The PQ-3B is a three band parametric equalizer that was tuned for bass guitar use. The complex interface of the PQ-3B was overwhelming for some (especially simple bass minds..) so the effect wasn't the biggest seller at the time of it's release. Nowadays it's a very desirable pedal due to it's short production and huge range of tone shaping possibilities.
the Low, Middle and High Level knobs boost or cut their respective frequencies and the Level knob controls the output volume level (from -18dB to +18dB). The Low, Middle and High knobs also feature individual Frequency knobs to shift the centre frequencies (25hZ to 400hZ for Low, 160hZ to 2.5kHz for Middle and 1khZ to 16kHz for High).
