[CAUT] duplex position

[Richard Brekne]

Hi David

The original patent has been posted many times.  Basically it claims 
that you set the thing to integer fractions of the speaking length. In 
practice this looks to me like at C88 one starts at a 1:1 relationship 
to the speaking length. Then as soon as that gets to be too long one 
goes over to a 1:2, or perhaps 2:3.  Different Steinway models may vary 
a bit.  I think Dale Erwin on Pianotech even mentioned that on some B's 
they started at 0.5:1  to add stiffness.  I suppose this might work to 
the intended purpose.  You know as well as the rest of us me thinks that 
there is plenty of disagreement in the piano world (including inside the 
Steinway organization) as to the placement of these, how critical it 
is.. the whole theory in general.  The only real experimentation I've 
seen seems to go slightly in favour of a tuned back duplex ala 
Steinway.  The front duplex on the other hand seems to work best tuned 
to non harmonic lengths... at least to my ears.

I'd suggest you do what seems most sensible to you. Given the wide 
variety of placements we see out there in both off the factory line 
instruments of all sorts and how all these sound... I cant see its going 
to cause you a major type problem one way or the other.... regardless of 
what benefit some optimization might yield.  I liked also the idea of 
using individual bars as methods for tweaking down bearing pressure on 
the back side of the bridge. The back length itself being the critical 
factor relative to the actual down bearing force (given an already 
decided deflection angle) as you no doubt already know.

Cheers
RicB

    List,

    Is there a clear cut way to position the duplex bars on a
    Steinway?   This is 100 year old B I'm restringing.   Top treble
    sections only.   I can position as I found it but is there a
    measurement from the bridge pins...?



    David Ilvedson, RPT

    Pacifica, CA 94044