The Roland Jupiter 4 Compuphonic Synthesizer is a vintage four-voice polyphonic synthesizer from 1978. It features an arpeggiator and even had 8 (count ‘em) user-programmable patches!

The Jupiter 4 was notable as the company’s first self-contained polyphonic synthesizer, and for containing digital control of analog circuits (termed “Compuphonic” by Roland), allowing for such features as programmable memories and voice assignment modes.

The Jupiter 4’s basic architecture was 4 identical voice cards, each with a VCO (with sub-oscillator), resonant low pass VCF (which could self-oscillate), and VCA. Modulation included an ADSR envelope and LFO. The LFO, routable to oscillator pitch, pulse width, filter cutoff and amplifier, was notable for being able to reach audio frequencies, allowing for crude FM and AM synthesis.

The Jupiter 4’s two most distinctive features were provided by virtue of its “compuphonic” digital control of the four voice cards:

An arpeggiator, with a choice of up, down, up/down, or random mode. The arpeggiator can be prominently heard in Duran Duran’s 1982 hit single “Rio.”

Four voice assignment modes, which, as well as simple 1 VCO-per-voice polyphony, included the ability to effect 4-VCO unison when one key was pressed, 2-VCOs per voice when two keys were pressed, and 1-VCO per voice when three or four keys were pressed. This effect can be heard on tracks such as “Seconds” by The Human League and “I Dream of Wires” by Gary Numan.

The final signal path also included a simple high pass filter and a stereo chorus effect. The Jupiter 4 had 10 preset sounds and also featured 8 memory locations for user-created patches.

Famous players include: 808 State, Vince Clarke, Depeche Mode, Thomas Dolby, Kitaro, Neruonium, Nick Rhodes, Tangerine Dream, Tears for Fears, Tomita, Stevie Wonder and Vangelis.

If you’ve used the Roland Jupiter 4 synthesizer, leave a comment with your thoughts!

Features:

• 4 voices
• 1 VCO per voice (triangle, square, square with PWM) and a switchable on\off sub osc
• 1 LFO (sine, square, ramp up and ramp down)
• HP filter, LP rez filter
• 2 env (ADSR) one for the filter, which you can invert, one for the VCA
• Ensemble/Chorus
• Arpeggiator

video demo via abertronic