This is an exact Tonebender MK1.5 pedal topology, but with a few part values tweaked a bit for better performance. We made the BIAS resistor adjustable on the BIAS knob in the center of the pedal, as there are some great sounds to be had by running higher bias than normal. It gets brighter and cuts through better when it's overbiased. Some people like the bias lower for a deeper but softer sound. There is also a blue BIAS trimpot inside to set the center setting of the BIAS knob. We set it at 5V at the shop and normally you should not need to use that. But at high or low temperatures it can come in handy if the bias changes. We also changed a capacitor value slightly to make it sound and work better. In addition, we added the CLEAN trimpot like our Sun Face, as it helps preset the pedal for cleaner, or less bassy tones that some people like, especially with hotter pickups. We recently changed a resistor value slightly recently to make them a bit louder. Some people, especially with humbuckers, were complaining that the normal MK1.5 was not loud enough for them, so this should help. Simply copying a schematic would have been easier, but we want to make the pedal as great sounding as possible, and allow it to work with various guitars and amps. So this is our updated take on a MK1.5 Tonebender.
The FUZZ knob is more useful on the Sun Bender than on a Fuzz Face/Sun Face, you can turn it down as much as you like and still get great tones.