GGG 1969 Fuzz not working - took some readings

[Bucksears]

I finished up the GGG 60's Fuzz Face and got no sound out of it whatsoever. I checked over all of my wiring and it appears to be correct. I'm using the Fuzz Face transistor set from Smallbear and the circuit is the PNP negative ground at GGG.
Here are the voltage readings that I measured:    (Input voltage is 9.05v)
Q1                   Q2
C - 8.90v          C - .41v
B - 8.89v          B - 8.90v
E - 9.05v          E - 8.98v

Are these way off? What should I look for? Are my transistors bad?
Thanks,
- Buck

[pyrop]

Looks like you are measuring wrong...
You have to measure from ground not Vneg... i.e. 1 probe to ground the other to probe...
Q1 emitter should be 0V as its connected to ground...

paulw

[Bucksears]

I'm pretty sure I'm measuring correctly (black probe to ground, red probe testing points).
Also, in GGG's negative ground parts layout, Q1's emitter is on the power supply rail, so that should be (correctly) reading the input voltage of 9.05v.

- Buck

[pyrop]

Ok missed the neg ground bit...
In the case of neg ground PNP fuzz faces measure as if the Vpos is ground...

paulw

[Bucksears]

I'll check using that method tonight, then.

Thanks!
- Buck

[Bucksears]

Ok, re-measured the voltages again using the '9V as ground' method and probed.

Q1                    Q2
C = -.13v           C = -.866v
B = -.15v           B = -.12v
E = 0v               E = -.05v

Do these seem way off?

- Buck

[Jackie Treehorn]

I did this build a year or so ago.  I ended up switching it to positive ground.  The negative ground version did not sound as good.

I had the same problem with the GGG Rangemaster.  I never liked the pedal and finally switched it to positive ground a couple weeks ago, rebiased, and it sounds great.

The great thing about the GGG layouts is that it's pretty easy to reconfigure!

[pyrop]

The voltages for my standard PNP pos ground FF with AC128's are in red below.

Ok, re-measured the voltages again using the '9V as ground' method and probed.

Q1                        Q2
C = -.13v   -0.31    C = -.866v   -5.3v
B = -.15v   -0.06v   B = -.12v    -0.5v
E = 0v  0v              E = -.05v    -0.25v
Battery 9.2v

Do these seem way off?

- Buck

Try getting Q2's collector closer to half voltage.. (mine seems to sound best biased a bit over half voltage).
Maybe try doing search for biasing fuzz face.
The neg ground PNP circuits also tend to have side effects like motorboating/oscillations.
Read this post from R.G. about it.... (EDIT) This one too

paulw

[Bucksears]

Thanks pyrop.
I'll switch things around just for the sake of experimentation. I'll post back with more info when that's done. Right, Jackie, GGG's layout allows for both pos. and neg. versions so that'll be easy.

(I guess it's ok to hijack my own thread)
BTW, I built the GGG Boutique Bender (neg. ground), which I love, and have some new transistors on the way for that one. That and the GGG Big Muff are my only fuzzes; I'm hoping that having a Fuzz Face will have most of my 'classic fuzzes' covered. No desire for a Vox Tonebender, Maestro or Octavia, etc.    GGG's Big Muff with the AMZ Presence Control #2 (I think that's the one I added) absolutely kills!