Did you know you can control the speed (pitch) of a specific cassette player with control voltage from your analog synth? There's a really cool bend of the GE Variable Speed Cassette Recorder by Chris Randall that gives you just that functionality. Unfortunately, and predictably, it doesn't track with normal 1v/Oct specifications of eurorack. This midi converter fixes that and allows you to control the tape machine melodically with MIDI, like a mono mellotron.
Chris Randall CV In Pitch Control Mod:
Gemini Horror Pitch Control Mod (necessary for full range):
This device converts 12 midi notes (just shy of an octave interval) into the appropriate notes to be sent, through a midi/cv converter, to the CV in mod. This allows you to actually play it like a normal keyboard. The notes aren't perfectly in tune, but they are close. This is because I can only choose from the 128 midi notes available. If you wanted perfect you probably wouldn't be using a modded cassette recorder and max for live to make music in the first place.
Choose the lowest note of the 12 notes you want to use with the “Low” parameter. The highest note, +11 semitones above that, will be displayed next to it. I included a re-trigger toggle with options for last, low and high note priority, as well as a toggle that lets through the other notes.
I've only tested it with my Moog Mother 32 (1 V/Oct (-5/+5 v) (0v = C3)), but it should work with other midi/cv converters with those voltage specifications. If you have another cv converter or synth with different specifications, such as 0-10v, and are willing to give me a table or list of the correct notes, I'll add that functionality in. I think you'll get a much wider range with 0-10v.
To have it work properly:
1) Turn the built in variable speed control on the cassette player all the way up for accurate pitch scaling. This knob changes the range of the cv input. When all the way down the cv in wont work at all.
2) If you haven't also done the Gemini Horror cassette mod, only the first 7 notes or so will work. Once that mod is added (and switched on) the rest of the range (+11 semitones) will open up as you lower the speed. I think as you lower the speed it opens up more room for the extra voltage, or something, I have no idea.
3) If you wired the cv in backwards (which I did at first), the pitch of the tape will go up as you go down from 0v (C3), which means this device wont work. There's a hidden “I wired it wrong” patcher inside the device, which just would need to be switched out with the “I wired it right” patcher. Either re-solder virtual or real wires to fix it, it's your call. Be sure to refreeze the device before you save it.
Tested with the GE-35367. I think it should work the same for all of the slightly different ones that look like it. If you could verify that the scaling works on your slightly different model that would be helpful!
Shout out to Gemini Horror and Chris Randall, for the bends! Also, maxforlive.com user Phatline, whose “Midi-Mono-ddg.mono 2” device was very very very slightly modified to make the retrigger on this device.