The Diablo is a modified BSIAB circuit and the Diablo+ version has an added boost at the output that's independent from the main overdrive circuit. I've laid it out for a 125B with top mounted jacks for a nice small footprint. Originals have a switch to run at 9 or 18 volts which I've left off-board so builders can choose their preferred voltage doubling method. Trim pots are extra controls, not for biasing, FYI.