This pedal is another mu-amp JFET transistor boost using two 5751 transistors in a stacked configuration. The controls for this pedal are—a volume knob controlling overall output level, a bias knob which controls the gain level of the transistors, and a 2-way bass switch which selects between a flatter response and a more bass heavy response. The bias knob controls the same range of gain as the switch in CWS001, but allows for a fine adjustment to any level in between. This, in conjunction with the volume knob allows for a balance to be found between a higher gain of the transistors with a lower output (more saturation), or lower gain of the transistors and more volume (low saturation clean boost).
The unavoidable effect of biasing a transistor while the pedal is engaged is a scratching noise that can be heard when the knob is turned, therefore it is best to set the bias and then use the volume to control output, or to change the bias while the pedal is not engaged. This noise is only really audible when the knob is turned when the pedal is on, but no signal is passing.
This pedal was built for use with guitar, but because of its increase in bass response it was found to work much better for bass guitar. When I built CWS004 for myself, another boost with a tone knob and flatter response, I gave this pedal to Vass, who currently uses it as an overdrive in La Dispute.