>What I was getting at was the claim that perhaps the loss of crown on a CC >board was due to the fact that the ribs are shorter as one goes up the >scale, and the shorter ribs were preventing crown from being formed, thus >creating the killer octave area. If that were true it would be more common >to have the killer zone forming in the seventh octave, rather than the >fifth or sixth as is most common. > >Terry Farrell No, I don't think that's the case. The loss of crown is because there is more bearing load on the structure in the killer octave, and on up into the treble than a thinned panel compression crowned board can be expected to support for long and still bend those short stiff flat ribs into a crown. As to the killer octave sound, it's hard to get a woofer to tweet, and if you want to move a diaphragm with a high frequency low amplitude driver, the diaphragm had better get smaller and stiffer as the frequency increases. Steinway's patents for diaphragmatic soundboards were from 1935 to 1937. So I wonder. Are there a greater number of Steinways out there from prior to 1935 with measurable positive crown in the killer octaves than Steinways made after 1937? Ron N
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