Wanting to build a germanium fuzz face

[pinkjimiphoton]

personally? these days i make them ALL npn. they sound exactly the same and play nice with more ubiquitous pedals.

just because this circuit is simple, that doesn't mean it is EASY. fuzzfaces can be a real bitch for beginners. too tired/lazy to read the whole thread, but consider adding a couple trimmers in place of the c resistors... it will make it much easier to dial in, and pretty much any transistors will work if you can bias them correctly. germanium flat out sounds better. end of story.

that said... they can be a pain in the ass. above and below certain temperatures, they don't like to work... the leakage and gain change substantially at different temps. my always reliable suzy q and fuzzface crapped out on me at two gigs this summer, both 95+ degree days. you can add a starve control to vary the voltage til it biases correctly if you want.
the brit face trick of using a reverse biased (from the transformer's junction) ge diode works ok in some cases, better in cold than hot tho. the theory was that one would compensate for the leakage of the other... i've tried it with some success, but the master bias/starve works a lot more consistently, and you can usually find a bias point that will work at any temperature.

unless you're a stickler for the originals, again, npn can be easier.... much easier to find proper npn's now than before.

as others said, getcho ass to geofex and read rg's fuzzface tech article. its' all in there.

you'll know your bias is right when with a guitar with a linear pot you can sweep from a compressed treble boosted crystaline tone to overdrive to distortion to cream to mean to fuzzy thick ass mud. ya wanna make it so the transition is smooth as you sweep your guitar control. barely on will give you some wicked "cleaner than when it's off" tones... and you should be able to dial in damn near anything once it's at a sweet spot.

as for gain... a lot of people say 80 for q1 and 100 for Q2 is good... and it can be with the right transistors. but it's more the RATIO from one to the next that matters than the exact gains in my experience (a couple hundred of 'em).... one of my fav has gains in the 200 range for both q's. higher gains will give you more balls. plain and simple. but lower gain will sound a bit sweeter. again, if you add trimmers and a master bias/starve pot you can use a surprising number of transitors.

you may find you like a 2k pot for the fuzz control. 1k sounds better to my ear, a good FF doesn't really need that much more gain. fwiw, 2k sounds better to my ear in si/ge hybrids.

you may also find a 50-100k output pot sounds better than a 500k... a bit less output and glass, but a more robust tone.

not trying to say i'm right, just my observations after building a shit load of them.

best advice i never took?

breadboard the whole @#$%in' thing first. when it sounds killer on the breadboard, and your pants are suddenly too damn tite, you'll know you got it.
the first time i gotta good fuzzface going, it was definitely a tumescentary situation.


good luck, welcome to the forum, and congrats on building THE coolest pedal ever made.

[Electric Warrior]

as for gain... a lot of people say 80 for q1 and 100 for Q2 is good... and it can be with the right transistors. but it's more the RATIO from one to the next that matters than the exact gains in my experience (a couple hundred of 'em).... one of my fav has gains in the 200 range for both q's. higher gains will give you more balls. plain and simple. but lower gain will sound a bit sweeter. again, if you add trimmers and a master bias/starve pot you can use a surprising number of transitors.

What matters even more is leakage. It has a much bigger impact on voltages than hfe.
Of course leaky transistors get so much leakier when it's hot, your fuzz face may crap out. I guess a bias pot on Q1C will help a lot. With higher leakage, the voltage on Q1C goes down while the one on Q2C goes up. A smaller resistance on Q1C will fix both issues at once.
I've tried a bias pot on Q2C before and it was rather useless. A glorified tone control.

you may also find a 50-100k output pot sounds better than a 500k... a bit less output and glass, but a more robust tone.

Less glass? Less bass! Like in most MK1.5 Tone Benders.

[pinkjimiphoton]

as for gain... a lot of people say 80 for q1 and 100 for Q2 is good... and it can be with the right transistors. but it's more the RATIO from one to the next that matters than the exact gains in my experience (a couple hundred of 'em).... one of my fav has gains in the 200 range for both q's. higher gains will give you more balls. plain and simple. but lower gain will sound a bit sweeter. again, if you add trimmers and a master bias/starve pot you can use a surprising number of transitors.

What matters even more is leakage. It has a much bigger impact on voltages than hfe.
Of course leaky transistors get so much leakier when it's hot, your fuzz face may crap out. I guess a bias pot on Q1C will help a lot. With higher leakage, the voltage on Q1C goes down while the one on Q2C goes up. A smaller resistance on Q1C will fix both issues at once.
I've tried a bias pot on Q2C before and it was rather useless. A glorified tone control.

the guy's already testing for leakage. i've used some insanely leaky q's with some great results in a lot of fuzzes over the years. stability in a FF? heresy!!

the point of the bias pots as i suggested is that you can work with a LOT more transistors that way. glorified tone control? sorta. can definitely affect the tone. but in this case my suggestion is again just to make it easier to dial in a fuzztone. you're a mojo guy. i could give a shit about that shit.

if you use standard values for the c resistors and your gain/leakage isn't "in the ballpark" it plain will sound like shit. if you use trimmers, you can dial it in more. ideally, dial it in, measure the trimmers and use the closest standard value you have. more stability that way, and you can make it sound the way it sounds best to YOUR ears.

again, a global starve control can be VERY helpful. then you can just twist it til it sounds good externally.

also, don't worry too much about the "4.5 volt biasing".... you may find you like it higher or lower... again, depending on which conponents you use.

EW is totally into mojo. i am not. therein lies difference in application and opinion. i don't care about mojo, i want it to sound good.

you may also find a 50-100k output pot sounds better than a 500k... a bit less output and glass, but a more robust tone.

Less glass? Less bass! Like in most MK1.5 Tone Benders.
[/quote]

both, actually. it'll still mud up if pegged. and again, depends on q's and how they are biased, like everything else about this circuit. also depends on whether it's a pnp or npn circuit to a point as well, and even the transistors themselves. the temperature, the phases of the moon, the day of the month, name it...

they have a mind of their own. [ definitely.