying the original Steinway board is that no two boards are alike. Some are well made, some are horrible. Most are too heavy, even when they were diaphragmatic, the weight was reduced incorrectly especially from the top treble.  I disagree with the impedance model because that's not how soundboards work.  You can have a heavy board and a light board and the fundamental frequency can be identical.  I also disagree with the statement that a heavy board sustains longer.  People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain. Technicians visit my shop from time to time and most believe the Gravagne statement. Until I show them a demo I have, and they can see it for themselves. For some reason, its not at first intuitive.
Spruce is chosen because it has a high strength to weight ratio than all other species. This basically gets screwed up when a board is made too heavy. Trying to acquire stiffness through mass has draw backs.

The cut off bar in most cases is a bad idea. What's the point of getting a bigger piano if you just reduce the size of the board? The chladni tests I have done show that acoustically, that area is important.  Further tests show that there really isn't much downward force in that corner anyway.  Based on the many boards i have studied that were over 50 years old with still plenty of crown, i'm content with the longest rib being 45". Over that, I may add a cut off bar, but it would be a small one. Also adding a cut off bar and determining its size or location willy nilly is not a good engineering approach because by altering 3 ribs you also change the whole stiffness curve of the entire scale, which should be based on smoothness/evenness so that a collective strength is built into the structure.  Also when you change a ribs length, you also change the position of the driving point, which should be lined up under the bridge. Location of Driving points are critical towards making a board better than the original because massed produced instruments skip that important step. After becoming aware of driving points I found three pianos so far that had them aligned- Richard Gertz MH, an early Weber, and a Stieff upright. Once the driving points of the ribs are aligned ( by adjusting the scalloping length and thickness), the panel too has to be adjusted because once the panel is glued on, it will alter the locations. This is the real reason to change the thickness of the panel in all the key areas, otherwise its a guess. After all of these procedures are done, I have removed only the unnecessary parts of the soundboard and left the structural integrity in tact. My boards usually come out at five pounds lighter.

-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-04-2020 09:17
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

Paul,
Math wouldn't help in this case. What I do is deflect the rib at the bridge location and measure the deflection of both ends until they are the same.
-chris

------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
------------------------------

Original Message:
Sent: 05-04-2020 12:48
From: Paul Klaus
Subject: Weight of Soundboard Assembly

( by adjusting the scalloping length and thickness)  Interesting. Math? 
Original Message:
Sent: 05-04-2020 12:27
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

The problem with copying the original Steinway board is that no two boards are alike. Some are well made, some are horrible. Most are too heavy, even when they were diaphragmatic, the weight was reduced incorrectly especially from the top treble.  I disagree with the impedance model because that's not how soundboards work.  You can have a heavy board and a light board and the fundamental frequency can be identical.  I also disagree with the statement that a heavy board sustains longer.  People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain. Technicians visit my shop from time to time and most believe the Gravagne statement. Until I show them a demo I have, and they can see it for themselves. For some reason, its not at first intuitive.
Spruce is chosen because it has a high strength to weight ratio than all other species. This basically gets screwed up when a board is made too heavy. Trying to acquire stiffness through mass has draw backs.

The cut off bar in most cases is a bad idea. What's the point of getting a bigger piano if you just reduce the size of the board? The chladni tests I have done show that acoustically, that area is important.  Further tests show that there really isn't much downward force in that corner anyway.  Based on the many boards i have studied that were over 50 years old with still plenty of crown, i'm content with the longest rib being 45". Over that, I may add a cut off bar, but it would be a small one. Also adding a cut off bar and determining its size or location willy nilly is not a good engineering approach because by altering 3 ribs you also change the whole stiffness curve of the entire scale, which should be based on smoothness/evenness so that a collective strength is built into the structure.  Also when you change a ribs length, you also change the position of the driving point, which should be lined up under the bridge. Location of Driving points are critical towards making a board better than the original because massed produced instruments skip that important step. After becoming aware of driving points I found three pianos so far that had them aligned- Richard Gertz MH, an early Weber, and a Stieff upright. Once the driving points of the ribs are aligned ( by adjusting the scalloping length and thickness), the panel too has to be adjusted because once the panel is glued on, it will alter the locations. This is the real reason to change the thickness of the panel in all the key areas, otherwise its a guess. After all of these procedures are done, I have removed only the unnecessary parts of the soundboard and left the structural integrity in tact. My boards usually come out at five pounds lighter.

-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-04-2020 09:17
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

Empirically. Yeah, thanks!
Original Message:
Sent: 05-04-2020 19:01
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

Paul,
Math wouldn't help in this case. What I do is deflect the rib at the bridge location and measure the deflection of both ends until they are the same.
-chris

------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-04-2020 12:48
From: Paul Klaus
Subject: Weight of Soundboard Assembly

( by adjusting the scalloping length and thickness)  Interesting. Math? 
Original Message:
Sent: 05-04-2020 12:27
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

The problem with copying the original Steinway board is that no two boards are alike. Some are well made, some are horrible. Most are too heavy, even when they were diaphragmatic, the weight was reduced incorrectly especially from the top treble.  I disagree with the impedance model because that's not how soundboards work.  You can have a heavy board and a light board and the fundamental frequency can be identical.  I also disagree with the statement that a heavy board sustains longer.  People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain. Technicians visit my shop from time to time and most believe the Gravagne statement. Until I show them a demo I have, and they can see it for themselves. For some reason, its not at first intuitive.
Spruce is chosen because it has a high strength to weight ratio than all other species. This basically gets screwed up when a board is made too heavy. Trying to acquire stiffness through mass has draw backs.

The cut off bar in most cases is a bad idea. What's the point of getting a bigger piano if you just reduce the size of the board? The chladni tests I have done show that acoustically, that area is important.  Further tests show that there really isn't much downward force in that corner anyway.  Based on the many boards i have studied that were over 50 years old with still plenty of crown, i'm content with the longest rib being 45". Over that, I may add a cut off bar, but it would be a small one. Also adding a cut off bar and determining its size or location willy nilly is not a good engineering approach because by altering 3 ribs you also change the whole stiffness curve of the entire scale, which should be based on smoothness/evenness so that a collective strength is built into the structure.  Also when you change a ribs length, you also change the position of the driving point, which should be lined up under the bridge. Location of Driving points are critical towards making a board better than the original because massed produced instruments skip that important step. After becoming aware of driving points I found three pianos so far that had them aligned- Richard Gertz MH, an early Weber, and a Stieff upright. Once the driving points of the ribs are aligned ( by adjusting the scalloping length and thickness), the panel too has to be adjusted because once the panel is glued on, it will alter the locations. This is the real reason to change the thickness of the panel in all the key areas, otherwise its a guess. After all of these procedures are done, I have removed only the unnecessary parts of the soundboard and left the structural integrity in tact. My boards usually come out at five pounds lighter.

-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-04-2020 09:17
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

Chris wrote:

"People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain."

Hmmm.  Not sure about that and not sure how you isolate mass from stiffness or ignore the impedance model.  How long a board sustains has to do with how much energy is transferred to the assembly from the vibrating string versus how much is deflected back to the string and how quickly energy dissipates from the assembly.  The ease with which the board moves (soundboard velocity) has much to do with how loud the attack is and is related to how much and how quickly the energy transfers.  Once the energy from the string has transferred there is no more sustain. 

A higher rate of transfer means higher velocity of the board (louder) initially but the energy will dissipate more quickly (shorter sustain).  Mass and stiffness both contribute to impedance characteristics. 

As the illustration shows, left side is lower impedance, energy transfers quickly, soundboard velocity is greater (amplitude is greater), volume at attack is greater, string dissipates more energy more quickly, sustain is shorter.

Right side shows higher impedance, energy transfers more slowly, soundboard velocity is less (amplitude is less), volume at attack is less, string dissipates energy more slowly, sustain is longer.  

Isn't that pretty basic?



------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-04-2020 12:27
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

The problem with copying the original Steinway board is that no two boards are alike. Some are well made, some are horrible. Most are too heavy, even when they were diaphragmatic, the weight was reduced incorrectly especially from the top treble.  I disagree with the impedance model because that's not how soundboards work.  You can have a heavy board and a light board and the fundamental frequency can be identical.  I also disagree with the statement that a heavy board sustains longer.  People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain. Technicians visit my shop from time to time and most believe the Gravagne statement. Until I show them a demo I have, and they can see it for themselves. For some reason, its not at first intuitive.
Spruce is chosen because it has a high strength to weight ratio than all other species. This basically gets screwed up when a board is made too heavy. Trying to acquire stiffness through mass has draw backs.

The cut off bar in most cases is a bad idea. What's the point of getting a bigger piano if you just reduce the size of the board? The chladni tests I have done show that acoustically, that area is important.  Further tests show that there really isn't much downward force in that corner anyway.  Based on the many boards i have studied that were over 50 years old with still plenty of crown, i'm content with the longest rib being 45". Over that, I may add a cut off bar, but it would be a small one. Also adding a cut off bar and determining its size or location willy nilly is not a good engineering approach because by altering 3 ribs you also change the whole stiffness curve of the entire scale, which should be based on smoothness/evenness so that a collective strength is built into the structure.  Also when you change a ribs length, you also change the position of the driving point, which should be lined up under the bridge. Location of Driving points are critical towards making a board better than the original because massed produced instruments skip that important step. After becoming aware of driving points I found three pianos so far that had them aligned- Richard Gertz MH, an early Weber, and a Stieff upright. Once the driving points of the ribs are aligned ( by adjusting the scalloping length and thickness), the panel too has to be adjusted because once the panel is glued on, it will alter the locations. This is the real reason to change the thickness of the panel in all the key areas, otherwise its a guess. After all of these procedures are done, I have removed only the unnecessary parts of the soundboard and left the structural integrity in tact. My boards usually come out at five pounds lighter.

-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-04-2020 09:17
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Original Message:
Sent: 05-05-2020 12:50
From: David Love
Subject: Weight of Soundboard Assembly

Chris wrote:

"People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain."

Hmmm.  Not sure about that and not sure how you isolate mass from stiffness or ignore the impedance model.  How long a board sustains has to do with how much energy is transferred to the assembly from the vibrating string versus how much is deflected back to the string and how quickly energy dissipates from the assembly.  The ease with which the board moves (soundboard velocity) has much to do with how loud the attack is and is related to how much and how quickly the energy transfers.  Once the energy from the string has transferred there is no more sustain.

A higher rate of transfer means higher velocity of the board (louder) initially but the energy will dissipate more quickly (shorter sustain).  Mass and stiffness both contribute to impedance characteristics.

As the illustration shows, left side is lower impedance, energy transfers quickly, soundboard velocity is greater (amplitude is greater), volume at attack is greater, string dissipates more energy more quickly, sustain is shorter.

Right side shows higher impedance, energy transfers more slowly, soundboard velocity is less (amplitude is less), volume at attack is less, string dissipates energy more slowly, sustain is longer.

Isn't that pretty basic?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-04-2020 12:27
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

The problem with copying the original Steinway board is that no two boards are alike. Some are well made, some are horrible. Most are too heavy, even when they were diaphragmatic, the weight was reduced incorrectly especially from the top treble.  I disagree with the impedance model because that's not how soundboards work.  You can have a heavy board and a light board and the fundamental frequency can be identical.  I also disagree with the statement that a heavy board sustains longer.  People seem to ignore the fact that to get something heavier to move requires more energy.  So if you input the same energy into a lighter board it will sustain longer because it took less of that energy to get the board moving and the rest of that input energy goes toward sustain. Technicians visit my shop from time to time and most believe the Gravagne statement. Until I show them a demo I have, and they can see it for themselves. For some reason, its not at first intuitive.
Spruce is chosen because it has a high strength to weight ratio than all other species. This basically gets screwed up when a board is made too heavy. Trying to acquire stiffness through mass has draw backs.

The cut off bar in most cases is a bad idea. What's the point of getting a bigger piano if you just reduce the size of the board? The chladni tests I have done show that acoustically, that area is important.  Further tests show that there really isn't much downward force in that corner anyway.  Based on the many boards i have studied that were over 50 years old with still plenty of crown, i'm content with the longest rib being 45". Over that, I may add a cut off bar, but it would be a small one. Also adding a cut off bar and determining its size or location willy nilly is not a good engineering approach because by altering 3 ribs you also change the whole stiffness curve of the entire scale, which should be based on smoothness/evenness so that a collective strength is built into the structure.  Also when you change a ribs length, you also change the position of the driving point, which should be lined up under the bridge. Location of Driving points are critical towards making a board better than the original because massed produced instruments skip that important step. After becoming aware of driving points I found three pianos so far that had them aligned- Richard Gertz MH, an early Weber, and a Stieff upright. Once the driving points of the ribs are aligned ( by adjusting the scalloping length and thickness), the panel too has to be adjusted because once the panel is glued on, it will alter the locations. This is the real reason to change the thickness of the panel in all the key areas, otherwise its a guess. After all of these procedures are done, I have removed only the unnecessary parts of the soundboard and left the structural integrity in tact. My boards usually come out at five pounds lighter.

-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-04-2020 09:17
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I see the photo now, thank you Nick.

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-03-2020 20:29
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Did not see a photo attached

Sent from my iPhone


Original Message------

Meant to add that heavier assemblies, such as found on old M&H boards (more sq. footage, more ribs for a given piano length, thicker rib endings at the central and longest ribs, and extra heavy bridges along with massive rim and beam foundation) resist the string impulses and are considered high (or higher) impedance systems. Overdone, such systems encourage longer sustain (not necessarily very audible), but at the expense of power output, especially "in your face" power.

Too much downbearing on any system increases impedance (resistance to string impulses), the negative effect sometimes referred to as "choking the tone." Force loading (bearing) and mass loading (amount of wood in the entire system inc. rim and beams) both affect impedance in a primary sense, yet differently regarding filtering of the harmonic spectrum.

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Fenton M. asked: "Terry, are you saying you don't worry about the small portion of the rib within the notch?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be    

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles. 

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.  

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.  



(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

David Love <This gets to the question of why do we set downbearing, what is its purpose?  

I've done practically a 180 on this point. I no longer am thinking of these systems exclusively as two opposing springs, according to the impedance model David has described. Yes the system has impedance, and yes the string system and board system are in opposition. But what the impedance is contributing, to the tonal performance, is not necessarily been proven. Actually, experiment by Dain and Paullelo suggest that a much higher involvement in efficiency of terminations, as opposed to the usual horribly inefficient bridge pin setup, has much to do with what sound comes out of a belly.

My observations lead me to define downbearing, almost entirely, as something we have to do because the bridge termination is such a poor structural system. DB is required, in my current take, because the pin terminations cannot retain their peak functionality for any length of time in a negative situation. Positive DB simply provides safety, so DB does not go negative, and yank on the pins.  Plenty of evidence, over the last few years, with folks building zero DB and rib-less systems, prove empirically, that the common impedance model, while describing a real physical effect, is not entirely describing what is happening in the complex piano board system, or does not describe what the interaction between efficient terminations and board system overall impedance actually is.
 
While its dangerous to go to the other extreme, and say impedance is not important at all...this would be foolish. But given attention to termination efficiency, pivot terminations, duplex involvement, the levels of impedance we have learned to assume, I think are not as absolute as they may sound. My observations, the last couple of years, in new as well as old boards, is get the DB off the board, to the degree that will not challenge the functionality of the horrible bridge pin termination system, and pay a lot off attention to the conditions that front bridge pin experiences.

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

All assemblies will have impedance characteristics no matter how you build it or how you set up the downbearing.  It's inherent in the system.  No question there are some different models being made.  I've heard assemblies that were on the stiff side, presumably needing less downbearing to stiffen them and some of them did have less (some didn't).  I wasn't thrilled with the result either way.  But I can't say it was wrong, just didn't appeal to me. 

I've also heard many pianos that had sections of the scale with negative bearing.  I can't say I was pointed to that because of audible termination issues or that I'm even convinced that it necessarily creates termination issues, I suppose, depending on where in the scale it falls.   

There are some very reputable builders who after setting up the piano go through and  tweak the bearing in order to balance the impedance levels (in layman's terms balance the attack and sustain phase of the tonal envelope).  Their claim to be able to accomplish that successfully.  I always do the same thing once the piano is strung, stable, terminations cleaned up, preliminary voicing procedures gone through.  Often I do that initially just to correct minor discrepancies in the residual bearing but I'm also paying attention, especially in the treble, to how that section balances (attack v sustain) to see if i can improve it.  These are pretty subtle changes and clearly won't compensate for a poorly executed set-up.  The lower part of the piano seems less sensitive to changes in bearing.  

The other issue, however, is just as important, in my opinion; loading the soundboard with potential energy.  Now any amount of downbearing will do that but the question is how much is too much and how much is too little or does it matter at all.  I think it does.  

Having heard lots of different designs (and redesigns) over the last 40 years I can say there are clear differences but also a limit to the range of what is acceptable.  I think there is a kind of "sweet spot" where the board not only has impedance balance (attack/sustain) but also has a certainly "liveliness" for lack of a better word.  I can't help but think that liveliness is related to the potential energy in the loaded system combined with the freedom with which the board is able to move in both directions (up and down).  The best pianos get that balance just right.  Lesser pianos don't.    

I can't claim to be able to clearly quantify that.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-06-2020 15:27
From: Jim Ialeggio
Subject: Weight of Soundboard Assembly

David Love <This gets to the question of why do we set downbearing, what is its purpose?

I've done practically a 180 on this point. I no longer am thinking of these systems exclusively as two opposing springs, according to the impedance model David has described. Yes the system has impedance, and yes the string system and board system are in opposition. But what the impedance is contributing, to the tonal performance, is not necessarily been proven. Actually, experiment by Dain and Paullelo suggest that a much higher involvement in efficiency of terminations, as opposed to the usual horribly inefficient bridge pin setup, has much to do with what sound comes out of a belly.

My observations lead me to define downbearing, almost entirely, as something we have to do because the bridge termination is such a poor structural system. DB is required, in my current take, because the pin terminations cannot retain their peak functionality for any length of time in a negative situation. Positive DB simply provides safety, so DB does not go negative, and yank on the pins.  Plenty of evidence, over the last few years, with folks building zero DB and rib-less systems, prove empirically, that the common impedance model, while describing a real physical effect, is not entirely describing what is happening in the complex piano board system, or does not describe what the interaction between efficient terminations and board system overall impedance actually is.

While its dangerous to go to the other extreme, and say impedance is not important at all...this would be foolish. But given attention to termination efficiency, pivot terminations, duplex involvement, the levels of impedance we have learned to assume, I think are not as absolute as they may sound. My observations, the last couple of years, in new as well as old boards, is get the DB off the board, to the degree that will not challenge the functionality of the horrible bridge pin termination system, and pay a lot off attention to the conditions that front bridge pin experiences.

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

On a related subject one of the things that I would like to see explored is whether phase cancellation is an inherent problem in piano soundboards.  This speaks somewhat to Chris's comment about the cut-off bar and whether it's necessary or why you would put one in at all (spoiler alert--many manufacturers do and did install cut-off bars routinely).  Phase cancellation is a phenomenon where multiple sound waves of the same frequency are operating out of phase with each other and when that happens the frequencies are diminished, or, if the are operating 180 degrees opposite each other they are lost completely.  It's a problem frequently encountered in the recording industry. 

Looking at various simulations of soundboard response like this one (there are some others including by Bernard Stopper posted some years ago) one wonders whether the natural properties of the SB create some sort of phase cancellations, what the effect of that is on what we hear, is it something that can be addressed, say, by some alternate form of rib design or structure, or even if it's a desirable thing to try and address.  Beyond my pay grade to be able to answer those questions.  

https://www.youtube.com/watch?v=qv3yeoklu3Q&feature=youtu.be

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-06-2020 16:16
From: David Love
Subject: Weight of Soundboard Assembly

All assemblies will have impedance characteristics no matter how you build it or how you set up the downbearing.  It's inherent in the system.  No question there are some different models being made.  I've heard assemblies that were on the stiff side, presumably needing less downbearing to stiffen them and some of them did have less (some didn't).  I wasn't thrilled with the result either way.  But I can't say it was wrong, just didn't appeal to me.

I've also heard many pianos that had sections of the scale with negative bearing.  I can't say I was pointed to that because of audible termination issues or that I'm even convinced that it necessarily creates termination issues, I suppose, depending on where in the scale it falls.

There are some very reputable builders who after setting up the piano go through and  tweak the bearing in order to balance the impedance levels (in layman's terms balance the attack and sustain phase of the tonal envelope).  Their claim to be able to accomplish that successfully.  I always do the same thing once the piano is strung, stable, terminations cleaned up, preliminary voicing procedures gone through.  Often I do that initially just to correct minor discrepancies in the residual bearing but I'm also paying attention, especially in the treble, to how that section balances (attack v sustain) to see if i can improve it.  These are pretty subtle changes and clearly won't compensate for a poorly executed set-up.  The lower part of the piano seems less sensitive to changes in bearing.

The other issue, however, is just as important, in my opinion; loading the soundboard with potential energy.  Now any amount of downbearing will do that but the question is how much is too much and how much is too little or does it matter at all.  I think it does.

Having heard lots of different designs (and redesigns) over the last 40 years I can say there are clear differences but also a limit to the range of what is acceptable.  I think there is a kind of "sweet spot" where the board not only has impedance balance (attack/sustain) but also has a certainly "liveliness" for lack of a better word.  I can't help but think that liveliness is related to the potential energy in the loaded system combined with the freedom with which the board is able to move in both directions (up and down).  The best pianos get that balance just right.  Lesser pianos don't.

I can't claim to be able to clearly quantify that.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-06-2020 15:27
From: Jim Ialeggio
Subject: Weight of Soundboard Assembly

David Love <This gets to the question of why do we set downbearing, what is its purpose?

I've done practically a 180 on this point. I no longer am thinking of these systems exclusively as two opposing springs, according to the impedance model David has described. Yes the system has impedance, and yes the string system and board system are in opposition. But what the impedance is contributing, to the tonal performance, is not necessarily been proven. Actually, experiment by Dain and Paullelo suggest that a much higher involvement in efficiency of terminations, as opposed to the usual horribly inefficient bridge pin setup, has much to do with what sound comes out of a belly.

My observations lead me to define downbearing, almost entirely, as something we have to do because the bridge termination is such a poor structural system. DB is required, in my current take, because the pin terminations cannot retain their peak functionality for any length of time in a negative situation. Positive DB simply provides safety, so DB does not go negative, and yank on the pins.  Plenty of evidence, over the last few years, with folks building zero DB and rib-less systems, prove empirically, that the common impedance model, while describing a real physical effect, is not entirely describing what is happening in the complex piano board system, or does not describe what the interaction between efficient terminations and board system overall impedance actually is.

While its dangerous to go to the other extreme, and say impedance is not important at all...this would be foolish. But given attention to termination efficiency, pivot terminations, duplex involvement, the levels of impedance we have learned to assume, I think are not as absolute as they may sound. My observations, the last couple of years, in new as well as old boards, is get the DB off the board, to the degree that will not challenge the functionality of the horrible bridge pin termination system, and pay a lot off attention to the conditions that front bridge pin experiences.

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

I suspect the main purpose of downbearing is to increase the sustain time in a soundboard. If it behaves like the weighted lath strip i have that is. It then utilizes the energy its given efficiently.  

I never said impedance doesn't exist. Its not really much different from fluid viscosity except you're dealing with sound waves through a solid.

I read the Giordano paper and its flaw IMHO is its academic nature. He says its "An Upright piano."  as if all are identical.
We don't know the brand, panel thickness, rib scale (H,W,L) or wood species. Those will have a significant bearing on the conclusions drawn. Plus he draws his conclusions by comparing to Wogram and Conklin, and again we don't know the data of those pianos either. 

Academic studies aside, My objection to the impedance model is that it doesn't prevent design errors, but tries to correct them after? Yes? At that point your kinda stuck with the design flaws (wrong panel grading, thickness, bad rib scale, bridge mass,etc.) and those related problems.

Why not just make a board that bypasses those problems to begin with?
-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
------------------------------

Original Message:
Sent: 05-06-2020 15:27
From: Jim Ialeggio
Subject: Weight of Soundboard Assembly

David Love <This gets to the question of why do we set downbearing, what is its purpose?

I've done practically a 180 on this point. I no longer am thinking of these systems exclusively as two opposing springs, according to the impedance model David has described. Yes the system has impedance, and yes the string system and board system are in opposition. But what the impedance is contributing, to the tonal performance, is not necessarily been proven. Actually, experiment by Dain and Paullelo suggest that a much higher involvement in efficiency of terminations, as opposed to the usual horribly inefficient bridge pin setup, has much to do with what sound comes out of a belly.

My observations lead me to define downbearing, almost entirely, as something we have to do because the bridge termination is such a poor structural system. DB is required, in my current take, because the pin terminations cannot retain their peak functionality for any length of time in a negative situation. Positive DB simply provides safety, so DB does not go negative, and yank on the pins.  Plenty of evidence, over the last few years, with folks building zero DB and rib-less systems, prove empirically, that the common impedance model, while describing a real physical effect, is not entirely describing what is happening in the complex piano board system, or does not describe what the interaction between efficient terminations and board system overall impedance actually is.

While its dangerous to go to the other extreme, and say impedance is not important at all...this would be foolish. But given attention to termination efficiency, pivot terminations, duplex involvement, the levels of impedance we have learned to assume, I think are not as absolute as they may sound. My observations, the last couple of years, in new as well as old boards, is get the DB off the board, to the degree that will not challenge the functionality of the horrible bridge pin termination system, and pay a lot off attention to the conditions that front bridge pin experiences.

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Well, yes but if downbearing increases sustain it does so by raising the impedance. Impedance just means the rate of energy transfer. Downbearing compresses the soundboard spring, the assembly gets stiffer, the impedance increases and sustain increases.

The purpose of designing ribscales and factoring in downbearing as a measure of the string load is ultimately to control impedance even though we use things like beam formulas, MOI, spring rates and various other checks and balances, including downbearing settings, as the calculus. Mass obviously plays a role as well but the general principle is light, but not too light, stiff but not too stiff.  The assembly must both be reactive and controlled.

Finding that balance that translates into something we like probably explains the range of designs that we encounter. I don't know if there's any formula that translates directly to some aesthetic model simply because we can't quantify taste. We recognize when something doesn't work but it's harder to pinpoint a specific tonal outcome from some set of numbers. The reality is that at some point (as Del Fandrich is fond of saying) you have to shoot the designer and build it. You take what you find and build another one tweaking this or that and hope that all other things remain constant. It's a constant process of moving toward some ideal. There are no shortcuts. 

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-08-2020 20:18
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

I suspect the main purpose of downbearing is to increase the sustain time in a soundboard. If it behaves like the weighted lath strip i have that is. It then utilizes the energy its given efficiently.

I never said impedance doesn't exist. Its not really much different from fluid viscosity except you're dealing with sound waves through a solid.

I read the Giordano paper and its flaw IMHO is its academic nature. He says its "An Upright piano."  as if all are identical.
We don't know the brand, panel thickness, rib scale (H,W,L) or wood species. Those will have a significant bearing on the conclusions drawn. Plus he draws his conclusions by comparing to Wogram and Conklin, and again we don't know the data of those pianos either.

Academic studies aside, My objection to the impedance model is that it doesn't prevent design errors, but tries to correct them after? Yes? At that point your kinda stuck with the design flaws (wrong panel grading, thickness, bad rib scale, bridge mass,etc.) and those related problems.

Why not just make a board that bypasses those problems to begin with?
-chris





------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-06-2020 15:27
From: Jim Ialeggio
Subject: Weight of Soundboard Assembly

David Love <This gets to the question of why do we set downbearing, what is its purpose?

I've done practically a 180 on this point. I no longer am thinking of these systems exclusively as two opposing springs, according to the impedance model David has described. Yes the system has impedance, and yes the string system and board system are in opposition. But what the impedance is contributing, to the tonal performance, is not necessarily been proven. Actually, experiment by Dain and Paullelo suggest that a much higher involvement in efficiency of terminations, as opposed to the usual horribly inefficient bridge pin setup, has much to do with what sound comes out of a belly.

My observations lead me to define downbearing, almost entirely, as something we have to do because the bridge termination is such a poor structural system. DB is required, in my current take, because the pin terminations cannot retain their peak functionality for any length of time in a negative situation. Positive DB simply provides safety, so DB does not go negative, and yank on the pins.  Plenty of evidence, over the last few years, with folks building zero DB and rib-less systems, prove empirically, that the common impedance model, while describing a real physical effect, is not entirely describing what is happening in the complex piano board system, or does not describe what the interaction between efficient terminations and board system overall impedance actually is.

While its dangerous to go to the other extreme, and say impedance is not important at all...this would be foolish. But given attention to termination efficiency, pivot terminations, duplex involvement, the levels of impedance we have learned to assume, I think are not as absolute as they may sound. My observations, the last couple of years, in new as well as old boards, is get the DB off the board, to the degree that will not challenge the functionality of the horrible bridge pin termination system, and pay a lot off attention to the conditions that front bridge pin experiences.

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Hi Terry,
I know that fitting the rib do the liner perfectly would be easy money for you you.
Do you eliminate that step as not necessary, or as an improvement?

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton
------------------------------

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Fenton M. asked: "Do you eliminate that step as not necessary, or as an improvement?"

Not necessary. I have no reason to think such a practice is harmful.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Original Message:
Sent: 05-06-2020 15:43
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi Terry,
I know that fitting the rib do the liner perfectly would be easy money for you you.
Do you eliminate that step as not necessary, or as an improvement?

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-06-2020 14:27
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton, hope you're doing well.

The impedance *is* affected by downbearing.  Since stiffness is a factor in the impedance characteristics and since increasing compression on the soundboard "spring" (which is a non-linear spring) does stiffen the assembly, more downbearing does raise the impedance level.  The question is how much downbearing is required to adequately stiffen the assembly the desired amount, since compression of the spring is, ultimately, a factor in determining just how stiff the assembly needs to be

Interestingly, we tend to calculate the rib scale based on load bearing principles not on impedance characteristics, but they are not unrelated.  If we were to build the board such that it achieved the requisite stiffness, say, without any downbearing what would we get?  One thing we would not get is the dynamics of how the board responds when the spring is compressed, or loaded, creating some potential energy in the system.  The board is ready to spring: strings pushing the board down and the board pushing back up with the forces necessarily equal.  That would be, presumably, a much different response than a board which is made with some higher level of load bearing capacity (stiffer) but then with zero downbearing.  Of course, if there's no downbearing load put on the board it sort of defeats the purpose of building the board based on load bearing principles.

This gets to the question of why do we set downbearing, what is its purpose?  I would say that the purpose are mainly two fold: First, to compress the board to its requisite stiffness for the purpose of controlling impedance. Second to introduce potential energy into the system.  Downbearing as a necessity for coupling the strings to the bridge, as is often cited, seems to be not that necessary owing to the bridge pin array which accomplishes that coupling whether there is downbearing or not.

Can there be too much downbearing such that the board is "over-compressed" and lacks freedom of mobility?  It seems to me that is possible and could be one reason that some pianos sound "choked".  Interestingly, some years ago some folks were advocating rescaling in a manner that basically just increased the string diameters and thereby the overall tension.  Given the same downbearing settings that would increase pressure on the board, flatten out the assembly somewhat more and possibly put the downward force from the strings out of balance with the upward force of the soundboard.  Not literally, because the forces are necessarily equal, but in terms of how the board is able to respond with inputs of energy.  Think of it like we might think about the spring in a piano hammer.  There is some ideal in which the spring can respond in both directions (left illustration).  If we have a soundboard that is too stiff either by compression or by design, we have something like the hammer pictured in the center.  Sadly, we can't needle soundboards (or lacquer them--at least not to increase stiffness).  If we have something like the picture on the right, then the spring is a bit flabby, the impedance characteristics in the soundboard will be too low with the resulting tonal response.  While the design plays a critical role in determining the final characteristics of the spring, downbearing also plays a role.  In our case, with a soundboard assembly, we are starting with something more akin to the hammer pictured on the right and achieving the requisite stiffness as pictured on the left by the downbearing.  In other words we are compressing the spring to both achieve the level of stiffness we want and to load the spring with potential energy.  Of course with a hammer there are some differences. We can't load the spring with downbearing and must achieve the desired stiffness through other means.  But that's another story.

(BTW I do try and fit the rib ends exactly the height of the notch so that the rib end is glued solidly to the bottom of the notch.  I don't worry too much about a perfect fit on the sides of the rib in those notches.)

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-05-2020 17:26
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'm in a room full of experts looking for small takeaways.

Thank you Jim perimeter cauls that are confined to the glue joint.

Terry, are you saying you don't worry about the small portion of the rib within the notch?

Either on side or bottom,

Sides are tough to nail without shimmimg.

And you certainly wouldn't want the ribs too tall, erring on the side of safety will be just the opposite with a small gap.

Questions to the List,

Other than looking at the physical size of a bridge or rib there's no way to know the mass of that soundboard system without weighing it?

Is the impedance of the system affected by the amount of down bearing?

So, can we find this "usefully balanced system"

On An already created structurally sound soundboard system by applying the appropriate down bearing?

Sent from my iPhone

Original Message------

David has this exactly right. Any "debate" as to the existence and / or operation of impedance (high or low or usefully balanced) in a piano soundboard is pointless. There can be no opinion on the matter.

Ref. http://whyyouhearwhatyouhear.com/chapterfiles/chpt19/other/JAS002128.pdf
by giordno

and
http://www.speech.kth.se/music/5_lectures/introd/introd.html#sound
intro and section by H. Conklin

------------------------------
Nick Gravagne, RPT
Mechanical Engineering
Nick Gravagne Products
Strawberry, AZ 85544
gravagnegang@att.net
928-476-4143
------------------------------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Original Message:
Sent: 05-03-2020 14:23
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

Typical and original S&SB S/B assemblies, without bridges, weigh approx. 17 lbs. give or take. Large "A" boards are similar. Bridges add about 6 lbs. more. Variations in weight from one old board to another (which aren't dramatic) are due to overall panel thickness, degree of edges thinning, and rib dimensions.

A S&S "D" board without bridges can weigh as much as 25 lbs.

These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of downbearing.

Original Message------

I believe I've seen reference to this before.

I'm interested in what a Steinway B sound board assembly might weigh.

Would some of those out there who build bellys be able to provide this info?

Weight of panel with ribs?

Weight of panel with ribs and bridges?

I've never weighed them but I do notice after I'm done some feel heavier than others

I'd like to start keeping track

Thank you list

Fenton Murray, RPT

Sent from my iPhone

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Nick G. responded: "So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests."

Actually, my thinking that a good (well designed) unsupported soundboard would not go flat with applied downbearing force was even without bridges. I'll throw out early that I'm not trying to be argumentative (as some might tend to think), but rather trying to understand. Being somewhat math and engineering challenged, it seems to me that a common (low treble to bass) arc length of an unloaded board with a 60-foot radius might be 30" (just a random example). Loaded to the point where it is flat, the rib tip-to-tip length of that arc (now a cord of the original circle) would increase by about 0.002 inches (assuming no compression of the spruce or pine rib). I do wish that I could do the engineering and math - but I can't (hey, even Clint Eastwood said that "A man's gotta know his limitations.") (I think Ron Nossaman made a presentation of this in one of the PTG Journals some years ago - anyone  know which issue?). But between rim deflection and rib compression, you only need that 0.002 inches. I sure know that even spruce doesn't compress much along the grain, nor does a heavy, thick hard maple rim deflect much - and 50 pounds (or whatever it might be) of downbearing on a rib will produce A LOT of pressure against a rim if one considers the unloaded soundboard as an arc. But gosh, two-thousandths of an inch (or more!) of movement/compression isn't hard to imagine. I remember years ago when I last read Ron's article, it sure made sense to me. Is that your argument - the the unloaded board functions as an arch and the rim prevents the arch from collapsing?

Again, my point is not to dredge up old arguments, but rather to try to understand.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Original Message:
Sent: 05-04-2020 17:25
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

I was thinking of the board without the bridges, since that was Fenton's first request as to weight. A bridge adds a significant stiffness and bending resistance to downbearing, in which case I might have said,  "such a structure, independent of attachment to the rim and beam foundations, would not adequately withstand the force of downbearing."

So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests.

I did a workup on this some years ago which I will now revisit. I might be able to supply some quantification here.

In any case, the larger point I was making is that such a relatively lightweight assembly, due to its paneling, cross ribbing, bridging and fixed attachment to a rigid structure is amazingly strong in resisting large downward forces. The S/B assembly should compress, but not flatten or reverse.

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Mr. Farrell,
I'll see your "engineering challenged" and raise you a "completely innumerate". That not withstanding try this experiment: Take a board and rib and bridge assembly to the rim and pre-load it without clamping it to the rim. Measure for setting the bearing. Un-load the system and clamp it down to the rim firmly.
Take your bearing measurements again. Compare your numbers.
In my shop we set the bearing with the bridge glued to the crowned panel and I learned how different the measurement were in the above scenario by mistake. Expensive lesson but informative.


------------------------------
Karl Roeder
Pompano Beach FL
------------------------------

Original Message:
Sent: 05-05-2020 10:15
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Nick G. responded: "So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests."

Actually, my thinking that a good (well designed) unsupported soundboard would not go flat with applied downbearing force was even without bridges. I'll throw out early that I'm not trying to be argumentative (as some might tend to think), but rather trying to understand. Being somewhat math and engineering challenged, it seems to me that a common (low treble to bass) arc length of an unloaded board with a 60-foot radius might be 30" (just a random example). Loaded to the point where it is flat, the rib tip-to-tip length of that arc (now a cord of the original circle) would increase by about 0.002 inches (assuming no compression of the spruce or pine rib). I do wish that I could do the engineering and math - but I can't (hey, even Clint Eastwood said that "A man's gotta know his limitations.") (I think Ron Nossaman made a presentation of this in one of the PTG Journals some years ago - anyone  know which issue?). But between rim deflection and rib compression, you only need that 0.002 inches. I sure know that even spruce doesn't compress much along the grain, nor does a heavy, thick hard maple rim deflect much - and 50 pounds (or whatever it might be) of downbearing on a rib will produce A LOT of pressure against a rim if one considers the unloaded soundboard as an arc. But gosh, two-thousandths of an inch (or more!) of movement/compression isn't hard to imagine. I remember years ago when I last read Ron's article, it sure made sense to me. Is that your argument - the the unloaded board functions as an arch and the rim prevents the arch from collapsing?

Again, my point is not to dredge up old arguments, but rather to try to understand.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-04-2020 17:25
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

I was thinking of the board without the bridges, since that was Fenton's first request as to weight. A bridge adds a significant stiffness and bending resistance to downbearing, in which case I might have said,  "such a structure, independent of attachment to the rim and beam foundations, would not adequately withstand the force of downbearing."

So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests.

I did a workup on this some years ago which I will now revisit. I might be able to supply some quantification here.

In any case, the larger point I was making is that such a relatively lightweight assembly, due to its paneling, cross ribbing, bridging and fixed attachment to a rigid structure is amazingly strong in resisting large downward forces. The S/B assembly should compress, but not flatten or reverse.

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

I'll see your "engineering challenged" and raise you a "completely innumerate".  I'd like to participate, but man...you guys just took all my chips! LOL

Re: clamping the assembly to the rim to take DB measurements, when you clamp, if you use a perimeter caul, the caul must only contact the panel directly over the actual rim glue surface. If your perimeter caul extends past the actual rim, even just a little bit, it also screws up the DB big time...took a while to figure this one out.

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Original Message:
Sent: 05-05-2020 10:33
From: Karl Roeder
Subject: Weight of Soundboard Assembly

Mr. Farrell,
I'll see your "engineering challenged" and raise you a "completely innumerate". That not withstanding try this experiment: Take a board and rib and bridge assembly to the rim and pre-load it without clamping it to the rim. Measure for setting the bearing. Un-load the system and clamp it down to the rim firmly.
Take your bearing measurements again. Compare your numbers.
In my shop we set the bearing with the bridge glued to the crowned panel and I learned how different the measurement were in the above scenario by mistake. Expensive lesson but informative.


------------------------------
Karl Roeder
Pompano Beach FL

Original Message:
Sent: 05-05-2020 10:15
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Nick G. responded: "So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests."

Actually, my thinking that a good (well designed) unsupported soundboard would not go flat with applied downbearing force was even without bridges. I'll throw out early that I'm not trying to be argumentative (as some might tend to think), but rather trying to understand. Being somewhat math and engineering challenged, it seems to me that a common (low treble to bass) arc length of an unloaded board with a 60-foot radius might be 30" (just a random example). Loaded to the point where it is flat, the rib tip-to-tip length of that arc (now a cord of the original circle) would increase by about 0.002 inches (assuming no compression of the spruce or pine rib). I do wish that I could do the engineering and math - but I can't (hey, even Clint Eastwood said that "A man's gotta know his limitations.") (I think Ron Nossaman made a presentation of this in one of the PTG Journals some years ago - anyone  know which issue?). But between rim deflection and rib compression, you only need that 0.002 inches. I sure know that even spruce doesn't compress much along the grain, nor does a heavy, thick hard maple rim deflect much - and 50 pounds (or whatever it might be) of downbearing on a rib will produce A LOT of pressure against a rim if one considers the unloaded soundboard as an arc. But gosh, two-thousandths of an inch (or more!) of movement/compression isn't hard to imagine. I remember years ago when I last read Ron's article, it sure made sense to me. Is that your argument - the the unloaded board functions as an arch and the rim prevents the arch from collapsing?

Again, my point is not to dredge up old arguments, but rather to try to understand.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-04-2020 17:25
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

I was thinking of the board without the bridges, since that was Fenton's first request as to weight. A bridge adds a significant stiffness and bending resistance to downbearing, in which case I might have said,  "such a structure, independent of attachment to the rim and beam foundations, would not adequately withstand the force of downbearing."

So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests.

I did a workup on this some years ago which I will now revisit. I might be able to supply some quantification here.

In any case, the larger point I was making is that such a relatively lightweight assembly, due to its paneling, cross ribbing, bridging and fixed attachment to a rigid structure is amazingly strong in resisting large downward forces. The S/B assembly should compress, but not flatten or reverse.

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Thanks for the input Karl. I'm not sure I could really even do that, as I don't preload a board (bridge on or off) when measuring for downbearing/bridge-height. I know most folks do the pre-loading thing, but not having ever done it with any success, I really don't even know what that means (at least in my shop with my soundboards).

However, I have preloaded unrestrained and clamped-to-rim soundboards with target downbearing loads to measure rib deflection. I haven't observed much difference, and I've never collapsed one.

When I do take my measurements to set bridge height (and hence downbearing), I do firmly clamp soundboard in place on the rim (per Jim's concern - yes, yes, DAMHIK!!!). But I do that to be sure to be taking into account any soundboard deformation potentially caused by angular differentials between soundboard panel and rim. I don't give any special treatment to the rib-to-rim joint - in fact I put zero effort into even having a rib-to-rim glue joint. I guess I put a little glue in there just to perhaps prevent a buzz or something....

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Original Message:
Sent: 05-05-2020 10:33
From: Karl Roeder
Subject: Weight of Soundboard Assembly

Mr. Farrell,
I'll see your "engineering challenged" and raise you a "completely innumerate". That not withstanding try this experiment: Take a board and rib and bridge assembly to the rim and pre-load it without clamping it to the rim. Measure for setting the bearing. Un-load the system and clamp it down to the rim firmly.
Take your bearing measurements again. Compare your numbers.
In my shop we set the bearing with the bridge glued to the crowned panel and I learned how different the measurement were in the above scenario by mistake. Expensive lesson but informative.


------------------------------
Karl Roeder
Pompano Beach FL

Original Message:
Sent: 05-05-2020 10:15
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Nick G. responded: "So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests."

Actually, my thinking that a good (well designed) unsupported soundboard would not go flat with applied downbearing force was even without bridges. I'll throw out early that I'm not trying to be argumentative (as some might tend to think), but rather trying to understand. Being somewhat math and engineering challenged, it seems to me that a common (low treble to bass) arc length of an unloaded board with a 60-foot radius might be 30" (just a random example). Loaded to the point where it is flat, the rib tip-to-tip length of that arc (now a cord of the original circle) would increase by about 0.002 inches (assuming no compression of the spruce or pine rib). I do wish that I could do the engineering and math - but I can't (hey, even Clint Eastwood said that "A man's gotta know his limitations.") (I think Ron Nossaman made a presentation of this in one of the PTG Journals some years ago - anyone  know which issue?). But between rim deflection and rib compression, you only need that 0.002 inches. I sure know that even spruce doesn't compress much along the grain, nor does a heavy, thick hard maple rim deflect much - and 50 pounds (or whatever it might be) of downbearing on a rib will produce A LOT of pressure against a rim if one considers the unloaded soundboard as an arc. But gosh, two-thousandths of an inch (or more!) of movement/compression isn't hard to imagine. I remember years ago when I last read Ron's article, it sure made sense to me. Is that your argument - the the unloaded board functions as an arch and the rim prevents the arch from collapsing?

Again, my point is not to dredge up old arguments, but rather to try to understand.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-04-2020 17:25
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

I was thinking of the board without the bridges, since that was Fenton's first request as to weight. A bridge adds a significant stiffness and bending resistance to downbearing, in which case I might have said,  "such a structure, independent of attachment to the rim and beam foundations, would not adequately withstand the force of downbearing."

So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests.

I did a workup on this some years ago which I will now revisit. I might be able to supply some quantification here.

In any case, the larger point I was making is that such a relatively lightweight assembly, due to its paneling, cross ribbing, bridging and fixed attachment to a rigid structure is amazingly strong in resisting large downward forces. The S/B assembly should compress, but not flatten or reverse.

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

David,

At the risk of reveling myself as an idiot in the presence of laureates, I will admit being confused. 

I have been making modifications to soundboards for some time thanks to the help of much smarter
people than me with pretty satisfying results. I have theoretical ideas that they help quantify for me.
So much thanks to Nick G, Del F. Chris C, Dale E. to name a few for lending their expertise and insight,
along with all the folks that post here. 

You wrote regarding DB:

There are some very reputable builders who after setting up the piano go through and tweak the bearing in order to balance the impedance levels (in layman's terms balance the attack and sustain phase of the tonal envelope). Their claim to be able to accomplish that successfully. I always do the same thing once the piano is strung, stable, terminations cleaned up, preliminary voicing procedures gone through.

I am trying to wrap my addled brain around how this is done once the piano is strung (along with other late process items that may be actually changed by any DB modifications done). My guess is that I am missing something here. Maybe raising or lowering duplex height (or hitchpin loop height in the case of Baldwin grands) would yield infinitesimal changes to load, maybe enough to start choking by the effect of restricted movement of the bridge, but negligible on the speaking side. In the case where pinblock is attached to the case separate from the plate, it would mean pulling everything out, restringing the piano, probably with new pinblock, etc. 

Can you please explain how this is accomplished? I would so love to be able to see how much difference DB changes make after the board is loaded. 



------------------------------
Dave Conte
Owner
North Richland Hills TX
817-581-7321
------------------------------

Original Message:
Sent: 05-05-2020 11:19
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Thanks for the input Karl. I'm not sure I could really even do that, as I don't preload a board (bridge on or off) when measuring for downbearing/bridge-height. I know most folks do the pre-loading thing, but not having ever done it with any success, I really don't even know what that means (at least in my shop with my soundboards).

However, I have preloaded unrestrained and clamped-to-rim soundboards with target downbearing loads to measure rib deflection. I haven't observed much difference, and I've never collapsed one.

When I do take my measurements to set bridge height (and hence downbearing), I do firmly clamp soundboard in place on the rim (per Jim's concern - yes, yes, DAMHIK!!!). But I do that to be sure to be taking into account any soundboard deformation potentially caused by angular differentials between soundboard panel and rim. I don't give any special treatment to the rib-to-rim joint - in fact I put zero effort into even having a rib-to-rim glue joint. I guess I put a little glue in there just to perhaps prevent a buzz or something....

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-05-2020 10:33
From: Karl Roeder
Subject: Weight of Soundboard Assembly

Mr. Farrell,
I'll see your "engineering challenged" and raise you a "completely innumerate". That not withstanding try this experiment: Take a board and rib and bridge assembly to the rim and pre-load it without clamping it to the rim. Measure for setting the bearing. Un-load the system and clamp it down to the rim firmly.
Take your bearing measurements again. Compare your numbers.
In my shop we set the bearing with the bridge glued to the crowned panel and I learned how different the measurement were in the above scenario by mistake. Expensive lesson but informative.


------------------------------
Karl Roeder
Pompano Beach FL

Original Message:
Sent: 05-05-2020 10:15
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Nick G. responded: "So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests."

Actually, my thinking that a good (well designed) unsupported soundboard would not go flat with applied downbearing force was even without bridges. I'll throw out early that I'm not trying to be argumentative (as some might tend to think), but rather trying to understand. Being somewhat math and engineering challenged, it seems to me that a common (low treble to bass) arc length of an unloaded board with a 60-foot radius might be 30" (just a random example). Loaded to the point where it is flat, the rib tip-to-tip length of that arc (now a cord of the original circle) would increase by about 0.002 inches (assuming no compression of the spruce or pine rib). I do wish that I could do the engineering and math - but I can't (hey, even Clint Eastwood said that "A man's gotta know his limitations.") (I think Ron Nossaman made a presentation of this in one of the PTG Journals some years ago - anyone  know which issue?). But between rim deflection and rib compression, you only need that 0.002 inches. I sure know that even spruce doesn't compress much along the grain, nor does a heavy, thick hard maple rim deflect much - and 50 pounds (or whatever it might be) of downbearing on a rib will produce A LOT of pressure against a rim if one considers the unloaded soundboard as an arc. But gosh, two-thousandths of an inch (or more!) of movement/compression isn't hard to imagine. I remember years ago when I last read Ron's article, it sure made sense to me. Is that your argument - the the unloaded board functions as an arch and the rim prevents the arch from collapsing?

Again, my point is not to dredge up old arguments, but rather to try to understand.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-04-2020 17:25
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

I was thinking of the board without the bridges, since that was Fenton's first request as to weight. A bridge adds a significant stiffness and bending resistance to downbearing, in which case I might have said,  "such a structure, independent of attachment to the rim and beam foundations, would not adequately withstand the force of downbearing."

So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests.

I did a workup on this some years ago which I will now revisit. I might be able to supply some quantification here.

In any case, the larger point I was making is that such a relatively lightweight assembly, due to its paneling, cross ribbing, bridging and fixed attachment to a rigid structure is amazingly strong in resisting large downward forces. The S/B assembly should compress, but not flatten or reverse.

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Dave

Steinway and others adjust the bearing by using nose bolts to flex the plate slightly.  It's not unusual when tearing down a Steinway to find that the player has been flexed.  Of course there are limits and one needs to proceed with caution. 

I (and many others) install WNG adjustable perimeter bolts, or a similar system, which allows you to change the plate elevation easily even when the piano is strung and at tension.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 11:18
From: Dave Conte
Subject: Weight of Soundboard Assembly

David,

At the risk of reveling myself as an idiot in the presence of laureates, I will admit being confused.

I have been making modifications to soundboards for some time thanks to the help of much smarter
people than me with pretty satisfying results. I have theoretical ideas that they help quantify for me.
So much thanks to Nick G, Del F. Chris C, Dale E. to name a few for lending their expertise and insight,
along with all the folks that post here.

You wrote regarding DB:

There are some very reputable builders who after setting up the piano go through and tweak the bearing in order to balance the impedance levels (in layman's terms balance the attack and sustain phase of the tonal envelope). Their claim to be able to accomplish that successfully. I always do the same thing once the piano is strung, stable, terminations cleaned up, preliminary voicing procedures gone through.

I am trying to wrap my addled brain around how this is done once the piano is strung (along with other late process items that may be actually changed by any DB modifications done). My guess is that I am missing something here. Maybe raising or lowering duplex height (or hitchpin loop height in the case of Baldwin grands) would yield infinitesimal changes to load, maybe enough to start choking by the effect of restricted movement of the bridge, but negligible on the speaking side. In the case where pinblock is attached to the case separate from the plate, it would mean pulling everything out, restringing the piano, probably with new pinblock, etc.

Can you please explain how this is accomplished? I would so love to be able to see how much difference DB changes make after the board is loaded.



------------------------------
Dave Conte
Owner
North Richland Hills TX
817-581-7321

Original Message:
Sent: 05-05-2020 11:19
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Thanks for the input Karl. I'm not sure I could really even do that, as I don't preload a board (bridge on or off) when measuring for downbearing/bridge-height. I know most folks do the pre-loading thing, but not having ever done it with any success, I really don't even know what that means (at least in my shop with my soundboards).

However, I have preloaded unrestrained and clamped-to-rim soundboards with target downbearing loads to measure rib deflection. I haven't observed much difference, and I've never collapsed one.

When I do take my measurements to set bridge height (and hence downbearing), I do firmly clamp soundboard in place on the rim (per Jim's concern - yes, yes, DAMHIK!!!). But I do that to be sure to be taking into account any soundboard deformation potentially caused by angular differentials between soundboard panel and rim. I don't give any special treatment to the rib-to-rim joint - in fact I put zero effort into even having a rib-to-rim glue joint. I guess I put a little glue in there just to perhaps prevent a buzz or something....

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-05-2020 10:33
From: Karl Roeder
Subject: Weight of Soundboard Assembly

Mr. Farrell,
I'll see your "engineering challenged" and raise you a "completely innumerate". That not withstanding try this experiment: Take a board and rib and bridge assembly to the rim and pre-load it without clamping it to the rim. Measure for setting the bearing. Un-load the system and clamp it down to the rim firmly.
Take your bearing measurements again. Compare your numbers.
In my shop we set the bearing with the bridge glued to the crowned panel and I learned how different the measurement were in the above scenario by mistake. Expensive lesson but informative.


------------------------------
Karl Roeder
Pompano Beach FL

Original Message:
Sent: 05-05-2020 10:15
From: Terrence Farrell
Subject: Weight of Soundboard Assembly

Nick G. responded: "So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests."

Actually, my thinking that a good (well designed) unsupported soundboard would not go flat with applied downbearing force was even without bridges. I'll throw out early that I'm not trying to be argumentative (as some might tend to think), but rather trying to understand. Being somewhat math and engineering challenged, it seems to me that a common (low treble to bass) arc length of an unloaded board with a 60-foot radius might be 30" (just a random example). Loaded to the point where it is flat, the rib tip-to-tip length of that arc (now a cord of the original circle) would increase by about 0.002 inches (assuming no compression of the spruce or pine rib). I do wish that I could do the engineering and math - but I can't (hey, even Clint Eastwood said that "A man's gotta know his limitations.") (I think Ron Nossaman made a presentation of this in one of the PTG Journals some years ago - anyone  know which issue?). But between rim deflection and rib compression, you only need that 0.002 inches. I sure know that even spruce doesn't compress much along the grain, nor does a heavy, thick hard maple rim deflect much - and 50 pounds (or whatever it might be) of downbearing on a rib will produce A LOT of pressure against a rim if one considers the unloaded soundboard as an arc. But gosh, two-thousandths of an inch (or more!) of movement/compression isn't hard to imagine. I remember years ago when I last read Ron's article, it sure made sense to me. Is that your argument - the the unloaded board functions as an arch and the rim prevents the arch from collapsing?

Again, my point is not to dredge up old arguments, but rather to try to understand.

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505

Original Message:
Sent: 05-04-2020 17:25
From: Nicholas Gravagne
Subject: Weight of Soundboard Assembly

I was thinking of the board without the bridges, since that was Fenton's first request as to weight. A bridge adds a significant stiffness and bending resistance to downbearing, in which case I might have said,  "such a structure, independent of attachment to the rim and beam foundations, would not adequately withstand the force of downbearing."

So, then, given a bridge on the board, an extrapolation of my thought suggests setting the completed assembly onto the rim, but without gluing it down or fastening it in any way. Then imagine 500 to 900 lbs applied evenly along the length of the long bridge. Central area deflections would be great due to the unfastened rib ends (rib ends require fastening referred to as "fixed" and not "free"). Such large deflections would wipe out the downbearing gaps as set on a new bridge with gage blocks and fish line tests.

I did a workup on this some years ago which I will now revisit. I might be able to supply some quantification here.

In any case, the larger point I was making is that such a relatively lightweight assembly, due to its paneling, cross ribbing, bridging and fixed attachment to a rigid structure is amazingly strong in resisting large downward forces. The S/B assembly should compress, but not flatten or reverse.

Original Message------

Nick G. wrote regarding a piano soundboard: "These structures are relatively lightweight, and independent of attachment to the rim and beam foundations, could never withstand the force of down bearing."

When you refer to "structures" I presume you are referring to a piano soundboard. I don't understand what you are suggesting that the rim and beam foundation does. I do realize that the soundboard has to set on something - otherwise it will just fall onto the floor! But certainly a soundboard setting unattached (except for gravity) on a large table can have the typical 500 or so pounds of downbearing applied to the bridges and the soundboard won't collapse - or at least is certainly shouldn't. Am I missing something?

------------------------------
Terry Farrell
Farrell Piano Service, Inc.
Brandon, Florida
terry@farrellpiano.com
813-684-3505
------------------------------

Original Message------

Dave

Steinway and others adjust the bearing by using nose bolts to flex the plate slightly.  It's not unusual when tearing down a Steinway to find that the player has been flexed.  Of course there are limits and one needs to proceed with caution. 

I (and many others) install WNG adjustable perimeter bolts, or a similar system, which allows you to change the plate elevation easily even when the piano is strung and at tension.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 11:53
From: Dave Conte
Subject: Weight of Soundboard Assembly

David

...and I actually knew that because I do it myself. Hence the comment about

appearing to be an idiot with an addled brain. So much stress from dealing with

SARS-CoV2, COVID 19 as it relates to trying to pry the benefits everyone else 

seems to have gotten so easily. I couldn't remember a simple thing like that.  

Now I have egg on my face - but did learn something in the process.

Thank you.

Original Message------

Dave

Steinway and others adjust the bearing by using nose bolts to flex the plate slightly.  It's not unusual when tearing down a Steinway to find that the player has been flexed.  Of course there are limits and one needs to proceed with caution. 

I (and many others) install WNG adjustable perimeter bolts, or a similar system, which allows you to change the plate elevation easily even when the piano is strung and at tension.  

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.  

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 13:37
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Dave,

Thanks for your question of this great group.

I have a question for the list:

A model or perhaps I should say system set up I find on pianos, more often than not, that I love the sound of, Is as follows:

These are vintage pianos with maple rims, healthy crown, and very light loading.

The seams at odds with logic, it has been my new formula on the last couple pianos.

Comments?

Fenton

I'm having a heckuva time posting to the list on my phone, going through the thread in order, finding replies etc.

Not asking for help here just making excuses

Sent from my iPhone

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.  

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.  

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*  

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:    

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.  

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*  

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:    

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Hi Fenton

All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 19:44
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Yes David!

Your your math pertaining to the Lowell gauge and free space under a string restated what at least I meant to say or very nearly so so we're in agreement.

I'm not sure what .003 for every mark on the low gauge means, but you said three marks is 1/2 a degree. Close enough if 3/16 is one mark then three marks is 9/16 of 1°. Like I could hit a 16th of a degree anyway.

Look for others to answer your four questions since I've already addressed them

Sent from my iPhone

Original Message------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Thank you David,
"All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree."
Not sure where I got 3/16 * for one mark, I think the late Ron N., God bless him. In any case this would have been just slightly more than 1/6.
Thanks for the trig lesson which I totally get after some Googleing.  Very enlightening.
As for where to measure from to determine back scale, center of unison? Same for downbearing with thread for preset bearing?

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton
------------------------------

Original Message:
Sent: 05-09-2020 22:08
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton

All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 19:44
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Yes David!

Your your math pertaining to the Lowell gauge and free space under a string restated what at least I meant to say or very nearly so so we're in agreement.

I'm not sure what .003 for every mark on the low gauge means, but you said three marks is 1/2 a degree. Close enough if 3/16 is one mark then three marks is 9/16 of 1°. Like I could hit a 16th of a degree anyway.

Look for others to answer your four questions since I've already addressed them

Sent from my iPhone

Original Message------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

why in heavens name do people use these Lowell gages instead of a digital angle gauge?    

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Original Message:
Sent: 05-10-2020 13:11
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Thank you David,
"All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree."
Not sure where I got 3/16 * for one mark, I think the late Ron N., God bless him. In any case this would have been just slightly more than 1/6.
Thanks for the trig lesson which I totally get after some Googleing.  Very enlightening.
As for where to measure from to determine back scale, center of unison? Same for downbearing with thread for preset bearing?

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-09-2020 22:08
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton

All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 19:44
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Yes David!

Your your math pertaining to the Lowell gauge and free space under a string restated what at least I meant to say or very nearly so so we're in agreement.

I'm not sure what .003 for every mark on the low gauge means, but you said three marks is 1/2 a degree. Close enough if 3/16 is one mark then three marks is 9/16 of 1°. Like I could hit a 16th of a degree anyway.

Look for others to answer your four questions since I've already addressed them

Sent from my iPhone

Original Message------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Because it's there.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-10-2020 15:07
From: Jim Ialeggio
Subject: Weight of Soundboard Assembly

why in heavens name do people use these Lowell gages instead of a digital angle gauge?    

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026

Original Message:
Sent: 05-10-2020 13:11
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Thank you David,
"All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree."
Not sure where I got 3/16 * for one mark, I think the late Ron N., God bless him. In any case this would have been just slightly more than 1/6.
Thanks for the trig lesson which I totally get after some Googleing.  Very enlightening.
As for where to measure from to determine back scale, center of unison? Same for downbearing with thread for preset bearing?

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-09-2020 22:08
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton

All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 19:44
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Yes David!

Your your math pertaining to the Lowell gauge and free space under a string restated what at least I meant to say or very nearly so so we're in agreement.

I'm not sure what .003 for every mark on the low gauge means, but you said three marks is 1/2 a degree. Close enough if 3/16 is one mark then three marks is 9/16 of 1°. Like I could hit a 16th of a degree anyway.

Look for others to answer your four questions since I've already addressed them

Sent from my iPhone

Original Message------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

Because it's there.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Speaking for myself I use it because it’s in my drawer
I’m certainly going to look into your recommendation
Is this Wixey a brand and model you’d recommend?

Sent from my iPhone


Original Message------

why in heavens name do people use these Lowell gages instead of a digital angle gauge?    

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Wixey is what I own. There are others out there, all about $39-ish.  I don't think it matters which one, they all probably use the same internal bits. Make a little bass for it and some 1/8 brass rod legs to mimic whatever you are doing with the Lowell gage. Made my base out of scrap in all of 5 minutes

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Original Message:
Sent: 05-10-2020 15:54
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Speaking for myself I use it because it's in my drawer
I'm certainly going to look into your recommendation
Is this Wixey a brand and model you'd recommend?

Sent from my iPhone


Original Message------

why in heavens name do people use these Lowell gages instead of a digital angle gauge?    

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Every smart phone has a measure app, that can also be used as a level bubble.

https://support.apple.com/en-lamr/HT208924
https://support.apple.com/en-gb/guide/iphone/iphbd435673d/ios

https://play.google.com/store/apps/details?id=com.gamma.bubblelevel&hl=us

------------------------------
Michiel van Loon
MEPPEL
The Netherlands
+31655150644
mvanloon@pianoman.nl
------------------------------

Original Message:
Sent: 05-11-2020 09:00
From: Jim Ialeggio
Subject: Weight of Soundboard Assembly

Wixey is what I own. There are others out there, all about $39-ish.  I don't think it matters which one, they all probably use the same internal bits. Make a little bass for it and some 1/8 brass rod legs to mimic whatever you are doing with the Lowell gage. Made my base out of scrap in all of 5 minutes

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026

Original Message:
Sent: 05-10-2020 15:54
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Speaking for myself I use it because it's in my drawer
I'm certainly going to look into your recommendation
Is this Wixey a brand and model you'd recommend?

Sent from my iPhone


Original Message------

why in heavens name do people use these Lowell gages instead of a digital angle gauge?    

------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------

Fenton wrote:

"As for where to measure from to determine back scale, center of unison? Same for downbearing with thread for preset bearing?"


That's a good question.  I can't speak for others but when measuring for the preset bearing, I lower the string until it touches the bridge at the point where the front bridge pin array is or would be.  That's more a matter of practicality.  It's true that if you were to lower the string until it touched the rear bridge pin line that the preset bearing would be less since the string would have to lower more.  In a perfect world the bridge contact point would be a peak on the bridge, such as you might get with a bridge agraffe, rather than a flat spot.   If that flat spot (the bridge cap) is sloped front to back, for example, that would yield a different residual bearing measurements at the front and the back than if the bridge cap were flat or, for that matter, sloped back to front.  Similarly if you do this on an unnotched bridge and lower the string until it touches the front of the unnotched bridge the preset bearing will be greater. 

When measuring the backscale I usually do it by section and just take an average since the backscale length is not uniform from note to note, especially where there's an duplex aliquot or even a staggered, vertical hitch pin array.

All the more reason to install adjustable perimeter bolts so you can tweak things after.  The other reason to install those is that board deflections may not be exactly as you precalculated.  Often they are pretty close if you're using a reliable method, but rarely are they exact.  So, again, the ability to change that some after the fact is a plus. 

Now I should add that I precalculate the thickness of the bridge cap before I make them using the the lowered string method, a gauge that sets on the string rest that represents the distance gap I want at the string rest for my preset bearing target, and a calibrated wedge that slips under the strings on the bridge root.  The wedge has markings on it to tell me the thickness at any given point and the width of the wedge is the same as the distance between the typical front to back bridge pin rows.  Once I determine the thickness that the bridge cap needs to be for each section (I usually take those measurements about every 6" in case the thickness of the cap is not uniform or is tapered (as it often is), then I make the bridge caps my predetermined thickness plus a mm and sand to the final height.  I can check that as I go by first measuring the height of the bridge body, adding the cap thickness and then measure to the top of the cap from the panel as I'm sanding. 

I just find that easier than putting on an extra thick bridge cap and trying to plane it to the correct height.  Usually I cut and glue on the bridge caps with the panel assembly already glued into the rim.  The bridge caps are trimmed flush to the bridge root using a flush trim router bit.  Once everything is cut and glued on and notched I check the bearing measurements again.  I can then make micro adjustments with the perimeter and nose bolts prior to stringing.  Once strung and pulled to tension and with the board stabilized at 40-50% RH I check the bearing again and correct as needed. 

Probably not a good method if you prefer to finish the board before gluing it in.  I do finish the bottom, of course, but finish the top after everything is done.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-10-2020 13:11
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Thank you David,
"All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree."
Not sure where I got 3/16 * for one mark, I think the late Ron N., God bless him. In any case this would have been just slightly more than 1/6.
Thanks for the trig lesson which I totally get after some Googleing.  Very enlightening.
As for where to measure from to determine back scale, center of unison? Same for downbearing with thread for preset bearing?

------------------------------
S. Fenton Murray
Royal Oaks CA

S. Fenton

Original Message:
Sent: 05-09-2020 22:08
From: David Love
Subject: Weight of Soundboard Assembly

Hi Fenton

All it means is that if .018  (rounding off) is the sine of 1 degree, then .003 is the sine of 1/6th of one degree.  So three marks is actually equal to 9/18  or 1/2 of one degree.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 19:44
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Yes David!

Your your math pertaining to the Lowell gauge and free space under a string restated what at least I meant to say or very nearly so so we're in agreement.

I'm not sure what .003 for every mark on the low gauge means, but you said three marks is 1/2 a degree. Close enough if 3/16 is one mark then three marks is 9/16 of 1°. Like I could hit a 16th of a degree anyway.

Look for others to answer your four questions since I've already addressed them

Sent from my iPhone

Original Message------

Edit:  *Correction on the final equation conversion of inches to mm's:

So on the Lowell gauge every mark is .003  so three marks (.009) is ~1/2 degree.  The total residual bearing will be a the sum of the front and back bearing.  So for a total residual bearing of 1 degree you would need 6 marks combined front and back.

That's different than calculating how high a stretched string should be over the rear string rest when it is lowered from the front until it just touches the bridge top.  In that case, let's say you wanted 2 degrees of bearing to start with before downbearing compression (which I'll call the "preset bearing") then you would calculate that distance as .0175 (which is the sin of 1 degree) x the length of the backscale x 2 (since you want two degrees).  So if you have 3" of backscale then the height of the string over the rear string rest when a string is stretched and lowered until it just touches the bridge top would be 3" x .0175 x 2 = .105".  That would be pretty typical of the mid treble.  Down lower in the tenor where you have a 6" backscale then that distance would be double that or .21".  If you work in mm's then just substitute mms for inches and your answer will be in mms.  Our last equation converting 6" to 152.4 mm's would read 152.4 mm x .0175 x 2 = 5.334 mms.*

Once the piano is pulled to pitch then you would measure the residual bearing by using the Lowell gauge to measure both front and back bearing and sum those two.

There are other questions related to this:

1. At how many degrees should preset bearing be set?
2. Should the preset bearing be uniform through the scale or should it graduate?
3. How much residual bearing should there be in each section?
4. When calculating the load for rib calculations should you use the preset bearing or the residual bearing since the residual bearing represents the final load on the board.  

And I'm sure there are other questions as well.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320

Original Message:
Sent: 05-09-2020 15:46
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

Hi David thanks for your response,

I would like to end up with perhaps a third of a degree in the bass to about 1 degree in the treble.

I'm cutting bridge height to give me about 30% more than that,  expecting to lose it as tension as applied.

I definitely could've kept more detailed notes on what I lose during stringing but this doesn't seem to be too far off.

The board is much stiffer in the treble but there's more of a load on those ribs.

I would love to hear comments on this.

I pull a string and read the gap at the plate for cutting bridge ht.

I think it's .0175 for each 1 inch of back scale is 1°

After stringing I use the Lowell gauge which is 3/16 of a degree for each mark

I measure from the front bridge pin both for length of back scale and reading the gap.

Sent from my iPhone

Original Message------

I heavy rim should reduce energy bleed to the rim and I think when you compare that with, say, a Bosendorfer which has a heavier panel (thicker anyway--I've not analyzed a Bos rib scale), a very lightweight, spruce rim, you can hear tonal differences.  My taste preference seems to accord with lower tension scales, heavy dense rims and lightweight assemblies.  That's the Steinway model but others have that as well with some slight variations.   I think if you change any one of those components significantly you probably have to change others.  For example you wouldn't probably want a very lightweight assembly with a high tension scale.  If so you would certainly want to back off on the bearing.  The Bos model seems to be high tension scale, lightweight rim, heavier soundboard assembly.

What do you mean by "light loading" in terms of numbers?

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

Fenton wrote:

"As for where to measure from to determine back scale, center of unison? Same for downbearing with thread for preset bearing?"


That's a good question.  I can't speak for others but when measuring for the preset bearing, I lower the string until it touches the bridge at the point where the front bridge pin array is or would be.  That's more a matter of practicality.  It's true that if you were to lower the string until it touched the rear bridge pin line that the preset bearing would be less since the string would have to lower more.  In a perfect world the bridge contact point would be a peak on the bridge, such as you might get with a bridge agraffe, rather than a flat spot.   If that flat spot (the bridge cap) is sloped front to back, for example, that would yield a different residual bearing measurements at the front and the back than if the bridge cap were flat or, for that matter, sloped back to front.  Similarly if you do this on an unnotched bridge and lower the string until it touches the front of the unnotched bridge the preset bearing will be greater. 

When measuring the backscale I usually do it by section and just take an average since the backscale length is not uniform from note to note, especially where there's an duplex aliquot or even a staggered, vertical hitch pin array.

All the more reason to install adjustable perimeter bolts so you can tweak things after.  The other reason to install those is that board deflections may not be exactly as you precalculated.  Often they are pretty close if you're using a reliable method, but rarely are they exact.  So, again, the ability to change that some after the fact is a plus. 

Now I should add that I precalculate the thickness of the bridge cap before I make them using the the lowered string method, a gauge that sets on the string rest that represents the distance gap I want at the string rest for my preset bearing target, and a calibrated wedge that slips under the strings on the bridge root.  The wedge has markings on it to tell me the thickness at any given point and the width of the wedge is the same as the distance between the typical front to back bridge pin rows.  Once I determine the thickness that the bridge cap needs to be for each section (I usually take those measurements about every 6" in case the thickness of the cap is not uniform or is tapered (as it often is), then I make the bridge caps my predetermined thickness plus a mm and sand to the final height.  I can check that as I go by first measuring the height of the bridge body, adding the cap thickness and then measure to the top of the cap from the panel as I'm sanding. 

I just find that easier than putting on an extra thick bridge cap and trying to plane it to the correct height.  Usually I cut and glue on the bridge caps with the panel assembly already glued into the rim.  The bridge caps are trimmed flush to the bridge root using a flush trim router bit.  Once everything is cut and glued on and notched I check the bearing measurements again.  I can then make micro adjustments with the perimeter and nose bolts prior to stringing.  Once strung and pulled to tension and with the board stabilized at 40-50% RH I check the bearing again and correct as needed. 

Probably not a good method if you prefer to finish the board before gluing it in.  I do finish the bottom, of course, but finish the top after everything is done.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

David Said,
"Downbearing compresses the soundboard spring, the assembly gets stiffer, the impedance increases and sustain increases."

I disagree with part of this. I'm not convinced that the board is getting stiffer by adding a load on top. Its stiff as it can get after compression has equalized. A load (mass) would be adding stress in the soundboard. To make the board stiffer you would add more ribs or make the panel thicker.  
I'm reminded of the video about mass and stiffness. They are discussing building oscillation, but i think the principle relates. 
https://www.youtube.com/watch?v=tB9XpE2Auaw

I'll also point to one of my chladni videos  https://www.youtube.com/watch?v=kdfrBX6fNMk at least you get live feedback from the board you are working on, regarding if the stiffness is in the ballpark of satisfactory.  In the treble the sand should go to the second strut area. Too high and the treble is too thin and adding a riblet may be called for. Too far away could indicate too much stiffness, so reducing panel thickness or rib height could be possible.  My computer software controls the stiffness of the rib scale  so that i never have problems in that area or the break.

The original question was about the weight of the soundboard. Weight is a very important factor and discussing things like impedance mismatching and filtering the harmonic spectrum don't help in the shop for making real time changes so that you can end up with a good product.  Steinways make their panels a little too thin in the treble and their ribs a little too tall and wide.  I found that their rib scale creates an uneven stiffness from bass to treble. This is mostly caused by two or three ribs (8,9,10) that don't fit with the rest of the ribs in scale. When these things are corrected I think they sound even better. I just installed a soundboard in a Behning 4'10" piano. The  original board weighed 15 lbs. That's a lot for a little board. I got it down to 10lbs. I found most boards (even steinways) have too much mass and weight can be reduced.  When i installed a much lighter than the original board in a Mason Hamlin AA, according to what I am hearing from others here, i should have an overpowering impedance disaster of a piano. Nope. I was a little worried about it going into a small practice room though. But I played on it a year later and those Ronsens sure are nice when they break in.

I use perimeter bolts on Steinways (or should i say impedance adjustment bolts), but try to avoid at all costs to adjust nosebolts to flex the plate. Frankly, too risky for me. I prefer to get the bridge height correct and not mess with it. 

-chris










------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
------------------------------

Original Message:
Sent: 05-09-2020 13:39
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'd also like to add that I've use the WNG plate support system on the last four or five pianos. I did not mind the acoustic dowel system, but it prevented fine-tuning of bearing.

Do any of you feel that something is lost in terms of tone by eliminating the acoustic dowel system?

Sent from my iPhone

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Well, the board functions like a spring.  It's either linear or non-linear.  If it's linear then it's not getting stiffer as it compresses, the relationship between force and displacement remains constant.  If it's non-linear then as force increases displacement decreases.  Soundboards are non-linear.  


You are right that the discussion has wandered from the original question of how much does a soundboard weigh.  I wouldn't say that reducing mass would make for an impedance disaster based on what we have been discussing.  Since much of the impedance derives from stiffness you can certainly have lighter weight board that is stiffer.  Simply changing the h/w relationship between the ribs allows you to reduce mass and add stiffness.  Ribs that are taller than they are wide will require less mass to achieve the same stiffness than ribs that are wider than they are tall because of the ^3 relationship between height and width in terms of load bearing properties.  Using different species of wood, or different materials altogether, can also make a difference.  I suppose it depends on how much mass you are talking about.   

I would be curious as to where you took off 1/3 of the weight from your structures.  Going from 15 lbs to 10 lbs is quite a lot.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 17:53
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

David Said,
"Downbearing compresses the soundboard spring, the assembly gets stiffer, the impedance increases and sustain increases."

I disagree with part of this. I'm not convinced that the board is getting stiffer by adding a load on top. Its stiff as it can get after compression has equalized. A load (mass) would be adding stress in the soundboard. To make the board stiffer you would add more ribs or make the panel thicker.
I'm reminded of the video about mass and stiffness. They are discussing building oscillation, but i think the principle relates.
https://www.youtube.com/watch?v=tB9XpE2Auaw

I'll also point to one of my chladni videos  https://www.youtube.com/watch?v=kdfrBX6fNMk at least you get live feedback from the board you are working on, regarding if the stiffness is in the ballpark of satisfactory.  In the treble the sand should go to the second strut area. Too high and the treble is too thin and adding a riblet may be called for. Too far away could indicate too much stiffness, so reducing panel thickness or rib height could be possible.  My computer software controls the stiffness of the rib scale  so that i never have problems in that area or the break.

The original question was about the weight of the soundboard. Weight is a very important factor and discussing things like impedance mismatching and filtering the harmonic spectrum don't help in the shop for making real time changes so that you can end up with a good product.  Steinways make their panels a little too thin in the treble and their ribs a little too tall and wide.  I found that their rib scale creates an uneven stiffness from bass to treble. This is mostly caused by two or three ribs (8,9,10) that don't fit with the rest of the ribs in scale. When these things are corrected I think they sound even better. I just installed a soundboard in a Behning 4'10" piano. The  original board weighed 15 lbs. That's a lot for a little board. I got it down to 10lbs. I found most boards (even steinways) have too much mass and weight can be reduced.  When i installed a much lighter than the original board in a Mason Hamlin AA, according to what I am hearing from others here, i should have an overpowering impedance disaster of a piano. Nope. I was a little worried about it going into a small practice room though. But I played on it a year later and those Ronsens sure are nice when they break in.

I use perimeter bolts on Steinways (or should i say impedance adjustment bolts), but try to avoid at all costs to adjust nosebolts to flex the plate. Frankly, too risky for me. I prefer to get the bridge height correct and not mess with it.

-chris










------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-09-2020 13:39
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'd also like to add that I've use the WNG plate support system on the last four or five pianos. I did not mind the acoustic dowel system, but it prevented fine-tuning of bearing.

Do any of you feel that something is lost in terms of tone by eliminating the acoustic dowel system?

Sent from my iPhone

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

Well, the board functions like a spring.  It's either linear or non-linear.  If it's linear then it's not getting stiffer as it compresses, the relationship between force and displacement remains constant.  If it's non-linear then as force increases displacement decreases.  Soundboards are non-linear.  

You are right that the discussion has wandered from the original question of how much does a soundboard weigh.  I wouldn't say that reducing mass would make for an impedance disaster based on what we have been discussing.  Since much of the impedance derives from stiffness you can certainly have lighter weight board that is stiffer.  Simply changing the h/w relationship between the ribs allows you to reduce mass and add stiffness.  Ribs that are taller than they are wide will require less mass to achieve the same stiffness than ribs that are wider than they are tall because of the ^3 relationship between height and width in terms of load bearing properties.  Using different species of wood, or different materials altogether, can also make a difference.  I suppose it depends on how much mass you are talking about.   

I would be curious as to where you took off 1/3 of the weight from your structures.  Going from 15 lbs to 10 lbs is quite a lot.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message------

Well, the board functions like a spring.  It's either linear or non-linear.  If it's linear then it's not getting stiffer as it compresses, the relationship between force and displacement remains constant.  If it's non-linear then as force increases displacement decreases.  Soundboards are non-linear.  

You are right that the discussion has wandered from the original question of how much does a soundboard weigh.  I wouldn't say that reducing mass would make for an impedance disaster based on what we have been discussing.  Since much of the impedance derives from stiffness you can certainly have lighter weight board that is stiffer.  Simply changing the h/w relationship between the ribs allows you to reduce mass and add stiffness.  Ribs that are taller than they are wide will require less mass to achieve the same stiffness than ribs that are wider than they are tall because of the ^3 relationship between height and width in terms of load bearing properties.  Using different species of wood, or different materials altogether, can also make a difference.  I suppose it depends on how much mass you are talking about.   

I would be curious as to where you took off 1/3 of the weight from your structures.  Going from 15 lbs to 10 lbs is quite a lot.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

I think it's reasonable to expect that precise predictions about deflection and residual bearing are difficult at best.  Having the option to tweak the bearing after, I consider nothing but a plus.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Original Message:
Sent: 05-09-2020 20:21
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'll admit I'm not good enough to set bridge height without having options like plate adjustments later

Sent from my iPhone

Original Message------

Well, the board functions like a spring.  It's either linear or non-linear.  If it's linear then it's not getting stiffer as it compresses, the relationship between force and displacement remains constant.  If it's non-linear then as force increases displacement decreases.  Soundboards are non-linear.

You are right that the discussion has wandered from the original question of how much does a soundboard weigh.  I wouldn't say that reducing mass would make for an impedance disaster based on what we have been discussing.  Since much of the impedance derives from stiffness you can certainly have lighter weight board that is stiffer.  Simply changing the h/w relationship between the ribs allows you to reduce mass and add stiffness.  Ribs that are taller than they are wide will require less mass to achieve the same stiffness than ribs that are wider than they are tall because of the ^3 relationship between height and width in terms of load bearing properties.  Using different species of wood, or different materials altogether, can also make a difference.  I suppose it depends on how much mass you are talking about.

I would be curious as to where you took off 1/3 of the weight from your structures.  Going from 15 lbs to 10 lbs is quite a lot.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Ok Chris, you installed a lighter soundboard, meaning less impedance (right?), and some would have predicted an overpowering impedance disaster.
I'm trying to learn something basic here. Generally speaking does less impedance mean more power but maybe less ability to play at low volume and does more impedance generally equate to more sustain, bloom, singing quality, but less power?

Thanks,
John

------------------------------
John Pope
University of Kentucky School of Music
Lexington, KY
------------------------------

Original Message:
Sent: 05-09-2020 17:53
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

David Said,
"Downbearing compresses the soundboard spring, the assembly gets stiffer, the impedance increases and sustain increases."

I disagree with part of this. I'm not convinced that the board is getting stiffer by adding a load on top. Its stiff as it can get after compression has equalized. A load (mass) would be adding stress in the soundboard. To make the board stiffer you would add more ribs or make the panel thicker.
I'm reminded of the video about mass and stiffness. They are discussing building oscillation, but i think the principle relates.
https://www.youtube.com/watch?v=tB9XpE2Auaw

I'll also point to one of my chladni videos  https://www.youtube.com/watch?v=kdfrBX6fNMk at least you get live feedback from the board you are working on, regarding if the stiffness is in the ballpark of satisfactory.  In the treble the sand should go to the second strut area. Too high and the treble is too thin and adding a riblet may be called for. Too far away could indicate too much stiffness, so reducing panel thickness or rib height could be possible.  My computer software controls the stiffness of the rib scale  so that i never have problems in that area or the break.

The original question was about the weight of the soundboard. Weight is a very important factor and discussing things like impedance mismatching and filtering the harmonic spectrum don't help in the shop for making real time changes so that you can end up with a good product.  Steinways make their panels a little too thin in the treble and their ribs a little too tall and wide.  I found that their rib scale creates an uneven stiffness from bass to treble. This is mostly caused by two or three ribs (8,9,10) that don't fit with the rest of the ribs in scale. When these things are corrected I think they sound even better. I just installed a soundboard in a Behning 4'10" piano. The  original board weighed 15 lbs. That's a lot for a little board. I got it down to 10lbs. I found most boards (even steinways) have too much mass and weight can be reduced.  When i installed a much lighter than the original board in a Mason Hamlin AA, according to what I am hearing from others here, i should have an overpowering impedance disaster of a piano. Nope. I was a little worried about it going into a small practice room though. But I played on it a year later and those Ronsens sure are nice when they break in.

I use perimeter bolts on Steinways (or should i say impedance adjustment bolts), but try to avoid at all costs to adjust nosebolts to flex the plate. Frankly, too risky for me. I prefer to get the bridge height correct and not mess with it.

-chris










------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-09-2020 13:39
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'd also like to add that I've use the WNG plate support system on the last four or five pianos. I did not mind the acoustic dowel system, but it prevented fine-tuning of bearing.

Do any of you feel that something is lost in terms of tone by eliminating the acoustic dowel system?

Sent from my iPhone

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Now I see that my question is addressed by Nick way at the beginning of this thread! Nevermind folks. Thank you for all the input above.

------------------------------
John Pope
University of Kentucky School of Music
Lexington, KY
------------------------------

Original Message:
Sent: 05-13-2020 11:07
From: John Pope
Subject: Weight of Soundboard Assembly

Ok Chris, you installed a lighter soundboard, meaning less impedance (right?), and some would have predicted an overpowering impedance disaster.
I'm trying to learn something basic here. Generally speaking does less impedance mean more power but maybe less ability to play at low volume and does more impedance generally equate to more sustain, bloom, singing quality, but less power?

Thanks,
John

------------------------------
John Pope
University of Kentucky School of Music
Lexington, KY

Original Message:
Sent: 05-09-2020 17:53
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

David Said,
"Downbearing compresses the soundboard spring, the assembly gets stiffer, the impedance increases and sustain increases."

I disagree with part of this. I'm not convinced that the board is getting stiffer by adding a load on top. Its stiff as it can get after compression has equalized. A load (mass) would be adding stress in the soundboard. To make the board stiffer you would add more ribs or make the panel thicker.
I'm reminded of the video about mass and stiffness. They are discussing building oscillation, but i think the principle relates.
https://www.youtube.com/watch?v=tB9XpE2Auaw

I'll also point to one of my chladni videos  https://www.youtube.com/watch?v=kdfrBX6fNMk at least you get live feedback from the board you are working on, regarding if the stiffness is in the ballpark of satisfactory.  In the treble the sand should go to the second strut area. Too high and the treble is too thin and adding a riblet may be called for. Too far away could indicate too much stiffness, so reducing panel thickness or rib height could be possible.  My computer software controls the stiffness of the rib scale  so that i never have problems in that area or the break.

The original question was about the weight of the soundboard. Weight is a very important factor and discussing things like impedance mismatching and filtering the harmonic spectrum don't help in the shop for making real time changes so that you can end up with a good product.  Steinways make their panels a little too thin in the treble and their ribs a little too tall and wide.  I found that their rib scale creates an uneven stiffness from bass to treble. This is mostly caused by two or three ribs (8,9,10) that don't fit with the rest of the ribs in scale. When these things are corrected I think they sound even better. I just installed a soundboard in a Behning 4'10" piano. The  original board weighed 15 lbs. That's a lot for a little board. I got it down to 10lbs. I found most boards (even steinways) have too much mass and weight can be reduced.  When i installed a much lighter than the original board in a Mason Hamlin AA, according to what I am hearing from others here, i should have an overpowering impedance disaster of a piano. Nope. I was a little worried about it going into a small practice room though. But I played on it a year later and those Ronsens sure are nice when they break in.

I use perimeter bolts on Steinways (or should i say impedance adjustment bolts), but try to avoid at all costs to adjust nosebolts to flex the plate. Frankly, too risky for me. I prefer to get the bridge height correct and not mess with it.

-chris










------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-09-2020 13:39
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'd also like to add that I've use the WNG plate support system on the last four or five pianos. I did not mind the acoustic dowel system, but it prevented fine-tuning of bearing.

Do any of you feel that something is lost in terms of tone by eliminating the acoustic dowel system?

Sent from my iPhone

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------

Hi John,

Honestly the Impedance thing doesn't work for me. I don't think its an either or situation regarding volume or sustain. I guess according to the theory i should have plenty of volume and only a little sustain?? But that's not the case, i am getting oodles of both.

I think its a Timbre issue. Afterall, we have all heard a horrible singer. They can have plenty of volume and sustain, it just won't sound good. 

My idea was to maximize the strength to weight ratio, increase the soundboards amplitude when it vibrates so that it acts more like an opera singers beautiful voice. 
Excuse me  if that sounds cliche, but that's the way i think of it. I just go into the shop, and build it the best i can and make improvements when i see them.

I have put all my latest advancements in a Steinway A that I will be delivering to Bolling Green Ky in about 2 months. It has Ronsen Hammers and has an absolutely fabulous tone. Maybe you'll get to try it.

-chris

------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720
------------------------------

Original Message:
Sent: 05-13-2020 11:16
From: John Pope
Subject: Weight of Soundboard Assembly

Now I see that my question is addressed by Nick way at the beginning of this thread! Nevermind folks. Thank you for all the input above.

------------------------------
John Pope
University of Kentucky School of Music
Lexington, KY

Original Message:
Sent: 05-13-2020 11:07
From: John Pope
Subject: Weight of Soundboard Assembly

Ok Chris, you installed a lighter soundboard, meaning less impedance (right?), and some would have predicted an overpowering impedance disaster.
I'm trying to learn something basic here. Generally speaking does less impedance mean more power but maybe less ability to play at low volume and does more impedance generally equate to more sustain, bloom, singing quality, but less power?

Thanks,
John

------------------------------
John Pope
University of Kentucky School of Music
Lexington, KY

Original Message:
Sent: 05-09-2020 17:53
From: Chris Chernobieff
Subject: Weight of Soundboard Assembly

David Said,
"Downbearing compresses the soundboard spring, the assembly gets stiffer, the impedance increases and sustain increases."

I disagree with part of this. I'm not convinced that the board is getting stiffer by adding a load on top. Its stiff as it can get after compression has equalized. A load (mass) would be adding stress in the soundboard. To make the board stiffer you would add more ribs or make the panel thicker.
I'm reminded of the video about mass and stiffness. They are discussing building oscillation, but i think the principle relates.
https://www.youtube.com/watch?v=tB9XpE2Auaw

I'll also point to one of my chladni videos  https://www.youtube.com/watch?v=kdfrBX6fNMk at least you get live feedback from the board you are working on, regarding if the stiffness is in the ballpark of satisfactory.  In the treble the sand should go to the second strut area. Too high and the treble is too thin and adding a riblet may be called for. Too far away could indicate too much stiffness, so reducing panel thickness or rib height could be possible.  My computer software controls the stiffness of the rib scale  so that i never have problems in that area or the break.

The original question was about the weight of the soundboard. Weight is a very important factor and discussing things like impedance mismatching and filtering the harmonic spectrum don't help in the shop for making real time changes so that you can end up with a good product.  Steinways make their panels a little too thin in the treble and their ribs a little too tall and wide.  I found that their rib scale creates an uneven stiffness from bass to treble. This is mostly caused by two or three ribs (8,9,10) that don't fit with the rest of the ribs in scale. When these things are corrected I think they sound even better. I just installed a soundboard in a Behning 4'10" piano. The  original board weighed 15 lbs. That's a lot for a little board. I got it down to 10lbs. I found most boards (even steinways) have too much mass and weight can be reduced.  When i installed a much lighter than the original board in a Mason Hamlin AA, according to what I am hearing from others here, i should have an overpowering impedance disaster of a piano. Nope. I was a little worried about it going into a small practice room though. But I played on it a year later and those Ronsens sure are nice when they break in.

I use perimeter bolts on Steinways (or should i say impedance adjustment bolts), but try to avoid at all costs to adjust nosebolts to flex the plate. Frankly, too risky for me. I prefer to get the bridge height correct and not mess with it.

-chris










------------------------------
Chernobieff Piano Restorations
"Where Tone is Key"
chernobieffpiano.com
grandpianoman@protonmail.com
Lenoir City, TN
865-986-7720

Original Message:
Sent: 05-09-2020 13:39
From: S. Fenton Murray
Subject: Weight of Soundboard Assembly

I'd also like to add that I've use the WNG plate support system on the last four or five pianos. I did not mind the acoustic dowel system, but it prevented fine-tuning of bearing.

Do any of you feel that something is lost in terms of tone by eliminating the acoustic dowel system?

Sent from my iPhone

Original Message------

No problem. We're all operating in a time warp and perpetual fog. Strange times.

------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
------------------------------