Duplex

[Carl Meyer]

Dammit, Ron!  In the words of Ronald Reagen "There you go again"  You're
using logic on a logic free subject.

When I read Ron O's description of his tuned duplex I thought "OMG, did I
make a mistake by eliminating the aliquots in this piano?  He did a great
job in justifying the tuned duplex, but when I read that it could take 6 mo.
to position the aliquots I
thought.  "What if I don't live that long?"  Don't get me wrong, I have
great respect and admiration of Ron, but I was looking at it from the human
aspect.  A great piano coming off the production line,  tuned superbly and
duplex tuned to perfection.  Now Joe Schmuck (pieanna tooner) toons for a
concert (he only has 40 minutes to curtain time).  He brings the note above
pitch and lowers it to tune.  He may or may not even know what a duplex
scale is let alone know how to tune it.  Next tuning is done by Jose Schlock
who lifts the pitch to sound good.  He knows how to tune a duplex, but he's
paid poorly and doesn't have the time to do it.  Or the inspiration, for
that matter.

The result, a great piano that is out of tune for a good portion of its life
and a duplex scale that is never in tune.

Progress????  You be the judge.

I'd better quit before I offend somebody.  That's not my intention.

Regards to all

Carl Meyer  Assoc. PTG
Santa Clara, California
cmpiano@home.com




From: "Ron Nossaman" <RNossaman@KSCABLE.com>
To: <pianotech@ptg.org>
Sent: Sunday, November 04, 2001 7:19 AM
Subject: Re: Duplex


> >Of course. All of the backscale string segments--at least all of them
within
> >a reasonable distance from the note being played--are affected.
>
> Exactly, which is why I've wondered for so long about the presumed benefit
> of a tuned rear duplex, especially the idea that the often severely
> shortened duplex lengths, while limiting soundboard movement, are
> increasing sustain and volume.  That must surely be magic. Building
systems
> with decent soundboards and long free back scales has convinced me,
pending
> evidence to the contrary, that tuned duplexes are utterly unnecessary. I
> can certainly concede that if a system has already been built with a tuned
> rear duplex, it probably wouldn't hurt to actually have the duplex in
tune,
> but I don't see how it is possible for the thing to stay in tune if you
did
> manage to get it there in the first place. I know that you know this
stuff,
> but I'd like to lay out a little real world duplex tuning scenario for the
> folks at home.
>
> Why does a string segment go out of tune? After the initial stretching and
> settling period, it's because of a change in string length. That's it.
> Changing string length changes tension, which changes pitch, whether the
> length is changed by the tuner, or by heat or humidity induced dimensional
> changes of the bridge and soundboard. If we assume it's bridge and
> soundboard rise/fall that changes these string lengths, we must assume
that
> for any given change to the speaking length, the back scale must change
> considerably more because the string length change that affected the
string
> tensions above the bridge is a higher percentage of the overall length of
> the segments below the bridge. Because of the friction at the bridge,
> limiting string rendering across the bridge these tension changes aren't
> equal above and below the bridge. Depending on whether the pitch is going
> up, or down, the back scale will be under either higher, or lower tension
> than the front scale. Tensions immediately on either side of the bridge
> will be the same for any given string, for very brief periods as they pass
> in the night. This will happen at different times in the cycle for each
> individual string because segment length proportions are different for
each
> string. If, on the other hand, the friction across the bridge wasn't any
> more than that encountered at the counter bearing bar and V bar, the
> segments above and below the bridge would have more nearly equal tensions
> and the pitches of the rear duplex and speaking lengths would remain more
> nearly, but still not precisely proportional. It isn't, and they won't.
>
>
>
> >Why is this
> >such a hard concept to grasp?
> >-------------------------------------------
> >Del
>
> Now THAT is a mystery that may never be solved.
>
> Ron N