A simple but heavy germanium fuzz using PNP transistors with normal power supply. What not to like?
The original used fairly high gain OC76 cans but others with less gain will work as well. Just keep the leakage reasonable low when selecting the transistors.
Two layout for this, one normal compact and one MOJO with 0,5w carbon comp resistors and axial electrolyctics.
You beauty - another PNP centre negative
ReplyDeleteInput to density 2 and it blows your socks off - really great fuzz. Used a couple of random PNP transistors (Q1 hfe 130, Q2 hfe 350) and its top notch.
ReplyDeleteTop job, Ian!
DeleteI'll tag it ASAP. And thganks for spotting the missing info on the input of the circuit. Looking at the schematic it should go to lug 3 of the Densisty ctrl but I suspect lug 2 works equally well.
"Random transistors"...I'm curious which one they are!
Q1 was a 2N109 (similar to an AC128 apparently) and I think Q2 was a Sanyo 2SB405. For the Density pot, I tried lug 3 as that's what I originally thought but the pot didn't really work well. On lug 2 its superb. Thanks Anders!!!
ReplyDeleteInteresting, I've been testing this with different transistor configurations. For me it sounds very similar with input on lug 2 to input on lug 3. Lug 2 gets it a tiny bit more saturated. I'm having an strange issue, when I roll down guitar volume, it starts to generate a lot of high pitch noise and sizzle. I considered three possibilities: 1) I messed something up with the board, 2) it's a feature, 3) I'm testing outside of enclosure, so I get more hum and noise, which may get amplified. I tested different transistors, some classics, some random, some oddball ones. My observations: I've been getting better results with equal gain for Q1 and Q2 (maybe matter of taste), low gain / high leak ones would still give passable results, like 2x 40 hfe AC128, some transistors do not generate sizzle on volume rolldown, like AC128 or AC188 (!?). I'll need to keep experimenting.
ReplyDeleteTest files are here if you want to listen: https://drive.google.com/drive/folders/1pIWBFlIAB80DQ2AyCdQuIEhWZV3hneni?usp=sharing
Just built the MOJO layout and didn't (should of) read the comments. Need to switch input to density 2 cause mine isn't doing much. Regardless, it sounds rad. I rolled through a bunch of germ combos and ended on some Japanese 2sb's, 110 and 200hfe.
ReplyDeleteInput to density 2 is the ticket. Works great now. Also, reverse log pot gives a bit better sweep here.
DeleteJust made the mojo version and it sounds great. Used a pair of CV7355's and it rips! I notice the current model is hybrid with 2N5138 in Q1 and a bias trimmer for Q2. Might try that next. It did take a while getting the right set of transistors and messing with the bias, but it's well worth it. Can't see any difference between the input going from lug 2 or 3 of density pot though. Same either way on mine.
ReplyDelete