CEM3394 Test

The CEM3394. A synth-on-a-chip, made by Curtis Electromusic Specialties, during the golden age of synthesizers.

The IC contains a VCO, VCF, VCA, a wave shaper, an external mixer and a cool sounding VCF modulator. Check out the datasheet for
a nice and tidy block diagram.

The CEM3394 was used in the Akai AX60, Sequential Circuits Six-Trax, MAX, Split8, and is still being used in the Doepfer Dark Energy.

Since I didn’t have much experience with op amps, this project became quite a challenge for me.
However, after some reading and simulation, I got around and did a PCB layout.

For pitch and gate CVs, I used the MIDImplant from Roman Sowa. Worked perfectly out of the box.

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After populating the PCB, wiring the pots and hooking up the powersupply, I fed it with some MIDI from my computer and it actually did work
on the first try. Didn’t expect that. I tend to mess up the simplest circuits most of the time.

Audio demo:
Filter modulation, filter, waveforms and more
http://www.djodin.com/cem3394_test3.mp3

3 tracks with the 3394, and software drums.  A bit out of tune.
http://www.djodin.com/cem3394_test2.mp3

Here is the schematic. Please take a look at the red note..