Tuning Duplex

[David M. Porritt]

Dan:

I was thinking of your post while tuning a Steinway this morning.  If
Ted Steinway thought so much of the duplex idea (actually tonally as
opposed to as a marketing ploy) why did he make the duplex device not
individually tunable.  When you cast the duplex oliquot as he did you
assume a precision of plate casting, bridge placement and notching
(both front and back) that just doesn't happen.  If you can really
get the first and last notes of an oliquot plate "in tune" the rest
of the notes are at the mercy of the above mentioned precision that
just doesn't happen in these one-of-a-kind, hand-made pianos.

Personally I think it was a simply a marketing tool and the duplex
devices were made in this way to keep production costs in line (no
individual pieces to adjust).

dave

*********** REPLY SEPARATOR  ***********

On 11/14/01 at 8:22 PM Duplexdan@AOL.COM wrote:

>To Greg Newell
>Dear Greg,
>
>Of late there has been a dramatic increase in interest in tuning
duplex 
>scales, both front and rear. As an individual who as espoused the
tuning
>of 
>duplexes for some years and has devoted a great deal of time to
research
>and 
>teaching of this procedure I am delighted to hear of another
colleague 
>interested in the subject. 
>
>I must be clear that I am not "the " authority, although I may be be
>guilty 
>of being the most avid enthusiast. "The" authority, as far as I'm
>concerned  
>was Steinway who invented the feature. If you haven't read his
patent, I 
>suggest you do, and if you like I will be glad to mail you a copy,
gratis.
>
>Getting on to your inquiry. You raise a few points and make some
comments
>all 
>of which I may not be able to thoroughly satisfy you with, but I'll
try to 
>get a leg up on the subject.
>
>First of all about bearing. Yes, moving the secondary bridge, also
called
>the 
>oliquot, push plate, or as I like to call it, the harmonic bridge,
would 
>theoretically affect the bearing. However the amount of movent of
this
>duplex 
>harmonic bridge is so negligible in the tuning process, the duplex
>generally 
>moving less than a quarter of an inch either way, that I suspect the
>effect 
>of alteration of the bearing would be negligible. At least in 15
years of 
>practice I have never worried about it and have an almost 1000
batting 
>average on improvement of the tone and sustain by tuning the rear
duplex.
>( I 
>can't discuss front duplexes because I have nothing worth offering
in the
>way 
>of support.)
>
>Point 2, duplexes "in tune" and sounding simultaneously.
>
>There are two theories about what happens to the duplex when the
speaking 
>length is activated. One theory is that the duplex sounds and
depending on 
>the note either helps or hurts the quality of the speaking length.
The
>other 
>theory, which I subscribe to, is that the length of the duplex scale
>portion 
>of the string is the key factor
>
>According to Steinway's original patent when the duplex portion of
the
>string 
>is an "oliquot" portion of the speaking length, meaning a low
fraction
>such 
>as a half a quarter, a third, that the vibrations of the speaking
length 
>proceding across the sounding board bridge and returning  are
copacetic
>with 
>the vibrations of the speaking length. Steinway speaks of
longitudinal 
>vibrations of the string being the important element. I believe he
means
>when 
>the transverse vibrations of the speaking length agree in a
fundamental
>way 
>with the longitudinal vibrations promoted in the duplex scale that
the 
>sustain and quality of the entire tone of the string is improved.
>
>My motto is: If it can be tuned , it should be tuned.
>
> I think that's the purpose of the duplex scale.
>
>I hope this has been somewhat helpful.
>
>Dan Franklin, RPT


_____________________________
David M. Porritt
dporritt@mail.smu.edu
Meadows School of the Arts
Southern Methodist University
Dallas, TX 75275
_____________________________