Soundboards

[pianoman]

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> From: Stephen Birkett <birketts@wright.aps.uoguelph.ca>
> To: pianotech@ptg.org
> Subject: Re: Soundboards
> Date: Friday, August 15, 1997 10:26 AM
> 
> James wrote:
> > I was always under the impression that pianos like Steinway & M&H's
were
> > loud and powerful because the case was so rigid and unmoving that it
sent
> > the soundboard vibrations right back to the soundboard giving maximun
> > sound.  On the other hand the Bosendorfers are sweeter gentler sounds
> > because the spruce solid construction vibrates when the sound hits it
> > thereby soaking up (wasting) part of this sound.  Maybe Del can shed
some
> >...
> Dear Stephen,
Is it your opinion then that a piano like the Bosenbdorfer having solid
planks of spruce edge and face glued to form the case actually do waste
part of the soundboards power in soaking up vibration?
James Grebe
pianoman@inlink.com

> Rigidity and mass of the case are two independent parameters. The
> stiffness of spruce is actually extremely high, but mass is low...which
is
> why it is used for sbs. Hardwoods are not much stiffer, but have a lot
> more mass. Case construction is also an important variable (e.g. 
> framing)...but this is less significant in pianos with iron frames, since
> all are much the same in effect. All-wood pianos exist with massive case
> walls or less massive ones, but these were always made of spruce (at
least
> in Viennese/German tradition). It is the relationship between stiffness
> and mass that determines the energy transfer from sb to case, i.e.
> impedance mismatch at the edge of the soundboard. In general harpsichords
> and early pianos were built to be as weak as possible in the framing
(this
> was the arrogant mistake Pleyel etc. made in the early 20th C harpsichord
> revival), to allow the case to be flexible and contribute to the tonal
> structure of the instruments....Boesendorfer is the continuation of this
> concept, insofar as it can be continued into the modern piano. Of course
> there are many other issues that contribute to tonal quality/
> 
> Stephen
> 
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> 464 Winchester Drive
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> email: birketts@wright.aps.uoguelph.ca
> 
>