Germanium Resistors

[Stickman]

Strictly speaking, that's not a bias but it will lower the headroom available to the circuit.

Most FF's have a "drive" or "fuzz" knob, which is closer to a bias. It's on the bottom right of this schematic:



That knob does two things, as far as I can tell. First, it's going to change the bias of the input signal on the first transitor. I'm not sure how much of an effect it will have, though, because 1K isn't very big. Second, it will choke off some of the current through Q2, essentially limiting the gain of that transistor which will result in less fuzz.

[keeperofthegood]

Originally Posted by Stickman

Strictly speaking, that's not a bias but it will lower the headroom available to the circuit.

Most FF's have a "drive" or "fuzz" knob, which is closer to a bias. It's on the bottom right of this schematic:



That knob does two things, as far as I can tell. First, it's going to change the bias of the input signal on the first transitor. I'm not sure how much of an effect it will have, though, because 1K isn't very big. Second, it will choke off some of the current through Q2, essentially limiting the gain of that transistor which will result in less fuzz.

Actually, I recall reading that this circuit is best done with different Hfe's. 70 and 30 and I don't recall the recommendation to make which one which, I think 70 in, 30 out but its been a few months. Using two with matched gains apparently makes for a poor sounding Fuzz.

[Stickman]

Originally Posted by keeperofthegood

Actually, I recall reading that this circuit is best done with different Hfe's. 70 and 30 and I don't recall the recommendation to make which one which, I think 70 in, 30 out but its been a few months. Using two with matched gains apparently makes for a poor sounding Fuzz.

Absolutely, "matching" means to match them to compliment each other, not to find identical ones. I haven't farted around with a lot of them myself, but my understanding is that some of them are so sensitive to temperature that simply handling them with your fingers will change how they behave.

If memory serves, the actual values of the 470 and 33K resistors in the circuit will need to be tweaked to match the transistors used. I think 70 & 120 are the accepted "best" hfe's for Q1 and Q2 respectively.

[2N1305]

Originally Posted by Stickman

Lots of people use the term "fuzz" for things that are definitely not fuzz. Big Muffs for instance...

In my opinion, paying $200 for a modern Fuzz Face clone, even with hand pick NOS germanium transistors, is a total rip off. Even today, the transistors still only cost $15-20 for a pair, and the rest of the component costs are negligible. The circuit was perfected 40 years ago, so there's no innovation involved, and the only trick is that you need to fiddle the resistor values a little bit to match the values of the transistors (which vary widely for transistor to transistor).

I agree with most everything you said. However it did seem a bit contradictory when you said Ge transistors were unreliable and had low gain, were generally "crappy", yet praise the sound of original Fuzz faces and admit the Si circuits are harsh and buzzy.

Frankly, I find their inconsistency and variations give them character. Makes product reliability an issue though...
So what does that tell us? don't convert Ge circuits to Silicon, it'll suck more!

Need Germanium? visit: 2N1305 on Gearlslutz ( www.gearslutz.com )

[Stickman]

Originally Posted by 2N1305

I agree with most everything you said. However it did seem a bit contradictory when you said Ge transistors were unreliable and had low gain, were generally "crappy", yet praise the sound of original Fuzz faces and admit the Si circuits are harsh and buzzy.

I really tried to choose my words carefully. I said, "By normal standards", meaning if you were going to use them as the designers intended. You know, to build a computer or as a component in a high fidelity amplifier or something like that.

Creating a circuit to deliberately push a component outside its operating parameters and then relying on its undocumented characteristics to produce pleasing distortion isn't what most people would consider a normal application. It's just a happy coincidence that some of the same characteristics that make Ge transistors substandard for many normal applications also make them great for FF circuits. See? Not contradictory at all.