I've just got the PCB for this pedal from Fuzzdog (super-fast delivery from those guys by the way) and the schematic it's based on seems a fairly straightforward Tube Screamer for bass.
I found another schematic online that indicates the master volume control as a dual-ganged 100kB pot, with half of it being used before the active Baxandall circuit. Anyone know which one is closest to the actual unit?
I've attached the schematic below: