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<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><EM>----- Original Message ----- =
<BR>>
Thanks for the post. I wont pretend to know one way or the other =
for
<BR>> sure mind you.</EM> </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial>Well, we certianly have that in =
common!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><EM>> But it does strike me that as =
a
consequence of <BR>> compensating for anisotropism that both the =
bending
stiffness and speed <BR>> of sound in both directions are evened out. =
Since
it is sound (waves) <BR>> traveling through that actually =
causes
whatever vibrational motion <BR>> soundboard =
displays....</EM></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial>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.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>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?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><EM>> its strikes me that speed =
of sound in
all <BR>> directions is an intregral part of that motion. <BR>> =
<BR>>
Be that as it may... lets just agree on the exact quote from Wogram and =
<BR>>
get back to the main question I had. He said<BR>>
<BR>> "From the measurements it can be concluded =
that the
two most<BR>> important functions of the ribs are =
to
stiffen the soundboard and to<BR>> compensate for =
the
differences in bending stiffness parallel to =
and<BR>>
across the grain (anisotropism). The bending stiffness exerts
a<BR>> greater influence than the mass. For this =
reason it
is more<BR>> advantageous to use narrow, high ribs =
than
ribs with a low and wide<BR>> section."<BR>> =
<BR>>
What I'm thinking about is that in principle achieving equal bending =
<BR>>
stiffness in both directions is in itself an independant objective from =
<BR>>
supporting crown. However In boards that have the grain going in =
the
<BR>> same direction as the bridge these two requirements must be =
balanced
<BR>> against one another.... perhaps even to some degree are at odds =
with
one <BR>> another ?</EM> </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial>I'm not sure that is true. Keep in mind that I =
am thinking
of a rib supported and crowned soundboard system.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><EM>> On the other hand.. if you =
built a
soundboard with grain <BR>> going perpendicular to the bridge and =
were able
to establish enough <BR>> crown support along the grain by way of =
cauled
laminants all going in <BR>> the same direction, then ribbing =
across
grain could be used exclusivly <BR>> to equalize bending =
stiffness.<BR>>
<BR>> It strikes me that the soundboard needs crown support more in =
the
<BR>> direction perpendicular to the bridge then paralell to
it.</EM></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial>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.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Terry Farrell</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial size=2><EM>> The bridge <BR>> itself is =
very stiff
lengthwise to begin with. The need for support <BR>> perpendicular to =
the
bridge appears (to me at this point) to be one of <BR>> the primary =
reasons
todays soundboard construction uses ribs in that <BR>> direction =
which in
turn requires grain to go paralell to the bridge. <BR>> <BR>> =
There is
much about all this I dont understand.... but I'd like to hear <BR>> =
what
problems this kind of configuration would have. <BR>> <BR>> =
Cheers<BR>>
RicB<BR></EM></FONT></DIV></BODY></HTML>