This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- Original Message ----- =20 > Thanks for the post. I wont pretend to know one way or the other for=20 > sure mind you. =20 Well, we certianly have that in common! > But it does strike me that as a consequence of=20 > compensating for anisotropism that both the bending stiffness and = speed=20 > of sound in both directions are evened out. Since it is sound (waves) = > traveling through that actually causes whatever vibrational motion=20 > soundboard displays.... And this is the heart of my question. Do sound waves travel through = soundboard wood (in any meaningful way) or does the soundboard assembly = act primarily as a diaphragm whose vibration is caused by the vibrating = bridge, which in turn is caused by the vibrating string. That is the way = I've always pictured it. And hence my "circle of sound" comments. I know a soundboard is not a speaker - but how different is it? A stereo = speaker does not rely on soundwave transmission through the cone = material - but rather it is simply driven by the coil and magnet and = electic current. Is not the soundboard simply driven in a similar way by = the strings/bridges? > its strikes me that speed of sound in all=20 > directions is an intregral part of that motion.=20 >=20 > Be that as it may... lets just agree on the exact quote from Wogram = and=20 > get back to the main question I had. He said >=20 > "From the measurements it can be concluded that the two most > important functions of the ribs are to stiffen the soundboard and = to > compensate for the differences in bending stiffness parallel to and > across the grain (anisotropism). The bending stiffness exerts a > greater influence than the mass. For this reason it is more > advantageous to use narrow, high ribs than ribs with a low and wide > section." >=20 > What I'm thinking about is that in principle achieving equal bending=20 > stiffness in both directions is in itself an independant objective = from=20 > supporting crown. However In boards that have the grain going in the=20 > same direction as the bridge these two requirements must be balanced=20 > against one another.... perhaps even to some degree are at odds with = one=20 > another ? =20 I'm not sure that is true. Keep in mind that I am thinking of a rib = supported and crowned soundboard system. > On the other hand.. if you built a soundboard with grain=20 > going perpendicular to the bridge and were able to establish enough=20 > crown support along the grain by way of cauled laminants all going in=20 > the same direction, then ribbing across grain could be used = exclusivly=20 > to equalize bending stiffness. >=20 > It strikes me that the soundboard needs crown support more in the=20 > direction perpendicular to the bridge then paralell to it. My suspicion is that you could do it either way - it is done = perpendicular to the bridge because it is simply quite a bit easier and = effective to span that shorter distance (perpendicular to long bridge) = with a number of ribs rather than spanning the lenght of the the bridge = with fewer ribs. Terry Farrell > The bridge=20 > itself is very stiff lengthwise to begin with. The need for support=20 > perpendicular to the bridge appears (to me at this point) to be one of = > the primary reasons todays soundboard construction uses ribs in that=20 > direction which in turn requires grain to go paralell to the bridge.=20 >=20 > There is much about all this I dont understand.... but I'd like to = hear=20 > what problems this kind of configuration would have.=20 >=20 > Cheers > RicB ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/b2/bb/a4/1d/attachment.htm ---------------------- multipart/alternative attachment--
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