a possible explanation of the virgil effect?

[jolly roger]

Hi Don,
              Take a close look at the position of the ribs, wrt to the
coupling effect and  each note,   Things tend to look less random.   I have
only measured the effects on two pianos, but I am starting to think that
the mechanical reactance of the board may have some thing to do with the
coupling effect. 

Roger


At 12:43 PM 8/15/01 -0600, you wrote:
>Hi,
>
>I read this with great interest. I wonder if the damping effect of the cast
>iron and the resultant energy *bleed* is the cause of the lowering of the
>pitch on three string unisons. It would certainly be variable from piano to
>piano as plates are not really too consistent.
>
>>My thinking was that when a string is struck and vibrates then there must
>>be an periodic increase in tension.  When a string of fixed length is
>>displaced then it seems to me that there must be an increase in tension.
>>For the fundamental, as the string swings up the tension increases, comes
>>back to nominal as the string comes back level, and increases again as
>>the string swings down.  This is happening several times a second.  Also, 
>>this is happening for all of the partials, just at different frequencies.
>This
>>increase in tension must be sustained by the plate.  Admittedly, the loads
>>in question are low and the deflections must be small.  But, cast iron has
>>high damping (by metal standards) and the vibrations are occurring several
>>times per second, so even a small amount of deflection could perhaps
>>dissipate consequential amounts of energy.  The amount of this deflection
>>will depend on how stiff the plate and pinblock arrangement are.
>---
>
>
>Regards,
>Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.
>
>Tuner for the Saskatchewan Centre of the Arts
>
>mailto:drose@dlcwest.com
>http://donrose.xoasis.com/
>
>3004 Grant Rd.
>REGINA, SK
>S4S 5G7
>306-352-3620 or 1-888-29t-uner
>