Tuning the Duplex (was ...Capo)

[Baldwin Yamaha Piano Centre]

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Hi Jason,
                  Back up a moment, the topic was originally noisy and 
aggressive capo bars, tuning duplexes is a whole different topic.
    Most are designed to be de tuned, and on rear duplexes, which only add 
a marginal amount to the tone quality, if all three strings are singing at 
the same pitch, that's usually good enough.
With sectional duplex bars, there's not a lot the average tech can do, 
other than rub them out so they are even.
Most forward duplexes are cast in the plate and again, it's limited as to 
what can be achieved.
When voicing,  you aim for the forward duplex to sing but not sing through, 
so as to be obnoxious, and obvious.
Next is to make sure the strings are rendered evenly, with lots of plucking 
and re tuning.
To raise the pitch of the rear duplex, rub down the speaking length of the 
string with a hammer shank, or brass rod, then re tune.  To lower the pitch 
rub out the duplex and hitch pin segment, then re tune. then compare the 3 
duplex strings, then start again.  It is a slow a laborious job.
With the front duplex, rubbing or seating it, will make the speaking length 
go sharp, Often at this end, friction and rendering is the cause of 
problems, along with the design.  I have de tuned many a forward section 
with a little dab of white glue to add mass to that string segment.  It 
will still sing, but not be annoying, and not dead like adding felt,
Ron Overs piano, is the best I have seen to date, that has control over the 
duplex voice.  Each note has a movable bearing bar.  A piano like this is 
sure worth spending a lot of time on.

Is this what you were looking for?

Regards Roger

At 06:04 PM 9/3/02 -0700, you wrote:
>Thanks, all, for responding. But I'm puzzled ... the duplex is there for a 
>design reason, after all, which I presume is to create additional 
>harmonics and add to the esthetic quality of the tones. Sounds like the 
>universal consensus is that the duplex is generally more trouble than it's 
>worth. *Not one* of you ever retunes the duplex??? (I say this without yet 
>having checked the archives for Ron Overs on "detuning the duplex" but the 
>title appears to substantiate my guess here.)

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