Soundboard thoughts / questions

[Ric Brekne]

Hi Terry, Stephane and others.

Terry writes:
    RicB wrote:

     > -- Given a low enough tensioned scale,  this could be
    accomplished by
     > running the grain of the soundboard (roughly) perpendicular to the
     > bridges. Especially if that soundboard was laminated crowned in that
     > direction.

    I wonder if there is an efficiency in concentrating soundboard spring
    strength by using ribs. Maybe building the crown support into the panel
    would make the whole soundboard too thick for optimal sound
    production. I
    don't know.

Yes... but I wonder if crown support built into the panel, designed for 
a low enough tension scale could avoid that kind of problem. 


     > Questions relating to the above:

     > -- What would be the needs and purposes for ribbing this kind of
    board
     > across the grain ?

    I don't know.

Well... I would at least think that getting cross grain stiffness up 
would be one concern.  But are there any others ? Ribs in this direction 
wouldnt have a lot of load support efficiency as you point out... so 
what else is there ?



     > Perhaps this all sounds a bit off the wall... but I would
    apreciate any
     > thoughtfull answers.
     >
     > Thanks
     > RicB

    I've got a question or two myself. Grain angle. Most manufacturers
    have the
    grain running roughly 45 degrees to the belly rail, parallel to the
    long
    bridge and perpendicular to the ribs. Was this done to facilitate
    compression crowning the soundboard? I can see that grain running
    parallel
    to the long bridge would be the most efficient arrangement for
    compression
    crowning. What effects does grain direction in the various areas of the
    piano scale have on tone, sustain, dynamics or whatever a designer
    would be
    concerned with?

    Terry Farrel

This kind of question has begun to cause an itch with me as well.  I 
think I'd like to hear some general discussion about the pros and cons 
of runing grain at roughly perpendicular to the bridges. And then put 
those pros and cons into the perspective of a laminated board  running 
in that same direction with crown laminated into the thing.  Del has 
mentioned several times he thinks compression crowning was an historical 
accident to begin with...   Given other discussions, I dont think grain 
direction in itself would have a determinate effect on tone, sustain, 
and dynamics unless grain direction forces some limitations on the 
stiffness/mass relationship of the whole thing.  I suspect on what I 
think I understand at this point that perhaps that might be that such a 
panel might not be able to support quite as much load as modern 
conventional panels can... which would force lower tension scales to 
compensate...  but other then that... well  thats kind of what I am 
asking about.

Cheers
RicB