From the MMK Electrics website:
Two Knobs, two transistors, two footswitches. An easy to use analog fuzz with cleanup function come together to give you classic fuzz and cleaned up fuzz tones at a footswitch click.
Silicon Fuzz Face – A usable fixed fuzz and bias, like having the “fuzz” control on your fuzz face slightly dialed back. Circuit cleans up to that classic glassed smooth bluesy tone.
There are three main parts to each of these circuits:
Bourns Audio transformer, high pass filter, and an internal thumb adjustable trimmer.
Fixed fuzz circuit built with Fairchild 2N2222A transistors.
A 2db op-amp stage to make up volume on cleanup volume engagement.
Controls:
Amplitude: A master volume control.
Frequency: A four position selector switch giving you the choice of expressing highs, mids, or lows on your guitar or bass.
Internal Trim: Sets your desired clean up. A set it and forget it function. Engage the function with the “Cleanup” footswitch. The Cleanup function will not affect your pedal chain engaged and in bypass.