[CAUT] Back duplex tuning

[Richard Brekne]

Hi folks.  Been a very long summer with lots of great experiences.  
Among them a week long seminar at Oberlin where I got to see first hand 
how well some of the criticisms about NY S&S hold up.... but thats 
another discussion entirely. 

Just before the summer I decided to start testing some of the claims 
about how useless the idea of the back duplex ala S&S stood up to 
reality.  One of the major beefs is that the back length once tuned wont 
stay tuned.  I found this an interesting claim when put aside other 
comments in other threads about the amounts of friction the bridge pins 
present.  In any case... after the summer I've had a chance too look 
pretty closely at 4 instruments (3 D's and a C) that I'd tuned the back 
lengths in the late spring.  Seen as unisons.... the back lengths hold 
their tuning far better then the speaking lengths do thats for sure.  I 
didn't measure pitch on back lengths, but I did tune them so that their 
unisons were very clean and just sharp of the <theoretical> correct.  (I 
just had this hunch for some reason that slightly more tension on the 
back lengths then front lengths was a good idea to start with). 

After tuning all four this fall I can observe that the back lengths are 
all pretty much where I left them this spring.  Slightly sharp of their 
theoreticals and nearly all the back length unisons are still very 
clean.  Seems to me that tho this is a very limited test... the claim 
that the back lengths wont stay tuned is well overstated.  Of course 
they will become out of tune in time... but then the speaking lengths do 
too and that doesn't seem to bother anyone.  They are not too awfully 
time consuming to tune to any given spec either.   So I come up with the 
following three points about the back duplex scale

1... it is easy to tune really.
2... it is remarkably stable compared to the speaking lengths.
3... when they do go out of tune.... then hey... just like the speaking 
lengths one should just re-tune.

I wont get into weather there is some acoustic benefit to doing so just 
yet.  I suspect in the end there is, but thats another discussion as well.

Cheers

RicB