Univox superfuzz. a few questions

[pauldumbell]

Hi all,
So i have been researching this one for days, and sourced the parts from my junk bin. even found a dual metal cap transistor from the 70s never been soldered and has a pretty close hfe rating on both sides. 142 and 147. no number on it though. I also only have 50k audio taper pots, no linear 50k pots in my stock. Im wanting to try the original
http://3.bp.blogspot.com/-cBIzyse_wes/T0EHt4QmTvI/AAAAAAAAA88/Y1fbps_nMsQ/s1600/univox_superfuzz_schematic.gif
http://4.bp.blogspot.com/-iTS4P9PwQIo/T0EIiZppAMI/AAAAAAAAA9M/avWpQeiwpMs/s1600/univox_sf_pcb.gif

there are a few other ones out there that are sameish, but im a stickler for getting things as close to the original as possible.

Im guessing that I could add a trimpot and I think I know where it needs to go on the pcb although it is not designated on this  etch template.

http://2.bp.blogspot.com/-qUs-0nVu4LI/T0EIhh0vPsI/AAAAAAAAA9E/Bb5jyEYFhG0/s1600/univox_sf_layout.gif

should it be where those bridges are drawn in?

So my questions. 50k audio...will they be suitable? and what value should the trimpot be? 10k? and is my assumption for trimpot placement correct?

thanks in advance
Paul

[Pyr0]

50k A will work, but the control will be bunched up at one end, if you are trying to make it as close to the original then get some 50k B pots.
And yes, substitute the trimmer for the jumpers, middle wiper goes to ground. 10 K will work.
I've built this and didn't need the trimmer, I just matched the two transistors by comparing Hfe's, and also measured and matched the 22k and 100k resistors in the tails.

[pauldumbell]

thanks pyro, etching the board as i type this...building it from garbage. cant wait to get it up, got a show in austin this weekend and the fuzzface aint cutting it.

[pauldumbell]

got it etched populated and running on the first try! not a penny spent! sounds so freaking good I almost passed out on the spot. gotta straighten out the offboard wiring for it. Iin my haste I mixed some wires up I reckon. Its full steam all the time and the tone switch is a kill switch. Back to the dungeon. I had to use a 20k trim pot on the octave as I had no other, but really could skip- it as my transistors and resistors in that section of the circuit are matched to the number. so the trimpot just pulls the octave down if i need it. this was the funnest build ever.

[pauldumbell]

24 hours since deciding to build the superfuzz, i got it built and all crammed into a hammond case and ripping like a chainsaw. Stuck with 50k audio pots, as i had some 47k linear and honestly the audio pots sounded exactly the same. I used  2n2714 all around with rages between 94 hfe and 159 hfe i placed them strategically on the board with 2 identical ones on the octave. 94 on q1 and 159 on q2  and q6 was in the 136 range, the others I just plopped in the empty spots and did a hail mary. What I find interesting about this pedal is that it really doesn't seem to care what transistors you give it.  I probably could have just thrown random unmarked ones from my junk box as long as the hfe was in the right ballpark. I mean its mean enough as it is, no need to put super high hfe transistors in there.Im really pleased with the results to say the least...tonally that is.  I kinda dont like hammond cases Ive decided. I would rather have a big honker the size of a grade schoolers lunch box because cramming all that jazz into such tight quarters can be quite unnerving. Optically It just looks like another unfinished hammond enclosure with some knobs and jacks. Too bad I aint an artiste. I gotta give my offboard work some attention. getting the components placed in an orderly fashion seems to be more laborious than the rest of the work.
Now it is time for me to gig my junk that I built!
Cheers
PAul