M&A A

[David Skolnik]

Ric, Paul, & All -
Shooting from the hip, so to speak. I've been accurately (but 
well-meaningly) chastised in the past for not actively trying to find 
the answers to the questions I ask.  I'm coming to accept that 
answers are not my roll. Perhaps something to aspire to.  In any 
case, I'll pick through Ric's post below and refer to one item of 
Paul's.  For the sake of space, I'm deleting all but the specific 
quote, so it would be necessary for a reader to access the original 
post to fully understand (if that ware possible)'

At 06:41 AM 2/18/2007, you wrote:
>Hi Paul.
>
>  Jim Ellis's article from way back.
Can you better identify the source?



>The problem with fitting a loose pin into this as something that 
><<directly causes>> false beats is that one attempts to go back to 
>Jim's article... define the pin as the pendulums <<support>> and as 
>such must claim horizontal movement of the pin as being the culprit. 
>This gets problematic immediately. Jim himself denies that 
>(stricktly) horizontal movement of the pin.. or that any in phase 
>movement by the termination in any /particular/ direction at all is 
>at root. In phase movement at the termination occurs in all 
>directional planes of string vibration.
>He cites general springyness of the termination as a whole, tho is 
>the first to go along with the idea that bridge pins can be a 
>contributing factor in the general condition. I also wonder about 
>the sidebearing of the string in this picture... it would seem to me 
>that even if a loose pin was involved.... the least likely direction 
>for in phase springyness would be the horizontal exactly because of 
>the side bearing the string has.

I haven't yet finished Jim's book on longitudinal waves (I'm working 
on it whenever I'm stuck in traffic or, oh, never mind), and perhaps 
I'll find that my preliminary visualization is completely misguided, 
but it seems that in the longitudinal forward and back direction, the 
pin could act as a pendulum and would be less inhibited by side bearing.

Quoting from Paul, albeit from a post that seems to come from Ric,

>Ric, I'd urge you to look at cycloidal pendula as an interesting and 
>maybe contributing factor with "springiness"; cycloidal pendula are 
>another class of pendulum where the "termination" is not a pivot 
>with a bearing but one or more curved surfaces on either side of the 
>period of the pendulum which foreshorten the period as the pendulum 
>swings in contact with the curvature--can you see the picture of the 
>string and bridge pin here at all?).

Paul - Interesting idea, though I haven't yet checked the 
math...don't wait up for me...but, conceptually, I question this as a 
factor, for this reason.  From the diagram I looked up, I would say 
that, for this to be an issue, the string would have to be flexible 
enough to comply with the curved profile.  In fact, we know (?) that, 
at that point, the string's stiffness is already contributing 
otherwise, as inharmonicity.  It doesn't seem you can have it both 
ways.  In any case, if the cycloidal model does apply, it would do so 
generally, not specific to real/false beats.

Another thing.  While you may be correct about the real/false 
semantics, I'd hold off on pressing it, at least until you've found 
the cure.  Otherwise we could solve the whole problem right now by 
renaming it "vibrato".  Problem solved!

A while back, Stephen Birkett had been actively seeking ideas for 
experiments to perform.  I've been meaning to go back and look at 
what was proposed.  In fact it may have been on CAUT (can I say that 
here?).  This subject would seem a likely candidate, though 
problematic.  In order to deconstruct the condition, he would first 
have to create it, in a lab setting, or else bring in field examples 
for forensic analysis.  CSI-Waterloo!  Maybe its a bit like 
synthesizing vs. sampling.  What do I know?   An alternative might be 
to develop a standardized set of tests and observations which 
interested techs could perform in the field, which could provide a 
statistical base.  It would have to be mostly non-invasive 
observation and testing, since time and opportunity would not always 
allow for such things as changing strings or removing bridge pins.

Long enough -

David Skolnik




>Then there are some empirical facts that simply cant be 
>ignored.  Purely from a statistical standpoint there is really no 
>identifiable correlation between the occurance  of false beats and 
>loose bridge pins. Way to many cases where the opposite happens... 
>way to many cases where the same false beat occurs when pins are 
>actually tight. Then there is also this famous <<test>> with the 
>screwdriver.  Why does  pressure with the screwdriver actually cause 
>the false beat to start up again and speed up with more pressure 
>when you've first put enough pressure on the pin to quite a false 
>beat ? Why does the application of mass to neighboring bridge pins 
>or back side pins also (sometimes) affect the presence of a false beat ?
>
>Strikes me that the whole presently and popularly accepted idea that
>bridge pin is /thee/ support for the string and that it /causes/ 
>false beats is a pretty large oversimplification of the whole 
>thing.... likely based on an equally over simplifed interpretation 
>of articles like Jims.  And as is very common in our trade the 
>collective we jumps on the wagon declaring a new (and just as 
>magical as any previous) Truth .  Viola !
>
>For my part.... I'll keep adding CA in appropriate circumstances... 
>because it does help... (another discussion entirely :) )... but 
>I'll also keep wondering about what the heck is really causing false beats.
>Clearly the loose pin thing is to thin.  Actually... when it comes 
>down to it... the recessed notch bit seems much more likely as it 
>allows the string itself to have a partial vibrating in several 
>planes at the same time at different lengths... the bridge pin 
>doesnt need to even get involved here. For that matter... string 
>imperfections at or very close to the termination can cause a string 
>internal springyness that could be at root.   The whole thing needs 
>IMHO a lot more looking into before any definitive explanation is available.
>
>Cheers
>RicB
>
>
>    Ric:
>
>    What has always struck me about that particular mythology is the
>    variability of beat speeds in real (false) beating. Attributing it
>    to loose bridge pins would lead us, no?, to believing that the loose
>    bridge pin is moving in some way in the bridge pin hole, wandering
>    in some oscillating manner that would create a "countable" beat,
>    sometimes as slow as one beat per second, and certainly much faster
>    in most instances, but still regular and countable. I share your
>    skepticism, and return again to some length differential being
>    created in the speaking length by way of termination deterioration,
>    particularly the notch part of the termination creeping forward in
>    the curve of the notch and creating a separation from the ideal
>    simultaneous contact of the string at pin and bridge top. This is an
>    old can of worms, I know, but maybe worth revisiting.
>
>    Paul
>
>    IF YOU WANT TO KNOW THE TRUTH, STOP HAVING OPINIONS!

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