wow, we live in an era where dads were using this pedal... I remember being in highschool whenit came out and me and my guitar friends were all snickering that they slapped grunge on a dirtbox, I mean grunge was like a big mudd or a DS1, not hard to come by at the time or even now LOL

andno, kurt didn't use the grunge, he did however take them ons tage and throw them into the audience once I'm told.. its not like kurt had aspectacular guitar sound or anything, that's not why we all liked nevermind in 92

my dad was in college in the early 90s, and kurt did use it that show and throw it in the crowd. mocking that grunge can't be a effect.

its an 80s opamp big muff circuit with a very different frequency response due to the 2 band tonestack... the big muff is not for everyone, the op-amp version is for an even smaller group of players and the stock grunge pedal is for no one.... but they were kinda funny when they were first released when I was a kid. EVERYTHING was 'grunge' back then.

you can mod these though... there are 2 pairs of back-to-back diodes creating hard clipping distortion marked on the board as D1 thru D4.... try removing D1 and D2 to make it into an op-amp driven supa tonebender with treb and bass controls (this can sound pretty cool, your distortion will be a bit more open and fuzzy with more output from the 'loud' control and the pedal will clean up a bit better with your volume knob)... you can also make the diode clipping assymetrical at either diode pair by clipping one leg of one diode from a pair and then soldering another diode (typically a germanium diode like on the boss SD1 and fulltone pedals) between that leg and the board (or you can replace one of the silicon type diodes in a pair with a higher or lower clipping threshold diode like a germanium diode or LED)... the rest of the pedal's faults are based in cheap components and its a lot of trouble to upgrade things without burning the traces off the PCB and even then, its more cost effective to just build a BYOC large beaver kit or something

To the ebst of my knowledge its circuit is the op-amp big muff of Siamese Dream fame.... just witch vastly inferior componentry (not that an 80s muff is anything to write home about in that dept) and a baxandall/james type tone network (treble and bass, flat in the middle, stock muff tone knob @5 sound available with the treble and bass up for those scooped mid tones heard on early mudhoney, pumpkins, etc)

like an actual big muff I feel like its a better bass effect stock, and then its still cheesey.... if you go into it and look at the board you will find 2 pairs of clipping diodes. If you clip the 1st pair (marked D1 and D2) you will get less compression, more output and a more interesting sustain (in my opinion). You will also hear more of the opamp stages clipping eachother than just squared off diode clipping making it sound more fuzzy in a 60s sense of the word. The old Supa Tonebender used this topology only with discreet tranistors like most big muffs and in my opinion sounds VASTLY superior to the big muff.

I am pretty sure that kurt was a DS1, DS2 and sansamp guy and never actually had the grunge in line, though he had it on stage as a joke once or twice... the gronge is an opamp bigmuff circuit with 2 band tone controls, more of a smashing pumpkins thing