The MB 33 is a rack-mounted TB-303 clone released in the mid-nineties by German synth maker MAM (Music And More). It's basically identical to the Freebass 383 (which had a different front-panel design). It is a true analog monophonic bass synthesizer with MIDI implementation so you can create 303-like bass lines from your sequencer. Its single VCO offers the same two basic waveforms as the TB-303: a sawtooth and square wave. But in the MB 33 they can be mixed together for a more interesting tone than the 303 could originally produce.