The Belle's circuit is based on a popular (especially in Nashville) overdrive pedal and Brian Wampler's special version offers everything you would expect: from a warm and clean boost at low gain levels, to transparent overdrive/medium distortion at higher gain levels.
Included among Brian's improvements are additional gain capabilities and a bass control for controlling overtones, all the way from smooth and creamy to tight and crisp.
Note: Battery operation is not supported.