Soundboard Installation & MC

[Ron Nossaman]

>
> Del& Ron
> >>>>>And this really was my main point that it does  stiffens up considerably
> which is certainly some part of the dynamic equation for its ablity to
> produce tone.
> Perhaps not stated very well but in our ongoing discussions about the rims
> and board function this one little piece of the pie seems to be ignored or at
> least not considered as important. 
>     No it isn't germain to the tension resonator argument and I wasn't
> supporting it although that's where the discussion  started. I was merely
> making the point that this stiffening from gluing the panel to the rim is
> important. Although I'm calling it a supporting agent I don't /didn't imply
> that this is how the crown in the board was derived in the first place nor
> will it keep it from going away over time. Perhaps I was unclear.


Hey Dale,
Then why the mention of the flying buttress, which isn't exactly an edge clamp?
OK though, that's cleared up. I have more observations and questions. The glued
edge does obviously stiffen the assembly, but the *additional* crown support
from the beveled rim surface is what you're after. I'll try to make sense of
this, but no guarantees. 

The rim bevel only aids crown support as long as the bevel angle is greater
than the landing angle of the crown. The landing angle (or what would be the
landing angle if the panel wasn't glued down) depends on the crown radius,
length of the ribs, and deflection under load. If the bevel angle is less than
the landing angle, the initial effect would be to depress rather than support
crown. This is virtually always the case when installing a new board. In the
case of a flat cutoff bar, the perpetual effect is to depress rather than
support crown, but the assembly is still stiffened. Do you increase the bevel
angles to accommodate the tighter crown radii in the treble? What do you do
with cutoff bars?

The degree to which the rim bevel supports, or depresses crown depends entirely
on how much crown there would be without it. In either case, the stiffness is
there. I don't think there's any substantial tonal benefit to this levered up
false crown, though I do think it gives a false impression of functional crown
to the rebuilder when the strings are off, even though there was precious
little if any measurable crown under string load. For me, that puts it in the
negative benefit category.




>
>      On a different note since some of the old compression crowned boards
> survived for longer than they should have based on our experience with them
> it will be disappointing not to be around to see just how long the modern
> variety rib crowned board will survive tonally by comparison.
> >>>>>>>>>Dale Erwin>>>..


Yea, too bad we'll miss it. One thing we can count on though is someone out
there in the future a hundred years from now will be saying "Sure some of them
still sound pretty good now, but how can we know what they sounded like new?" 
"They had wood back then, you know, and special tone wood at that." "The secret
lacquer formula they used still has us stumped too." "If only they had written
down their secrets instead of taking them to the grave..." "We'll never prove
anything now."

Ron N