S&S DUPLEX SCALE

[Ron Nossaman]

>
> List, Would anyone be able to give me a full explanation of the duplex scale
> on the Steinway&Sons, and what the nickel plates (located near the hitch
> pins) actually do?
>                                             
>                                     Thankyou, Stuart



Well, yes... and no. The primary function of the duplexes (front and back) is
to make noise. That's it. Theoretically, it's supposed to be organized noise
that supports and augments the note(s) being played. In practice, it's not
nearly that simple or dependable. The front duplex of any given unison is
supposed to have some relationship to the speaking length or frequency of  that
same unison. It get's it's impetus from energy bleeding past the V bar from the
speaking length. The rear duplex of any given unison doesn't necessarily have a
definable relationship to the speaking length of the same unison, and I don't
think that it's really necessary that it does. The rear duplex in powered in
general from bridge movement rather than by bleed through from individual
speaking lengths, so the rear duplex segment that supports any specific
speaking length isn't necessarily on the same unison as that speaking length.
That's the basic idea.

In an actual piano, it's highly unlikely at any given time that the front
duplex segment on a unison is "in tune" with the speaking length for a number
of reasons. Original placement of the counter bearing bar, the pitch of the
unison, and the tension differences between segments as the tuning drifts will
virtually insure that the front duplex won't be "in tune" with the speaking
length most of the time, if ever. Same for the rear duplex.

The duplexes are there in the first place to "enhance" the sound in areas of
the piano that normally have problems with sound production. That would be, of
course, from about octave five to the top. You don't see front duplexes in the
agraffed tenor and bass, and the rear duplex in the tenor is usually braided
off. Duplexes are an attempt to overcome, or somewhat disguise soundboard
design deficiencies from the "killer octave" to the top. With an efficient
soundboard design, active duplexes aren't needed, nor are they desirable.

That's the short version. For the full discussion, and a guarantee of something
to fill your spare time for the next week, refer to the archives.

Ron N