Hello Richard, (and hello Kjell Sverre!) Since I also was there at that last lecture of the last day... :-) > Chaladni patterns are created by exciting the panel to one of the > reasonant frequencies found, and you dont do that by just taking out a > plastic hammer and smacking the bridge with your hand. I always thought that knocking at the soundboard would make it resonate at something like the fundamental resonance frequency? Mr Fandrich called it a "broadband impulse tone generator" I believe? > Aslo... The fundemental frequency mode pictures I have > seen never follow the edge pattern of the soundboard /rim. I think that the pictures shown at the lecture showed areas well away from the rim that "contained sand" and I seem to remember that they were indicated by Udo Steingraeber as noteworthy. But you are right that the objective of the described practice was not modal analysis as such. As Udo Steingraeber stated, "that's in the design process". This practice as I understood it was instead used in the production process as a way of indicating stiff areas, or maybe rather points, close to the the rim/soundboard connection, with special care taken to the area in the upper treble where the bridge closes in to the belly rail (right word?), a.k.a. the "killer octave". And a thing I think we both noticed, Richard, was the strikingly long and singing sound of the upper treble part of the Steingraeber grands at hand at the Treff. Who knows... :-) -- Best regards, Östen Häggmark, Stockholm
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