Baldwin SD-10

[Farrell]

> There is simply no way any potential soundboard expansion is going to be
> felt between the edges of the soundboard and the outer rim. This notion
> doesn't even make any theoretical sense, let alone any practical sense.

Ahhhhh, technically correct, BUT if does make MARKETING sense!

If it sells - it must be right/best/whatever! Sad but true.

Terry Farrell

----- Original Message -----
From: "Delwin D Fandrich" <pianobuilders@olynet.com>
To: <pianotech@ptg.org>
Sent: Thursday, September 06, 2001 10:24 AM
Subject: Re: Baldwin SD-10


>
> ----- Original Message -----
> From: "Farrell" <mfarrel2@tampabay.rr.com>
> To: <pianotech@ptg.org>
> Sent: September 06, 2001 4:48 AM
> Subject: Re: Baldwin SD-10
>
>
> > > The soundboard was designed to leave it approximately 5/8" short of
the
> > > outer rim all along the perimeter. The rationale, if I remember
> > > correctly, was to give the sound board room for expansion or
contraction
> > > depending on the season.
> >
> > So is the soundboard not glued to the inner rim so as to allow it to
> expand
> > to the outer rim? Or is it glued, and they simply designed the inner rim
> to
> > compress as the soundboard expands toward the outer rim? Kinda hard to
> > figure.
> ---------------------------------------------
>
> This subject keeps coming up in one form or another from time to time.
>
> There is simply no way any potential soundboard expansion is going to be
> felt between the edges of the soundboard and the outer rim. This notion
> doesn't even make any theoretical sense, let alone any practical sense.
>
> Most pianos have an inner rim that is somewhere on the order of 35 to 45
mm
> thick. Even if the inner rim is coved in a misguided attempt to 'increase
> the radiating area' there is still a minimum of about 20 to 25 mm of glue
> surface around the inner rim. The glues or adhesives used to bond the
> soundboard to the inner rim are typically quite rigid--that is, they do
not
> creep under load. They will fail before they will allow any creep. For any
> soundboard expansion to be felt around the outside parameter of the board
> there would have to be some slip across the glue line but, since the
> adhesives used do not allow that, the only possible way the gap between
the
> edge of the soundboard and the outer rim could change after assembly is
for
> the adhesive to fail catastrophically--and that's a whole other issue.
>
> The same logic applies to the notion that the edges of the soundboard must
> contact the outer rim to somehow 'reflect' sound back into the
> soundboard--or whatever it is that's supposed to happen out there. As long
> as the soundboard remains glued to the inner rim it simply doesn't matter
if
> the edges contact the outer rim or not. This may be an aesthetic
> consideration to some, but it is neither a performance nor an acoustical
> consideration.
>
> Del
>
>