Pianotech

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

On 8/30/2014 7:54 PM, Ed Sutton via Piano Technicians Guild wrote:

> Relative to previous discussions:
>
> How do the actions of the front duplex string segments (whatever
> those actions may be) become audible sound? What surface of the piano
> is moving to create sound waves, and how does the energy get
> transmitted to that (those) surface(s)?


Ed, you need to start reading the Journal and list postings, and
attending classes in this stuff.

Transverse string vibrations cross the capo by a rocking action,
activating a transverse vibration in the duplex. This vibration then
reflects back through the capo and into the speaking length. If there is
a low partial in the duplex that corresponds to one of the partials in
the speaking length it will reinforce that partial enough to be audible
by the same mechanism that lets you hear the speaking length tone(s).
This is much more likely from a long front duplex (say, 40mm), than it
is from a short duplex (say, 20mm), which is why short duplexes are
quiet. That's pretty much it. Though a very big deal is typically made
of it, invoking conversational molecules, intuition, and tiny pointy
tailed fire breathing demons, it's really extremely simple.

Next, someone will demand to have proof that transverse vibrations cross
capos. I discovered something fun many years ago playing around in the
shop plucking strings before a rebuild tear down. I lifted the damper of
a note in octave 6 and plucked the duplex. The resulting tone was the
fundamental of the speaking length, which I thought was pretty cool.
When I lifted the middle of the duplex segment, the speaking segment
just past the capo dipped down slightly as the string rocked on the
capo. This is exactly how transverse waves cross capos into the duplex.

There is still no documentation or demonstration that longitudinal waves
cross capos, but transverse waves most certainly to.

And Jim I, this is how long front duplexes rob energy from the speaking
length, as they move with a wider excursion, which takes more to drive them.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

Ron-

 Yep, done that myself.
How about the hissing sounds?
How about plinking the duplex when the damper is down?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------


Original Message:
Sent: 08-30-2014 21:49
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 8/30/2014 7:54 PM, Ed Sutton via Piano Technicians Guild wrote:

> Relative to previous discussions:
>
> How do the actions of the front duplex string segments (whatever
> those actions may be) become audible sound? What surface of the piano
> is moving to create sound waves, and how does the energy get
> transmitted to that (those) surface(s)?


Ed, you need to start reading the Journal and list postings, and
attending classes in this stuff.

Transverse string vibrations cross the capo by a rocking action,
activating a transverse vibration in the duplex. This vibration then
reflects back through the capo and into the speaking length. If there is
a low partial in the duplex that corresponds to one of the partials in
the speaking length it will reinforce that partial enough to be audible
by the same mechanism that lets you hear the speaking length tone(s).
This is much more likely from a long front duplex (say, 40mm), than it
is from a short duplex (say, 20mm), which is why short duplexes are
quiet. That's pretty much it. Though a very big deal is typically made
of it, invoking conversational molecules, intuition, and tiny pointy
tailed fire breathing demons, it's really extremely simple.

Next, someone will demand to have proof that transverse vibrations cross
capos. I discovered something fun many years ago playing around in the
shop plucking strings before a rebuild tear down. I lifted the damper of
a note in octave 6 and plucked the duplex. The resulting tone was the
fundamental of the speaking length, which I thought was pretty cool.
When I lifted the middle of the duplex segment, the speaking segment
just past the capo dipped down slightly as the string rocked on the
capo. This is exactly how transverse waves cross capos into the duplex.

There is still no documentation or demonstration that longitudinal waves
cross capos, but transverse waves most certainly to.

And Jim I, this is how long front duplexes rob energy from the speaking
length, as they move with a wider excursion, which takes more to drive them.
Ron N

With my Fully Tempered Duplex Scale, (FTDS), no duplex hissing is heard. Since the duplex rests are softer than the usual brass or cast iron rests, the increased damping must account for some of the effect. Also since FTDS has duplex ratios longer in the top treble and somewhat shorter than usual in the lower treble, the coupling arrangements are shifted. No allegorical creatures need apply.

-------------------------------------------
Edward McMorrow
Edmonds WA
425-299-3431
-------------------------------------------


Original Message:
Sent: 08-30-2014 23:17
From: Ed Sutton
Subject: Transmission of front duplex sound

Ron-

 Yep, done that myself.
How about the hissing sounds?
How about plinking the duplex when the damper is down?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------


Original Message:
Sent: 08-30-2014 21:49
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 8/30/2014 7:54 PM, Ed Sutton via Piano Technicians Guild wrote:

> Relative to previous discussions:
>
> How do the actions of the front duplex string segments (whatever
> those actions may be) become audible sound? What surface of the piano
> is moving to create sound waves, and how does the energy get
> transmitted to that (those) surface(s)?


Ed, you need to start reading the Journal and list postings, and
attending classes in this stuff.

Transverse string vibrations cross the capo by a rocking action,
activating a transverse vibration in the duplex. This vibration then
reflects back through the capo and into the speaking length. If there is
a low partial in the duplex that corresponds to one of the partials in
the speaking length it will reinforce that partial enough to be audible
by the same mechanism that lets you hear the speaking length tone(s).
This is much more likely from a long front duplex (say, 40mm), than it
is from a short duplex (say, 20mm), which is why short duplexes are
quiet. That's pretty much it. Though a very big deal is typically made
of it, invoking conversational molecules, intuition, and tiny pointy
tailed fire breathing demons, it's really extremely simple.

Next, someone will demand to have proof that transverse vibrations cross
capos. I discovered something fun many years ago playing around in the
shop plucking strings before a rebuild tear down. I lifted the damper of
a note in octave 6 and plucked the duplex. The resulting tone was the
fundamental of the speaking length, which I thought was pretty cool.
When I lifted the middle of the duplex segment, the speaking segment
just past the capo dipped down slightly as the string rocked on the
capo. This is exactly how transverse waves cross capos into the duplex.

There is still no documentation or demonstration that longitudinal waves
cross capos, but transverse waves most certainly to.

And Jim I, this is how long front duplexes rob energy from the speaking
length, as they move with a wider excursion, which takes more to drive them.
Ron N

Again, my question is, in the case of a standard front duplex with hissing, how does the hissing reach my ears? Is it transmitted through the wire, to the bridge and soundboard, is the wire capable of boving enough air to make a sound wave I can hear, or is the vibration transmitted to case or plate parts which create a sound wave? No hidden agenda here, just a naive question. ------------------------------------------- Ed Sutton Editor Piano Technicians Journal ed440@me.com 704-536-7926 -------------------------------------------
Original Message: Sent: 08-31-2014 00:20 From: Edward McMorrow Subject: Transmission of front duplex sound With my Fully Tempered Duplex Scale, (FTDS), no duplex hissing is heard. Since the duplex rests are softer than the usual brass or cast iron rests, the increased damping must account for some of the effect. Also since FTDS has duplex ratios longer in the top treble and somewhat shorter than usual in the lower treble, the coupling arrangements are shifted. No allegorical creatures need apply. ------------------------------------------- Edward McMorrow Edmonds WA 425-299-3431 -------------------------------------------
Original Message: Sent: 08-30-2014 23:17 From: Ed Sutton Subject: Transmission of front duplex sound Ron- Yep, done that myself. How about the hissing sounds? How about plinking the duplex when the damper is down? ------------------------------------------- Ed Sutton Editor Piano Technicians Journal ed440@me.com 704-536-7926 -------------------------------------------
Original Message: Sent: 08-30-2014 21:49 From: Ronald Nossaman Subject: Transmission of front duplex sound On 8/30/2014 7:54 PM, Ed Sutton via Piano Technicians Guild wrote: > Relative to previous discussions: > > How do the actions of the front duplex string segments (whatever > those actions may be) become audible sound? What surface of the piano > is moving to create sound waves, and how does the energy get > transmitted to that (those) surface(s)? Ed, you need to start reading the Journal and list postings, and attending classes in this stuff. Transverse string vibrations cross the capo by a rocking action, activating a transverse vibration in the duplex. This vibration then reflects back through the capo and into the speaking length. If there is a low partial in the duplex that corresponds to one of the partials in the speaking length it will reinforce that partial enough to be audible by the same mechanism that lets you hear the speaking length tone(s). This is much more likely from a long front duplex (say, 40mm), than it is from a short duplex (say, 20mm), which is why short duplexes are quiet. That's pretty much it. Though a very big deal is typically made of it, invoking conversational molecules, intuition, and tiny pointy tailed fire breathing demons, it's really extremely simple. Next, someone will demand to have proof that transverse vibrations cross capos. I discovered something fun many years ago playing around in the shop plucking strings before a rebuild tear down. I lifted the damper of a note in octave 6 and plucked the duplex. The resulting tone was the fundamental of the speaking length, which I thought was pretty cool. When I lifted the middle of the duplex segment, the speaking segment just past the capo dipped down slightly as the string rocked on the capo. This is exactly how transverse waves cross capos into the duplex. There is still no documentation or demonstration that longitudinal waves cross capos, but transverse waves most certainly to. And Jim I, this is how long front duplexes rob energy from the speaking length, as they move with a wider excursion, which takes more to drive them. Ron N

Ed:

I'm not sure this question is getting answered adequately but in my opinion the answer is of course the duplex can make noise without coupling back to the bridge and soundboard.  Soundboards don't do hissing and jangling noises very well.  Simply run your fingernail across the duplex with the speaking length muted and you will hear a fair bit of hissing and jangling.  There is no coupling back to the soundboard via the speaking length.  Longer duplexes, as pointed out, are more capable of making noises that are audible than shorter ones but noise certainly can come from the duplex directly.  

You see this problem not infrequently in so-called "high impedance systems" (meaning very stiff assemblies) where the energy can't dissipate through the soundboard quickly enough and effectively overloads the duplex area and it jangles.  Ron Overs reported this potential problem as has Del Fandrich and Ron Nossaman for that matter.  The solution proposed was to mass load the soundboard using brass weights under the bridge.  Added mass will help to absorb some of that energy, though both too stiff combined with mass loading will also reduce power.  Better to not build the board so stiff up there to begin with, IMO.  Shortening the duplex and detuning it will not necessarily solve the problem though it can help.   

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


Original Message:
Sent: 08-31-2014 08:39
From: Ed Sutton
Subject: Transmission of front duplex sound

Again, my question is, in the case of a standard front duplex with hissing, how does the hissing reach my ears?
Is it transmitted through the wire, to the bridge and soundboard, is the wire capable of moving enough air to make a sound wave I can hear, or is the vibration transmitted to case or plate parts which create a sound wave?
No hidden agenda here, just a naive question.

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

Ron,
What property of the wire allows the T-modes of the duplex segment and speaking length to couple together?

-------------------------------------------
Edward McMorrow
Edmonds WA
425-299-3431
-------------------------------------------


Original Message:
Sent: 08-30-2014 21:49
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 8/30/2014 7:54 PM, Ed Sutton via Piano Technicians Guild wrote:

> Relative to previous discussions:
>
> How do the actions of the front duplex string segments (whatever
> those actions may be) become audible sound? What surface of the piano
> is moving to create sound waves, and how does the energy get
> transmitted to that (those) surface(s)?


Ed, you need to start reading the Journal and list postings, and
attending classes in this stuff.

Transverse string vibrations cross the capo by a rocking action,
activating a transverse vibration in the duplex. This vibration then
reflects back through the capo and into the speaking length. If there is
a low partial in the duplex that corresponds to one of the partials in
the speaking length it will reinforce that partial enough to be audible
by the same mechanism that lets you hear the speaking length tone(s).
This is much more likely from a long front duplex (say, 40mm), than it
is from a short duplex (say, 20mm), which is why short duplexes are
quiet. That's pretty much it. Though a very big deal is typically made
of it, invoking conversational molecules, intuition, and tiny pointy
tailed fire breathing demons, it's really extremely simple.

Next, someone will demand to have proof that transverse vibrations cross
capos. I discovered something fun many years ago playing around in the
shop plucking strings before a rebuild tear down. I lifted the damper of
a note in octave 6 and plucked the duplex. The resulting tone was the
fundamental of the speaking length, which I thought was pretty cool.
When I lifted the middle of the duplex segment, the speaking segment
just past the capo dipped down slightly as the string rocked on the
capo. This is exactly how transverse waves cross capos into the duplex.

There is still no documentation or demonstration that longitudinal waves
cross capos, but transverse waves most certainly to.

And Jim I, this is how long front duplexes rob energy from the speaking
length, as they move with a wider excursion, which takes more to drive them.
Ron N

On 8/30/2014 10:17 PM, Ed Sutton via Piano Technicians Guild wrote:

> Ron-
>
> Yep, done that myself.
> How about the hissing sounds?

That's outside "normal" function, and likely a combination of long
duplexes and poor capo shaping. You can't pin all ills on one cause.
Often just lifting strings will clear that up enough to get you by.
Oddly, I don't recall ever having capo and/or duplex noises on a cheapo
import with short front duplexes and one long half round counter bearing
per section. Either I'm remembering wrong, the cheapo piano shapes capos
better than the makers of pianos with tuned duplexes, or the long "tuned
duplex is the major culprit. I vote for the latter. The short duplex
seems to make capo shape less critical. Note to the purveyors of
perpetual infinitesimal argumentation: "less critical" does not mean
completely unimportant.

> How about plinking the duplex when the damper is down?

It'll go "plink". Lift the damper and plink again and the speaking
length will sound it's fundamental (at least). It's quick and non
destructive. Try it, it's interesting.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

On 8/30/2014 11:24 PM, Edward McMorrow via Piano Technicians Guild
> Ron,
> What property of the wire allows the T-modes of the duplex segment and
> speaking length to couple together?

Property of the wire? All the properties that make it music wire.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

In the area of the compass just above where the dampers stop, if you pluck one string of the longer duplexes of a Steinway with cast-in duplex rests while damping the speaking lengths with your finger you will hear the hiss. If you then add a mute to two of the duplex lengths and pluck the undamped duplex again the hiss is mostly gone. Therefore much of the hiss is beats between the duplex segments and most of the energy is coupled to the air directly from the string. Some does come from the capo but obviously none can come from the soundboard because the strings are all damped by your finger in the speaking length. 

For example I tested note 69 (an F) on a 1915 B today. The speaking length is 137mm, the duplexes are nominally, (because unequal duplex speaking lengths are created by the angle of the duplex rests), 43mm. This gives a duplex ratio of 3.18. When you play the note the duplex mostly behaves because it is just far enough from T-mode consonance to not be overtly troublesome. The hiss you hear by plucking is barely heard, but it is there, especially with hard playing. 

-------------------------------------------
Edward McMorrow
Edmonds WA
425-299-3431
-------------------------------------------


Original Message:
Sent: 08-31-2014 13:48
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 8/30/2014 11:24 PM, Edward McMorrow via Piano Technicians Guild
> Ron,
> What property of the wire allows the T-modes of the duplex segment and
> speaking length to couple together?

Property of the wire? All the properties that make it music wire.
Ron N

It seems that the the "jangle" which is present when, for example, a soundboard is made too stiff and energy which can't be dissipated through the soundboard via the speaking length becomes excessive in the duplex scale, is also an example of the duplex scale coupling directly with the air.

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


Original Message:
Sent: 08-31-2014 22:33
From: Edward McMorrow
Subject: Transmission of front duplex sound

In the area of the compass just above where the dampers stop, if you pluck one string of the longer duplexes of a Steinway with cast-in duplex rests while damping the speaking lengths with your finger you will hear the hiss. If you then add a mute to two of the duplex lengths and pluck the undamped duplex again the hiss is mostly gone. Therefore much of the hiss is beats between the duplex segments and most of the energy is coupled to the air directly from the string. Some does come from the capo but obviously none can come from the soundboard because the strings are all damped by your finger in the speaking length. 

For example I tested note 69 (an F) on a 1915 B today. The speaking length is 137mm, the duplexes are nominally, (because unequal duplex speaking lengths are created by the angle of the duplex rests), 43mm. This gives a duplex ratio of 3.18. When you play the note the duplex mostly behaves because it is just far enough from T-mode consonance to not be overtly troublesome. The hiss you hear by plucking is barely heard, but it is there, especially with hard playing. 

-------------------------------------------
Edward McMorrow
Edmonds WA
425-299-3431
-------------------------------------------

So perhaps a customer complaint about duplex noise could be resolved by building a little lid to cover the front section?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------


Original Message:
Sent: 08-31-2014 23:35
From: David Love
Subject: Transmission of front duplex sound

It seems that the the "jangle" which is present when, for example, a soundboard is made too stiff and energy which can't be dissipated through the soundboard via the speaking length becomes excessive in the duplex scale, is also an example of the duplex scale coupling directly with the air.

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


Original Message:
Sent: 08-31-2014 22:33
From: Edward McMorrow
Subject: Transmission of front duplex sound

In the area of the compass just above where the dampers stop, if you pluck one string of the longer duplexes of a Steinway with cast-in duplex rests while damping the speaking lengths with your finger you will hear the hiss. If you then add a mute to two of the duplex lengths and pluck the undamped duplex again the hiss is mostly gone. Therefore much of the hiss is beats between the duplex segments and most of the energy is coupled to the air directly from the string. Some does come from the capo but obviously none can come from the soundboard because the strings are all damped by your finger in the speaking length. 

For example I tested note 69 (an F) on a 1915 B today. The speaking length is 137mm, the duplexes are nominally, (because unequal duplex speaking lengths are created by the angle of the duplex rests), 43mm. This gives a duplex ratio of 3.18. When you play the note the duplex mostly behaves because it is just far enough from T-mode consonance to not be overtly troublesome. The hiss you hear by plucking is barely heard, but it is there, especially with hard playing. 

-------------------------------------------
Edward McMorrow
Edmonds WA
425-299-3431
-------------------------------------------

On 9/1/2014 7:42 AM, Ed Sutton via Piano Technicians Guild wrote:

> So perhaps a customer complaint about duplex noise could be resolved
> by building a little lid to cover the front section?

You'll likely find that just the longest duplexes are noisy, as the
short ones typically aren't loud enough to be audible. A dab of glue on
the string, or Pitch Locks are a good quick fix.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

Let's play a game. No, not that one, another and simpler game.

Suppose one were to replace the original counter bearing bars of a tuned
front duplex with a softer material, like a phenolic or some such. Being
softer, this counter bearing would tend to somewhat absorb and diminish
the transverse pulse reflection from the speaking length and, being a
"lossy" termination, also somewhat lower the pitch of the reflection
produced so it no longer corresponds to the pitch that activated it
across the capo so it isn't continually reinforced from the speaking
length. Not enough to mute it and kill the speaking length, but enough
to prevent it's building to audible levels in the duplex. The result
would be a quiet and clean sounding duplex by means of understandable,
documented, and demonstrable physical string actions and effects via
transverse vibrations, with no need to invoke undocumented and non
demonstrable longitudinal effects.

Despite my apparent lack of affinity for razors of any sort, I've always
been a big fan of Occam's Razor, stating that among competing
hypotheses, the one with the fewest assumptions should be selected.
Other, more complicated solutions may ultimately prove correct, but-in
the absence of certainty-the fewer assumptions that are made, the
better. This is otherwise known as the KISS principle, or Keep it
Simple, Stupid. By all observed evidence, this seems to be impossible
for nearly everyone.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

On 9/1/2014 4:46 PM, David Love via Piano Technicians Guild wrote:
>Better to not build the board so stiff up there to begin
> with, IMO.

Of course, but not all of us are born with complete knowledge of
everything there is to know and resulting superiority that you seem to
possess. We have to try a few things to find out what we've got and
learn. Having never heard one of my pianos, you have no idea what I'm
building now or have ever built, nor Ron Overs, who's too stiff
soundboard is not in any way lacking power.


> Shortening the duplex and detuning it will not necessarily
> solve the problem though it can help.

That's nicely vague. Which problem is that? Of a certainty, no one has
been ignorant and stupid enough to suggest that shortening the duplex
will fix a too stiff treble, which is actually fairly rare and brought
up by you unnecessarily often and without cause for unknown reasons.
More usual is the dink and very short sustain of famously too flexible
compression crowned soundboards with 45mm c-8s, and noisy front duplexes
in the 40mm+range. The much repeated diagnosis of a much invoked too
stiff treble is to clamp a medium size Vise Grip on a rear bridge pin in
the affected area and see if the sound clears up from the added mass.
The rear pin is used to eliminate a false beat misdiagnosis, which would
otherwise be inevitable.

We've been here many many times.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

I have no interest in engaging in the type of hostile exchange that you seem so fond of.  I claim no superiority but have experienced the jangle of a too stiff soundboard assembly.  The alternative is not "dink".  I'm not sure what 45 mm C88 has to do with it since I never mentioned that.  We're talking about the jangle that can occur emanating from the duplex alone and it can occur with a soundboard that is too stiff in that region.  The "nicely vague" comment referred to that problem being addressed by shortening and detuning the duplex which helps but does not completely solve the problem.  Adding stiffness and mass increases sustain (slower energy loss) and decreases power, that's a fact that even you are aware of unless you are in denial.   If you want this to be the Nossaman show have at it.  Please, serve yourself.       

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


Original Message:
Sent: 09-01-2014 19:41
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 9/1/2014 4:46 PM, David Love via Piano Technicians Guild wrote:
>Better to not build the board so stiff up there to begin
> with, IMO.

Of course, but not all of us are born with complete knowledge of
everything there is to know and resulting superiority that you seem to
possess. We have to try a few things to find out what we've got and
learn. Having never heard one of my pianos, you have no idea what I'm
building now or have ever built, nor Ron Overs, who's too stiff
soundboard is not in any way lacking power.


> Shortening the duplex and detuning it will not necessarily
> solve the problem though it can help.

That's nicely vague. Which problem is that? Of a certainty, no one has
been ignorant and stupid enough to suggest that shortening the duplex
will fix a too stiff treble, which is actually fairly rare and brought
up by you unnecessarily often and without cause for unknown reasons.
More usual is the dink and very short sustain of famously too flexible
compression crowned soundboards with 45mm c-8s, and noisy front duplexes
in the 40mm+range. The much repeated diagnosis of a much invoked too
stiff treble is to clamp a medium size Vise Grip on a rear bridge pin in
the affected area and see if the sound clears up from the added mass.
The rear pin is used to eliminate a false beat misdiagnosis, which would
otherwise be inevitable.

We've been here many many times.
Ron N

And just so we're clear on what I did say and did not say, I never said Ron Overs' piano lacked power.  I said that Ron, among others had reported that making the soundboard too stiff can cause the duplex to jangle. This in answer to Ed's question about whether noise from the duplex must couple back to the soundboard before it becomes audible.  The answer is no it doesn't and this was an example reported by many on this list including Del F, Ron O. and you.  I've had similar discussions with Nick Gravagne.  The problem can occur when the board is too stiff.  

I went on to say that there is a trade off when adding stiffness which is a loss of power.  Sustain and power operate along a continuum. More of one by changing stiffness means less of the other.  If you push the sustain characteristics up too far in the treble the duplex can start to jangle for reasons given.  All of this you know.  You may try and compensate in other ways (which I didn't really get into) but that's a separate discussion and I mentioned that only as an aside.  The main point was directed to Ed's question about the noise emanating directly from the duplex.  So please, be more careful if you are going to pull what I say out of context.  

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


Original Message:
Sent: 09-02-2014 00:44
From: David Love
Subject: Transmission of front duplex sound

I have no interest in engaging in the type of hostile exchange that you seem so fond of.  I claim no superiority but have experienced the jangle of a too stiff soundboard assembly.  The alternative is not "dink".  I'm not sure what 45 mm C88 has to do with it since I never mentioned that.  We're talking about the jangle that can occur emanating from the duplex alone and it can occur with a soundboard that is too stiff in that region.  The "nicely vague" comment referred to that problem being addressed by shortening and detuning the duplex which helps but does not completely solve the problem.  Adding stiffness and mass increases sustain (slower energy loss) and decreases power, that's a fact that even you are aware of unless you are in denial.   If you want this to be the Nossaman show have at it.  Please, serve yourself.       

-------------------------------------------
David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
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Original Message:
Sent: 09-01-2014 19:41
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 9/1/2014 4:46 PM, David Love via Piano Technicians Guild wrote:
>Better to not build the board so stiff up there to begin
> with, IMO.

Of course, but not all of us are born with complete knowledge of
everything there is to know and resulting superiority that you seem to
possess. We have to try a few things to find out what we've got and
learn. Having never heard one of my pianos, you have no idea what I'm
building now or have ever built, nor Ron Overs, who's too stiff
soundboard is not in any way lacking power.


> Shortening the duplex and detuning it will not necessarily
> solve the problem though it can help.

That's nicely vague. Which problem is that? Of a certainty, no one has
been ignorant and stupid enough to suggest that shortening the duplex
will fix a too stiff treble, which is actually fairly rare and brought
up by you unnecessarily often and without cause for unknown reasons.
More usual is the dink and very short sustain of famously too flexible
compression crowned soundboards with 45mm c-8s, and noisy front duplexes
in the 40mm+range. The much repeated diagnosis of a much invoked too
stiff treble is to clamp a medium size Vise Grip on a rear bridge pin in
the affected area and see if the sound clears up from the added mass.
The rear pin is used to eliminate a false beat misdiagnosis, which would
otherwise be inevitable.

We've been here many many times.
Ron N

On 8/30/2014 11:20 PM, Edward McMorrow via Piano Technicians Guild

Ed,
In your opinion and impression, what are the approximate differences in
sound with the different front counter bearing materials you've tried
with your system, and how dramatic were the differences? I did a M&H BB
a while back that used rosewood counter bearings originally, but it was
in far too bad shape when it came in to make any sort of assessment.
Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

On 9/2/2014 8:39 AM, David Love via Piano Technicians Guild wrote:

> And just so we're clear on what I did say and did not say, I never
> said Ron Overs' piano lacked power.

No, you said that when you mass load a stiff board it diminishes power.
Ron's piano at the rebuilders' showcase had the stiffest board I've ever
seen in a piano, and the most mass loading I've ever seen as well, and
most decidedly did not lack power.


> I said that Ron, among others
> had reported that making the soundboard too stiff can cause the
> duplex to jangle.

This is absolutely wrong. No one familiar with the phenomenon has EVER
said anything like that at all. The noise produced has absolutely
nothing to do with the duplex and never did. It's a case of the resonant
frequency of the soundboard being higher than the frequency of the
strings driving it. Mass loading with whatever minimum weight works
(I've seen 20 grams make the difference) lowers the resonant frequency
of the board and clears up the noise.

Look at the animations here
http://www.acs.psu.edu/drussell/Demos/SHO/mass-force.html
The first is what we have with a too stiff treble. The third is what we
want. I've explained it and posted this URL a dozen times in response to
comments and questions about stiff treble noises. I can only hope that
someone will eventually listen and look at it.

Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------

No, I said as the board gets stiffer you trade sustain for power.  Power meaning the percussive power that is evident at the attack. You raise the impedance, you slow the board down, effectively, the energy dissipates more slowly but at a lower level.  Mass loading does not increase the power.  This discussion has occurred ad nauseam on this and the old list and you have participated quite a bit. Maybe you forgot.  The jangles can result from a board which is too stiff which may also raises the resonant frequency.  Interestingly, if you want to lower the resonant frequency you can also just make it less stiff.  Energy in the speaking length which can't dissipate through the board is delivered to the duplex scale (remember that rocking motion) and the duplex vibrates at an audible level.  The jangling noise has everything to do with the duplex because that's where it comes from.  Mass loading the board seems to help.  You can also remove the jangles by muting the duplex (by your explanation that wouldn't accomplish anything) but that simply robs the speaking length of even more energy.  Try it (of course I know you have) but I guess you prefer this route.  

I didn't hear Ron's piano at the showcase but there are other factors that can contribute to power:  scale design, hammer mass and density, downbearing settings, (the piano of Ron's that I heard in Reno had hammers that were quite heavy and quite dense--Abel performance hammers.  That piano certainly had power. I don't know how the piano at the showcase compared in that respect).  At any rate this isn't a discussion about Ron Overs' pianos.  There are some pretty simple rules.  Stiffer boards will deliver less power at attack and more sustain.   If you go too far with the stiffness you will diminish power to, perhaps, an unacceptable level, depending on what you're after but I'm not here to discuss preferences.  However, you can also deliver some unwanted noise in the duplex and the duplex will make those noises all by itself without having to couple back to the soundboard to make them audible (in answer to Ed's question) 

I know you've built some boards and tried all this out, so have I.  But if you want the last word, have at it.  

Nice animations though.  



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


Original Message:
Sent: 09-02-2014 11:16
From: Ronald Nossaman
Subject: Transmission of front duplex sound

On 9/2/2014 8:39 AM, David Love via Piano Technicians Guild wrote:

> And just so we're clear on what I did say and did not say, I never
> said Ron Overs' piano lacked power.

No, you said that when you mass load a stiff board it diminishes power.
Ron's piano at the rebuilders' showcase had the stiffest board I've ever
seen in a piano, and the most mass loading I've ever seen as well, and
most decidedly did not lack power.


> I said that Ron, among others
> had reported that making the soundboard too stiff can cause the
> duplex to jangle.

This is absolutely wrong. No one familiar with the phenomenon has EVER
said anything like that at all. The noise produced has absolutely
nothing to do with the duplex and never did. It's a case of the resonant
frequency of the soundboard being higher than the frequency of the
strings driving it. Mass loading with whatever minimum weight works
(I've seen 20 grams make the difference) lowers the resonant frequency
of the board and clears up the noise.

Look at the animations here
http://www.acs.psu.edu/drussell/Demos/SHO/mass-force.html
The first is what we have with a too stiff treble. The third is what we
want. I've explained it and posted this URL a dozen times in response to
comments and questions about stiff treble noises. I can only hope that
someone will eventually listen and look at it.

Ron N

On 9/2/2014 10:18 AM, Ronald Nossaman via Piano Technicians Guild wrote:

> Look at the animations here
> http://www.acs.psu.edu/drussell/Demos/SHO/mass-force.html


This is essentially the same thing but may be easier to picture.
http://www.acs.psu.edu/drussell/Demos/basemotion/BaseMotion.html

The soundboard overruns the string (driver) frequency and produces
chaos. And it does sound truly nasty. Again, the first animation shows
the problem and the third is what we want.

Ron N


Original Message------

Relative to previous discussions:

How do the actions of the front duplex string segments (whatever those actions may be) become audible sound?
What surface of the piano is moving to create sound waves, and how does the energy get transmitted to that (those) surface(s)?

-------------------------------------------
Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
-------------------------------------------