Did you know you can control the speed (pitch) of a specific cassette player with control voltage from your analog synth? There's a cool bend of the GE Variable Speed Cassette Recorder by Chris Randall that lets you do just that. 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 machines pitch with MIDI, like a monophonic mellotron.
There are 2 versions of this device. A Max for Live instrument which converts MIDI to CV, and this device, a MIDI Effect which just converts the MIDI to the closest MIDI notes notes to be sent, through an external MIDI/CV converter, to the tape machine. The CV version is more accurate should be used if you have a DC coupled interface, such as the ES 8. ( https://stevieschmidt.gumroad.com/l/gswzi )
The range of the device is 12-14 MIDI notes (12 in ±5v mode and 14 in ±10v mode). The notes aren't perfectly in tune, but they are within 10 cents. 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. The MIDI/CV Instrument version isn't perfect either but it is closer.
Low parameter, which chooses the lowest note of your range. (The highest note will be displayed next to it)
Re-trigger toggle, with options for last, low and high note priority.
A toggle which lets through out of range notes unscaled or throws them away.
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 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. Once you lower it too much though, because it can get ridiculously low, the scaling becomes inaccurate.
3) If you wired the CV input 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 (only for ±5v mode) 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 or with your MIDI CV converter 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.
Chris Randall CV In Pitch Control Mod:
Gemini Horror Pitch Control Mod (necessary for full range):