Experiment: string termination / duplex

[Bill Ballard]

At 3:26 PM -0500 9/18/03, Cy Shuster wrote:
>This is a great experiment!  May I suggest another test case?  I would be
>interested to know the results of modifying Situation 1 so that both
>duplexes are not perfectly in tune with the speaking length, but yet still
>within a millimeter or two of the same length.  Is there any difference in
>sustain in these two cases?

An interesting proposal: one pitch in the SL, and two separate (but 
equal) pitches in the duplexes. The other variation to be observed 
will have all three (of four) lengths at different pitches

At 9:32 PM +0300 9/15/03, Calin Tantareanu wrote:
>- Of course I realise that this experiment doesn't exactly reproduce the way
>a string is fixed in a piano, because I used 2 agraffes instead of 1 agraffe
>and 2 bridge pins.

It's important. You see how the front duplexes depends on a steep 
climb from the agrapphe/capo (actually forced on it by the block). 
The rear duplexes have side bearing forced on them by the board: 
that's why bridges apply their coupling friction laterally. So yes, 
if you want to compare the activity and influence of both these 
duplexes, they should each be equally "awake" (up at the same pitch).

Whether or not the monocord is coupled to a flexible diaphragm, or 
attached to a rigid structure (the base), would be another variable 
to match. And how large the diaphragm, and also how heavy the wire. 
All of these go into impedance matching.

You observations would seem to suggest that the speaking length 
seemed to suffer when the immediate neighbors were completely 
stopped. It makes sense that the speaking length would prefer that it 
continue outside its terminations, vibrating and not still. "Still" 
would be the functional equivalent of a stiff termination.

I'm glad you got the grant funding for this project <g>.

Bill Ballard RPT
NH Chapter, P.T.G.

"May you work on interesting pianos."
     ...........Ancient Chinese Proverb
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