I have a very successful hookup from roll player to pipes: a Wangerin
Funeral freestanding unit I purchased from Minneapolis, which
originally played dreadfully boring funeral rolls on three ranks of
Wangerin organ,

I wired a two-rank Kilgen organ to this vacuum pneumatic unit using a
very simple Peterson relay to control the two stops, flute and string.
You really don't need or want more than two ranks of pipes, and they
should both be only at 8' (piano) pitch.  Any higher pitch and the
music really gets shrill on the high notes.  But two mild 8' stops are
perfect.

There is a little trick in the bass, though, that gives the bottom more
punch.  Low piano "C" plays the 16' sub-bass octave.  The next octave,
through wiring, has the option of repeating the bottom 16' notes again.
This works for most rolls, and gives more definition to the notes if
they're "single hole" notes.

Most piano rolls work well, providing they have the sustain "built in"
as extended notes.  Even with those, I devised a color coding so I can
see at a glance which ones are the best for organ, rated 1-4.  Visitors
thoroughly enjoy listening to these rolls.  Fox trots are the neatest,
and dancing is bound to happen.

What I just described was my "downstairs" player organ.  On my "upstairs"
pipe organ and grand piano, I often play them together from MIDI files.
Again, using a single mildly voiced 8' stop is perfect for the organ.
Visitors are welcome.

Devon Hollingsworth, in Chicago suburb