I need to correct Mr. Tom Lear about the Dynavoice valves.  The little
valves are a specially formed biscuit shape with three wings to center
them.  They are not sponge neoprene, however; they are natural gum
rubber and they still seal very well after all these years.

Their downfall was the fact that they had extreme valve travel which
will not allow for softer playing.  This was a major complaint about
the Dynavoice when it was new.  They also seemed to have excess lost
motion between the pouch and the natural gum rubber valve stem.

The valves are one piece of moulded gum rubber: valve, stem, and wings.
The pouches sometimes destroyed themselves because they had to travel
quite far to even reach the valve stem, and some had trouble getting the
valve all the way up to the top seat without a stretch.  Talk about
slowing down the works!  The pouches were also made of gum rubber and
I was surprised at their longevity.

Let us all get one important thing straight about all valves:  The
*only* time a valve should leak any air is during the time it is in
motion.  A valve should have only enough travel to get sufficient air
out of the pneumatic and back in when it goes off.  Both should be fast
for repetition's sake.  Any excess travel lets needed air into the
system and degrades the playing of all the other notes.

I am sorry I did not make myself sufficiently clear to you, Mr. Lear.

D. L. Bullock    Piano World    St. Louis

 [ Craig correctly noted that the Duo-Art expression system is dependent
 [ upon a small amount of air flow at all times, but I don't agree that
 [ it must come from leaking valves.  A small flow through a bleed at
 [ each end of the Duo-Art action stack serves the need just as well,
 [ and it is easily adjusted or replaced if the valves begin to leak
 [ after many years of service.  -- Robbie