From Steve.Ridley@bbc.co.uk Sat Jul 20 18:08:12 1996 20 Jul 96 21:07:57 +0500 20 Jul 96 21:07:40 +0500 Comments: Authenticated sender is 20 Jul 96 14:03:43 +0500 (5.67b/IDA-1.4.4 for ); Sat, 20 Jul 1996 18:38:31 +0100 X-Nvlenv-01Date-Transferred: 20-Jul-1996 18:38:02 +0100; at link1.bbc X-Nvlenv-01Date-Posted: 20-Jul-1996 18:37:50 +0100; at bh2.bbc Subject: Run an MS20 from V/Oct. From: Steve.Ridley@bbc.co.uk (Steve Ridley-MV) Date: 20 Jul 96 18:37:41 GMT References: I can hardly believe no one knows about this already. It is possible to control an MS20 from a V/Octave keyboard or MIDI/CV converter without a special interface. If you don't believe it, try it. When I first got my MS20, I noticed that the filters don't track the keyboard at all. I plugged the keyboard CV to the filter CV in, but then the filter tracked the keyboard slowly in the lower octave, then went screeching off in search of tweeters to kill! I soon realised that the filter was tracking exponentially. I looked at the schematics and sure enough, both the VCOs and the VCFs have exponential converters on the modulation inputs. So, if you stick a V/Octave input into the modulation inputs and adjust the MG level for correct scaling, it all works and the filters track too. Here's how you do it. 1. Plug the performance wheel into the keyboard CV input (middle, right) to disconnect the keyboard. 2. Plug the V/octave CV from your MIDI/CV converter or another synth into the Total jack (top left). 3. Plug S-trigger from your MIDI/CV or synth into the MS20 trigger input. 4. Play a note on your MIDI keyboard or the controlling synth, and adjust the MS20 performance wheel until you get a sensible pitch. 5. Adjust the VCO mod levels until playing an octave on your MIDI or other synth keyboard gives an octave out of the MS20. Then adjust the MS20 performance wheel to coarse tune the MS20 and use the tuning pot to fine tune it. 6. The filter mod level pots adjust filter tracking in the same way. 7. Enjoy. You lose use of the performance wheel on the MS20, but that's not a big problem if your MIDI/CV converter or your other synth has pitch bend. You will need a V to S trigger converter to control the MS20 of synths without S-trigger outputs, but they're simple to make (two resistors and an NPN transistor, plenty of circuits posted elsewhere). I don't have the MS20 in front of me, so apologies if the names of pots and jacks are not exact. Believe me, it does work. STEVE RIDLEY