SQ-2 © 1991 Ensoniq
The SQ-2 is a 76-key programmable digital sample-playback synthesizer and workstation. Following the success of the compact SQ-1, Ensoniq engineered the SQ-2 to appeal directly to gigging keyboardists, church musicians, and studio composers who demanded a wider, semi-weighted keybed for piano-centric performances along with a complete, self-contained multi-track songwriting environment.
The sound generation core of the SQ-2 relies on Ensoniq’s 21-voice polyphonic, 8-part multi-timbral digital engine (upgradable to 32 voices in later production revisions). It utilizes 16-bit linear acoustic and synthetic waveforms compressed into a high-fidelity internal ROM pool, featuring a pristine grand piano, rich strings, punchy brass, and an array of classic synthetic textures. Each individual sound patch can layer up to three digital macro-oscillators, with each path featuring its own independent 4-stage digital filter (selectable 2-pole or 4-pole slopes), an LFO, and a dedicated envelope generator. The mix is glued together by a built-in 24-bit Ensoniq Signal Processor (ESP) chip, providing studio-grade digital reverb, chorus, delay, and distortion algorithms.
The physical unit is wrapped in a sleek, elongated black metal and plastic chassis, dominated by a 76-note velocity-sensitive keyboard. The streamlined front panel utilizes a custom, backlit alphanumeric LCD screen alongside a functional matrix array of soft-touch editing buttons, a master data slider, and pitch/modulation wheels. Around back, the SQ-2 features a dedicated slot for Voice/Sequence RAM and ROM expansion cards, standard 5-pin MIDI In/Out/Thru connections, dual footpedal inputs, and a main stereo analog audio output pair.
The Full-Size Performance Expansion: While the original SQ-1 keyboard targeted the budget-conscious consumer with a standard 61-note unweighted layout, the SQ-2 was built specifically for keyboardists who found 5 octaves too restrictive. The 76-note semi-weighted keybed provided the necessary octave span to naturally perform classical arrangements and split the keyboard between a heavy left-hand acoustic bass and a right-hand electric piano.
The Built-In 16-Track Studio: The standout feature of the SQ-2 was its integrated 16-track hardware sequencer. It features an 8,500-note on-board memory pool (expandable to 31,000 notes via a custom RAM expansion card) that lets musicians record full, multi-instrument song arrangements in real-time or step-time. Because of its robust multi-timbral architecture, a user could compose a complete rhythm section, bass line, and melody track entirely inside the keyboard without ever touching a computer.
The "32-Voice Plus" Motherboard Upgrade: Mid-way through its factory production run, Ensoniq released a heavily upgraded motherboard revision for the SQ-2 (often badged as the "SQ-2 32-Voice"). This update did not just bump the maximum polyphony from 21 to 32 voices; it also doubled the internal ROM memory wave pool, adding a pristine new acoustic grand piano multi-sample that became a favorite for gigging stage performers in the early 1990s.
Seamless Auditioning Loops: The operating system of the SQ-2 features an incredibly elegant "Compare" function within its editing matrix. If a sound designer modifies a complex filter envelope or changes an effects algorithm, they can press the Compare key while playing a loop to instantly flash back and forth between the edited patch and the original saved factory preset. This allowed for risk-free, rapid sound-design experimentation during live recording sessions.