When Sequential Circuits released the Prophet-600 in 1982, they made a bold move: take the architecture that made the Prophet-5 legendary and strip it down to its essentials, then add something the Prophet-5 never had—MIDI support and a built-in sequencer. It became the first American synthesizer to ship with MIDI, a detail that mattered more than most people realized at the time.
The Prophet-600 is a six-voice analog synthesizer with dual voltage-controlled oscillators per voice, each capable of sawtooth, triangle, and pulse waveforms with adjustable pulse width. The filter is a 24dB resonant low-pass design built on Curtis CEM chips, paired with two independent four-stage envelope generators—one for filter modulation and one for amplitude control. An LFO with basic waveforms can modulate oscillator frequency and pulse width, while a dedicated modulation wheel lets you shape the sound in real time. Oscillator sync is available for those classic harmonic sweep effects, and oscillator B includes fine-tuning for that characteristically fat detuned analog sound. The synth runs on a Z80 microprocessor that handles tuning stability, digital envelope generation, and MIDI communication, while the built-in arpeggiator and real-time polyphonic sequencer let you record and playback up to six-note performances at variable speeds.
The Prophet-600 earned respect as a capable workhorse, though it developed a reputation for envelope instability compared to its more expensive sibling. That changed when the community discovered the GliGli mod, a CPU replacement that transformed the synth into something genuinely special—adding extra LFO shapes, unison detune, and overhauled MIDI implementation. Even in its original form, the Prophet-600 remains a solid entry point into the Sequential legacy, with enough character and control to hold its own in any setup.
