Hello List, I would like to add another variable into the discussion; in theory at least, I think it is possible that RC and RC&S boards might have a different tone character even if they are built with the same average mass/stiffness numbers as the CC board. I say this because the ribs are located in a periodic sort of a structure. We have a rib, and then there is no rib for some distance until the next rib. In such structures, one often runs into resonant effects that are caused by periodic discontinuities. As a wave travels through the board, every time it reaches a change in stiffness, mass, or dissipative loss, some reflection will happen. The portion that is reflected back may add in or out of phase with the other waves that are on the board. The problems usually start when the wavelength of the vibration is approximately two to four times the distance between the discontinuities (depending on the type of discontinuity). In a CC$S design, the ribs are extra stiff to take up more of the load, and the panel itself will be less stiff (if I understand correctly). so the stiffness is probably less uniform over its surface. On the average, the stiffnes can be made to be the same as in a CC board, but under dynamic conditions this is not the case. This is not an effect that can be measured statically by attaching a dial indicator and pressing down on the board - the board has to be in motion, and the relevant resonant modes have to be excited. One way out of that would be to design the CC&S board more closely spaced but weaker ribs. Once again, this is strictly a theoretical observation. Best regards, Vladan ============================= The question is whether or not there is some common acoustic properties and tendancies that CC boards have in general that RC and RC&S boards do not. Of course no two boards are acoustically identical, and I dare say that goes for any type of construction. __________________________________ Do you Yahoo!? All your favorites on one personal page – Try My Yahoo! http://my.yahoo.com
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