[CAUT] Re: Back length tuning

ed440@mindspring.com ed440@mindspring.com
Fri, 2 Dec 2005 16:04:32 -0500 (GMT-05:00)


Ric and Jim-

I was going to post a thought to Jim about this, so I'll post it to both of you.

I'm assuming Jim's comment is correct, since I've never know him to be wrong, and since I've also observed what he mentions.

However, when back scales are tuned to 2nd, 3rd or 4th partials of speaking lengths, the result is chromatic back scales in one to one correspondences to speaking lengths, with resultant sympathetic responses all across the treble scale.

If the back scales were re-arranged so that, say they produced series of minor 9ths or augmented 11ths above the associated speaking lengths, the response might sound the same, but to get it, you would have to do some darned tricky backscale tuning!!

If you're going to tune the back scale, it will go a lot faster if you tune simple aliquots of the associated speaking lengths.

Ed Sutton

-----Original Message-----
From: Ric Brekne <ricbrek@broadpark.no>
Sent: Dec 2, 2005 3:44 PM
To: caut@ptg.org
Subject: [CAUT] Re: Back length tuning

Hi Jim

How do you account for claims that changing the frequency of a back 
length can effect a change in the sound characteristics for the 
corresponding speaking length of a string then ?  And while I have your 
ear... grin... I've also heard discussion along the lines that 
longitudinal vibration zips right past the bridge termination and can 
play a part in excitation of transverse modes in the back length.  If 
you get time to jot down some thoughts on that matter I would be greatfull

Thanks
RicB



Jim Ellis writes

Before any of you go head-over-heels tuning the back lengths of strings to
the overtones of their corresponding speaking lengths, you need to be aware
that the notion that an individual string couples from speaking length to
its corresponding back length across the bridge is a myth.  It does not,
and cannot, unless that particular bridge termination is defective.  Whole
groups of speaking lengths do couple to whole groups of back lengths by the
vibrations of the bridge, but individual coupling does not occur between a
single speaking length and its corresponding back length the way it does at
the front duplex where it merely bleeds across a single termination point.
I have found cases where a back length would vibrate at the frequency of a
speaking length of another string as much as two octaves away from it.

Sincerely, Jim Ellis
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