Roland TB-303

Misunderstood at its 1981 launch, then reborn as the sound of acid house. The TB-303 is a small bass synthesizer with its own step sequencer, and its resonant filter produces a rubbery, squelching line that sounds nothing like a bass guitar, which turned out to be its appeal. In Chicago, Phuture's "Acid Tracks", often cited as one of the first acid house records, paired that squelching resonance with TR-909 drums. By the late 1980s the silver box had defined the acid house movement. Producers still twist its cutoff and resonance knobs live, and its acid line remains one of the most imitated sounds in dance music.