If I had to get 36 to 48 inches of vacuum -- without neighbors com-
plaining about the new airport next door -- I would go to a positive-
displacement pump.  That is, pistons or our good old reliable bellows.

The four-bellows pumps used in Duo-Arts and Ampicos can easily draw 50
to 60 inches when in good condition.  A good player tech could build
one from scratch, though there should be plenty of salvage units around
needed new leather and cloth.  They needn't make much noise.

The tiny pneumatics in the Dynavoice have their good side: not much
volume of air will flow through a tight action when it's playing a lot
of notes.  So the player pumps I mentioned will probably make 48 inches
and to spare.

Dynamic blowers (basically enclosed fans) are best for high volume and
low pressure, like organs.  The Dynavoice calls for just the opposite.

Mike Knudsen