MXR Bass Octave Pedal DeluxeThe M288 Bass Octave Deluxe is a dual voice octave pedal that offers analog tone, true bypass, and a variety of tonal options. MXR's 18 volt Constant Headroom Technology provides high headroom and superior tracking. Use the Dry knob to mix in your direct signal, and hit the Mid+ switch to add up to +14dB of internally adjustable mid frequencies (400Hz or 850Hz). Finally, mix in two separately controlled octave voicesGrowl (for throaty tone) and Girth