Tuning Duplex

[Duplexdan@AOL.COM]

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