The first electric to vacuum interface that I ever saw was on an
Aeolian residence pipe organ installation.  The console, "Concertola"
and a Steinway Duo-Art Grand were all located in the music roll of the
palatial home.  The organ was in the basement and spoke through tone
openings into the various rooms of the residence.

The piano could be played remotely from the console.  Aeolian simply
mounted some of their organ magnets on a board and tubed them into the
stack and other functions.  As I recall, the sustaining pedal was
operated from a switch on the swell shoe: you moved the toe of _your_
shoe sideways to engage the switch.

I don't know what vacuum level the piano operated at, but a similar
situation existed in a Robert Morton Theater Organ located in the Aztec
Theater here in San Antonio.  The upright piano (brand name Winter) sat
in a stripped down case.  The magnet board was located on top of the
stack.  Vacuum for the piano was supplied by a Spencer OrgoBlo with the
supply coming off the intake of the blower located next to the 25 horse
power monster that blew the organ.  The vacuum level was high; after all,
you were looking for volume to fill the theater.

In these days of modifications and modernization of pipe organ
installations, it should be fairly easy to pick up used organ magnets.
Two brands that I have used are Wicks and Kilgen.

The Kilgen magnet is the easiest to work with as it does not require
screws for mounting and its compact design allows for mounting a lot
of magnets in a small space.  It is simply press fit into a hole
drilled in the bottom bung, or elsewhere, of the organ chest.  You can
solder a 1/8" or larger nipple to the exhaust port and connect it to
whatever you want to run.

Wicks magnets can be mounted over brass nipples and they in turn are
tubed to whatever you want them to activate.

If you want new magnets, made especially for player piano use, Organ
Supply Industries (OSI) has them in their current catalog on page 5-7.
They are their part number:  5909.14.  Here is the description as
I cannot find them in OSI's online catalog.

  "Designed to interface with piano and other vacuum operations.
   1/8" brass nipple accommodates standard piano tubing and extends
   1/2" from the magnet cap.  60 ohm coil."

The new price list pegs them at $7.92 each.  Not cheap when you are
considering 100 of them.

The last batch of Wicks magnets that I bought from a local pipe organ
technician I paid fifty cents apiece for.  Kilgen magnets may run a bit
more as they are more difficult to find.

Ed Gaida

 [ I believe the OSI player piano valve is a simple variant of the
 [ organ chest magnet valve, which must be at least 80 years old.
 [ This is the valve with the horseshoe core and two coils which lift
 [ a felt-faced steel disc from the port (magnet cap).  It's proven
 [ very reliable.  OSI may offer a quantity discount.  -- Robbie