Newton Hunt wrote: > > Hi Fred, > > My commiseration. I remember those days. 15% in winter and > 85% in summer. Movement as far as 100 cents season to > season. What a pain with 145 pianos and being the only one. > > Still back to the original post about the no pin block > piano; I am still puzzling over the dynamics of your > observations. How DOES that work? > > Newton Newton, The best I have been able to puzzle out over the years is that the soundboard/bridge/plate operate more or less as a system. Soundboard pushes up with added humidity, but bridge is constrained by the plate (relatively shorter length of wire on hitch pin side tending to "pull down" on the back of the bridge). So the bridge "rolls" (speaking length side rises more than back side). Since the notches aren't parallel to the bridge sides, one side of the notch moves more than the other. Thus, one side of the unison moves in pitch more than the other. Possibly the bridge also tends to move "sideways" relative to the plate in some fashion. That's all very well, but it sure doesn't seem like the geometric differences would be enough to account for the pitch difference - upwards of 15 - 25 cents - between left and right strings. And it sure doesn't tell me why this often happens worst in the highest treble (octave 7) where the notches are closest to parallel to the bridge. So frankly, I haven't the foggiest idea how it happens. Just know it does, from long years of observing. Regards, Fred Sturm University of New Mexico "A mind is not a vessel to be filled, but a fire to be kindled."
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