Question : Tuning a piano where pitch is 2-3 cents flat and a string breaks @ let's say note C-64. Humidity hasn't changed unless profane comments muttered under ones breath is a factor but now three or four notes on either side of the break are a few cents sharp. I thought with less force bearing down on the bridge at that specific point that the bridge rises and increases tension on the adjacent strings. Is this a convenient but incorrect explaination of what is going on here and does this fit somehow into our current discussion? Tom Driscoll > Thomas Cole wrote: >> Trying to understand how a lossy termination results in a lower pitch, I >> imagine that there is an effective elongation of the speaking length due >> to the reduced rigidity of the drier wood parts in the cap and root of >> the bridge, and possibly the board, and that there is an effective >> shortening of the speaking length when those parts are made more rigid by >> the uptake of moisture. In other words, a less stiff termination is more >> likely to move with the vibration of the string and so the actual point >> of termination has to be somewhere behind the bridge pin. > > Effectively, yea, that's it. It's been observed and noted (if not > quantified to infinity) in actual trials. A flexible termination acts like > a longer speaking length than a rigid termination. In a piano, this would > translate into a string of given tension on the high humidity (higher > compression/stiffer) board producing a higher pitch than the same string > at the *same tension* on a dryer (lower compression/more flexible) board. > It makes it a lot harder to come up with a simple consumer grade one > sentence specific explanation of why pianos go out of tune with humidity > changes, but I'm becoming more convinced that it's a real factor. > Ron N >
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