Tuning Duplex

[Phillip L Ford]

On Fri, 09 Nov 2001 08:27:13  
 Ron Nossaman wrote:

>Tuning the rear duplex is an attempt to make a design feature work like it
>was intended to by moving the aliquots to where they presumably should have
>been all along. Also presumably, the positioning isn't that far off or it
>was never intended to be a tuned system in the first place. With that in
>mind, moving an aliquot a millimeter or two won't have a realistically
>measurable affect on downbearing angles across the bridge. There's not a
>lot of difference between a 1:1000 slope, and a 1:1005 slope. It will
>immediately affect the back scale segment tensions because the deflection
>angle from the aliquot to the hitch will change a whole lot more than the
>downbearing angle at the bridge because it was a much higher angle in the
>first place, and the aliquot movement was a much higher proportion of the
>string lengths involved.
>

>Ron N
>
Ron,
I've thought that the change in tension in the portion of the
string between the aliquot and hitch pin was one of the
things in the minus column of a tuned duplex versus a 
system like the Baldwin system where there is no friction
point between the back of the bridge and the hitch.  In the
tuned duplex system there's just one more friction point
and one more string segment whose tension has to be
equalized, not to mention that you can't set downbearing
on the fly, so to speak, like you can with the Baldwin
system.  But I've wondered if friction at the aliquot is
sufficient to cause the string not to render across it in
normal tuning and playing so the tension in this small
string segment near the hitch is irrelevant to tuning
stability.  What do you think?

Phil F