[CAUT] More on Single String Beats

[Michael Jorgensen]

RicB,
    Could the phenomenon where three strings tuned individually produce a
lower pitch when played as a unison relate to this thread?  The unison pitch
is often equal to the lowest pitch read of any one of the three strings at
any point during the attack/decay. This suggests that strings can be forced
to produce pitches different from what they are tuned to.  Perhaps a
soundboard/bridge refuses to vibrate at a given pitch in a given location,
thus being at war with the string, creating a false beat?  Adding mass might
change that condition.
-Mike    


On 4/16/07 7:39 AM, "RicB" <ricb at pianostemmer.no> wrote:

> 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
>     -- 
>