[AH] CV TO MIDI

[Chris Stecker]

Ok I don't know about any great, general purpose CV->MIDI converters, but
here's what I plan to do for this same problem, using MSP.

First, we'll build a simple cicuit that takes in CV, uses it to control a
VCA which is gating a simple fixed oscillator.  Several of these circuits
can be put in one box, with each CV input controlling the level of a
different frequency tone.  The resulting signals are mixed together and
sent out of the box as an audio signal.

Now, we send that audio signal to the Mac sound in, and then the MSP patch
takes over.

In MSP, a bank of filters isolates the different frequencies we sent in.
As in a vocoder, each filter is followed by an envelope follower, which
extracts the CV signal we used to modulate the tone.  Now the CV's are in
the digital world (still as signals, though) and we can do whatever we want
to them.  We can set up a simple map to generate CC messages out of MAX,
based on the voltage, or we can build more elaborate detectors which
actually construct note-on messages based on the CV signal.  Of course, we
may just want to use them in MSP as signal modifiers, without ever going
into MIDI.

I understand that 1) This concept is not new.  Buchla used it in his
original "ghost boxes" to store CV on magnetic tape (c. 1963), and Disney
used it store surround sound mix info for "Fantasia" (c. 1936).  and also
that 2) not everyone has access to a power mac and MSP.  Sorry.  It's just
one solution.

-Chris