[sdiy] Polyphonic MIDI to CV???

[Grant Richter]

Buchla used a 32Khz scanning frequency on his keyboards (32 keys in 1
millisecond). The voltages were output by a DAC driven by the scanning
counter. The system had high note priority (latched at the highest note),
but would "pause" and trigger at each key actually touched. So putting a
demultiplexer made of 4 sample and holds gets you polyphonic output.

The beauty of they system is it works with all the touch keyboards. So the
polyphonic adapter can be used with the 217, 218 and (I think) the 219.

The Buchla "black and white" keyboards had polyphony, velocity and
aftertouch in the 1960s. Don Buchla patented keyboard velocity and
aftertouch sensing for the Kimball Organ company in 1962? or something. If
you do a patent scan for Buchla you can find the correct details.

> From: Peter Grenader <pgrenader at mksound.com>
> Date: Mon, 18 Feb 2002 05:28:49 -0700
> To: <KPEEK1 at prodigy.net>, <synth-diy at dropmix.xs4all.nl>
> Subject: Re: [sdiy] Polyphonic MIDI to CV???
> 
> If it's any help, Buchla's 264 Quad Sample and Hold/Polyphonic Adapter did
> just this using a non-midi voltage keyboard.  I have not seen a schemo for
> this box.  I have worked with a couple of them however.
> 
> The bottom section consisted of a super-sensitive 4 step sequencer or sorts.
> If the output of a keyboard was connected and if up to four keys (in this
> instance, touch plates) were hit simultaniously,  this device would
> demultiplex them and send four different descrete output voltages
> corrosponding to the key drepressed.  Possibly there was a slight (very
> slight) arpeggiation was required - I don't remember (it was 22 years ago).
> 
> For two years using this device I did not realize that this was its design
> intention.  I patched it basically to do Analog Shift Register type voltage
> distributions.  Then one day it was explained to me that it was Don's
> attempt to create multi voltage sources from a single keyboard.
> 
> I tried it, and oh golly, it worked.
> 
> Hope this helps.
> 
> -Peter
> 
> on 2/18/02 12:19 PM, KPEEK1 at prodigy.net at KPEEK1 at prodigy.net wrote:
> 
>> Here is my simplified question:
>> 
>> If I have two monosynth modules and two separate MIDI
>> to CV/Gate convertors, then I can play two-note
>> polyphony provided the two MIDI to CV are on different
>> MIDI channels (eg. Channel 1 and 2)
>> 
>> I order to accomplish this I need to play each note on
>> a separate keyboard or input device. I want to make
>> something where I can play two and three notes and
>> have each assigned to separate monosynth modules like
>> the Oberheim SEM 4 voice but using a MIDI controller.
>> 
>> How can I make it where the notes are prioritized and
>> the second note played go to the second monosynth? The
>> third note to the third monosynth etc.?
>> 
>> I know some commercial MIDI to CV convertors do this,
>> but I would prefer to build one if possible.
>> 
>> Thanks!!!!!!
>> 
> 
> 
>