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
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