Electro-Harmonix Octave Multiplexer XO Pedal Generates deep, phat bass tones one octave below the notes you play Two separate smoothing filters enable you to tailor your sub-octave signal to the exact bass sound you desire Run your vocals through it and sound just like Ike Turner This is a monophonic device and works only on single notes 9V Battery included, EHX 96DC power supply optional