Problems With Duplex Scaling Of Pearl River Grands?

[Richard Brekne]

Tuning the back duplex (and any so called non speaking length for that 
matter) can and does involve both the placement of the termination 
devices and adjusting the tensions on those segments.

For example... if the back length of a given string is exactly one half 
of its speaking length... then this string can be tuned to exactly an 
octave... or slightly above an octave, or slightly below. Slightly 
meaning a pretty significant deviation.  Friction from the bridge pins 
is great enough that there is a window for variation here that will 
remain stable no matter how hard you play.  In other words... you can 
purposely put more tension or less tension on the back scale relative to 
the front scale and expect it to stay there over long periods of time. 
Or you can if you choose equalize the tension to the speaking length if 
you want and expect the same.

If your regular tuning method (for the speaking length) does not include 
very large movements of the string... this will not change the tension 
on the back length either.

There are a lot of ways of regulating the tension on the back scale. I 
use a string stretcher and apply pressure to the string as nearly 
horizontal and in a direction away from the bridge pin to do this.  To 
increase back scale tension (and hence frequency) I push on the speaking 
length, to decrease on the back length.  I find this allows me to 
actually decide the pitch of the segment as long as it is within the 
window of what can remain stable mentioned above.

Cheers
RicB


    Many of the messages on this thread are talking about a tuned front
    and/or
    rear duplex. What that duplex should be tuned to aside, how does one
    actually go about tuning either the front or the rear duplex?

    -- Geoff Sykes
    -- Los Angeles

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