We have been talking about Universal stacks and how wonderfully tight
they are. That is true. However, there were other stacks built in the
twenties which were equally tight and hair-trigger responsive. One of
those happens to be the old Schultz players. You don't see to many of
them around here, but when the stacks are resealed and the valves
rebuilt and adjusted, that player can actually be pumped up and still
be playing the roll from the huge horizontal top reservoir, a few
seconds later, and that's with an air motor running. The difference
is the extra large reservoir, of course. The universal stack doesn't
have one that big.
One requirement to rebuilding the Schultz valve is to make sure the
valve pneumatics easily collapse on their own with the hook in place,
and are practically air-tight. You have to be able to open them up and
watch them drop quickly on their own weight.
Another requirement is that the poppet (valve) in the valve well be
travelled already and have a very nice sanded suede finish to hook
into. The inside valve seats can be purchased from PPC. These are
special seats which are very thin, giving you the clearance you need
for the edge seal.
Finally, When the hook connection has been made, the first thing you
must do is (1) temporarily seat the valve pneumatic where it is to go
and notice the rise of the pneumatic leaf. Too high, and it will hit
the top of the channel board. Too low, and it will fully close before
the valve can seat. You may have to bend the hook a little . (2) After
the valve pneumatics are glued down with hot hide glue and absolutely
nothing else, and are fully dry and tested for leakage, Adjust the
angle of each poppet valve at the hook, so that it does not have to
tip at all to seat perfectly smack on its inside valve seat. You need
a good eye to see this. Get a good strong light to cast a dark shadow.
Go back through your valves several times to recheck.
By then having used Phenoseal especially at the end grain points and
to coat the channel covers, etc with, you will have a beautifully
cartridge-tight player that you can really put the expression into
with the treadles. You'll wonder why they put two pedals on this player
when all they needed was one! Of course, we are assuming that you have
also replaced the inside pump flaps too and tested the pumps for
air-tightness. Any pump-- motor governor or no-- should hold a vacuum
for at least 15 seconds if it is fully restored and factory tight.
Some pumps will hold a vacuum for over two-three minutes, depending on
your reservoir cloth and flap/wood tightness.
It's not a lot of fun to have to work when you play a pump player.
And the best players had a great amount of expression capability, too.
So if you find that you are having trouble getting expression, the
problem is actually an unfavorable ratio of feeder air volume/pressure
to losses. If the loss is too great, or if the loss isn't enough, then
you'll have problems with expression. Likewise, if the reservoir
springs and cubic capacity are not sized correctly, you will have
problems, too. So if, in the case of the Universal player with the
electric drive motor, your losses and maximum tension aren't adjusted
for stack demands and balanced with the treadles, you won't be able to
pump it with realistic dynamics.
This is all a very important part of a responsive player piano. When
it's right, people just seem to gravitate to it all the time. Let some
little thing be off, and something about it you don't like, and it
won't get used as much. You may not be able to put your finger on it,
but that's one of the things. Another thing is the tone and power of
the instrument, the I think the appearance is also important. It has to
look inviting and mysterious, so it has to be pretty.