[CAUT] More on Single String Beats

[RicB]

Hi David

Try a very slight tap on the bridge pin itself, essentially enough to 
lower it about a 10th of a mm if you get my meaning. I find this works 
actually quite often way up there and suspect it has to do with some 
micro level impreciseness of the termination. If the bridge pin is 
notched for example due to years of wear and tear, and is essentially 
holding the string in that notch (as would be expected I suppose), and 
if that notch is such that it effectively lessens the solidity of the 
string to bridge face interface... well you see where I am going.  I 
dont really see an internal resonance (as I understand the term to mean) 
being a part of this.... but then I haven't really looked at what kinds 
of resonances bridge pins themselves are capable of either ... :)

That said... ... I think it would be cool if Jim Ellis chimed in with 
some perspectives on how a string itself (independent of the termination 
per se') can <<cause>> a single string beat.

Cheers
RicB

    By coincidence, I was experimenting with just such a false beat this
    morning on a newly rebuilt Steinway L fro the '20's.  On note C#7,
    treble-most string had a beat of appoximately 6-7 bps.  There was no
    change in adding mass (as screwdriver) to any other part of the
    system.  In fact even touching the bass of the bridge pin with
    varying amount of force and from different directions produced
    virtually no change.  What did accelerate the beat rate was moving
    the screwdriver up the pin towards the top.  The pin did not seem to
    be loose.  It seems possible that some aspect of the pin sets up an
    internal resonance that could interact with the frequencies created
    by that string.  I'd love to try something like pulling the pin and
    changing the length, or take complete measurements of weight, length
    and diameter, and then alter one at a time.  Well, I mean note the
    changes of weight and length.  What's interesting too, is that
    sometimes, a blade placed on top of pin of a vibrating string
    vibrates quite noticeably, and at other times, such as this, not.

    As far as your theory, I'm not sure I see how that might work.  Care
    to elaborate?

    David Skolnik
    Hastings on Hudson, NY
    --