Alesis S4

Back in 1993, this rackmount module made waves as the rack version of Alesis's debut flagship synth, pioneering the ADAT optical digital interface for seamless all-digital integration with recorders.

Housed in a compact 1U chassis, it packs 64-voice polyphony and 16MB of 48kHz stereo samples into its ROM, expandable via PCMCIA cards up to 24MB, using sample playback synthesis with digital filters, LFOs, and envelopes to blend up to four tones per program. Four assignable knobs offer hands-on tweaking of key parameters, while the onboard QuadraVerb 2-inspired effects processor delivers four simultaneous FX sends routed to one stereo main plus two aux outputs. It holds 128 preset and 128 user programs, plus 100 each of preset and user mixes for 16-part multitimbral setups, with MIDI in/thru/out, pedal inputs, and that game-changing ADAT out for pro studios.

Players have long praised its vast, high-quality soundset—from lush stereo grands and drum kits to synth classics—for punching above its weight in dense arrangements, though some note the editing depth rewards patient explorers over knob-twiddlers.