Ensoniq ESQ-1

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A fully operational Ensoniq ESQ-1
Dates1985 - 1989
Technical specifications
Polyphony8 voices
Oscillator3× single-cycle wavetable-lookup oscillators per voice
LFO3 (triangle, saw, square and noise)
Synthesis typesubtractive
Filter1 analog resonant low-pass per voice
Attenuator4 VCA (3 DCA, 1 VCA)
Envelope - Four levels, four rates
Storage memory40 patches internal
80 extra with an expansion card
Keyboard61 keys
External controlMIDI

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 signal path includes analog resonant low-pass filters and an analog amplifier.

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.


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[edit]

See also[edit]

Ensoniq SQ-80


  1. ^ "Behind the Release: School of Seven Bells Recombine for "Ghostory" | SonicScoop". Retrieved 2015-09-21.
  • Ensoniq ESQ'1 Digital Wave Synthesizer and Sequencer Musicians Manual Version 2.0 (PDF). Ensoniq. 1986. Model # MM-10, Part # 9310000701, Rev. 2. Your new ESQ 1 is acctually two powerful device -- an eight voice, poly-timbral Digital Synthesizer, and a flexible eight-track MIDI Sequencer -- built into one packaeg. ...", "The Synthesizer - With three Digital Wave Oscillators per voice, thirty-two sampled and synthetic Waveforms to choose from, and 15 routable Modulation sources, ... The ESQ 1 also has an Amplitude Modulation (AM) mode which can produce bell and ring-modulator type effects and a Sync mode for hard sync effects. ...", "The Sequencer - The built-in Sequencer can record and play back 2400 notes (expandable to 10,000 with the optional Sequencer Expander Cartridge). It will store 30 different Sequences, which can be combined into 10 songs. Sequences and Songs can be saved to tape or via MIDI to diskette using ...
  • Ensoniq ESQ'M Digital Wave Synthesizer Module - Musicians Manual Version 1.0 (PDF). Ensoniq. 1987. Model MM-11, Part #9310001301.

Further reading[edit]

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