Permanent Soundboard Crown!

[Farrell]

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Hey Ric, maybe you'll enjoy this one more - it goes even further - from =
the Bluthner web site:

At the beginning of piano making the soundboard consisted solely of a =
thin wooden board, stiffened with bars glued on the underside and the =
bridges on the upper side. Further development was derived from the =
soundboard of a violin with its spherical crown. However the soundboard =
of a violin is made of a thick piece of wood being shaped by grinding, =
chipping and sanding into its final form.

=20
A piano soundboard is made from a thin board being bend by force into =
this form. This method however produces disadvantages comparable to =
those which one will experience when you try to put a sheet of paper =
atop a ball.

Studies made by Bluthner research and development department have proven =
that tensions and compressions develop on the edges that are =
inhomogeneous and not controllable. In contrast, the soundboard that =
Bluthner has developed has a cylindrical curvature so that the tension =
of the soundboard can be exactly defined. The ribs are planed to fit the =
curvature needed and therefore the tension of the soundboard remains =
intact over the decades. In fact, even under difficult climatic =
conditions the curvature will remain in a constant form since not only =
the rib structure will hold it in place but also the red beech inner rim =
is preformed to the correct angle to receive and retain the soundboard's =
curve tension. Because the soundboard is pre-stressed in this fashion it =
can be fitted exactly and remain under curve tension permanently. The =
bridge, of course, is adapted to the tension and curvature of the =
soundboard in its optimum position. This ensures that string vibrations =
in their full spectrum are transferred to the soundboard. By utilizing =
the resonating surface, the special design of the Bluthner soundboard =
generates tone significantly better.=20

Ok, new terms now. "Curve tension" - any engineers out there? Look that =
up in your old Engineering 101 book. Cylindrical curvature? The top of =
their inner rim in not more-or-less planar (and the few that put a =
slight rise in the concave curved side doesn't count)? And somehow the =
angled inner rim retains the soundboard's curve tension! Also, how does =
one go about adapting a bridge to tension and curvature? The curvature I =
can roll with, but the tension? Who/what is pulling where? Or maybe they =
are just pulling our leg?

Fun thoughts.

Terry Farrell

----- Original Message -----=20
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: "Pianotech" <pianotech@ptg.org>
Sent: Wednesday, January 28, 2004 1:53 AM
Subject: Re: Permanent Soundboard Crown!


> Grin...
>=20
> Funny how we keep running into this from so many places isnt it ?  You =

> simply have to wonder :)
>=20
> Cheers
> RicB
>=20
> Farrell wrote:
>=20
> > From the Kawai US web site - enjoy!
> > =20
> > *The Drying/Re-Moisturizing Process.* Kawai employs an inventive=20
> > method to create a permanent soundboard crown.=20

SNIP
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