JIMRPT@aol.com wrote: > Del; > Didn't someone, or several someones, do some experimentation using a priciple > something similar?? It seems to me that the thrust of this experimentation > was to place iron shavings on the soundboard , excite the board with some such > device and see the vibratory patterns, etc., that developed, or am I just > having hot flashes? > Jim Bryant (FL) ------------------------------------ Yes. If memory serves, these are called Chladni figures. They are derived by layering the soundboard surface with a fine sand and driving it with shaker connected to a variable frequency sine wave generator. The signal generator is swept very slowly through its various bands, stopping when the sand arranges itself into distinct patterns. These figures show the resonant modes of the soundboard. I have never conducted one of these tests, but I have seen the results. They are interesting but fairly useless in terms of analyzing the working soundboard. These tests have all been conducted on bare soundboards. That is, unloaded. In one case the bridges were not even on the board. To be useful it would have to be done with string tension and downbearing. Then, of course, the plate would cover much of the surface being examined. Del
This PTG archive page provided courtesy of Moy Piano Service, LLC