Stein grand unique board

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip L Ford" <fordpiano@lycos.com>
To: <pianotech@ptg.org>
Sent: January 06, 2002 1:17 AM
Subject: Re: Stein grand unique board


> But I question whether having them reflect back
> from the rim is necessary for the soundboard to serve its function in the
assembly
> or whether this wave traveling and reflection is really the thing that we
need to
> worry about in designing a soundboard system.

Any movement of the rim assembly will detract from the amount of energy in
the soundboard system still available to produce audible sound. The energy
to produce that movement has to come from somewhere.



> If you can separate the soundboard
> completely from the rim (I realize that the Stein was not completely
disconnected)
> and have it still function properly in the assembly, then perhaps the
conventional
> idea that the rim needs to be heavy to 'reflect waves' is not correct.

That Stein soundboard system was/is not even close to being completely
disconnected from the rim assembly. Nor were those of the run of new some
pianos I examined a while back in which either the rib notches had not been
cut deeply enough or the rib feathering had not been taken down enough--or
both--and the soundboard was held off the inner rim surface by about 3 or 4
mm. A floating soundboard? No, it was still held in place by the ribs.
Though, in this case, perhaps not for long.



> Or perhaps the idea that the rim needs to be heavy is correct but
> for a different reason.  One way to design would be to do as Ron N
suggested.
> Make the rim heavy so that you essentially have an inert attachment for
the
> soundboard.
> We know this works, and can work well.  It also eliminates one of the
variables that
> you have to worry about.
> But, as you say, the assembly works as a whole.  Perhaps the rim should be
one of
> the variables.  Perhaps if you had a really thin rim, or a solid rim with
a knife edge
> sitting on top of it that the soundboard is sitting on which allows it to
act as a simply
> supported member, or some other idea I haven't thought of yet you might
get a sound
> that is more to your liking.  Since the assembly works as a whole, chances
are if you
> use one of these other rim designs you will have to change your board
design, and rib
> design, and bridge design and you'll be giving up the opportunity to use a
couple
> hundred years of accumulated wisdom but you might have some fun in the
process.

The rim is one of the variables. In the current scheme of things soundboards
work best when attached to a rim that is both massive and stiff. Ron is not
alone in saying this, nor is he the first. Nor was I--the notion goes back
at least 125 to 150 years, probably some longer.

I don't know if lighter, more flexible rims can be made to give equivalent
(or better) performance with soundboard systems using totally different
design concepts. I've not heard a piano yet with a 'Select Hardwood' rim
that I really liked all that much, though some are certainly a lot less bad
than others.

I do know that Baldwin's experience was not good when they tried arbitrarily
changing from a maple rim to a poplar rim. I also know that our own
experience was not what I expected when I put one of our soundboard systems
in a Yamaha with a light and flexible rim.

As long as the perimeter of the soundboard is fixed to the rim, be it either
clamped-edge or a hinged-edge, there are going to be energy losses to the
rim. The only way around this that I can see is to convert to a fully
piston-mode diaphragm (i.e., like a perfectly rigid loudspeaker cone)
operating completely independently of the rim. Which might well be doable
but I'm not going to spend a lot of time on it just now.

So, in my opinion and using soundboards of either more-or-less conventional
design, or of some other design but still fixed to the rim, I also say that
the rim, being part of the overall system, should be both massive and stiff
so that it does not readily absorb energy from the vibrating (and bending)
soundboard.

Del

>
> Phil F
>
>