Samiksha Jaiswal

Ensoniq ESQ 1

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Manufacturer  Ensoniq
Polyphony  {{{polyphony}}}
Dates  1985 - 1989
Timbrality  9
Ensoniq ESQ-1
Oscillator  3× single-cycle wavetable-lookup oscillators per voice
LFO  3 (triangle, saw, square and noise)

Ensoniq ESQ-1 is a 61-key, velocity sensitive, eight-note polyphonic and multitimbral synthesizer released by Ensoniq in 1985. Although its voice generation is typically subtractive in much the same fashion as most analog synthesizers that preceded it, its oscillators are neither voltage nor "digitally controlled", but provided by a custom Ensoniq wavetable chip. The rest of the signal path is analog, including resonant low-pass filters.


The synth also features a fully functional, if crude by modern standards, 8-track MIDI sequencer that can run either its internal sounds, external MIDI equipment, or both, with a capacity of 2,400 notes (expandable via cartridges). It provides quantization, step-editing, primitive forms of copy/paste editing, and can be synchronized with external MIDI or tape-in clock.

ESQ-1 can store 40 presets internally, and features a cartridge slot for additional storage capability. ESQ-M, a rackmount version of the synthesizer, was released circa 1987, with the same specifications but without the sequencer.

Notably, the sound chip at the core of the synth is a brainchild of Robert Yannes, father of the popular SID chip. Other than both being based on phase accumulation, they however don't share any further similarities.


The ESQ-1 features eight voices with three oscillators per voice, and is fully multi-timbral. The wave ROM accessed by the soundchip contains 32 different waveforms, including standard synthesis waveforms such as sawtooth and square, but also less usual ones such as "piano", "voice", or "bass" (note that, although multi-sampled, these are still single-cycle waveforms, not true samples as such).

Each oscillator can be independently volume-controlled via its dedicated digitally-controlled amplifier, or modulated with an LFO, or an envelope generator. Oscillator amplifiers provide room to be overdriven, and thus produce moderate analog distortion as an additional effect on, for example, synth leads or organ sounds.

ESQ-1 has three independent LFOs, and three independent envelope generators which can be programmed to modulate any number of parameters. The fourth envelope generator is hardwired to the main output amplifier though it can still be used as a modulation source for other parameters as well. The fourth envelope generator also provides programmable panning for each voice. Its envelope generators allow precise level/rate settings and therefore provide more flexibility than typical ADSR envelopes. Like many other synthesis parameters, they allow use of negative values. Furthermore, they provide some rarely seen features, such as the option to tune the attack portion of the envelope with regard to keyboard velocity (enabling a voice to have a soft attack when played softly and vice versa) or envelope key-tracking (for instance, having shorter notes on a piano sound higher up the keyboard, mimicking the real instrument behaviour).

Its low-pass filters are analog (CEM 3379), but digitally controlled, and thus can be modulated by a significant number of sources, including LFO, envelopes, velocity, aftertouch, modulation wheel, et cetera. Even though the filter resonance can be driven to extreme effect, the resonance setting features only 32 steps, and the filters do not self-oscillate. The ESQ-1's keybed doesn't feature aftertouch, but the synthesis engine is capable of processing polyphonic aftertouch over MIDI.

Furthermore, Ensoniq ESQ-1 features amplitude modulation, oscillator sync, monophonic mode, and portamento.


Each section of the synthesizer is called to screen via a dedicated button, and settings inside each category are made by using one data slider or two +/- buttons. Settings do not influence the sound directly, but rather, changes are heard only when the next note is played. In other words, one can't use the data slider to change the filter cutoff setting as a way of producing a live filter sweep, but can use any of the modulation sources for the same effect (including envelopes, the modulation wheel, modulation pedal, or external controllers over MIDI). Any modulation source can be set up to modulate each page of any given program.

Notable users

  • School of Seven Bells
  • Alpha Wave Movement
  • References

    Ensoniq ESQ-1 Wikipedia

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