Stretch Vs.Temperament, (was Beat Rates)

[A440A@AOL.COM]

Ron writes: 
>I never have liked the strings of a unison moving in opposition theory.
>I  don't think that's even possible in a piano.

    Hot damn,  chaos comes again! 
  This is how it seems to me: 
    If two strings are struck, it is not logical to me that the system will 
be so perfect that they move in phase, and the least bit out of phase will 
create, due to coupling, an alternating system of energy transfer between the 
two.  In a coupled system, if one string is unstruck and another is,  the 
unstruck string will begin moving, but it will NOT move in phase with the 
first.  It will absorb energy from the struck string and, in an attempt to 
"catch-up",  will lag behind.  At some point, energy will equalize and the 
two strings will go in and out of phase, but the period at which they will be 
in phase is temporal.  
     
    With three strings struck, there is a tertiary transfer created which is 
far more complex and contains more resultant modes of vibration, and the 
three strings will never be totally in phase.   
   I can't see these things happening, but the logic of G. Weinreich seems to 
explain what I hear happening as I fecklessly move strings around while 
listening to the results.  There is a fixed amount of energy in the string 
when set into motion, so faster transfer (via bridge movement) to the 
soundboard will result in greater momentary amplitude but faster decay. The 
unison that contains its own choral effect will seemingly go on longer.   I 
think a really good tuner can manipulate the unison to give the best 
compromise.  Setting three strings of all unisons to "dead-on" ETD setting 
will not only create some unisons better than others, but will often create 
unisons that lack the sustain of the micro-mistuned ones.  I think the ear is 
the better judge of unisons because of this.   
      My normal unison is formed by setting two strings to the SAT, and then 
tuning the middle string aurally. This allows a more consistant sounding set 
of unisons, and I feel like the piano's sustain is brought under my control.  
It also side-steps the question of flattening of the unison by the addition 
of the second or third string.  I don't see that in my results, and even so, 
it appears that what Virgil Smith is pointing out as an effect of unison 
flattening is in the .3 or less cent range, and that is easily obviated by 
choice of stretch made earlier.  
Regards, 
Ed Foote