so i figured, since i finally have a wee bit of downtime between jobs, i'd slap one together.
so i vero'd it up.... this IS verified, with a caveat or two we'll get to later...
i changed the input and output caps from 3.3n to 39n
i experimented with a bunch of npn's... si doesn't work well in this circuit. ended up with 3 ac128's, all over the place in hfe... one's about 40, one's about 60, and one's about 100. i say about cuz they're ge. if ya BREATHE too close to them, the gain changes of course.... i socketed them, and found little difference swapping them around tonally, but ended up with the usual low gain in q1 and worked up from there. i did look up the 2sc175's, and their gain is in the ballpark with what i used.. of course i made the circuit npn so it would play nice with other stomps.
also went with an 18k rather than the 15k resistor from q2 b to ground, as it was handy and i was too lazy (some things never change) to dig thru my resistor drawer for the proper size. close enough for rocknroll, right?
sound wasn't super impressive. not BAD, but not great. i found several bias points on each q that seemed to work out pretty well, still a work in process where that's concerned.
but the "fuzz" control just plain sucks. it doesn't really do much of anything, you have about 1/4 of its sweep that's actually useful, and below that, it just plain doesn't pass signal. looking at how its drawn, it looks weird to me...
so first question, can someone explain how the hell its supposed to work as drawn?
to ME, it looks like it should be varying the bias to q2, which it kinda does, if really @#$%in' poorly.
it seems to me a fixed resistor would work better.
further, the dc to the pot as its drawn damaged one pot, literally smoked the mother@#$%er.
so my spidey sense said, i bet this was drawn wrong <seen a bunch of those over the years, like the shatterbox... i know one of the guys here drew it, so i respect that and have no doubt they did it "right" to the original unit they traced, but still maintain it was a screw up by the designer in the first place that was reproduced for years by the fabricators... there's a thread here somewhere, i called mine the scatterbox cuz it sounded like shit.. but i'd found by moving ONE component, it went from useless 60's fizz to an actual decent sounding and useable fuzz>
so i looked around at the schematic, and to my understanding, that 1 meg fuzz pot should have a blocking cap at each end, really. yeah, without one, its a feedback loop for q2, but not a useful one. seems weird. i can't see any reason to add a pot that literally makes zero difference tonally...other than destroying it.
now, i am a fuzzaholic, but i'm no @#$%in purist. i don't gaf if something is "right", "original" or "correct to the period cuz i drew the mofo myself" or any of that crap.
half the damn drawings of schematics on the net are full of mistakes.... lets not go there now...lol
but anywho, looking at it, i pondered what would happen if i moved the fuzz pot second connection, on the schematic at the junction of the c resistor and c on q2 to the OTHER side of the 1u cap from q2 c to q3 b....
and bingo. suddenly, instead of a useless pot that barely does anything, it acts like a "contour" pot to the fuzztone itself. not a huge difference, but eminently useable by comparison to the schematic.
now, i'm too stupid to understand all involved in this minor circuit change... but it seems like it lets you blend some of the clean signal from the buffer stage (q1) around q2 to affect the overall tone... like a pan control like ya see in some of the super primitive fuzzes sometimes. does that seem right? it DOES make a huge diff in the overall sound of the pedal.
it went from super wooly and shitty sounding to a really nice overdrivey kind of fuzz, where adjusting the fuzz pot actually changes the tone somewhat (it didn't do anything but phart as drawn)... and the volume controls the overall level of fuzz as predicted. it also reacts properly to the guitar's knobs, which it did NOT do as drawn...
i don't have the capability of doing video these days unfortunately, but if ya mess with this circuit, its way better with the mod. in this case, on the vero, move the fuzz 1&2 connection from c1 to j17 instead, and you'll immediately see which variant works and doesn't.
also, as shown on the schematic, it SMOKED q3 at one point. i never before encountered a ge getting hot enough to burn my finger!!!!! surprisingly, tho, once it cooled down again after i swapped that one wire, the q still works. weird. fuzzes are weird. add germanium, and shit gets REALLY weird.
but anyways... this is what i done did, and the results...
so... is the fuzz control supposed to be a bias control? or do ya think the connection was inadvertently (or nefariously) moved to the wrong side of the 1u blocking cap before q3?
am i crazy? <duh> or on point? what do ya think?
look forwards to your observations, fam.