Accu-just HPs in Steinway D :>)

[Delwin D Fandrich]

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----- Original Message -----=20
From: "Mary C. Smith" <MarySmith@mail.utexas.edu>
To: <caut@ptg.org>
Sent: May 30, 2002 8:23 PM
Subject: Re: Accu-just HPs in Steinway D :


> Weighing in with another idea of someone knowledgable to consult with =
on
> this...Del Fandrich has lots of experience designing scales and such. =
He
> might be able to shed some light on the waste length question. Del, =
are you
> reading this???
>=20


Hi Mary,

Yes, I've been reading this. Most of it, at least.=20

And you should know better than to call that back section of the string =
the 'waste length.' Or did I forget to make that distinction? I might =
have. As may be, there is no 'waste length' between the front string =
termination and the back termination. It all serves some function with =
the possible exception of the length of string between the two bridge =
pins.=20

The backscale -- that length of string between the trailing bridge pin =
and whatever type of back string termination exists -- must be long =
enough and free enough to allow the desired amount of bridge movement =
without undo restriction.=20

Personally, I don't care whether this length is tuned to some specific =
partial of the speaking length or not. I became disillusioned with them =
back in the 1970s and have yet to hear a piano in which the tuning of =
the backscale to some specific partial of the fundamental could =
definitively be credited with improving the acoustical performance of =
the piano.=20

In the real world -- and by the nature of the piano -- it would be =
pretty hard to come up with any backscale string length scheme in which =
at least some of the backscale lengths didn't end up being tuned closely =
enough to some partials of some speaking strings to force sympathetic =
resonances at some frequencies. In these discussions we often tend to =
forget that the bridge does not move in individual segments, but as a =
unified whole. That is, when the hammer at E-80 is played and it hits =
the strings associated with E-80 causing them to vibrate, the whole =
bridge -- or at least a good part of it -- is set in motion as a result =
and that motion is felt for some distance on both sides of the bridge =
pin set dedicated to E-80. That bridge motion is going to force the =
movement of all of the other strings that are coupled to it in the =
vicinity of E-80, both on the speaking side and on the backscale side. =
Somewhere some of them -- probably quite a lot of them -- are going to =
be sympathetically resonant no matter how clever we try to be with the =
backscale.

Some of the so-called tuned duplex schemes in common practice place a =
bearing bar so close behind the bridge as to demonstratably impede the =
motion of the bridge. No amount of hammer hardening or fooling around =
with hammer strikepoints or 'tuning' of the backscale lengths is going =
to help. The backscale simply needs to be longer than provided for by =
the placement of the bearing bar.

I don't yet know if there is an 'optimum' length for any given =
backscale. I do know that if the backscale lengths are too short both =
power and sustain suffer. Personally, I'd prefer to err on the side of =
them being too long rather than too short. (This is not an impedance =
issue -- that is, a short backscale does not simply add stiffness to the =
system. It physically restricts the motion of the bridge and that is =
quite another thing.) I have also learned that -- assuming similar =
backscale lengths -- backscales terminating on vertical hitchpins are =
less restrictive than are those terminating on the conventional =
hitchpin/bearing bar arrangements.

Del

(PS  A side note -- this is among the issues we discuss in the Wednesday =
class given at the beginning of the Big Convention which I have agreed =
to do at least one more time. The latest version of this class will be =
presented this year in Chicago.)

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