The TB-303 is THE sound of acid and techno house music! It's a monophonic analog bass synthesizer married to a pattern-based step sequencer released in 1982. It features a single analog oscillator with two waveforms (ramp or square) and has a simple but excellent VCF (filter) with resonance, cut-off, and envelope controls. There are also knobs to adjust tuning, envelope decay, tempo and accent amount.