The Octave Multiplexer Pedal from Electro-Harmonix is an analog sub-octave generator which produces a sub-octave note one octave below the note you play. With two filter controls and a Sub switch, the Octave Multiplexer allows you to shape the tone of the sub-octave from deep bass to fuzzy sub-octaves.
This pedal features three knobs. The High Filter knob adjusts a filter that will shape the tone of the sub-octave's higher order harmonics. The Bass Filter knob adjusts a filter that will shape the tone of the sub-octave's fundamental and lower order harmonics. The Blend knob is a wet/dry knob.