Ditto, ditto, and ditto. Terry Farrell ----- Original Message ----- > I've never understood the importance of sound travelling through the > soundboard parallel to the grain and across the grain. When we "hear" a > piano, we're sensing air pressure differences, which are created by the > diaphragmatic movements of the board. Wogram states clearly in the > excerpts you provided, that the ribs are there to equalize the stiffness > of > the board across and parallel to the grain, to optimise the diaphragmatic > response. He says nothing about the speed of sound transmission throught > the wood, at least in the excerpts provided. Where does this idea come > from? > > Your online dictionary gives transmission speed as ONE EXAMPLE of > anisotropism, but Wogram is specifically referring to bending stiffness, > not transmission speed, as the anisotropic property being influenced by > the > ribs. > > I was watching Andre Bolduc's taped class on soundboard replacement the > other day, and he talked about the treble "reflector". On S&S > soundboards, > this strip of maple is attached to the beveled end grain of the soundboard > at the high treble end, according to Andre it's to keep the sound from > leaking out of the end grain. Huh?? Where does this idea come from? > > Mike > > >> [Original Message] >> Prompts me to ask a bit about an idea being thrown around in an off list >> dialoug I am having with a couple folks. The idea is not mine but it >> sounds intriguing. Let me throw this at you (and whomever else might be >> interested to comment). I'll let the fellow who threw this at me speak >> up for him/her self if they so choose. >> >> The primary acoustic function of the ribs is to transfer sound cross >> grain more or less as fast as it otherwise buzzes along the grain. What >> if we could make a soundboard with enough crown support perpendicular to >> the bridge without support from the ribs (or nearly as much as we use >> in todays instruments) ? >> >> The idea that strikes me as being able to perhaps do exactly this is to >> allign the grain perpendicular to the bridge, and construct a >> pre-crowned soundboard panel of several laminants, all with grain going >> the same direction. With the grain going perpendicular to the bridge and >> what crown support the unribbed soundboard would have, cross grain >> ribbing would be able to do their acoustic job and provide a bit of >> extra support to the curvature of the wood while being of much smaller >> dimensions. In addition... the bridge itself would function like the >> ribs in speeding sound cross grain. It might be a way of approaching >> the different requirements of the bass and high treble areas. >> >> Cheers >> RicB
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