Jim, So wouldn't a slippery bridge pin be advantageous in helping to eliminate this "set". I would think a graphited bridge cap should be slippery enough? I understand we can't equalize the tension in all the segments because why? They are different lengths? David I. ----- Original message ----------------------------------------> From: James Ellis <claviers@nxs.net> To: <caut@ptg.org> Received: Mon, 12 Apr 2004 22:20:24 -0400 Subject: Why a string goes out of tune. >Wim, >If you didn't understand what I was saying, I feel sure there are others >who didn't as well. I'll try again. You say you can't believe that the >pitch of the speaking length can be changed as much as 50 to 100 cents >before the string will move at the bridge. Well, I can, because that's >what I measured. It will depend upon how much of a "set" the string has >taken at the bridge. I would expect it to be more in some cases, and less >in others. I'll admit I did not take many measurements. I plan to make >more measurements in the future, and I expect to find a very wide range of >values, for the very reason I just mentioned. >No, Wim, I am NOT saying playing the note softly will equalize the tension >across the bridge. You know that. I said pounding will cause it to move >if it is about ready to move anyway. If the tension is not equalized >across the bridge, but the string is about ready to move, but you play >softly, nothing will happen. But if you do pound, or if the pianist >pounds, then it will move, and the pitch of the speaking length will change. >Now consider the fact that you have a whole bunch of strings whose tensions >are only partially equalized across the bridge, because there is no way you >can completely equalize it. All it takes is for the relative humidity to >change, the bridge to swell or shrink, or the temperature to change so that >the difference in expansion coefficient between wood and steel will cause >the string to slip a microscopic amount at the bridge, or someone to pound >the key; the string will move at the bridge, and your perfect unison tuning >will be spoiled. I think this makes lots of sense. >Sincerely, Jim Ellis >_______________________________________________ >caut list info: https://www.moypiano.com/resources/#archives
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