Piano Sound: was something else

[gordon stelter]

Well, it WILL reflect some vibration back, regardless.
The stiffer, denser, and more rigid the rim is, the
more vibrations will be relected back into the board.
What is not reflected will be tranmitted to the
case/rim, and either carried back to the board
somewhere else or dissipated as heat in the rim wood
fibers. I think it is optimal that this vibration be
dissipated by heat in the lampshades and curtains of
the room the piano sits in, not the piano itself.  In
other words, as much of the pianist's finger pressure
as possible should be converted to sound and LEAVE the
piano, before being absorbed by soft materials. I
believe the softer case woods in many modern pianos,
Asian or otherwise, largely contributes to their
relatively impotent tone when compared to high quality
pianos from 100 years ago!!!
     That said, the relationship between stiffness and
density will play a vital role in the piano's tonal
"personality". Some pianos ( Boesendorfer, old
Chickerings, Emersons, etc. ) use spruce for case and
beams, so that some of the energy transmitted to them
will still be converted to audible resonance. Spruce,
while light, is still considered a "hardwood" as the
fibers between the rfesonant vacuous cells are tightly
compacted. So it has both high transmittal and
resonant properties. But not the best reflective  
properties when used in a case application, as it is
not dense enough, overall, to make extremely rigid
structures.
     At the other extreme are old Knabes, which have
the most "rock hard" rims (and cases) I have ever
seen! In these pianos a fast, loud, rather hard tone
is emitted, as vibrations are quickly kicked back to
the board, which is held very rigidly by massive rock
maple cases.  I have seen many 100 year old Knabes
with excellent crown.  It should also be noted that
these boards have a heavy coat of finish, usually
shellac, which is extremely stiff ( and brittle ) when
fully cured. This brittleness surely aids vibrations
as they travel across the face of the board. ( But I
use 2 part "conversion" varnish, as it also has this
property but is more impervious to humidity, and is
inedible to the house crickets that live here. "Down
side" is that it emits formaldehyde fumes like crazy
for several months as it cures. ) 
     On many old pianos the cases were also veneered
with rosewood or ebony. This was not just cosmetic, as
these very dense woods transmited vibrations around
the case to where they could be re-absorbed by the
board. The builders new this.
    Gordon Stelter

--- Tony Caught <caute@optusnet.com.au> wrote:
> So you says that a rim  reflects or has to reflect
> ?. And why should it. ?
> 
> Tony Caught
> caute@optusnet.com.au
> 
> 
> ----- Original Message -----
> From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: Monday, September 16, 2002 5:13 PM
> Subject: Piano Sound: was something else
> 
> 
> > We keep ridiculing this, without really knowing
> what it refers too.
> Similiar subjects come up and get discounted more or
> less out of hand also.
> Yet much is made of the importance of string /
> soundboard impedance match to
> sustain and power. Perhaps there are other
> "impedance matches" to the
> strings energy that play an important / significant
> roll in the "end
> product" sound of the piano. Perhaps its not so much
> a matter of whether one
> rim reflects more  or better then another... but
> rather that one rim
> relfects an optimal amount.. ??
> >
> > RicB
> >
> > Farrell wrote:
> >
> > > This is what I am describing on the S&S upright.
> And are you speaking in
> reference to the "magic circle of sound"? Does a
> laminated rim "reflect"
> sound better than a solid timber frame?
> > >
> > > Terry Farrell
> > >
> 
> 
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