[ William Faulkner wrote in 050926 MMDigest:

> MIDI seems like a possibility.  The limitations I have seen in the
> English systems are (1) small bellows, not allowing for slower
> cranking speed and tempo variation (which is done by better
> organilleros in Mexico on select songs), ...

Building this valuable feature into a system made from off-the-shelf
circuit boards would be an interesting challenge.  It would require
a MIDI sequencer that can accept timing pulses from an external source
-- I think some have this feature.

> ... (2) a softer sound than the German instruments, ...

So, you should build an organ from scratch, with suitable pipes
(Bourdons, mostly).  This fits well with what I say later on...

> ... and (3) a non-transparent way to program the chips.

Do you mean to make it difficult for someone to copy the music
arrangements from the memory chips or whatever storage medium?  If
so, you cannot use actual MIDI, since anyone can buy a MIDI recorder
and capture the MIDI byte stream at that point.

The proprietary systems, such as Hofbauer's, do not use MIDI as an
intermediary.  This protects the arrangements, but also makes it
impossible for others to put their own arrangements into the system.

> I may even retrofit an older Mexican/German organ with the MIDI
> system, if I can find a way to program the Mexican melodies and
> arrangements into the MIDI system.

Rather than hack up a genuine barrel organ, sell it to a collector,
who will pay well for it.  Use the money to build an organ from
scratch, using softer voiced pipes as mentioned above.  Also, this
gives you the chance to use direct-electric valves in a very simple
wind chest, doing away with pneumatics and stop sliders.  Each rank
of pipes will have its own valves.  This also lets your arrangements
be very flexible, controlling every pipe individually and not just
through stop registers.

Hope this helps

Mike Knudsen