Ryan, I, currently do not have a strung grand in the shop! (darn!) So, I'll leave it up to someone else to attempt the experiment. I really agree with your assessment of what is really happening. It's the whole structure that is reacting, IMO. Joe Joe Garrett, R.P.T. (Oregon) Captain, Tool Police Squares R I ----- Original Message ----- From: Ryan Sowers To: joegarrett at earthlink.net;pianotech at ptg.org Sent: 4/5/10 6:27:42 PM Subject: Re: [pianotech] pitch change The jack idea is a good one Joe! I look forward to hearing the results of this. Just don't pop out the soundboard! The other thing to consider is the pitch change in uprights when you push up on the keybed with your knees. You can sometimes get a pretty dramatic change in the octaves by doing this (especially on small pianos). My thinking is that since the keybed is attached to the plate that flexing the keybed causes the plate to also flex and change the octave widths. Some day I hope this leads to the holy grail of piano features: The Piano Whammy Bar! This phenomenon again makes me think that plate flex is possibly the greatest factor in seasonal tuning change - not because the plate itself is reacting to humidity (of course) but because expansion of the beams, soundboard, belly rail, keybed, etc is causing stresses on the plate to change. On Mon, Apr 5, 2010 at 4:24 PM, Joseph Garrett <joegarrett at earthlink.net> wrote: It seems to me, that if you have a grand in the shop, put a jack under the soundboard and just jack it up 1mm at a time and measure the pitch change. That would, at least, be a starting point of consideration, I should think. Change the humidity in your shop 10% see how much the soundboard will move. A piano will react very quickly to an increase in humidity, but will purge that humidity very slowly. (an article in Scientific American, 1970's proved all of this phenomenon). Those two quick experiments should tell us wether or not the soundboard swelling will change the pitch markedly. Of course, that is only one faction in the whole equation of pitch changing, due to atmospheric conditions, but it's a start. I'm really suprised that studies were not done and documented by some manufacturers. With all the Soundboard experiments that were, supposedly done, by Baldwin, there must be some documentaion laying around somewhere.?????? Joe Joe Garrett, R.P.T. (Oregon) Captain, Tool Police Squares R I -- Ryan Sowers, RPT Puget Sound Chapter Olympia, WA www.pianova.net -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100405/74bc5395/attachment-0001.htm>
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