MXR M-82 Bass Guitar Pedal Bass Guitar Envelope FilterSeparate Dry and Effect controls let you dial in the perfect mix of effected and direct signals, so you can bring the funk without losing the low end. It's wide range of filter tones can be shaped with the Decay and Q controls, and a simple twist of the Sensitivity knob can tailor the pedal for your attack as well as adjust for passive or active basses. The Bass Envelope Filter's power supply circuitry is designed to withstand over voltage or polarity