Yamaha DI-01 Distortion

This is currently on hold till I figure out the tone control issue or someone can shed more light on this circuit. Build at your own risk.

I stumbled across the schematic for this effect and thought it was another variation of the Marshall Bluesbreaker circuit. But realized it actually predates the Marshall circuit by several years. Korg made a re-labeled version for Yamaha, the DI-01, and both still fetch decent prices. Apparently they were built like tanks. Sounds pretty decent too. Not sure what clipping diodes were used, but 1N4148s are probably a good place to start. Easy fit in a 1590B.