Chines and multi-piece rims

[Delwin D Fandrich]

----- Original Message -----
From: <A440A@AOL.COM>
To: <pianotech@ptg.org>
Sent: March 03, 2002 3:43 AM
Subject: Re: Chines and multi-piece rims


> Del writes (and confuses me):
>
> >The continuous bent rim has certain manufacturing advantages but it has
> >no acoustical advantages that I am aware of.
>  <big snip>
> >So, having said all that, there is at least one compelling reason for my
> >use of a multi-piece rim: its potential acoustic superiority. I can
better
> >shape the treble soundboard and I can more easily float the bass end of
the
> >soundboard.
>
> Greetings,
>    Perhaps I am reading it wrong,  but these two statements seem to be
taking
> different paths.

Not really. We are used to the idea of the continuous bent-lamination rim
being somehow inherently superior to the mult--piece rim. Yet I have never
heard anything approaching a compelling argument proving -- or even
explaining adequately -- this supposed acoustical superiority.


>
> Does "its potential acoustic superiority" refer to the
> geometry it makes possible?

This comment refers to the soundboard's shape and size.


>
>    I don't think we can discount the acoustical importance of the rims,
since
> they are not only massive, but are entrained via their connections in the
> string-bridge-soundboard-case-plate-string -etc circle.  Wouldn't the
> "impedance" of the rim have a measurable effect?

I am not discounting the acoustical importance of the rim. I'm emphasizing
it and capitalizing on it. Yes, the impedance of the rim is measurable. But
a multi-piece rim can be built with just as much mass and stiffness as a
continuous bent-laminate rim.


>
> I know we can use uprights
> with their jointed constructions as a case in point,  do they have the
same
> output as a continuous wrapped grand?

They certainly can have. Our 122 cm vertical easily matched or exceeded the
power and sustain of a certain well-known 5' 10 1/2" grand.


>
> Would it be fair to draw comparisons
> with the Lucite cased grand that has been on display (or did it have a
wooden
> inner rim?)

I've not studied the structure of pianos using Lucite casework. Nor have I
spent a lot of time listening to them.


>
> (I have never installed a soundboard, or untwisted a case, but I have sure
> sat in front of'em for a long long time)

I've never untwisted one either. I'm not sure it would be possible. Or
necessary.

Del