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

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

    Registered Piano Technician
    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. 

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------


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

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

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



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

    Registered Piano Technician
    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

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



  • 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.

    Registered Piano Technician
    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.

    ------------------------------
    Willem "Wim" Blees, RPT
    Mililani, HI 96789
    ------------------------------



  • 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.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 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.

    Registered Piano Technician
    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
    ------------------------------



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

    Registered Piano Technician
    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.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Registered Piano Technician
    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.

    ------------------------------
    Kent Burnside, RPT
    Franklin TN
    615.430.0653
    ------------------------------



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

    Registered Piano Technician
    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.



    ------------------------------
    Willem "Wim" Blees, RPT
    Mililani, HI 96789
    ------------------------------



  • 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.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 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.

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

    Jon Page
    ------------------------------



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

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

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Registered Piano Technician
    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.

    ------------------------------
    Garret Traylor
    Trinity NC
    336-887-4266
    ------------------------------



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

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

    ------------------------------
    Willem "Wim" Blees, RPT
    Mililani, HI 96789
    ------------------------------



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

    Registered Piano Technician
    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.

    ------------------------------
    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
    ------------------------------



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

    Registered Piano Technician
    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.

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------



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

    Registered Piano Technician
    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.

    ------------------------------
    Carl Lieberman
    RPT
    Venice CA
    310-392-2771
    ------------------------------



  • 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...

    ------------------------------
    Benjamin Sloane
    Cincinnati OH
    513-257-8480
    ------------------------------



  • 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?

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Registered Piano Technician
    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. 

    ------------------------------
    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

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Member
    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 ?????

    ------------------------------
    James Kelly
    Pawleys Island SC
    843-325-4357
    ------------------------------



  • 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

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 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.

    Registered Piano Technician
    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?

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------



  • 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!

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Registered Piano Technician
    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.    
     

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



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

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

    Registered Piano Technician
    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
    ------------------------------



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

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

    Registered Piano Technician
    Posted 03-19-2017 01:26

    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.

    Registered Piano Technician
    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.

    Registered Piano Technician
    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.

    Registered Piano Technician
    Posted 03-19-2017 21:34
    I am inclined to think that the plate does in fact have SOMETHING to do with it. We cannot say with total certainty that the plate does not move or flex in any of this. The very fact that when you drop tension on a grand with a plate wedge, the wedges drops out. What does that say? That the plate was compressed under the tension.  Then it expanded when the tension was released. 

    Exactly how much, where, what does it looks like...I cannot answer but it makes sense that there is movement in the frame under 20 or more tons of tension.

    Right at the break where there is a strut would  (in my mind) make that specific area LESS compressible, therefore DIFFERENT in its response to soundboard movement (and possibly contributing to the tonal issues). Add to that sometimes significant tension jumps right there...etc.

    The fact that Jim I. has found improvement with scale alterations is evidence that that is PART of the issue. I think Del's point about string breakage and local pitch change (something I have pondered for a very long time) is evidence that the plate is ALSO involved.

    So I do believe this to be a several legged issue with a primary moving part (soundboard) and several other moving (reactively) parts as contributing factors.

    Pwg

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



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

    Registered Piano Technician
    Posted 03-20-2017 20:17
    Seems like there's a conflating of at least two issues going on.  

    First, what fundamentally drives the change in pitch.  It seems pretty clear that it's the expansion and contraction of wood accompanying changes in the EMC: primarily soundboard, to a lesser degree bridge caps, rim, maybe pinblock (not convinced), and then temperature as it relates to the strings (cold air blowing over an open piano will drive the pitch sharp before it ever has any effect on the EMC).  

    Second there's the manor in which that change is manifested on any given note or notes.  In this case it seems that the issues are scale, plate contraction, possibly some bridge twisting (it's worth noting that the top of the tenor often sees the strings placed at the front of the bridge and the first notes in the treble section they are in the back of the bridge this being at the dogleg and it wouldn't surprise me if the bridge undergoes some twisting there--and in other similar places.  

    So the general changes that occur in any piano will vary first as a function of reactivity in #1 and the specific changes will vary depending on the nature of the components in #2.  

    The severity of the RH changes and levels even in the presence of a dampp-chaser will also have an impact as on either side of the soundboard the RH can be different to varying degrees affecting the ability of the DC to do it's job.  

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



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

    Posted 03-20-2017 16:48



    You presented a problem. You offered a potential hypotheses on what the answer could be.  I disagreed with your hypotheses.
    The grammar error was yours, i was simply responding in kind. I clearly stated that I don't believe the resonant modes theory applies to piano soundboards. So i personally don't see the point of trying to map out  all the possible modes with computer software.

    Simply stated: I disagree that the curvature of the bridge causes the socially unacceptable behaviour (again your words). I was offering the counter that the problem you're hearing is a bad rib scale. And perhaps the socially unacceptable note is directly above a rib? 
    -chris

    ------------------------------
    ChrisChernobieff
    Chernobieff Piano and Harpsichord Mfg.
    Lenoir City TN
    865-986-7720
    chrisppff@gmail.com
    www.facebook.com/ChernobieffPianoandHarpsichordMFG
    ------------------------------



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

    Posted 03-19-2017 04:06
    x = distance from front termination to bridge

    y = rise and fall of bridge crown due to humidity change

    # = string length, i.e., 1 single wound bass string. I.e., 2 double wound plain wire string. 1.666 1 double wound plain wire string w/ 1 single with hitch pin loop

    So you hope that 

    x1 = y

    and 

    x2 = y

    at the same time. and

    x1.666 = y

    at the same time

    Good luck creating a board to compensate for that variance in string length

    ------------------------------
    Benjamin Sloane
    Cincinnati OH
    513-257-8480
    ------------------------------



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

    Registered Piano Technician
    Posted 03-15-2017 12:06

    I don't know.  It seems that if it was the bridge more than the soundboard then Dampp-Chasers would be more effective installed over the top of the bridge than under the soundboard.  But they aren't and they aren't.

     

    David Love

    www.davidlovepianos.com

     






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

    Registered Piano Technician
    Posted 03-15-2017 12:54
    David,
    Heat rises.
    Roger





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

    Registered Piano Technician
    Posted 03-16-2017 01:29
    So what? The ambient RH is different on the top side of the board than underneath and dc's are effective even with the lid open. If crown changes with emc with the board out of the piano why wouldn't it change with the board in the piano?

    I too have made bridge caps out of laminated epoxy infused material and seen no obvious difference in pitch shifts with changes in humidity than with those with caps that were not laminated and epoxy infused. 

    I've measured crown and bearing differences with before and after dc installations in the shop. I've also measued changes in bridge height and sounboard height with changes in emc using dc's.  The method is to set a metal straightedge (I used an aluminum box beam) across the rim at the widest cross grain point. Measure down to the top of the board and measure to the top of the bridge right adjacent to it. Change the emc and measure the change in bridge ht and sb ht to the cross beam again. If the changes correspond then the bridge rise is totally driven by the soundboard rise and the bridge does not contribute. If the bridge was expanding upward on its own and independently then those two nunbers would be different. They weren't measuably different in my trials.

    Rooms as one often finds in institutional settings are often influenced by temperature as well as humidity with changes between ac and heat and are not reliable measures of pitch swings since piano wire will respond to temperature changes.

    Ron himself on many occasions reported seasonal changes in piano tone driven by expansion and contraction cycles related to humidity (something we are all familiar with) and what we must presume to be an effect on soundboard crown with a resulting change in impedance.

    Observationally I've also found that old, dead, crack laden, zero crown and less crown responsive boards as found on many old pianos tend to be less or even non pitch reactive to rh chsngea than newer high crown and more reactive boards. That would argue for soundboards being more responsible since, presumably, bridges would remain more consistently reactive to rh changes over time.

    So I don't agree that soundboard crown is not mostly responsible for pitch changes that accompany changes in humidity and the concomitant change in emc.

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



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

    Registered Piano Technician
    Posted 03-17-2017 17:55
    David,
    Maybe I misunderstand what you were referring to. Were you comparing the installation of a heat source above the soundboard verses below?
    Roger



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

    Registered Piano Technician
    Posted 03-18-2017 00:46

    No.  If you put a hygrometer on the bridge and one up against the underside of the soundboard while the DC is on the one under the soundboard will read lower than the one laying on the bridge (I've done that).  The effect of the DC seems pretty localized to the cushion of air that rests up against the underside of the board and has the impact, in my experience, of stabilizing the tuning pretty effectively by controlling the EMC of the soundboard panel.  The top of the bridge is exposed to a different level of humidity than the underside of the SB so, I would guess, that the EMC of the bridge cap is probably somewhat different than the soundboard generally when a DC is engaged. One could measure that with a moisture gauge pretty easily I would imagine.  I haven't done that but maybe I will at some point.    

     

    If the bridge were the main culprit then I would think that delignit bridge caps sealed with epoxy, lacquer and whatever else would be more dimensionally stable and therefore more pitch stable.  But in my experience they aren't and I have several of those out there.  Similarly, if the pinblock was the culprit then a damp-chaser installed under the soundboard which has virtually zero effect on the pinblock would have no pitch stabilizing influence at all.  But it does. 

     

    The plate has nothing to do with it.  While the overall pitch change might be nominally influenced by plate contraction, it is still not the reason that pitch shifts with a change in humidity.

     

    This is all a pursuit of the untamed ornithoid, otherwise known as a wild goose chase, IMO. 

     

     

    David Love

    www.davidlovepianos.com

     






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

    Registered Piano Technician
    Posted 03-18-2017 12:56
    In my experience, a grand with DC system AND a full cover will remain remarkably stable. The cover seems to expand the controlled space well into the area above the soundboard, even to the pinblock area.

    Without the cover...not so good.

    Pwg

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



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

    Registered Piano Technician
    Posted 03-15-2017 13:04
    In addition to the bridges, the entire top of the board is not humidity controlled by the DC (or your system). We know that when the room is well controlled the tuning remains stable. Does it matter whether it's the bridge or the bridge and the (top of) the board that's causing instability?

    ------------------------------
    Mario Igrec
    http://www.pianosinsideout.com
    ------------------------------



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

    Registered Piano Technician
    Posted 06-16-2017 13:51

    Very interesting, Fred! This would give a logical explanation to the baffling difference in effectivity between Dampp-Chasers in uprights and grands. Encapsulated as they are in uprights, the ideal humidity reaches the bridge.

    The difference is a huge one, at least over here in our challenging climate (typical indoors RH >10% in January, <80% in early August.) 



    ------------------------------
    Patrick Wingren, RPT
    Jakobstad, Finland
    0035844-5288048
    ------------------------------



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

    Registered Piano Technician
    Posted 02-19-2017 21:40
    I think the experience tuners have had maintaining Kimball Grands made in the 1970's and 19809's can illuminate some of the variables regarding how a soundboard/bridge structure influences pitch rise and fall with rising and falling humidity. Some of these pianos had both horizontally laminated bridges and soundboards, (full plywood, FP). Some had solid spruce boards with horizontally laminated bridges, (mixed plywood, MP).

    The ones with FP seemed to react to humidity changes at about half the rate of the ones with MP. The ones with MP would move out of tune much more like the standard piano soundboard/bridge structure. But no controls to compare the behavior of a standard structure were available to quantize the behaviors and get truly good data. Since these Kimball grands were copies of Bosendorfer scales; Bosendorfers would make good control specimens since they have traditional soundboard/bridge construction.

    Horizontally laminated bridges would theoretically increase in thickness with rising humidity much that same as a traditional bridge, but resist getting wider or longer. Same can be said for laminated soundboards. So these structures do offer specimens to tease out which elements cause how much change

    So my experience indicates that there are many factors at work but the one incontrovertible fact we do know is that wood expands with rising humidity and contracts with diminished humidity.

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



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

    Registered Piano Technician
    Posted 02-19-2017 21:46
    It's incredibly difficult to find anything using our current search function, but I think that the last time this conversation came up with Ron was here:

    Pianotech
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    ------------------------------
    Peter Stevenson RPT
    P.S. Piano Service
    Prince George BC
    250-562-5358
    ps@pspianoservice.com
    ------------------------------



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

    Registered Piano Technician
    Posted 02-20-2017 01:15
    Yes there is other measurable evidence in the down bearing between humidity cycles as well as tonal changes that accompany changes in crown.  Ron pointed out not infrequently that compression crowned boards undergo tonal changes with seasonal changes. Whether his own rib crowned and supported designs undergo changes at a different rate is another question.

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



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

    Posted 02-20-2017 08:13
    This could be tested empirically with simple models.
    1) To what exrent does a change in downbearing change the pitch of a string?
    2) To what extent does a change in side bearing on the bridge change the pitch of a string.
    (Test with various string lengths and tensions, also with wrapped strings.)

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Posted 02-20-2017 08:33

    Ed Sutton<This could be tested empirically with simple models.

    Additionally...How does a the behavior of a belly with  bridge agraffes differ from a pinned bridge in this regard? I don't service any older pianos with bridge agraffes, but Pheonix agraffes are being retrofitted in some shops, I think. Steingraber's Phoenix is not applicable, because it has a CF board. But the chap in Australia, Stuart, is making bridge agraffe instruments with wooden soundboards, no?

    Interestingly, Steingraber's CF Phoenix has a highly migratory pitch and experiences unison movement with changes in temperature.

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



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

    Posted 02-20-2017 08:50
    Jim,
    A search of piano patents provides a great history of "almosts."
    Bridge agraffes seem to offer great benefits...if...!
    I believe Ron had designed a bridge agraffe, but his health did not allow him to develop it.
    Ed

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Posted 02-20-2017 09:06
    Right Ed...

    My point is not so much about agraffes being a good or almost good idea, but re the original pitch shift question. Rather, that a vanilla spruce soundboard piano with an agraffe system, no matter the agraffe's strong or weak points, effectively eliminates the offset pin effect on changing string tensions with RH induced changes in bridge cap dimension. So it would be a good way to see what happens in a belly where the bridge pin effect is entirely eliminated as a variable. 

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



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

    Posted 02-20-2017 09:24
    Another thought in eliminating the bridge pin offset as a variable..this one easy...to see what effect the board's changing crown, in and of itself has on pitch.

    Record pitch in sample strings at several points in the scale. Jack up the board from underneath, with several spaced floor jacks, raising the entire board structure in relation to the string plane. Compare sample pitches as the board is forced up. No RH change will have occurred so this isolates the effect of crown from bridge pin offset. It does not eliminate bridge roll, but the cap/pin offset portion of the bridge is eliminated. 

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



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

    Registered Piano Technician
    Posted 03-15-2017 00:27
    A number of pianos that I service have good tuning days and bad tuning days. By good tuning days I mean days when I can easily get nice clean unison's. Bad tuning days are when I can't get a clean unison, on that same piano, to save my life. My own U1 is an example. Somehow I remember Ron mentioning that with changes in RH the expansion/contraction of the wood, specifically in the bridge, could cause the three bridge pins to lose their exact straight line across, and right angle to, all three strings. This would, in effect, cause the three strings in a unison to be ever so slightly not the same length. This was attributed to fact that the bridge pins are not equidistant from the edge of the bridge, in that the first of the three strings is near the edge of the bridge and the last of the three is nearer the middle. The bridge would not have to rock or tilt as a result of, say, soundboard movement, more than a tiny bit for those three strings to become unequal in length and therefore impossible to make clean unison's.

    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------



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

    Registered Piano Technician
    Posted 03-15-2017 10:30
    Ron challenged me to set up an experiment to test bridge expansion whereby various bridge models (quartesawn maple caps, laminated caps, pins epoxied, pins not epoxied etc.) are exposed to changes in temperature and moisture content, and then the bridge and pin height are measured. My readings were disappointingly not so varied at the outset and so I sort of lost interest. I have better equipment now and this thread makes me want to try again. 

    Related to Fred's data collection and chiming in on what Jim I. is suggesting, perhaps bridge height changes could be measured off a dial indicator mounted on a straight edge across the top of the rim, or similarly in a controlled experiment.

    When is the deadline for the grants? Any day now, right?

    ------------------------------
    Jude Reveley, RPT
    President
    Absolute Piano Restoration, Inc.
    Lowell, Massachusetts
    978-323-4545
    www.absolute-piano.com
    ------------------------------



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

    Posted 03-15-2017 10:52
    Jude-
    Take a look at Jim Ellis's articles, about ten years ago. I'd suggest something similar:  train rail monochord, carefully controlled string attachments, create a steel plate bridge top which can be cranked up and down, or rotated horizontally to slightly change the offset of the bridge pins. Set up various string gauges and lengths taken from piano scales. Raise and lower the bridge and measure the change of pitch, then rotate the bridge to measure the change when the bridge pin offset is changed.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Posted 03-15-2017 14:29
    Jude,
    Controlled experiments in a piano are just about impossible. If you measure a rise or fall at the top of a bridge, is that because of soundboard, bridge root, or bridge cap, and is it swelling or twisting? And how is its relationship to the plate and string terminations changing...or not?
    Ron's tests were usually done on models or jigs where he could examine each variable in isolation.
    This is why I suggest just testing two variables of bridge top movement on a monochord.
    If, for example, we show that rise and fall of the bridge top surface does not cause much pitch change, then we don't need to hypothesize soundboard, bridge or bridge cap rise as a cause.
    If tests show (as Ron suggested) that a change in the offset of the bridge pins causes a significant pitch change, then we must ask what can cause this. Ron's idea was that the swelling bridge cap pushed the strings further up the angled bridge pins, thus increasing the offset and the string tension.
    This might be tested by making a bridge on the monochord with an iron root and maple cap, then drying the cap, tuning the string, then putting some drops of water on the cap, producing a quick humidification of the cap, and measuring the pitch change, if any.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Registered Piano Technician
    Posted 03-15-2017 21:59
    Jude, 

    The deadline for submission of proposals to the Research Grant Committee is not until April 1. So you have a couple of weeks yet to write something up and submit it. We would be delighted to receive a proposal from you on this very timely and pertinent subject for our consideration.

    Best,

    Alan

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



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

    Registered Piano Technician
    Posted 03-15-2017 22:05
    Hi, Jude,
      As you said, the deadline for applications to the PTG Foundation Research Grant program is soon, April 1.
    Full information is on the Foundation website.   ptgf.org
    Link to the Research Grant page is

    Applications are welcome.
    Thanks.
    Claude Harding
    PTG Foundation





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

    Posted 03-20-2017 09:58
    The working hypothesis of matching a frequency to a resonant mode on piano soundboards will show it is not equal to the reciprocal of stiffness. It may have validity on violins and such, but those are based on different principles, and a different method of construction. At the most, you will make micro changes that a pianist most likely won't even notice. And what benefit is to be gained when the real issue of a correct rib structure is not addressed?   The same with the bridge curvature creating more resonant modes theory.  My conflict with these two ideas stems from what seems to be a build from the top down mode of thinking, instead of build on a solid foundation first, then build up way of thinking.  The proposed solution of making a board even stiffer, because of assumed load modes, should be ringing those counterintuitive alarm bells. Maximum flexibility should be the goal. The loads are properly accomodated when the rib structure is designed in sync with the string scale, and the downbearing set accordingly. I have shown in numerous posts, that rib scales in most pianos are crude and sloppy. Look at the way they are finished off- with a square and hand plane.  The need for accuracy of these critical structural elements of the soundboard, I believe, has never been fully appreciated.  When I make the ribs for my soundboards, each is carefully mic'd. I have calculated that being off a thousandth of an inch can result in a 60 lbf difference of bending stress. There's the source of the resonant mode i'd say.  I further make sure that the ribs have a smooth transition from each other in square area. This assures that the load is shared rather than one rib taking the brunt of the load over its neighbor.

    ------------------------------
    ChrisChernobieff
    Chernobieff Piano and Harpsichord Mfg.
    Lenoir City TN
    865-986-7720
    chrisppff@gmail.com
    www.facebook.com/ChernobieffPianoandHarpsichordMFG
    ------------------------------



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

    Posted 03-20-2017 15:24
    <...working hypothesis of matching a frequency to a resonant mode on piano soundboards 

    Point of information...One does not match a frequency to a resonant mode. Rather one wants driving frequency to steer well clear of resonant modes. A perfect match will fail catastrophically. A close match will have no sustain, and bark and explode with impact noise.

    Stating the word "resonant mode" in the singular is erroneous. There is not only one "resonant mode" in a board.  Depending on the panel stiffness(by ribs or by compression or by both), panel thinning at the edges, grain angle to the ribs, ways in which the bridge root interferes with the panel's mobility, thickness of panel, number of ribs, string scale, shape of case, size or case/board etc etc etc, the board will be populated by numerous resonant modes, at various driving frequencies.

    Though the board has a "tap" tone, the other localized frequency dependent resonant modes, are very hard to empirically detect and locate physically in real time. No one I am aware of, has the analytic ability to completely predict, in finite elements analysis, the location of these modes with respect to the location of driving frequencies. Though I use an excel spreadsheet for some portion of my design work, and it sounds like you do too, these tools are very coarse tools and utterly incapable of predicting multiple resonant mode locations at various frequencies. I don't even pretend to predict these elements, and employ other empirical procedures to "proof" a one-off board. 

         

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



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

    Registered Piano Technician
    Posted 03-30-2017 15:58
    Yesterday, as I tuned a Steinway A (old, restrung), a G4 string broke. This caused, as expected, a rise in pitch of the neighboring strings. I thought I'd measure and document the change. It was a very minor pitch adjustment, on the order of raising 1 to 2¢, so this was a piano in stable condition. 

    The unisons below G4 fell about 3¢. This was true for about three unisons. Beyond that, the next two unisons went about 2¢ and 1¢ flat, then no significant change. The unisons above also went sharp, but as they had not yet been tuned, I didn't bother to note how much. On previous occasions, I have found the effect pretty symmetrical on either side of the broken string.

    Once the string was repaired and brought to pitch, the neighboring strings came back to pitch, pretty precisely (I didn't feel the need to touch them up).

    This familiar scenario is pretty amazing. One string breaks, and that much change occurs. Put one string on and pull it to tension, and that much change occurs. There are several aspects to this.

    One is that pitch change is an extraordinarily precise and refined way of measuring. I doubt very much that any ordinary measurements of distance change (bridge height, whatever) would pick this up, yet some physical movement must have occurred.

    Another is that the whole system is very complex and inter-related. When we think of RH change affecting pitch, we tend to think only of wood. In fact, it is wood that is subjected to the enormous forces of many strings, something like 230 of them, acting in different directions (cross stringing, bridge counter-pinning, down bearing or up bearing.

    Those forces are temporarily in balance when the piano is in tune. A change of some sort throws off the balance, and the system reestablishes equilibrium. That reestablishment will follow patterns, depending on the particular design (different tensions of the different strings, lengths, etc.) Some of those changes will be surprising, unexpected.

    Just some musings, no conclusions. But it is musings like these (together with other observations over the years) that have led me to think that it could, indeed, be the bridge itself that is the major factor.


    ------------------------------
    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
    ------------------------------



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

    Registered Piano Technician
    Posted 03-30-2017 16:06
    Back in 1996, I did a small experiment with vertical displacement of piano strings, and the relationship of that to pitch. I included the results in a letter to the editor of the Journal, partly in response to an article of Del Fandrich. I am going to quote that, as it is interesting in giving some actual measured figures of distance displaced versus pitch change.

    -------------
    I removed the bridge pins from three unisons of a 30-year-old Hamilton (Baldwin model 243 studio): D#3, the lowest plain wire unison; D3, a wrapped unison on the treble bridge; and A3, a plain wire unison higher on the bridge, chosen as the highest unison convenient to get at with hands and tools. I then placed round stock of various diameters between the bridge and the strings, measuring the resulting pitches. The accompanying chart shows the results:

    .016" .061" .109"
    D3 0.0 7.5 16.7
    D#3 0.0 12.1 32.5
    A3 0.0 9.8 21.5

    This turned out to be a somewhat problematic experiment. I had planned to measure pitch first with the wires crossing the bare bridge, then again after placing two pieces of each dimension between the strings and the bridge, lined up over the middle of the bridge pin holes. I thought this would come closest to what actually happens when a bridge rises.

    Unfortunately, this proved unworkable. I was unable to get reliable, clean pitch readings in this manner on any of the three instruments I tried, due to the fact that front bearing was less than or equal to rear bearing. Readings were unreliable both on the bare bridge and with two pieces of round stock (center pins and bridge pins) in place. I had to press down on the front bearing point to get readings, and wasn’t sure the pressure wasn’t influencing the pitch. I decided it would be more accurate to dispense with two bearing points, and instead place one piece of round stock on the bridge where it was solid -I chose right behind the front bridge pin holes. I used .016” harpsichord wire for an initial reading, as it was the smallest wire which gave good termination, then a .061” center pin, then a .109” bridge pin. I repeated the steps at least three times to be sure I was getting consistent readings.

    If anyone is interested in repeating this experiment. I would point out that accurate placement of the wire/pins is critical to obtaining consistent results. A very small movement fore or aft will change the readings quite a bit. I tried for as much consistency as my eyesight would allow. I make no absolute claim for the reliability of my figures within more than a cent or two, but I think they are suggestive enough even at that level of accuracy.

    Obviously the lowest plain wire unison, D#3, changed pitch considerably more than its neighboring wrapped unison, and also more than a plain wire unison higher on the bridge.
    ----------


    ------------------------------
    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
    ------------------------------



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

    Registered Piano Technician
    Posted 03-30-2017 19:17
    Fred,
    Having read the various responses these past weeks I believe there are many factors contributing to the rise and fall of pitch. Del's comment and your experience, as I'm sure many of us have, regarding the pitch change of adjacent strings leaves yet another question. It isn't humidity affecting the rise and fall of those adjacent strings. What is happening?
    Roger

    Virus-free. www.avast.com





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

    Registered Piano Technician
    Posted 03-30-2017 19:50
    From the available evidence, I would say either a slight bridge rise, or reflexing of the plate, or a combination of both. What else could I be missing?

    Pwg

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



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

    Registered Piano Technician
    Posted 03-31-2017 00:58
    Fred,
    That experience of a broken string causing its neighbors to rise in pitch, followed by the neighbors returning to pitch after the string is replaced leads me to the opposite conclusion as you. The dimensions of the bridge could not have changed. The height of the bridge changed because the curved more pliable soundboard flexed.

    Despite Ron's measurements and musings, it never made any sense to me that the dimensions of the bridge were changing with the changes in relative humidity. The accepted wisdom that the bridge board system is flexing seems like it is true.

    Carl

    Sent from my iPad
    CarlPianoTech.com




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

    Posted 03-31-2017 09:33
    <Fred,  That experience of a broken string causing its neighbors to rise in pitch...

    But that's not what he observed. Fred said a few strings below went flat and a few above went sharp.  This is a more complex result than all just going one direction. The opposite effects on the two sides of the broken string suggest, to me, a very fine and somewhat non-linear response to changing plate loads. I am having trouble visualizing the the non-linearity, as my poor limited brain wants to see simple linear effects..   


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



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

    Registered Piano Technician
    Posted 03-31-2017 10:40
    Jim,
    Sorry if I was unclear. The unisons on both sides of the broken string went sharp. The unisons above had not been tuned. Therefore I did not have a before baseline, therefore I did not bother to measure them. I assume, from previous experiences, that they behaved much as the unisons below.

    My own take is that we are dealing with a total entity in which the tension of the strings is the major contributing factor, tons of strain applied by 230 or so individual strings at similar but different tensions, and at different points along their pitch curves (the amount of difference in tension versus the degree of pitch change at that particular point of the curve).

    What could be happening in the case of a broken string is a change in the plate itself, or the plate plus the piano frame. There is no particular reason to suppose it is entirely bridge and/or soundboard related. More likely, there are multiple factors involved that we are unlikely to tease apart.

    More to the point is the sensitivity of the system. Tiny change in dimension, or removal of something like 1% of the total web of tension (broken string), and a noticeable effect occurs. I have always been astounded by the phenomenon I described. Why would one broken string have that effect? Why would replacing it put everything back where it had been? Crazy stuff! RH effects are also mysterious and crazy, in their details.

    ------------------------------
    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
    ------------------------------



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

    Registered Piano Technician
    Posted 03-31-2017 11:59
    It might be interesting to see what happens in a CP70, where there are no bridges, only a plate/frame. Remove a string and see what happens to the pitch of the surrounding ones. Anybody own one of these?
    I have seen this phenomenon in a Chinese grand in the treble where there happens to be a lot of crown up there. The strings in the area go crazy sharp if one breaks, and then settles down after the string is replaced. The whole soundboard/bridge/plate assembly is just one big complicated spring held compressed by the 280 string/springs. It's why raising, or, lowering the pitch, is always a fight.
    Paul McCloud
    San Diego




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

    Registered Piano Technician
    Posted 04-01-2017 00:42
    I think it's the plate. Reactions are fairly predictable (broken strings alwayspush adjacent strings sharp) and this is true whether there is downbearing or upbearing on the bridge.

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



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

    Registered Piano Technician
    Posted 04-01-2017 12:07
    I've experienced the pitch of notes adjacent to the broken string going sharp many times. This experience is so consistent that years ago I stopped trying to retune adjacent notes before replacing the string. The effect is greater with double strings than with single-hitched strings. Snip multiple adjacent strings in a section and the pitch rise of adjacent strings goes up in a logarithmic curve. 

    My theory is that when the string breaks the sudden release in tension is like a kick that causes a sudden displacement of the bridge not only up but backward (the string flies backward). Suddenly rolling backward, the bridge causes some additional increase in (rear) downbearing, beyond what the soundboard causes by popping upward. When we replace and tighten the string, with it we are pulling the bridge forward, and we know from experience with soundboard deformation that most bridges seem to be in a permanent state of forward roll.  

    To me knowing exactly what happens is less useful than knowing that this is a universal experience and that the solution is to install and pull the replacement string to pitch before assessing and correcting the pitch of surrounding strings.

    ------------------------------
    Mario Igrec
    http://www.pianosinsideout.com
    ------------------------------



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

    Registered Piano Technician
    Posted 04-01-2017 15:46
    Mario said:

    My theory is that when the string breaks the sudden release in tension is like a kick that causes a sudden displacement of the bridge not only up but backward (the string flies backward). Suddenly rolling backward, the bridge causes some additional increase in (rear) downbearing, beyond what the soundboard causes by popping upward. When we replace and tighten the string, with it we are pulling the bridge forward, and we know from experience with soundboard deformation that most bridges seem to be in a permanent state of forward roll. 


    I know you didn't intend an overly-close read on this, but it might be helpful, if only to avoid elevating imagery to hard fact, albeit immeasurable.

    the sudden release in tension is like a kick that causes a sudden displacement of the bridge not only up but backward (the string flies backward).
    1) does this imply that whatever bridge movement presumed to take place would NOT happen if the subject string, rather than breaking, was (pitch) lowered, by hand turning?  
    2) what sort of measurable movement (and distortion) would have to occur to allow this one section of bridge to move "up [and] backward" ?

    Suddenly rolling backward, the bridge causes some additional increase in (rear) downbearing, beyond what the soundboard causes by popping upward.
    Why would backward-rolling bridge cause increase in rear downbearing?

    most bridges seem to be in a permanent state of forward roll. 

    Can you explain this in terms of stress and distortion?

    Thanks

    ------------------------------
    David Skolnik
    Hastings-on-Hudson NY
    914-231-7565
    ------------------------------



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

    Registered Piano Technician
    Posted 04-01-2017 16:46
    David Skolnik, indeed I was sharing a perception more than a worked-out theory. And you are right, the bridge rolling back (or straightening from a rolled-forward state) would not increase the overall downbearing. 

    You said, "1) does this imply that whatever bridge movement presumed to take place would NOT happen if the subject string, rather than breaking, was (pitch) lowered, by hand turning?" Yes, that's my assumption based on informal observations when removing a string. I am curious now and will test this at earliest opportunity.

    I sense that answers lie in the fact that the tension is lost suddenly.

    If you buy that the bridge is typically rolled forward (corroborated by the S-shape distortion in many old soundboards), it makes sense that with the sudden loss of tension, the bridge would unroll slightly in the broken string area, pulling the surrounding strings backward and adding tension to them. 

    ------------------------------
    Mario Igrec
    http://www.pianosinsideout.com
    ------------------------------



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

    Registered Piano Technician
    Posted 04-01-2017 18:10
    Another possibility has to do with the strings torsional affect on the bridge. In modern pianos, all strings weave between the bridge pins in the same direction, so they are all exerting a rotational force on the bridge in a counter-clockwise direction. This might have a localized affect on the wood of the bridge, such that when one of the strings disappears from the picture, the wood is able to "exert itself" to return toward what would be its rest condition. That could mean that the pins of the adjacent notes are rotated a bit clockwise.

    This sort of image could also possibly explain the oddities of pitch behavior at bridge ends, and of either side of struts, where there is a certain amount of unpinned wood. 

    BTW, that Steinway A I wrote about has a flat board, and a probable zero down bearing (though you can't tell while a piano is strung). It is quite unlikely that upward pressure is being "released" by the string breakage.

    ------------------------------
    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
    ------------------------------



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

    Posted 04-01-2017 18:30
    Fred< BTW, that Steinway A I wrote about has a flat board, and a probable zero down bearing (though you can't tell while a piano is strung). It is quite unlikely that upward pressure is being "released" by the string breakage.

    I am going to set up an experiment next week with a triage rebuild that didn't get a new board. I have a dial indicator beam set up that I use to test deflection changes on lunloaded/loaded boards. The plan is simply to set up a dial indicator over the bridge, suspended from a beam on the case top, and raise the board locally with a floor jack under that dial indicator, to see what happens to sample pitches. This would eliminate the instantaneous change in pressure effect leaving only the rise in the soundboard/bridge component.

    I have my hunches, which I will keep to myself for now. The only problem I anticipate is that if there is a pitch change, we still will not be able to nail how much is the plate changing and how much is the increase in string tension due to the rise of the board. Can't imagine how one would isolate these two components for a test., but am open to ideas.    

    I am inclined to agree with David Love in terms of the plate changing dimension. In rebuilding and restringing, it is quite surprising to see how the plate dimension, even a short plate, changes unloaded to loaded. The string lengths at the bass can vary at least 1mm, sometimes more between loaded and unloaded states. We tend to think of the plate as static and unyielding, but on a micro, level, those densely packed molecules still are somewhat mobile. It remains surprising and to some degree hard to believe, even after seeing it again and again in real- time with my own eyes. 

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



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

    Registered Piano Technician
    Posted 04-01-2017 19:44

    Jim --

    Plates flex, as we know from the occasional one that cracks under the extreme tension of the strings. In addition to monitoring the changes in deflection of the soundboard at the bridge during stringing, it might be interesting to monitor the deflection of the plate, perhaps at the hitch pins, as well. 



    ------------------------------
    Geoff Sykes, RPT
    Los Angeles CA
    ------------------------------



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

    Registered Piano Technician
    Posted 04-02-2017 15:37
    Jim,

    I've been thinking along these same lines.  On a STRUNG piano I would want to set up a magnetic dial indicator on the plate as close to the hitch pins as possible with the business end trained on the back side if the bridge, another as you have described for the top of the bridge, and yet another mag on the plate somewhere but trained on the front of the bridge. That way when I snap the string I capture any possible bridge movement (theoretically).

    If the rear one shows movement, but not the front, that would imply plate movement. If both front and rear show complementary movement that would imply bridge movement largely. Top is obvious. Of course it doesn't tell us anything about the pinblock end of things but I'm sure something could be added.

    Probably best to snap more than one string to increase the odds of getting data.

    Just a thought out thought. 

    Pwg


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



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

    Posted 04-02-2017 21:12
    Or take a piano that's going to the dump, remove a few unisons and cut a notch through the open bridge. Replace the strings, now not touching the bridge, raise and lower tension on the strings and measure the pitch change of the neighbors, both on and off the bridge.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



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

    Posted 04-03-2017 19:33
    good idea Ed...I'll try this on my7 next pre-rebuild core

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



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

    Registered Piano Technician
    Posted 06-11-2017 21:33
    Jim,

    What were the results of your experiment when you jacked up the
    soundboard?

    FWIW, when I set up that same experiment, I put a dial indicator on top
    of the bridge as I jacked up the bottom of the soundboard at A4. I
    placed my jack on bathroom scales to record how much upward pressure I
    was putting on the soundboard. When I reached 15-20 cents sharp I
    stopped because I was at 150 pounds of upward pressure. Maybe I was
    wrong to stop, but I felt like I was pumping up a car tire that was
    ready to pop. The piano was a 1915 Hardman baby grand.

    Since then I have thrown away the raw data, not knowing how interested I
    would later become in this topic later on.

    Curious to hear about your findings,
    John Parham




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

    Posted 06-12-2017 09:43
    Hi John,

    Thanks for pointing out the thread where this discussion happened...I had lost track of it. 

    No I haven't messed around with this yet...its high on my list of things to do. My mom died a couple of months ago. As the trustee of her estate, I am taking some extended time with sibs, family, dealing with the trust, clearing/selling the house etc...believe it or not, all a very life affirming experience. So, though right now I'm in the shop, I'm mostly building us a kitchen...taking kind of a rebuilding break, doing things for my family. My son is doing the S&S action frame rebuilds, but I'm mostly taking a break...no pianos on the floor to molest...but molest I will, after a break.

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



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

    Posted 03-31-2017 06:24
    Hello Fred

    This 'old' restrung S&S 'A' - how old is 'old'?  (mine is 1914, Hamburg) Repair - did you replace the pair? (Roslau Blue?) or, if the break was at the Wrest Pin, did you slacken off its 'pair' and pull it round? I know, when a Bass covered string breaks and it's possible to do so, you do go for a knot (unless it's a 'performance' S&S) so the 'borrow-from-your-neighbour' seems appropriate here?   Michael   UK