Axe grinder guitar effect circuit electronic.
The Axe Grinder might be a pretty routine fuzz if it weren’t for a couple of subtle but significant features. Like a Distortion Intensity Knob that provides smooth control of clipping from just a hint when you really get in on to pure square waves when you even think of picking.
And the Distortion Tone, Distortion Level and Clean Level controls are like having a built in mixer and EQ, letting you precisely set the amount of distortion and its tone as well as the mix of clean and distorted signal. You probably never realized you could get so many sounds from a “simple” fuzz.