Yes Tony, we are on the same thread here, indeed!
I have long envisioned a soundboard NOT attached
at the rim. And not of wood, but a very light one of
open cell styrene board ( as in common or modified
insulation panel ) attached to carbon composite ribs
( as in fishing poles, golf clubs, etc. ) of the
proper shape and size to keep the bridges "in place".
In fact, the ribs would be attached directly to the
bridges, on TOP of the soundboard, mitered into
notches in the bridges, with the styrene acting as a
resonant diaphragm. And the styrene might hang at 90
degrees to the floor, not parallel with it. Or be in
layers with spacing, as it is so light that multiple
layers could be used. Combined with a very rigid rim,
this arangement ought to have terrific sustain. And if
you added screw-stringer tuning, would almost never
go out of tune due to the otherwise lack of wood.
I know this sounds a bit obnoxious. I too like
yhe esthetics of wood. But its awfully fun to think
about!
Gordon Stelter
--- Tony Caught <caute@optusnet.com.au> wrote:
> Hi Gordon,
>
> I try to look at this another way, I know that what
> you are saying seems to
> be the general consensus but.
>
> The original vibrations come from the strings, these
> vibrations are
> transmitted along the bridge to other strings
> causing them to vibrate in
> sympathy with the original strings and at the same
> time, to the soundboard.
> Now the soundboard is vibrating in a very complex
> manner. It must be to
> allow machines like Tunelab to pick up all the
> harmonics of a particular
> note when other notes are sounding as well.
>
> Now all these frequencies travel at different wave
> lengths and if they are
> reflected back from the rim out of phase then they
> would cancel out the
> frequency coming from the string.
>
> Thus, IF the rim is reflecting the vibrations back
> into the soundboard the
> resultant sound will vary in accordance to the pitch
> of the notes and key in
> which they are played. I would prefer a sound that
> comes from the strings
> without any rim echo.
>
> The firmer the rim or the edging of the soundboard
> the better but my
> thoughts are this. If the rim is solid and rigid
> then the soundboard will
> be held in a more exacting position. If it is solid
> it will also not
> vibrate. Yes it will transmit the sound but it will
> not vibrate as the
> soundboard does, thus the vibrations stop at that
> point.
>
> Possibly in the ideal piano the rim should be rigid
> and solid, the
> soundboard attached only by the ribs with the boards
> thickness varying from
> 1/4" in the bass to 1/2" in the treble with possibly
> the ribs becoming
> closer as they progress to wards the treble. This
> way the rim cannot
> possibly reflect the vibrations back and the board
> would be totally reliant
> on the strings for the sound generation.
>
> When the sound or vibrations are leaked to the case
> whether this is via the
> rim or the pressure bar or the iron frame the energy
> is taken away from the
> soundboard to the detriment of the tonal qualities
> of the piano.
>
> A solid rim is ideal for holding the soundboard and
> thus the bridges
> attached to the soundboard in an exact position. If
> the soundboard is
> attached only via the ribs less restrictions are
> there to allow the
> soundboard to vibrate freely. If soundboard is
> vibrating freely then there
> is less energy lost. If the soundboard has more
> energy then the sustain will
> be longer, the volume louder and the tone more
> harmonically rich.
>
> Some manufacturers are heading this way but at a
> slow pace. But as you have
> heard from Ron Overs and Del Fandrich and and first
> you have to prove you
> are right over 50 years to be accepted. There are
> many other aspects of
> construction to be considered, maybe if this thread
> carries on they also can
> be explored.
>
> Now, what do you think. Lets see if we can build on
> this concept or should
> it be cast aside.
>
> Regards
>
>
> Tony Caught
> caute@optusnet.com.au
>
>
>
> ----- Original Message -----
> From: "gordon stelter" <lclgcnp@yahoo.com>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: Monday, September 16, 2002 6:26 PM
> Subject: Re: Piano Sound: was something else
>
> >
> > --- Tony Caught <caute@optusnet.com.au> wrote:
> > > So you says that a rim reflects or has to
> reflect ?. And why should it.
> ?
>
>
>
> > 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
>
>
> _______________________________________________
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