EQD Speaker Cranker schematic I found: Source: http://drdfx.hu/en/oomph/ (interesting post with analysis of similar boosters btw)
Based on the gutshots below, the differences I can see is:
- The 1N60P diode with cathode towards ground is replaced with a 1N4004.
- Gain pot upped from B5K to B10K.
- Added "Heat" knob seems to be just a pot wired in series with the 10K collector resistor: lug 1 to the 10K resistor, lug 2 to collector, lug 3 unconnected? Not sure about value since it's under the PCB, probably B10K or B5K?
- A100K volume pot on the output.
- Added 100r resistor on 9V input for filtering.