> >Now to the other subject of single strings exhibiting a difference of pitch > >from three strings which are tuned identically. In my studies, I found > >that this difference exhibits itself more in the 5th and early 6th > >octave on the piano and not as much elsewhere. I have not found 1 and 2 > >cent variances as some have claimed. What are your findings? I find > >greater differences between the pitches of the prompt sound and the > >later decay sound (the TuneLab shows this quite clearly). It is easy to > >confuse these two sources. > > > >Jim Coleman, Sr. > One thing to keep in mind in all this speculation is that there are a few details that are known about coupled strings. We know that two strings which vibrate in a theoretically assymetrical mode will have a canceling effect regarding the force exerted by either on the bridge. This would result in an infinitly rigid bridge response which in turn will result in very long and even decay. Since one string vibrating by itself is neccessarilly more symetric then two strings very close to one another on the bridge and vibrating at the same frequency (or very nearly so) it is to be expected that a single string will have a much quicker decay rate then two such coupled strings. Now this is relative to sound level but this may also influence this buisness about frequencies lowering slightly in coupled strings. There is an impedance variance in the bridge as seen from each individual change from a non coupled to a coupled situation. The so called killer octave is also the area of the piano with the least degree of sustain if I understand things correctly, so we may actually be dealing with an area in the scale that for some reason has the least amount of coupling affect. (as seen from how coupling affects sustain and sound level) Increased coupling results in greater sustain and more even decay, and perhaps less variance in frequency throughout the decay. If this is so then the only questions would be why this is the case, and what to do about it. It might be interesting to play around with both increasing and decreasing the coupling capacity of unisions in this area and see what happens in each different case. musing a bit on Sunday afternoon... grin.. Its been a beautiful springy day in Bergen. -- Richard Brekne Associate PTG, N.P.T.F. Bergen, Norway
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