If you want to know what this sounds like on guitar, just take a listen to the Smashing Pumpkins album Siamese Dream.
This pedal is based on Billy Corrigan's late 1970's IC Big Muff. Using the IC op-amp to shape the fuzz gives this pedal a very chainsaw like quality to the fuzz, much like the op-amps of the BOSS HM-2 give it that unique sound. To my ears, even with the Sustain (gain) turned all the way down, this pedal give less of a fuzz tone and more a of a distortion sound.
I didn't pick up this pedal because I'm a fan of the Pumpkins or Billy (I like a few songs but am not a huge fan) but because I was interested to see what an op-amp fuzz could do for me and my tonal bag of tricks.
I first tried the pedal straight into my amp with nothing else in the chain. It sounded ... ok. It felt like many other guitar distortion pedals sound when you try it with a bass... like the bass was just too much for it. When I hit my B string is when I realized that this was not a bass pedal. so, that's when I gave up...
Nope! I realized that there was some really great sounding stuff going on but there was too much going on all at once to get any sort of really good, usable tone. I simply added in my handy dandy Mix Blender into the signal chain! I put the Pi in the effects loop and blended the tone into my dry signal and BOOM!
THAT was what I knew I was hearing in that jumble! That chainsaw doom grind layered with the dry signal of a low B!
While the Pumpkin Pi more than proves itself worthy of a spot on the dirt section of your pedal board, a very important take away from this story is also, "Never dismiss the utility and effectiveness of blending your dry signal with your dirt tones to being out the best of both."