Duplex

[Duplexdan@AOL.COM]

Don ,

Thank you for your response regarding the suggestion as to the physics of 
duplex sustain. Personally, I have never gone past the empirical phenomena 
itself in trying to scientifically explain it. But I do believe you have a 
good point, and I'll tell you why.

Some years ago at my first PTG National which was at the Statler Hilton in 
NY, among other great and memorable events was a huge class by John Ford 
Senior on piano strings, stringing , pinning etc. My memory of this ancient 
event is marked by my recollection of a dispute I had with Big John on the 
question of bi chords. 

My point was : if you pull one side of a bi chord its bound to affect the 
tension and the pitch of the other side. John adamantly disputed this saying 
that the bearing points of the bridge pins, the agraffes, coils etc inhibited 
this consequence.
After many years of tuning I am even more convinced that what you do to one 
side of the rope around a tree affects the other.

 Now transferred to the question of the duplex which you raised, this seems 
to be a cogent point. Steinway in his patent discusses various types of 
vibrations: transverse and longitudinal. At one point I tried to understand 
the original German text which translation has dubious authenticity, 
especially with Schwingungen and Langsschwingungen as the critical focus of 
the discussion. But I abandoned this because of my limitations in linguistics 
and the need to concentrate on the actual phenomena itself. But he did 
specifically discuss the affect of one part of the string on the other as you 
mention.

So. Bottom line. I think you are probably right: that the excitation of the 
speaking length activates the duplex around the "trees" of the bridge pins, 
hitch pins etc. and this excitation "feeds back" to the speaking length 
increasing the sustain. After all , some physical cause does exist because 
the phenomena is palpable (to the ears, that is).

Thank you very much for your input , and I look forward to hearing some 
"exciting" duplex scale tuning tales.

Dan Franklin, RPT