M&A A

[PAULREVENKOJONES]

IF YOU WANT TO KNOW THE TRUTH, STOP HAVING OPINIONS!


In a message dated 02/20/07 02:04:30 Central Standard Time, ricb at pianostemmer.no writes:
Hi Dave 

Jims Article was entitled "Unisons - The effect of tuning on persistence 
and timbre"  September 1982
Dave, as Ric says above, the article is from...:-) (thanks Ric).
. 

Its a good read and it shows (I think) where the present idea that the 
pin is the kind of support the article refers too in the pendulum 
analogy, and that falseness is caused by horizontal movment of same 
support.  Give it a read. 

My take is that, well aside from the obvious observation that loose pins 
and the presence of false beats do not occur simultaneously more then 
what can be called randomly, the article just shows how a termination 
for an oscillating object can alter the period of the object. A better 
interpretation to translate to pianos IMHO would be to say that the 
bridge and pin assembly as a whole can come to oscillate in phase with 
one (or more) frequencies of the string and in one (or more) direction.
I would love to see some really carefully constructed experiments with the right optics, metrics, etc. to see the movement of the string at a point in its length as close to the bridge as possible with the hypothesis that it is not only rotating transversely, but in small arcs of rotation in the plane of the string plane as well because of the springiness of the termination, and possibly cycloidal effect combined. I know that this has longitudinal effect, and that this is an extension of Jim's article. Birkett's high speed films show quite clearly, particularly the bridge-end films, significant movement of the strings not only in and out of phase, but right up to the pin, which I would dearly love to see more closely. Some of these questions are not answerable by math alone but by better observational technique, even though I've always believed that the right question, properly asked, contains the best, if not only, answer. In some manner, the principle of parsimony needs to work here better; there are too many factors possibly involved in the cause of real beats and we need to shave away the least likely.
 
This fits better with the more technical article in the 5 lectures, and 
explains why loose pins can not be statistically associated with false 
beats.  It also eliminates the whole problem with this horizontal motion 
of the pin thing.
I agree, Ric. Can we yet shave loose pins from the "cause" plot?


Your comments relative to longitudinal modes are interesting, and I see 
where you are going. Tho the longitudinal modes are very much higher 
frequencies then the transverse we ultimately hear in much of the 
piano....especially where the classic false beat is usually a big 
problem... there is perhaps no reason why these could not create a false 
beat.... if and only if there are two horizontals at nearly the same 
frequency... and I dont think they function this way... but perhaps I am 
wrong.
I think maybe you're right. Particularly since we cannot correlate any given longitudinal mode with a  "real" beat speed with any accuracy at all. So statistically unlikely.


In anycase one is still confronted with some clear observational data 
that as I mentioned cant be ignored. 

Cheers 
RicB 


   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? 
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