FuzzFace biasing, reducing variables...

[momo]

OK, this is yet another FF debug, I read so many here, but I still have not found the answer...been on this thing all day, long day..

So just to cut to the chase, I'm getting some fuzz.
I have a bunch of germs, did the R.G leakage thing, I think I'm in ballpark values with the germs.
I have a classic fuzz layout,

Fuzz pot: 1K
Output pot: 500K

Q1 bias resistor is still 100k,
Q1 Emmiter, follower to Q2 base is a 50k pot( not sure if this should stay at 33k and work elsewhere)
Output resistor :470r
Q2 collector resistor :1K+ a 20K trimmer pot, 10K pot was not enough..


So basically , depending on the germs, I find myself tweaking the 50k pot, trying to stay in the 33k ballpark and trimming on the 20k pot to get about -4.5 to -5v, but it does not always translate to fuzz tones. Sometimes the fuzz is at -3v or even less ....... I get from a boring real clean sound, to farty gated sounds, or at best, an OK overdrive, but nothing creamy and no sustain....

sorry for yet another debug, can't find a facepalm emoticon here, I would put a big one


I'm thinking my problem is more the germs than the setup?, other than that 33k resistor which should not change?

thanks for your time...



Obviously, I have been tweaking all day in every direction with multiple germ combinations and I am still not smiling!

So
I noticed in all the modded circuits, the 33k Q2b resistor never changes....
I put a 50k pot on there.
I did that because the usual 10 pot was not getting into great fuzz.

[LucifersTrip]

It's seems you're a little flustered...Not sure exactly what you're saying in some of your descriptions.

Post the schematic you're using.

Here's good working voltages:
q1e: 0
q1b: 0.1     
q1c: 0.578   

q2e: 0.447
q2b: 0.578   
q2c: 4.51

Q2C voltage doesn't have to be 4.5. Many people like it 6V+

...and you definitely shouldn't need more than 10-15K on Q2C or you've chosen the wrong transistors.

[Gus]

Have you looked in the "links" at the top of the page?
http://www.diystompboxes.com/analogalchemy/emh/emh.html 
Fuzz-Face

[momo]

Hi,
So everything rocks!

The 50 k pot replacing the 33k resistor to bias was a good idea but I was not going for .5v at Q1....
Once I did that it was easy.
I will now replace the pot with whatever value it has for a resistor.
So I now have a great fuzz with nice changeover harmonics at the end of notes.
Here is what I have:

Q1: AC 451  Hfe 78 , leakage 30mv biased at -.5v
Q2: 2SB22 Hfe 138, leakage 48mv biased at -4.65v
Output cap:.047 greencap
added a germanium diode on B-E junction on Q1...

that 2SB22 is gnarly and I think is what gives the overtones...
I'm happy!

thanks for your time with me on this.