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Player Piano Valve Design Parameters
By Bill Chapman

Following up on Douglas Heckrotte's observation that a 30-foot tube
versus a short tube leading from the tracker bar to the striker made 
no real difference in sounding the notes.  I, too, have puzzled over
the fact that players have different length tubing, shorter in the
middle and longer at both ends of the keyboard.

I had a faulty primary valve near the middle of the keyboard so
I routed the signal to the highest "A" primary valve and routed back
to the secondary valve near the middle.  I could hear no discernible
delay using the longer route to the note.

I have wondered if the signal from the tracker bay may act more like
sound wave (1,126 feet per second, according to Wikipedia) with a
frequency of 1.  Perhaps it is something in between a full transfer
of molecules being pushed through the tube and a bumpity-bump -- like
the steel balls suspended from strings that transmit the bump instantly
to the last steel ball in the line.  In any case it remains a bit of
a mystery to the layman.

Incidentally I noticed seeing ultra fine tubing used in a rebuilt
orchestrion where the tubing was about one-half the size of ordinary
5/32" tubing.  It was in a control circuit, not a playing note.
Did the early builders miss a refinement, or would dust and dirt mess
things up?

Bill Chapman - 80 deg. F. and still air, rel. humidity 19%
in La Quinta, Calif.


(Message sent Sun 26 May 2013, 16:23:33 GMT, from time zone GMT-0700.)

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