Robbie's post on emulating a fairground (band) organ was intriguing.
I went through some of the mental phases of designing an electronic
classical/church pipe organ with the same premise: base it on
commercially available MIDI hardware and software, rather than the
usual custom incompatible hardware design of Allen, Rodgers, etc.

I think one could start a little smaller and simpler and work up to
the full-blown fairground effect with even less custom hardware hacking
than Robbie envisioned.

First, I know a guy (Bill Budenholzer) who has tweaked his Roland Sound
Canvas synthesizer to get some very authentic band organ sounds.  One
year he gave me one of his "musical Xmas cards", a cassette tape of
Christmas songs done on his MIDI computer setup.

One piece struck me as sounding a LOT like a pipe-based orchestrion.
At the time I didn't even know Bill was into automatic music.  When I
asked him, he "confessed" that it was no coincidence.

So it can be done.  Outboard MIDI "tone module" synths (often called
"clock radios" for their size and shape) have the advantage over Sound
Blaster cards in that they can be used with any computer (even the
8-bit antiques that Bill and I use) and can be played directly from a
MIDI controller keyboard.  Newer models allow for downloading sampled
sounds, but have such powerful synthesis techniques that you might do
better not to.  Layering detuned tones to simulate Dutch bourdons is
easy.

A MIDI controller is a keyboard with no or rudimentary sound
generation, but it outputs MIDI commands as you play the keys, and
registration changes as well.

Rather than wire up an old organ console (a lot of work), you could
stack up two or three MIDI controllers to simulate organ manuals.  Rock
bands already do something close.  You'd probably have to wire up your
own pedal keyboard, though.

There are all sorts of MIDI routing boxes that can be used to tie
the keyboards and synths together, though here I'd concede that a
computer is more flexible, and allows for recording, hand
editing, and even notation composing.

Let's keep the ideas rolling.

Mike Knudsen

 [ Thanks for your suggestions, Mike.  I have a lot of investigating
 [ to do, that's for sure.  :)  -- Robbie