Korg Prophecy MP 201 MIDI to CV to Macbeth M5 help!

The Moog Forum Controllers Forum
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Hello everyone

I’ve been wrestling with a very frustrating problem and I’m hoping someone can help.

I have been trying to connect the MP 201 in MIDI to CV mode (patch 34) to a Macbeth M5 synthesizer using a Korg Prophecy as a midi controller with limited results.

I can get about 2 1/2 octaves triggered, but the sound is always on. I’ve connected it as I think it should be (#1 to CV in, #2 to Gate in on the M5). It’s as though it wasn’t passing through the ADSR of the M5, and just S (sustain) does anything, and that’s just a volume change. It seems to work best when the root # is 28 and it’s on bipolar mode.

We crossed referenced the hook up with a Vostox, instead of a MP 201 and that had no issue. It worked. Someone else with a similar set up, uses a Kenton Pro as a MIDI to CV converter (w/ a Prophecy & M5) with no issues.

Is there something obvious (or not so) that I’m missing to make this work? Maybe a trip back to the factory?

Love to get this MP 201 working just for the MIDI to Cv or I’ll have to buy some other MIDI to CV converter.

Thanks in advance for any helpful advice.

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I don’t have an answer for you but a few things to try.

You are right, if the Envelope isn’t ‘firing’ (as I say), you’ll just get the Sustain level.

Your problem is the gate, either the 201 isn’t hearing what it want’s via Midi, or the Gate signal is not adequate for the Macbeth for whatever reason.

First the 201. It needs to hear Note ON’s on channel 2 of patch 34 (assuming you haven’t tweaked it). By default, the 201 is listening on Midi channel #1, so be sure that your Korg is sending on #1, that nothing is filtered out, and that the Midi messages are coming across either DIN or USB (and your MP-201 is setup accordingly). An easy first test is to see if the Midi light is flashing on the 201, but it could be any data, clock, and often, a pulsing channel 1 light can be misconstrued as Midi data (e.g. the light bleeds through from below the front panel).

If you are not getting any flashing of the Midi light as you play your controller, you certainly have an issue. If you are seeing flashing, doublecheck the USB/DIN settings and Midi channel.

Next check the output of the cable coming from channel 2 with a Multimeter or voltmeter, you should see a spike from 0-5V then back down between tip and ring of a standard 1/4" cable. If it is sending voltage properly, see about comparing it against the Kenton Pro’s Gate 1/4"; voltage could be different or possibly worse, the length of the gate signal ‘on’ is not appropriate for the Macbeth.

If you have a 2 channel o-scope, you can look at the waveform side by side and see how they differ. Another thing you can try if you don’t have a voltmeter is to send #2 to CV in on Macbeth or a Moog product and you should hear a very sharp rise in tone for a short period of time. Best to start with a base voltage of the bottom of your keyboard range; this bit is implementation specific but on my Voyager Old School, the input of CV is additive to the base note (that which the synth most recently played); so it’s an offset, not an absolute voltage/note.

If this works, see about ‘listening’ to the output of the Kenton to try and ascertain the difference.

I’m betting it’s a Midi issue and not an issue with Gate but I have no experience with Macbeth gear. Let us know how it works out.