Ensoniq ESQ-1

Ensoniq ESQ-1 is a 61-key, velocity sensitive, eight-note polyphonic and multitimbral synthesizer released by Ensoniq in 1985. It was marketed as a "digital wave synthesizer" but was an early Music Workstation. 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 true digital oscillators, 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, 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.

The ESQ-1 had a particularly easy user interface, especially for a feature-filled digital synthesizer of the time and a multitimbral workstation/sequencer , by way of a then-large 40-character x 2-line display, ten softkeys (5 above and 5 below display), and system of all dedicated direct-access buttons per ten-parameter/patch page, meaning there was no "menu diving" within hierarchical series of sub-pages whatsoever.

ESQ-1 can store 40 rewritable sound patches internally, and features a rewritable EEPROM or fixed ROM cartridge slot for access to 80 additional patches. ESQ-M, a rackmount version of the synthesizer, was released circa 1987, with the same specifications but without the sequencer and a significantly smaller display and less user-friendly interface.

Notably, the sound chip at the core of the synth, the 5503 Digital Oscillator Chip (DOC), is a brainchild of Robert Yannes, father of the popular Commodore SID chip.The chip was previously used in Ensoniq's Mirage sampler, later in ESQ-1's enhanced successor SQ-80, as well as the Apple IIGS personal computer.