From MXR:

The MXR Vintage Bass Octave upgrades the warm analog sub-bass vibes of a classic circuit with superior tracking, cleaner headroom, and the versatility that modern players demand. This pedal delivers an impressive range of smooth, musical sounds—from a tone-thickening growl to chest-rumbling dub tones—all in the space-saving MXR mini housing.

The voice of the Vintage Bass Octave is rich and throaty, and it comes in two forms—one octave down and two octaves down. Each can be dialed in separately with the Oct 1 and Oct 2 volume controls, and with a Dry volume control to dial in your clean signal, you can concoct just the right blend for your rig. For extra clarity and definition, use the Mid switch to boost your clean signal’s midrange at 800Hz by +6dB. Want even more of a boost? Just remove the bottom plate and adjust the internal trimpot to kick it up as high as +13dB. Finally, this pedal comes equipped with Constant Headroom Technology™, a custom circuit that provides clean, crystal clear headroom by producing 18-volts from a 9-volt power source (not included).

The Vintage Bass Octave is a pedalboard-friendly must-have for bass players who want to plumb the sonic depths of their instrument.

Input Impedance: 1M Ω
Bypass: THW BP
Signal to Noise: A weighted (Vref IV RMS) - 93 dBV
Output Impedance: <1KOhm
Trigger Threshold: -74 dBv @100Hz
Dry Gain: -∞ 7dB
Octave Gain 1: -∞ 1.6 dB @ 150Hz in
Octave Gain 2: -∞ 1.7 dB @ 150Hz in
Mid Switch: 400 Hz or 800 Hz @ 6 dB
Power Requirements: 9 VDC @ 45 mA (not included)