Soundboard stiffening (was Re: No downbearing)

[Richard Brekne]

Erwinspiano@aol.com wrote:

> In a message dated 2/1/2004 12:51:33 PM Pacific Standard Time, 
> fordpiano@earthlink.net writes:
>
>     Ric writes
>
>  My own degree of understanding of these matters still remains at a
> >rather young stage, yet one theme comes back again and again in
> >these discussions. That is that the sound that the panel is able to
> >project is dependent upon its stiffness and mass.  Certainly any
> >particular combination of these is in itself independent of string
> >coupling. John Hartman is correct in saying that down bearing can
> >increase the stiffness of the panel without added to the panels
> >mass... tho the strings have mass to... and these  things have a
> >habit of working both ways in some sense or another... Still
> >essentially John is correct..........
>    I think I can hear Del gnashing his teeth. If stiffness was all 
> that one wished then running ribs at 90 degrees to the grain is the 
> least stiff configuration. If the ribs are run at substantially less 
> than this the stiffness also goes up without adding mass.

I dont think I said anything like "stiffness was all that one wished" 
Dale. I said that the combination of stiffness and mass was the 
important bit... more specifically the stiffness to mass ratio was 
important.

The desire to counter anisiotropic, inhomogeneous nature of wood tends 
to limit ones options a bit as to rib orientation.

But I still dont see that any of this has anything to do with String 
coupling per se.

Maybe its more sematics that is hanging this discussion up then anything 
else... but let me put it this way. You can attach a wire as solidly as 
you like to just about anything... create exactly the same degree of 
coupling... but if one the one hand you couple the string to a panel 
made of water soaked balsa and on the other hand a panel of steel  you 
are definantly going to get completely different sounds... regardless of 
the coupling... and most certainly regardless of whether the string 
coupling effected any static downwards pressure on either panel.

So Davids question as to whether he could walk into a store.. measure 
negative bearing at a spot and conclude without further ado that there 
is a <<problem>> must be answered with a no. You need to know more, and 
you need to define better exactly what  the <<problem>> relating to this 
condition  is /(could be).

In the first place... its quite concievable that no << problem >> can be 
associated with any particular instance of localized negative 
downbearing.  Then, in the second place.. you immediatly open a 
monsterous can of worms, as much of what can be considered a <<problem>> 
in this context, is going to boil down to whether any particular type of 
sound is pleasing or not... good or bad... acceptable or not.... a 
subjective sumphole to suffocate in :)

RicB