I wonder if anyone has ever tried to actually isolate any of the factors mentioned and get to the bottom of the question, or if there is simply a tendency to replace one set of assumptions with another ? One could actually contrive a tuning pin in a block fastened to a <<plate>> that is strong enough not to give and take the entire soundboard/bridge assembly out of the question. One could actually measure any differences (if any) resulting from different soundboard/bridge assembly types in similar fashion. One could even take the cyclic pressures of wooden parts out of the equation if one wanted to. I would assume we dont really know because its not interesting enough a question to warrant the time and eventual expense of really finding out. I mean ok... in passing its an interesting question, and fun to toss around some ideas... reason a bit with some known facts. I know from experience for example that pianos with very very tight pins hold seasonal pitch better then those that are just tight. Now I havent actually gone and done any controlled experiment to confirm this or not... so I cant be certain. But if its true then that points in the direction of tuning pins having something to do with pitch loss. The reasoning relative to wood / seasonal changes below also lines up as a good indicator. But unless somebody actually takes the time to do a series of controlled experiments to confirm things, there will always be a significant element of the <<guess>> in any reasons we give as probable. I would guess... :)... that pitch loss is a result of a conglomerate of issues. But I dont really see what we can do about it beyond contriving systems like DC units which demonstrably have a positive effect. Cheers RicB /Then do you have a "combined" explanation of pitch drop over time? />/ />/ />/ Regards, />/ Don Rose / > / With every cycle, bridge caps crush, bridge pins migrate, soundboards with high panel compression > > flatten, tuning pins migrate in the block. None of these tends to raise pitch in the long run. > > The universal assumption is that the tuning pins are turning backward, > which seems unlikely to me, > but none of the affects of cyclic pressures on wooden parts are considered./ >
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