« Synthesizer Library Podcast

Episode 005 - Ensoniq ESQ-1

Published: Sep 15, 2015 by Adam Anderson

Featuring digital oscillators and analog filters, the now-vintage Ensoniq ESQ-1 offers flexible sound design options. Prices these days won't hurt your wallet, but lugging it around may hurt your back. We'll showcase how sounds are built in the ESQ-1 and touch on some of the other features in this '80s classic.
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Show Notes


The Ensoniq ESQ-1 is a hefty hybrid digital and analog synthesizer with 8 notes of polyphony. During the Yamaha DX-7 dominated 1980s, the ESQ-1 struggled to gain popularity. Today, however, it has seen a surge in popularity but still can be had for a few hundred dollars.

Sound Design

Each sound can be made up of:

  • Three digital oscillators (choose from 32 waveforms)
  • Three digitally controlled amplifiers (which mix the three oscillators)
  • One low-pass analog filter with resonance per voice

There are many modulation points along the way including pitch modulation of the oscillators, volume modulation of the DCAs, filter cutoff and resonance modulation. The modulation of these values can be controlled by:

  • Three LFOs
  • Four ADSR-style Envelopes (envelope 4 is hardwired to the final output DCA)
  • External MIDI controller, Velocity, Keyboard range, Modulation wheel, and more.

The ESQ-1 is also capable of producing sounds with Amplitude Modulation between Oscillators 1 and 2. This function is sometimes called a Ring Modulation effect. This produces “sidebands” which give the tone an inharmonic, almost metallic feel.

You can easily get lost in the ESQ-1’s sound design features. Fortunately, the manual is very well written. Check the resources below if you need the manual.

Sequencer and MIDI

But wait, there’s more. The built-in 8 track sequencer is very capable. It is handy for sketching melodies, controlling external MIDI equipment, or even as a manual arpeggiator. Since each of the 8 tracks in the sequencer can have a different sound assigned to it, the ESQ-1 is truly polyphonic. It can play 8 notes of 8 different sounds at the same time. In fact, you can use the sequencer to set up 8 sounds on 8 different MIDI channels then use an external sequencer or DAW to trigger all of those sounds on 8 different MIDI channels at the same time.