close enough>??

[Roger Jolly]

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>
Hi Kevin and Johnathan,
                                      I think what you are referring to, is 
a phenomena known as string coupling.
Typically it is in the .1 to .2 cent range. ( Just audible to me. 1 or 2 
cents would be clearly audible) For a long time I thought it appeared 
random and more noticeable in the treble.
Since I have been observing the effect with respect to rib location.  I am 
stating to conclude that the effect, is greater at the mid point between 
the ribs.
Stiffness of the board is critical in the treble, and I think that is why 
it is most noticeable in this register.
I suspect that the effect is proportional to the fundamental frequency, and 
the stiffness of the board in any particular area.  This is why I think it 
is less noticeable in the lower registers. Just a rambling theory.
I have not measured enough pianos to really have a firm opinion on the subject.
Regards Roger




>Somewhat off topic (or is it) ...  I remember Virgil Smith doing a study
>here once where he showed that tuning unisons caused the pitch level of
>the note to drop.  I believe it was something like 1-2 cents.  (anyone
>know what I'm talking about, or have I gone mad?)
>
>     I saw that demonstration too. In our class, it could be demonstrated 
> by hearing the beat rate of the third tenth octave check, but they had 
> trouble measuring it with a machine.
>     Kevin E. Ramsey
>
>
>Jonathan Finger RPT.
>Boulder Chapter, PTG

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