ELECTRO-HARMONIX / OCTAVE

The Octave Multiplexer is a monophonic octaver that generates a rich sub-octave sound. It generates a sound one octave below the note you play, and you can use independent two-band filters to shape the tone to your liking. It produces unique effects on guitar and bass, as well as vocals. *This product responds only to single notes; it does not support chords.

■Guitar Effects Pedal
■Octaver
■HIGH FILTER: Controls the high harmonic tones of the octave sound.
■BASAS FILTER: Controls the fundamental and low harmonic tones of the octave sound.
■BLEND: Controls the balance between the original sound and the octave sound.
■SUB: On/off switch for the BASS filter, which controls the low frequencies of the octave sound.
■Power Supply: 9V battery or 9VDC center-negative adapter (sold separately).
~From the manufacturer's website~
This produces a sound an octave below the note you play, which can be further controlled with the filter. It also has a two-band filter. It can be used with both guitar and bass, and passing vocals through it will give you an Ike Turner-like voice.