Chines and multi-piece rims

[Delwin D Fandrich]

----- Original Message -----
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: <pianotech@ptg.org>
Sent: March 03, 2002 7:46 AM
Subject: Re: Chines and multi-piece rims


> Ok. I read you there.
>
> Let me carry this a tad further though for clarification of the issue. I
should think that you could never increase the mass of a rim too much -
except of course regarding cost considerations and/or possibly aesthetic
consideration.
-----

Perhaps. But there are also some practical limits beyond which the results
will be neither audible nor measurable.


>
> I ask that from strictly an acoustical perspective. Isn't that what we
want to do with a rim - immobilize the soundboard edge so that energy is not
lost there.
-----

Yes. Unless the designer has some other ideas about piano tone production.
Bosendorfer comes to mind. As does the Chickering/Marshall & Wendall
'semi-hinged' inner rim. Or, for that, the floating bass and the floating
treble.


>
> If that is true, then can I also assume that there is no acoustical
difference between the spruce many-multi-piece outer rim of a Bosendorfer
(aren't Bechsteins also like this? - perhaps others?) and a laminated bent
maple rim common to many American pianos (assuming again that there is
sufficient mass/stiffness to adequately immobilize the soundboard edge).
-----

Ah, but there are acoustical differences among these various rims. Just as
there is between continuous bent-laminate rims made of maple and those made
of Select Hardwoods -- even if their shapes are so similar as to otherwise
be virtual clones. Obviously, competent pianos can be built both ways but
each approach requires its own variations in soundboard design, scaling and
hammer characteristic. Acoustic response will differ as well. Whether these
differences are good or bad is for others to judge, though I have my
opinions.

Del