The TB-303 acid sound comes from high resonance, low cutoff, and accent/slide/octave programming

The characteristic ‘acid’ squelch of the Roland TB-303 is not a fixed preset but the result of specific parameter settings plus programming technique. Raising the filter resonance toward self-oscillation while sweeping the cutoff frequency down produces the nasal, gurgling, squelching quality that gives ‘acid’ its name. On top of that filter behaviour, three sequencer features animate the line: accent (emphasizing selected steps with extra volume and filter modulation), slide (portamento gliding between consecutive notes), and octave jumping. Programming these into an otherwise simple, repeating bassline creates the unpredictable-sounding movement that defines the style, prioritizing exploration of texture over melody. The same approach applies to any 303-emulating hardware or software clone that replicates these parameters — a case of a budget instrument becoming genre-defining when used contrary to its intended purpose.

Examples

On a TB-303 or clone: set resonance high (toward self-oscillation), set cutoff low, enable accent on selected steps, enable slide between notes, and program a short repeating pattern. Then sweep cutoff and resonance in real time over several bars — each knob move yields a distinct squelch. Adding octave jumps and accents varies a two-note pattern.

Assessment

Name the two filter parameters and the three programming features that together produce the acid sound, and explain what each does to the signal. Distinguish an accent/slide-programmed acid line from a plain filtered bassline.