stupid simple overdrive mk 4 with lame video even

[pinkjimiphoton]

first the circuit, random stuff i threw together on my breadboard earlier today, starting with my ssod idea.



then a vero, which is verified, built tonite:



i tried this thing with an ass load of transistors... ge, si, npn, even some pnp's.... and just about everything seemed to work to some degree. go figure.

but it's sweet spot is an hfe between about 80 and 140, and as low as 58 to as high as 468 worked well with some transistors, so pretty much anything will work.  i reccomend socketing and just trying transistors til it sounds good.

in the video, it's gotta ac176 hfe of 80 in it. i'm playing an epi lp prophecy plus with a 57 classic in the neck, and a burstbucker at the bridge thru an ancient 40 watt 2x12 piggyback shin ei kustom knock off, set clean with a bit of reverb. it's a cool ass amp.

anyways, you may want a master volume. for me, i just turn my guitar up and down. it cleans up really nice like a good fuzz should, and has a nice overdrive charachter. check it out:


ummmmm.... i'll be back with the video, youtube is taking FOREVER. 

ok.... here ya go.... beware. not my most amusing videe but it's short

[Granny Gremlin]

Wait, wait: there was a v/mk3?

[pinkjimiphoton]

Wait, wait: there was a v/mk3?

yeah, only dif between that and this was the e is grounded directly, no led in the feedback loop, and the 4.7m resistor's top connected to the node at c, the bias pot, and the output cap. also, the values were different, .047 in cap, .47 output cap and no ge diode clipper at the end.  this one sounded way better so i didn't bother to build it up.  v3 and v4 were born out of the same breadboard session.

[pinkjimiphoton]

so like usual, i went back to this thing today for a little bit, as i always seem to do, and f'd with it some.
when all was said, i boxed it and realized oh @#$% it's not hitting unity gain!!!

so i opted to fix it up.
first i tried an assload of q's.... ge, si, unobtanium, whatever was around... seemed to like a sweet spot of around 100 with ge, and 500 with si, tho with si it is very much a fuzz, not an overdrive. seemed to need more gain. so i tried mpsa13 which i had a bag handy of, with a gain of around 2.6k... made a nice oscillator to annoy my neighbor's dogs with, but wasn't very useful. was thinking i needed a gain more like in the 700-1000 range when the answer stomped in my face.

look at the output cap, what do ya see?

i built a @#$%in' treble booster. 20n isn't much bottom end.
so i tried the first poly cap i saw, .47uF and replaced it. nice. now i could hit unity easily, but still very much a fuzzbox.
so i began eliminating parts.
first to go, the ge diode clipper. simply wasn't useful for anything beyond a c*nthair of compression and a bit of fizz.
next to go was the led. that took care of the fuzz issue. the customer i cobbled this together for specifically asked for something that would make his amp just sound louder for leads, like cranking the volume up a couple notches. so i didn't want a fuzz per se. for him, anyways. me? nother story, watch for the ssfuzz coming soon.
so i lost three diodes from the circuit, exchanged a cap, and put a 120pF cap from the output rail to ground to tame the high end a little bit. worked out great.
again, this thing worked to various degrees with almost every transistor i threw in it, some sounded like poo, some sounded absolutely killer... pnp, npn, si, ge, both forward AND REVERSE biased.
yah, may seem weird, but peeps do it all the time. no reason you can't too. see devi ever's stuff... in some cases, the only dif from one model to the next is the direction of the q's.
bc337 was a real standout for si fuzz, 5088 and 5089 worked too for a high gain fuzzy sputter that sounded cool thru my peavey tube amp and my kustom in parallel.
but the best SOUND as it were, at least for the customer's request, was with a ge q around 97hFe

for a nice fuzz, leave the clippers in, and disconnect the ground connection from the gain pot (you may need to reverse the direction of the pot spin) so it acts as more of a gain knob and less of a volume... right now, it controls gain AND volume as shown in the schematic on this page, but you don't have to do it that way. as a gain control it works different, equally valid  but in this case it's for someone who wanted a specific function. if you wire it as a variable resistor and use it as a gain, you may wanna tack a master volume on. 100k or so should do fine.
if'n anybody builds one, gimme a shout and let me know. you'll know when the transistor is right... socket and play with it.
fwiw, my output cap ended up being .68uF.

peace!