---------------------- multipart/alternative attachment In a message dated 12/31/2004 1:47:55 P.M. Pacific Standard Time, claviers@nxs.net writes: Jim Nice post. Happy new year Dale Erwin I won't repeat the previous posts, because I don't believe it's necessaty. Ron Nossaman is mostly correct. The drastic change in pitch of one section when the tension is off an adjacent section has more to do with the plate than it does the soundboard. But it's not so much "compression" of the plate as it is "deflection". It's the fact that the plate wants to bow up when it's under tension. Release the tension of one section, and the plate straightens out a little. Put the tension back, and the plate bows up again. That's what the nose bolts and the "horn" are for - to minimize the upwatd bowing. It may not be obvious to the eye, but if you will put a rigid beam across the piano, and some dial indicators measuring both plate and board deflection at different places as you change overall tension, you will see what's happening. I have done that, and the dial indicators tell the story. It's both plate and board, but as Ron says, I believe in this case, it has more to do with the plate than it does with the board. Another point missed here. If you look at one string only, and see changes in neighboring strings, a part of that change will be coming from compression in the bridge itself - i.e., forces on bridge pins being reflected to neighboring bridge pins. If you look at the bridge on a microscopic scale, you will see that it is not a rigid body at all. On the cell-to-cell scale, it is somewhat springy too. Conclusion: Because of the obvious plate deflection, you can't assume anything about the board. When you change the tension, everything moves just a little bit, but not in the same direction. Sincerely, Jim Ellis ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/caut.php/attachments/09/cf/82/29/attachment.htm ---------------------- multipart/alternative attachment--
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