S&S D Duplex

[Sarah Fox]

Oops....  I sent this and another post in private, rather than to pianotech.
(Just when you all think I have my head screwed on straight, I exclaim, "But
wait!  There's more!")
... Sarah

> Hi Del,
>
> > The major problem I have with this whole tuned backscale discussion is
> that
> > it requires thinking of each string (or unison) and its associated
bridge
> > segment as a series of mono-chords (mono-unisons?) acting independently
of
> > each other. The do not, of course, what happens to one unison happens
also
> > to the adjacent unisons for some distance up and down the bridge. In
other
> > words, when the strings of, say, C-64 are vibrating and causing the
bridge
> > to move it is not just the backscale strings of C-64 that are set in
> motion
> > in response. The backscale strings of all of the unisons for some
distance
> > on either side of C-64 are also set in motion. In real life it would be
> > pretty difficult to come up with any backscale length
> > arrangement--deliberately tuned or not--that did not have at least a few
> > adjacent backscale string segments harmonic with some driving string
> > segment. (Unless, of course, you try to explain the generation of sound
> > energy by the soundboard in some way that does not have the bridge
moving
> in
> > response to the vibrating energy in the strings. Then, I suppose, all
bets
> > are off.)
>
> I completely agree.  This is why I was arguing that the tuning of much of
my
> Wissner duplex to sevenths might have been by design, since the duplex
> segment that would resonate to a main segment's vibration would be a
> half-step away, hence on the adjacent note.  Although Wissner
worked/studied
> under Steinway, perhaps he disagreed with Steinway's rationale regarding
> duplex effects, regarding all vibrational energy as passing through the
> bridge.  Or perhaps he shifted corresponding main segments and duplex
> segments by a half step to partially decouple duplex resonances from
> longitudinal waves (see Robin Hufford's post -- now I understand what is
> meant by a "longitudinal" wave) while maintaining coupling for transverse
> waves, thus softening the duplex effect somewhat over certain note ranges.
>
> Peace,
> Sarah
>