Mike Jardin asked some questions about the Pianocorder.  First, I'm curious
where Mike is getting the parts.  I don't believe these have not been in
production for a long time.  There's a lot of these systems in the LA area
maintained by a technician who bought the rights to use the DBA
Universal Piano Co. His name is Randy Cox and he can be reached
at 714-283-4242.

I cannot speak for the mechanical difficulty of installing one of these
systems (talk to Randy), but I've had some experience with the electronics.
The most notable point w/r/t the electronics is that it structured very
similarly to pneumatic reproducing pianos.  In particular, there are
two D/A converters for expression control -- one for the bass cleff and
one for the treble cleff.  I don't recall there being any support for
cresendos, just discreet levels.  I don't remember if there are 3 or 4
bits going to each converter.  This arrangement makes transcribing
pneumatic rolls into Pianocorder format straightforward (except for
the cresendo issue), but it makes the MIDI conversion a problem because
MIDI assigns a velocity value to EACH note.  It is possible to play
notes in the base and treble cleff simultaneously with differrent velocities,
it is not possible to play notes in the same cleff simultaneously with
differrent velocities.  This makes the job of the MIDI converter box hard.

Frankly, this also makes conversion of MIDI performances to pneumatic
reproducing piano format difficult as well.  Mike Ames has made an Ampico A
available to me for experiments in this area, but there's only so much
time in the day...

A word of caution w/r/t the Pianocorder's electronics (and probably
some of the other systems which I've not seen the insides of yet).  The
Pianocorder systems I've seen did NOT have isolation transformers.  This
results in the possibility of line voltage to be present where you think
there should be "ground", including wiring to the cassette recorder.  They
use plastic knobs for a reason!

I've only seen (and tried) one commercial MIDI converter design for the
Pianocorder.  It worked pretty well and _seemed_ to have the necessary
circuit isolation.  I talked to the engineer that designed it a couple of
years ago.  It turns out that he's the same engineer that designed the
Pianomation electronics for QRS.