Unison coupling

[Ron Nossaman]

>Ok tho.... say you can establish through measurements that the so
>called killer octave is most susceptible to this.. how can you tell if its got
>anything to do with soundboard impedance with these measurements.. wouldnt you
>have to actually check the soundboard for each case ??


By listening to the piano. Listening is what defined the killer octave in
the first place, not instrumentation, and that's why I said I probably
wouldn't be able to use data that someone else had collected. I would
really want to listen to the piano the data came from to try to evaluate
the soundboard assembly and take duplex configurations into account. Some
of the measurements I plan to take are from pianos exhibiting the loud
attack, distortion, and short sustain characteristic of low soundboard
impedance. Other measurements will be taken from pianos not manifesting
these symptoms. I'll start with a relatively small group of pianos
demonstrating the widest divergence in attack/sustain characteristics in
the low treble. If I get a correlation between killer octave sound
production problems, and unison coupling, I can add more pianos to the
sampling over time to see if the correlation still connects. If I don't get
a correlation from the limited sampling, I haven't wasted a whole lot of
time on nothing. 

Ron N