There is several versions of this one but the 4-knob version seem to be the most common version.
Initially, it was a custom fuzz for doom band Conan but it was later slightly modified and morphed into Dunwich/Magic Pedals lineup of pedals. Traced by evilarsen and fuzzhead who both dig the sounds coming out of this doom circuit...
...and here is what evilrsens build looks like.
Add little mojo in mine with Q1-Q4 2N2219 and Q2 2N1306.
ReplyDeletehttps://ibb.co/BZHrQsH
Thanks for the traces, evillarsen. I want to experiment like other variations of this and Chtulhu I've seen with bass cut pot at input or using germanium transistors and diodes for the clipping.
DeleteNice! Mojo Throne transistor setup. Might whip a work-alike layout since some cap values diifers in the mojo version and as Alex stated, it has an input cap blend. But it have Vishay Dale resistors that most value markings is impssible to read...
DeleteLifting ground on C9 and R13 would bypass tone, right? Would be nice to put that on a toggle.
ReplyDeleteKinski, I wanted to bypass the tone too, to get the Cthulhu tone. But the way the tone is set up is a little different than normal Muff scoop. It's pretty flat at noon, and then cuts bass or treble.
DeleteYes, what Alex said. Tonestack pretty flat as is...
DeleteMy build of this sounds pretty killer. Anyone have any issues with whine/oscillation when the knobs are cranked up? I tried running a buffer before mine to tame it, but it doesn't sound as if it agrees with a buffer too well.
ReplyDeleteMine is pretty noisy when cranked, no squealing though, only feedback. Listened to some demos and it behaves the same. Kind of like it.
DeleteI don't think it pairs well with a buffer since Q1 and Q2 is essentially a fuzz face and they hate buffers....
I recognized the FF portion of the scheme later on and figured as much in regard to the buffer situation. My pots may be enough out of tolerance enough to warrant a resistor on a lug or two to prevent the squeal. It's usually a pet peve of mine, but in this case, it kind of works out.
DeleteYeah, a limiting resistor would work if you want some noise reduction. A small avlue resistor between the board and lug 3 of the Boost control seems like the best solution?
DeleteHello all!
ReplyDeleteI've just finished my clone (thank you, Anders!), but it's not working. Between C4 and R7 the signal it's OK, but between R7 and Q4's base it's very weak. What's strange, at the Q4's collector it's a relative strong signal. At pins 1 and 3 of the tone pot the signal is relative weak again and almost dies after C10. It's clear that I made a stupid mistake, but I can't find it. I rechecked almost all the values of the components (all transistors were tested before soldering them) and seems to be OK. The only strange value is the 470K resistor which is indicated as 100 K on the board (I will try to change it tomorrow).
So, please, anyone can help me with the voltages of Q4 and Q5?
Thank you very much!
Hi Radu!
DeleteI will take voltages from my clone but I'm not home at my desk until the weekend.
Hoefully you get it sorted until then.
Here is my voltages:
DeleteBattery reads 9,48v and all potentiometers is at max.
Q1:
C: 1,34
B: 0,6
E: 0
Q2:
C: 4,87
B: 1,34
E: 0,7
Q3: Identcal to Q2
Q4:
C: 3,8
B: 0,6
E: 0,0016
Q5:
D: 5,8
G: 5,15
S: 3,4
Thank you a lot, fuzzhead! I will test mine tonight. I think that Q5 is the problem.
DeleteI repaired it fast, due to fuzzhead's help: Q5 was burned! I think that I made a stupid mistake, soldering a bad BS170 instead of throwing it :)
DeleteThank you, fuzzhead!
Perfect! Glad you got it working!
DeleteAnother happy build. Put this one together over the eater break and it worked first time. I made it completely stock (apart from using a 820ohm resistor as the 845 was just too damn elusive.)
ReplyDeleteFired up first time, sounds epic and roars like a beast. Can't wait to try it out in anger!!
Thank you so much!
Epic skull busting as soon as I fired this baby up. Thanks for a great layout!
ReplyDeleteDidn't work out for me, I will need to diagnose it... I have very low output.
ReplyDeleteI looked at the schematic and I think I saw a difference with the diagram : the 2 diodes are reversed. I don't know how much a difference it makes but...
My bad, solder was overlapping on another strip AND I had a bad Fuzz pot...
DeleteNow, the LED wont light when clipping, is this normal behavior ?