Pianotech

Topic: A question for Ron who is, unfortunately, no longer here.

1.  A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 15:20
In one of his last posts Ron hinted that the expansion/contraction of the soundboard in response to changes in relative humidity is not sufficient to cause a piano to go out of town. I wish he had had the opportunity to expand on that. My question, then, for the rest of you, is what does cause a piano to go out of tune? It can't be as simple as tuning pin slippage since a piano can go both sharp and flat. And in my experience, in normal homes, it has almost always been in response to mostly changes in RH. I'm not looking for anyone to directly answer my question so much as I am interested in the conversation that the question will hopefully generate. 

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Geoff Sykes, RPT
Los Angeles CA
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2.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 15:44
Geoff,
Maybe you misread that comment or Ron N. said that in context to something else, but every journey(man/person) piano technician knows that the rise and fall of a soundboards reaction to humidity is a cause of pianos going out of tune. It's as evident as the sun rising in the East and setting in the West.
Roger





3.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-16-2017 09:18
It strikes me as odd that with the exception of one sentence by Mr.Parham no one seems to be thinking about the wrestplank in this discussion. They are usually made of similar material to the bridge, frequently mated to a flange on the stringing frame and always connected to all of the tuning pins. A small dimensional change there would possibly have a significant effect on string tension.

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Karl Roeder
Pompano Beach FL
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4.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 10:25
I am inclined to agree that the wrest plank could be a significant factor in all of this, at least in certain situations. There is though a difference between a pinblock design fitted to a flange without plate bushings, and one designed WITH plate bushings with little or no contact with a flange. It would seem to me that the bushingless design would give greater possibility of exacerbating this whole issue (though I could be wrong on that). But in reality it seems that they all behave essentially the same way but in varying degrees.

That almost sounds contradictory but I'll leave it for now.

What I think might be quite useful in figuring this out (in addition to all the other measurement arrangements) is an overhead HD camera(s) to observe the slow movement of the soundboard/bridge assembly. The idea would be to shoot a frame every hour or so, starting with the piano at very low humidity  (maybe 25% rh) and gradually increase it to 65% or more over several weeks. The camera would record whatever (if any) movement front to back, or skewing of the bridge, etc.  Overlay comparison of photos from extreme to extreme could present valuable data in this regard, particularly when combined with all the other measurements discussed.

Obviously to do this effectively one would need a room with total humidity control. 

Anone else think this might be useful, or am I dreaming?

Pwg

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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
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5.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 11:25

Although thought provoking at times, with many of Ron's writings I struggle to find what was the purpose. Wood expands and contracts. How does the ratio of movement of one part over the other matter?
In the reprinted article in the current journal, in my opinion was one of his weaker articles. I just don't get the strawman argument of comparing a soundboard to architectural structures. Does a soundboard get made differently if one believes in buttress or non buttress?

I did find two articles of Ron's that i thought were fantastic in which i enjoyed very much. They were about pinblocks. In 2009. The first was drilling in two passes for more accuracy and eveness. The second was making your own multi-dense pinblock with more density on top layers and less on the lower layers. Both are great ideas, well thought out, instructive and useful.
Kudos Ron.






6.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 16:20
Geoff

If, indeed, Ron said something to that effect, then all of us have been "barking up the wrong tree" to not only ourselves, but our customers, as well. There must be something else that Ron meant.

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Willem "Wim" Blees, RPT
Mililani, HI 96789
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7.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 16:45

I think this is the most bizarre post I have seen since joining the guild.
At the very least copy and paste the comment in question.






8.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 18:00
No, Wim, not all of us.
My guess is that people who have designed or analyzed a few piano scales will easily understand what Ron said, and that those who have not designed or analyzed a few scales, will not understand what Ron said.

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Ed Sutton
ed440@me.com
(980) 254-7413
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9.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 16:50
My recollection is that Ron pointed to the expansion/contraction of the bridge as a much larger factor than the so-called 'rise and fall of the soundboard' for explaining the main reason for seasonal pitch changes.  As usual, he made a pretty compelling argument, with physical data to back up his conclusion. 

Granted, there is the long-held belief that the soundboard's rise and fall is the culprit, but can anyone point to actual data that confirms this, or are we just repeating what we have been told, with no evidence to back it up?

I wouldn't bet against him. 

Mark Potter
West Jefferson, OH






10.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 17:24
Mark,
Two observations support the soundboard rise and fall theory. The rise and fall in pitch occurs mostly in the mid sections of the piano whereas the very end notes (86, 87, 88) do not rise and fall much. Also, many pianos have a greater rise and fall rate of those strings located near a notched-out (a deep cut in the bridge to facilitate the clearance of the plate strut)  bridge (on uprights) which supports the theory that the soundboard is reacting, not the bridge cap.
Roger 





11.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 17:46
Mark-
Your understanding is correct, and it appears that you read and understood things that Ron posted many times.
Thank you.
Ed Sutton

Mark wrote:  My recollection is that Ron pointed to the expansion/contraction of the bridge as a much larger factor than the so-called 'rise and fall of the soundboard' for explaining the main reason for seasonal pitch changes.  As usual, he made a pretty compelling argument, with physical data to back up his conclusion.  
Granted, there is the long-held belief that the soundboard's rise and fall is the culprit, but can anyone point to actual data that confirms this, or are we just repeating what we have been told, with no evidence to back it up?
I wouldn't bet against him.  
Mark Potter
West Jefferson, OH


------------------------------
Ed Sutton
ed440@me.com
(980) 254-7413
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12.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 19:05
Ed,
Maybe, there is a misunderstanding about the perpendicular rise and fall of the bridge verses the rise and fall of the whole structure. I don't recall what Ron said, but if there wasn't any distinction mentioned between the vertical expansion of the bridge, verses the longitudinal expansion of the bridge and how it plays on the theoretical 60' radius curve, then we could be talking past each other. My guess, Ron may have been comparing the two different expansions dimensions and then concluded that the longitudinal expansion contributed more to the overall rise and fall than the cross grain expansion of dense maple bridge.

Roger




13.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 19:29
No, I don't think that is what he concluded. See his 2016 articles about bridge cap expansion and false beats to begin to understand what he said.

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Ed Sutton
ed440@me.com
(980) 254-7413
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14.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-20-2017 07:32
There's one aspect of Ron's theory about bridge expansion/contraction that confuses me (and I apologize in advance if he dealt with this and I'm simply forgetting it now).  If the primary cause of pitch rise and fall comes from dimensional changes to the bridge rather than the soundboard, why do we see so much increased stability when we install a Piano Life Saver in a grand?  The system would seem to have little or no impact on the bridges, yet the pitch movement is reduced dramatically.

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Kent Burnside, RPT
Franklin TN
615.430.0653
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15.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 18:17
Isn't the bridge connected to the soundboard?  Also, the bridge is made of a much denser material than the board.

Here is an opportunity for someone to do some research into the matter. The Foundation is offering research grants to technicians who want to spend the time to do the research.

If any of you are interested, go to PTGF.org, and click on the research grant link. The deadline is April 1.



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Willem "Wim" Blees, RPT
Mililani, HI 96789
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16.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 19:27
See the March Journal for a reprint of one of Ron's articles, which examines one of those "obvious" explanations that "everyone knows in true." Ron uses real research to support his conclusions.

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Ed Sutton
ed440@me.com
(980) 254-7413
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17.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 21:37
I believe Ron stated that the rise in pitch was due to a swelling of the bridge cap pushing the strings up the pins thus increasing the length of the wire segment across the bridge due to the slant of the pins. The fall in pitch is due to the shrinking of the bridge cap and decrease in the string segment length. The low tenor has such a marked fluctuation due to the lower tension or breaking percentage.

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Regards,

Jon Page
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18.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 02-19-2017 21:45
Jon,
Very well put.
Thank you.

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Ed Sutton
ed440@me.com
(980) 254-7413
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19.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-08-2017 09:38
A year or two ago I used to tune for a university that had Boston GP156s
in practice rooms. In the winter they dropped 20 cents at A4 and rose 20
cents at A4 in the summer. I set up a simple measurement system to see
what was actually moving. These are the things I measured at A4 from the
winter to the summer or vice versa (can't remember now):

- Lateral movement of the bridge
- Vertical movement of the soundboard directly in front of the left
bridge pin
- Vertical movement of the soundboard directly behind the left bridge
pin (to see if the bridge tilted
- Vertical movement of the bridge measured from the middle of all six
bridge pins
- Vertical movement of the front bridge pins

I wanted to see if the vertical movement of the soundboard was great
enough to account for a 20-cent change in pitch.

My conclusion: The soundboard did NOT move up or down enough to account
for that pitch change.

Other factors I did not include were total length of each of the three
strings, downbearing and the effect of the wooden pinblock.

Ron contacted me when about my results, which started a conversation
about why pianos go sharp and flat. I got distracted by work and we
never finished our conversation.

I will revisit my data soon.

I also set up an experiment under a grand piano to see how much upward
pressure I would have to apply on the soundboard to account for a 10- to
20-cent pitch change. My set up was crude, but simple. I put a hydraulic
jack on a bathroom scale under A4, then set a dial indicator on top of
the bridge to measure the upward movement of the SB/bridge assembly. I
don't remember all the numbers, but I do remember that I stopped at 150
pounds upward pressure because I was afraid I was going to break
something. It would be fun to repeat that experiment to also measure
string grooves before and after. I can't remember how much of a pitch
raise I eventually reached, but I remember that my other experiment did
not show as much soundboard movement as I had to generate to reach
approximately 20 cents change in pitch.

What have you all done to test this soundboard-only-causing-pitch-change
theory?

Just curious who's out there setting up ways to verify all the things we
believe.

Good discussion,
John Parham




20.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-08-2017 10:53
Hi John,
Perhaps for discussion, some insight might come from a different instrument such as a guitar. As they say bend a note/string and simply observe how much deflection is occurring relative to cent change.

My experience does show that a beefy Climate Control System with provisions such as a piano cover to limit air movement and sometimes a room dehumidifier makes for a highly stable piano.

When customers are unwilling to invest the results will be consistent with what you are finding at least in our environment.

Most clients are not aware of the 20 cent drift. I never float pitch and always tune to A440 unless requested to do so.

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Garret Traylor
Trinity NC
336-887-4266
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21.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-09-2017 00:17
Garret,

Yes, that's an interesting side topic and thanks for brining it up.

For now, I'm still interested in fining out who is setting up static
measurement systems to record what is moving when a piano goes sharp and
flat.

- How much does the soundboard move up and down with humidity change?
- How much does the bridge move up and down with humidity change?
- How much do the bridge pins move up and down with humidity change?
- If the bridge moves up, then down, do the bridge pins move down with
the bridge, or do the pins stay a bit higher instead of moving down
again when humidity drops?
- What is the relationship between downbearning and pitch change?
- Since each string length in a unison has three strings of different
lengths, what kind of pitch changes can we expect from each of the three
strings and why?
- What is the relationship between string tension and pitch change?
- How much difference does three different string lengths in one unison
make, therefore three different tensions, since inharmonicity between
those same three strings (in the same unison) have to be different
because of higher tensions from progressively longer strings? We have
already published an article in the Journal about how tuning
three-string unisons changes the initial pitch of the middle string. If
we add tension (and therefore inharmonicity) to the equation, what else
should we consider when tuning unisons?

Fun questions and more for us to figure out,
John Parham




22.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-09-2017 02:30
To those of you who find this information interesting and useful, I would like to suggest you do some in depth research, and get paid for it.

The PTG Foundation is offering Research Grants which will help fund your purchases of equipment, supplies and tools. If you're interested, please go to ptgf.org and click on the "research grant" for more information.

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Willem "Wim" Blees, RPT
Mililani, HI 96789
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23.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-14-2017 22:34
I'm coming rather late to the discussion, but I have come to the conclusion that Ron was, indeed, correct, and that the bridge must have a greater impact than the soundboard. This is based on a lot of observation and cogitation over the years, but the clincher was my recent experience beta testing the "PianoAir" system for Dampp-Chaser. 

This system controls the RH of air below the soundboard within 1%, i.e. + or - 0.5%. No, that's not a misstatement. The bottom is sealed with plastic, and the nose bolt holes are plugged with foam rubber. I won't go into how it works except to say that there is no heat involved (non-disclosure statement - though it seems this will not go into production).

I installed it on a Kawai RX-2, an instrument that is very susceptible to pitch change related to RH change, typically cycling 40¢ on the most unstable notes (up and down seasonally). This is in a university setting, so I can see the piano whenever I want to, and I do so about once a month. The ambient RH range is about 10% to 60% seasonally. There is also the typical institutional HVAC circulating air constantly - constant motion. I had earlier installed a dry humidistat (35% RH) with two heating rods, and that had reduced the pitch swing to maybe an extreme of 30 - 35¢ - helpful but not great.

I had high expectations for PianoAir. It includes two dataloggers, one in the cavity and one under the keybed, The cavity one recorded a straight line between 34.7% and 35.3%, mostly 34.9% to 35.1%, while the other mimicked the readings of my hygrometer for the room conditions. So what were the tuning results? Indistinguishable from the humidistat plus heating rods. Same expected pattern of notes changing pitch in the same amounts (including left string/right string patterns.). I'll note that the lid is constantly down (voice studio with a bunch of stuff always on the lid).

I am still beta-testing, now having added a wool string cover, and we shall see if that makes a difference (if it does, it would include the bridge in the picture). But to me, this seems to present pretty good evidence for the soundboard not being the major factor. With the environment of one side of the board so well controlled, it seems likely that the moisture content would be stabilized considerably more than with its previous scenario (the hygrometer plus rods had no effect during the time when ambient RH was below 35%). Yet the tuning stability was not improved, following a full seasonal cycle. The bridge, however, is exposed to the ambient RH (I put my hygrometer in there under the lid, and found that the air there comes pretty close to ambient). 

So here you have some actual data to go by.

BTW, someone said the notes on the extremes of the bridges move the least. This is certainly not true in all cases and all models. In some pianos (Hamilton studios, Steinway and Mason uprights) the top octave moves more than anywhere else - I have measured consistent 70¢ changes there, where the max elsewhere was 40¢. And, of course, the lowest plain wires at the bottom of the treble bridge (closest to the edge of the soundboard) typically has one of the largest pitch changes, almost always larger than the strings crossing the middle of the bridge. Of course, this is due to scaling issues, as has been pointed out for many years. (I wrote about it myself in the Journal in 1996, so that's at least 20 years).

One thing is certain: this subject is not nearly as simple as most people who express an opinion would like to believe. My own obsession has been the left/right phenomenon. If the MyPTG search function functioned halfway adequately (for instance, allowing you to specify author), I could refer you to many threads. Bottom line, other things being eliminated, the culprit in that case also seems to have to be the bridge. What mechanism, I haven't been able to imagine.

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Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
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24.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-14-2017 22:45
Yow! Really interesting.

So, in your opinion, are the changes in the bridge from changes in RH horizontal or vertical? Or, perhaps, both? 

Thanks for sharing your observations.

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Geoff Sykes, RPT
Los Angeles CA
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25.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-15-2017 01:50
Fred!
Really fascinating data.  This is obviously a complex phenomenom that is not understood.  One obvious possibility is that the movement is in the bridge.  Could there also be an asymmetry between the top and the bottom of the soundboard?  Could the bottom of the board be more rigid because of the ribs?  Another idea, instead of the entire bridge changing dimensions, could the movement be in the glue interface between the bridge and the bridge cap?  Or in the glue interface between the top of the sound board and the bridge?  Either of those glue joints could swell with changes in humidity.

My intuition with no empirical data, points me to the glue joint between the sound board and the bridge, as the location with the most movement.

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Carl Lieberman
RPT
Venice CA
310-392-2771
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26.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-14-2017 23:00
Respectfully,

Single winding copper wound strings vs. double winding plain wire strings. Why won't European manufacturers wheigh in the argument? PTG vacuum? No...

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Benjamin Sloane
Cincinnati OH
513-257-8480
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27.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-15-2017 07:33
Fred,
What is the feasibility of using this system inside a vertical piano, or on the top side of a grand piano?

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Ed Sutton
ed440@me.com
(980) 254-7413
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28.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 17:06
In response to Ed's question about vertical and top side of grand application, I will simply say that it is possible to control a sealed environment. It is not possible to control an unsealed environment. Any leakage will lead to control failure. The practicality of sealing either a vertical or the top side of a grand is quite challenging.

If you were simply to do the sealing, the RH within that confined space would remain nearly constant, only moving very gradually (one assumes), through the migration of moisture through the "solid" bodies of wood and finish. Use of a Dampit or Hydroceel might serve to provide adequate stabilization if needed. It might be possible to take a grand, seal the top entirely with a data-logger inside, and verify that the interior RH stayed nearly constant while the ambient RH changed. If it did, some experimental data could be derived.

(I have a client who made himself a plexiglass box for his violin. He determined through experimentation how much water in what form needed to be placed in the box to maintain his ideal RH. Simply a matter of vapor pressure, he told me. I think it was a glass jar with a particular diameter opening).

Interestingly, I think that pitch change is probably one of the most refined ways of measuring certain things, like gradual elongation of wire under stress, or minute changes in wood expansion and contraction. But it is such a complex interactive system, that it is very difficult to isolate components.

Eg, the bridge is very much affected by the string tension, the side bearing on the pins and/or down bearing or lack thereof. (A lot of manufacturers have tried alternate bridge pinning patterns to eliminate the "twist" vector of strings on the bridge, over the years, going back at least to the 1840s). So what the bridge does in isolation, compared to what it does with strings attached, and with varying pin offsets and down bearings, may vary considerably. 

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Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
------------------------------



29.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 18:29
A piano with a glass soundboard, and the maker claims it is less sensitive to humidity. 
I wonder if it shows any left/right unison shift?
http://www.stemco.nl/eng-crystalsoundboard.html

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Ed Sutton
ed440@me.com
(980) 254-7413
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30.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 20:40
I am thinking of converting my round glass top kitchen table into a piano. I recall seeing a picture of a piano that had a curved keyboard . All I need is a source for a round plate but that should not be a problem. When I was looking for a part called a spider to fix my washing machine I made the mistake of searching the internet. I now get about 100 emails from foundries in China willing to make me washing machine spiders. The only problem is they want my bank information and the minimum order qty is 1000.
Too bad no sound samples are on the web site. Wouldn't glass be sensitive to temperature changes and fog up like a car window ?
Is this thing even real ?????

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James Kelly
Pawleys Island SC
843-325-4357
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31.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 21:28
Crystal soundboard video here: https://www.youtube.com/watch?v=sa3OrAbNPNw&feature=youtu.be

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Ed Sutton
ed440@me.com
(980) 254-7413
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32.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 23:24

The glass soundboard is very fascinating. Since a traditional board can last a hundred years, I'm not sure that qualifies as vulnerable. I wonder what movers think of a piano having a glass soundboard. There goes the insurance rates.






33.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 23:57
Hmmm. Glass vs Carbon Fiber? While they may be resistant to changes in RH, they are both susceptible to changes in temperature. Perhaps even more quickly so than wood. Throw a spotlight on that glass soundboard and what happens to the tuning?

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Geoff Sykes, RPT
Los Angeles CA
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34.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-18-2017 12:56
My interest in this is because a piano with a non-hygroscopic soundboard, if all other parts are standard, would enable some tests to discern how much humidity induced pitch change was caused by soundboard movement.
I don't know if many of these pianos exist, or how accurate the maker's claims may be.
It would not be a simple test, but would require several kinds and conditions of pianos with glass soundboards in a variety of climates.

So, once again I think that a monochord, with simple, controlled structures could provide information at an affordable price.
Pieces of pin block with a simple string with a clamped "other end" termination might show the degree to which humidity change could move the tuning pin. Several kinds of pin blocks in various conditions, different lengths of tuning pins, various gauges and tensions of strings, and different humidity ranges. A simple one string test becomes 50 tests!

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Ed Sutton
ed440@me.com
(980) 254-7413
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35.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-15-2017 12:05
Fred,
Here are couple of observations I've noticed that suggest the entire soundboard assembly is the culprit rather than only the bridge. First, I was the person who mentioned the ends of the bridge (i.e. the treble) were not moving as much as the mid section. This observation may be false because the back scale in the treble is usually equal to the speaking length. It was demonstrated at a Westpac piano physics class a couple of years ago that a short (relative to speaking length) back scale contributes more to pitch change than a long back-scale. I'm still puzzled as to why the few strings near the bridge cutout* (Yamaha U1 is a classic example) in upright pianos move much more than the rest of the piano – the tenor break is an exception because of the lower tension and short back-scale. Also, I have observed on more than a few occasions the rapid pitch change of my Steinway "D" while tuning when an air conditioning system is blowing air over the soundboard. I don't believe the bridge alone could react that fast. This suggests the large surface area of the sound board is the cause of the rise and fall.
 
* The cutout is that portion that is removed to accommodate the plate strut.
Roger





36.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-15-2017 14:45
A couple of thoughts:

Roger<Also, I have observed on more than a few occasions the rapid pitch change of my Steinway "D" while tuning when an air conditioning system is blowing air over the soundboard.

There are short term and long term ambient effects to deal with. Air blowing over the piano in the short term will change the temperature of the wire and experience a marked change, independant of other RH related effects. Change in wire temps happens quite quickly.  Continual air blowing over the board and piano will exact a long term RH change. But even in a hot box with a fan blowing, RH still takes more time than a tuning to make a measurable difference in the board's EMC and dimension.

Mario< In addition to the bridges, the entire top of the board is not humidity controlled by the DC (or your system).  

On the top vs bottom portion of the board with a DC question, because the heater bars are radiant heat sources, the entire cros section of the  board itself becomes a secondary radiant heat source. This secondary radiant heat source then the effects the "barrier" layers of air on both sides of the board. The barrier layer is a several molecule thick layer of undisturbed air which clings to the board, if the air in either cavity lacks sufficient velocity to disturb that barrier layer. This barrier layer is the interface which I think we want to pay attention to and preserve. It can survive some air movement, but once serious convection is occuring, the barrier layer is constantly supplied with fresh air of a different RH than the undisturbed barrier layer was. This barrier mechanism has been well researched in storm window and insulated glass research.

In my own experience, having gone through considerable trouble to install epoxy laminated caps, I have seen the same wider-than-I-would- like-to-see swings in some, note the word  "some" of those pianos. I don't install them any more, as they were a real problem (make that pain in the ass) to fabricate and made capping the bridge a rather complicated calculated process. I did't see the value, so I opted for really nice quartered maple and the pin hole saturated with Jamestown Penetrating Epoxy (water thin/high epoxy solids/no thinning solvents). 

In Fred's beta test, the most interesting part of the the data to me would be the left/right string discrepancies. He didn't specify what that discrepancy was. The left/right strings have different string front segment lengths, and thus the front segment has greater elasticity, ie the bandwidth where change in string tension will effect the threshold of pitch change is different. While I think there are many vectors involved, I feel, that despite the fact that we are good at setting stable pins, some front segments are harder to read accurately than other front segments. I would not minimize the ability of an accurately and consistently set front segment to temper an instrument's tendency to vary widely past the SL pitch change threshold. This is particularly so around the tenor side of the alto strut, where front segments are almost universally (grands) much longer and harder to read than further down in the tenor.

Interesting topic. Though I don't think we will nail down a unified theory, just thinking about it and working the problem has resulted in tunings which continue to be more and more stable...sometimes surprisingly so...for me. This leads me to pay more attention to the tuner vector, and the ease of reading the front segment vector, which is usually not even mentioned in these discussions. Re Fred's Kawai, I have several Kawais whose rendering and front segment tends to be misleading. Its not the only vector, but I think it needs to be considered as a credible vector.    
 

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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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37.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-15-2017 21:56
Jim,

You wrote: "In Fred's beta test, the most interesting part of the the data to me would be the left/right string discrepancies. He didn't specify what that discrepancy was. The left/right strings have different string front segment lengths, and thus the front segment has greater elasticity, ie the bandwidth where change in string tension will effect the threshold of pitch change is different."

In another discussion years ago, someone pointed out that in grands, the front segment is longer on the right string than on the center or left. If memory serves, it was Fred who pointed out that the opposite was true on uprights, and yet the patterns of out-of-tune-ed-ness were the same, appearing to indicate that front segment length is not the reason.

Fred?

Alan


------------------------------
Alan Eder, RPT
Herb Alpert School of Music
California Institute of the Arts
Valencia, CA
661.904.6483
------------------------------



38.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 16:43
With respect to right/left pitch change patterns caused by RH change, the pattern is identical in uprights and grands: right string moves more in the overall direction, left moves least (and fairly often moves in the opposite direction, so when right string is sharp of target, left is flat - especially in smaller Yamaha grands in my experience, and this can be + and - 10-15¢).

I assume Jim is referring to the length of the string from tuning pin to front termination. Those patterns are inverse, uprights compared to grands. Furthermore, "waste length" (tuning pin side) varies by tuning pin pattern, and the pattern of the Steinway B is a case in point, an experiment set up for us to observe. Alternate unisons have wildly different waste lengths, yet the pitch of the alternate unisons do not vary in a zig zag fashion. 

To other question having to do with the effectiveness of a Piano Lifesaver system in a grand, my own experience is that the net effect on pitch variation is quite modest, maybe 25%. That is in my climate, which does have extremes on the low side, but those extremes are also common in the upper midwest and New England. I know many of you have far more tuning stability with your systems. I infer that you are dealing with the higher side of the equation (trying to drop high RH more than raise low RH), and that the system is more effective in that operation. I'd also note that the RH lowering is done entirely by heat, which might also raise the temp of the strings and thereby lower pitch (keep it from rising), especially in uprights.

Looking at my beta test piano today, I pulled the hygrometer I had placed under the wool string cover. It isn't a data logger, but does store max and min. Result? The string cover has zero noticeable effect on RH. The RH under the cover matches ambient, 16% at the moment. The underside of the board is 35%. I had placed the hygrometer so its sensor was reading down into a plate hole toward the soundboard.

------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
------------------------------



39.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 12:06
Jim,
You are correct. The reaction to the tuning from the air blowing over the piano is the air temperature on the strings – my mistake in believing otherwise. Sometimes we get blinded by the subject of humidity to overlook the obvious. If I'm correct this thread has been concentrating on whether the bridge or the soundboard is the primary ingredient to humidity related pitch change. I'm still in the camp of the soundboard as the primary. Yesterday I experimented with a pitch raise I performed on an upright piano. The piano was approximately 18 cents flat. I decided to see what effect an 18 cent pitch raise would have on one untouched string. The string was A4 -- upper string. After a complete pitch raise to A440 the upper string of A4 dropped 6 cents from its previous 18 cent position. This was obviously due to the soundboard compression – no humidity factor. This observation discounts the bridge expansion and contraction as a factor. It would seem to be a simple experiment to measure independently the rise and fall of a soundboard and the bridge with a dial gauge. I'm still puzzled by the "alternative facts."
Roger



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40.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 12:18
Did you consider string frame compression as a factor?

------------------------------
Regards,

Jon Page
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41.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 14:47
Al Sanderson used to talk about that...compression of the cast iron frame (in a pitch correction).

I am coming to think that this whole thing is a multi-faceted issue, all working together, rather than a simple one point responsibility. 

Pwg

------------------------------
Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
------------------------------



42.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 17:47
Jon,
If you're referring to the compression of the cast iron frame, I didn't. I'm not a metallurgist, but I don't think cast iron will not compress and expand (i.e. resiliency) with varying pressure or room temperatures.. Once compressed, always compressed.
Roger



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43.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-17-2017 18:13
Then you have to find another explanation for why the remaining adjacent strings to one that breaks suddenly go sharp. The two affected strings apply a nominal load to the soundboard assembly so blaming everything on soundboard motion is not a good -- at least not a complete -- explanation. 

ddf

--
Delwin D Fandrich
Piano Design & Manufacturing Consultant
6939 Foothill Court SW, Olympia, Washington 98512 USA
Email  ddfandrich@gmail.com
Tel  360 515 0119  --  Cell  360 388 6525





44.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-18-2017 13:22
Del,
Yes, those notes just above the treble break are a real puzzle. I thought it might have to do with string length (hence tension), but some of the worst culprits are Yamaha U1 and P22, and they go to the trouble of curving the V bar a bit to compensate. I did careful measurements of string lengths, and the length curve seems very smooth, within measuring error. Yet the note on the bass side will be within 5¢ while the note on the treble side will be 20¢ off, consistently. 

[Related and also curious is the fact that this is reversed on the Hamilton 243. More pitch change below that break, less above. In that case, the string lengths aren't so smooth, though I never went to the trouble to measure.]

The bottom line, for me, is that this subject is far more complex than we tend to think it is, and blanket statements are almost all wrong when it comes to assigning causes. As soon as you get beyond the broad statement and question it rigorously, the statement falls apart. (It doesn't happen that there is all the chatter of different people's anecdotal experiences rather than actual scientific testing).

I'd be interested to know what happens with bridge agraffe systems, either Stuart with wooden board and bridge, or with combinations of carbon fiber board and wood bridge (Phoenix). In both cases, I believe the set up is zero down bearing, which adds another wrinkle.

------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
------------------------------



45.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-19-2017 01:26
Edited by David Love 03-19-2017 01:35

It's not unusual for unisons on either side of the break to vary in terms of tension and BP%.  In the same manner that low tension and BP% in the low tenor results in greater pitch shifts in that section it would be expected that differences on either side of the breaks would do the same.  I'd probably look there first.  Personally I've not encountered variations from 5-20 cents in those sections on normal pitch shifts but some differences do occur.  That would be a reasonably and not so mysterious explanation.

 

David Love

www.davidlovepianos.com

 

PS  It may also be worth noting that on pianos where I've taken the trouble to reconfigure scales to more precise semi-log patterns, these variations across breaks and in the low tenor are much less pronounced.  That would also lead me to believe that irregular scale patterns contribute to variations in pitch shifting associated with these humidity swings that are mostly driven by soundboard changes.  Other factors?  Probably, but it appears to me to be to a much lesser degree given the evidence.  




46.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-19-2017 01:41
Fred,

FWIW -- Up till about 1987 the Hamilton scale had a tension of about 175 lbf at G-59 and about 215 at F#-58. That got a little less bad after 1987 but it still wasn't what it should have been.

ddf

------------------------------
[Delwin D] Fandrich] [RPT]
[Piano Design & Manufacturing Consultant]
[Fandrich Piano Co., Inc.]
[Olympia] [WA]
[360-515-0119]
------------------------------



47.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-19-2017 17:07

Up till about 1987 the Hamilton scale had a tension of about 175 lbf at G-59 and about 215 at F#-58.
Delwin Fandrich,  03-19-2017 01:40

Thanks, Del. That is very curious, as it would lead one to believe that the larger pitch change would occur just above the break (to the significantly lower tensioned note). And yet the opposite occurs (this being based on 1963 Hamiltons - observed consistently over at least 15 - 20 years, once I started noticing that it was different from other pianos. I only have one Hamilton left in my inventory as of a couple years ago, and it is from about 1980. I used to have 30, so I had plenty of opportunity to notice and verify and puzzle). 

With a fairly new Yamaha U-1, I measured strings on either side of the break as carefully as I could, plugged the lengths and diameters into a spreadsheet, and saw very minor difference in tension and break point %, essentially right in line with the curve above and below. And yet the note above the break consistently moves a lot, and is a major symptom in customers saying the piano is out of tune. This occurs on many other pianos as well, but almost all of us tune U1s.

I think the reason some of us obsess about these things has to do with the regular seasonal changes in RH we experience. People who live in the coastal area of northern CA through WA, in Europe, or other places where RH stays within fairly short bounds typically tell me they never observe many of the things I do, or not to the same extreme. It may mostly have to do with the low end of the RH range (below 20%) creating more extreme reactions.

My experience is confined to NM, and includes over 30 years of tuning the same 60 - 95 (the inventory has grown) pianos on a regular basis, a few times a year. The changes in pitch that occur when our humid season arrives, end of June or so, are the most extreme, and hard not to notice. It's pretty dramatic, as the pianos will have stabilized under 10 - 20% RH over more or less six months (varies somewhat from year to year). When the rains come, you would almost think the pianos had never been tuned. 

------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
http://www.artoftuning.com
"We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
------------------------------



48.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-19-2017 17:41
Fred< I plugged the lengths and diameters into a spreadsheet, and saw very minor difference in tension and break point %, essentially right in line with the curve above and below.

I have smoothed these transitions, with new bridges, or adjusted bridges to achieve a decent continuation of the SL multiplier over treble breaks/doglegs, to see what effect it had on this phenomemon. While improved, the movement is not eliminated. Seasonal ambient conditions New England aggressive. 

While I have no inspiring conclusions to offer, there are two other, either coincidental, or circumstantial, or related observations in this area, particularly around the first treble strut that really bug me about any piano in this area;  That is, in this area the notes tend to exhibit other  socially unacceptable behavior, ie...

-become harder to read front segment, or get agreeable front segment compliance
-is tonally, the most challenged area of any piano of any provenance, high end or low end of the price range. Voicing this area is the often very, very picky work, often unsuccessful in terms of developing good fundamental sustain vs short sustained explosions in the attack. 

I don't know what it is, and continue to try and tease out working hypotheses. My curiosity, and working hypotheses continue to focus on the actual frequency we are dealing with here, as related to board resonant modes which are forced on the soundboard/bridge composite by the curve of the damn bridge. The bridge concentrates loads in this area. The board has to be made stiffer to accommodate these loads. The added stiffness then populates this area with a high(er) concentration of unavoidable modes.

When a string's frequency is at or close to a resonant mode, the vibration behaves in an aggressive manner that, is, if not catastrophic, is way too close to a catastrophic threshold. Wild excursions of the string, that much energy being concentrated in a very short period of time,  must have more energy available to overwhelm other parts of the equilibrium, ie pin torque, front segment equilibrium tension, termination friction...more?     

Clearly  a lot to prove here, but the whole gestahlt just seems like these frequencies themselselves. in the context of a pianos shape, have no intention of playing nice with the other children.




 

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



49.  RE: A question for Ron who is, unfortunately, no longer here.

Posted 03-19-2017 21:34