[CAUT] Fwd: Mason & Hamlin soundboard model with tuning fork

[Delwin D Fandrich]

Yup, that's pretty much it. I've been looking for a simple demonstration
setup but that hasn't happened yet. What I do know is that the demo setup
proving that you can make a board resonant at A=440 Hz but wedging it up
from one side doesn't tell us much of anything about how soundboards work.
Or about soundboard crown. Or about the interaction between strings and
soundboards. About the only thing that device proves is that somebody in
marketing didn't know much about how soundboards work. And that he or
she--probably he--didn't really want to learn about anything that might
upset his cheap and easy demo setup.

ddf

Delwin D Fandrich
Piano Design & Fabrication
6939 Foothill Court SW, Olympia, Washington 98512 USA
Phone  360.515.0119 — Cell  360.388.6525
del at fandrichpiano.com — ddfandrich at gmail.com


-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Ron
Nossaman
Sent: Friday, May 11, 2012 4:35 PM
To: caut at ptg.org
Subject: Re: [CAUT] Fwd: Mason & Hamlin soundboard model with tuning fork

On 5/11/2012 4:08 PM, Alan Eder wrote:
> Got it, and thanks for the explanation. Is there any simple 
> demonstration model that can readily A/B the effects of crown (with 
> its attendant resonance/sustain and power/projection) vs. no crown, 
> preferably on the same piece of surrogate soundboard? That is what is 
> really needed to faithfully get the point across.

That's what's needed to get the point across, agreed, but the problem is
that the point is incorrect. Crown, per se, isn't necessary to soundboard
function. Crown in a compression crowned board as is used by Steinway is an
artifact of high panel compression bending flat ribs up into a curve when
the panel rehydrates. The ribs are actually resisting the formation and
maintenance of crown. Loading this panel with string bearing pushes the
crown flatter, and makes the assembly stiffer as the panel compression level
reaches it's physical limit. The stiffness is what you're after. Given
enough stiffness built into the assembly, crown isn't needed. Stiffness can
be achieved with crowned ribs, acting as support beams, but the ribs need to
be considerably stiffer than those in a compression crowned board to support
string bearing with measurable positive crown without high panel compression
levels.

I not only don't know of a simple demo of how soundboards work, I don't know
how to explain it adequately without spending most of a day doing it.
Ron N