Weird Fuzz Face Problem

[spfautz]

After much troubleshooting I finally got my fuzz face clone working again.  Or so I thought...

Now the pedal functions normally when bypassed.  When the pedal is engaged, I hear fuzzy goodness when I strike the strings, but only for a moment.  Right after a note is played the tone and volume suddenly decrease.  It sounds as if someone is turning a voltage sag knob after every note.  Higher strings seem to sag almost instantly, while lower notes have a longer delay before the change.  When playing notes quickly, it is as if the pedal doesn't have the required time to charge up, and all the notes (except the first) are low volume and muffled (kind of like talking with your mouth closed).  The "charge up" nature of this problem makes me thing its a capacitor issue, but I don't really know.

Thanks,

Stefan

[Govmnt_Lacky]

Check the value of your input electro cap? Is it 2.2uF -OR- 22uF 

[spfautz]

2.2uf

[spfautz]

Any other thoughts?

[snarblinge]

i have had similar issues when testing out some transistors. have you got a trimmer in there to bias it?

sounds like a bias issue

[spfautz]

I don't have a trimmer.  I did have this pedal working correctly at one point though.  If  were to put a trimmer in where would it be?  What exactly does biasing do?

[darron]

sounds like a gating issue from missbiasing. strange it was working earlier. if it's germanium it might have shifted with temperature. not a dying battery?

best info is here:

http://www.geofex.com/article_folders/fuzzface/fffram.htm

[LucifersTrip]

+1 to snarblinge & darron.

It sounds EXACTLY like it's misbiased

what are the voltages of EBC for each transistor?

also, you never told us what exact schematic you used, transistors used (gains/leakages), substitutions, additions, etc...

most importantly, the voltages.

[LucifersTrip]

What exactly does biasing do?

http://en.wikipedia.org/wiki/Bipolar_transistor_biasing

bottom line, you'll be adjusting the surrounding resistors (for a FF, usually the 8.2K or 33K) so the transistor works how it should in the circuit and sounds how you want it to

[spfautz]

This is where I got the layout from diy-layout.com/28. 

So now the pedal appears to be working more normally again.  I hear the tone change a little still, but it sounds more like what I expect from a fuzz pedal (almost phaserish on long sustained notes).  I'm suspecting that the power from the wall (using a one spot) could be inconsistent.

Could this lack of bias control have always been there, but the effects more pronounced if my power source was sending 8v instead of 9v?

Here are the current voltages (which none are 9v)

Trans 1: C 7.9, B 7.9, E 7.72
Trans 2: C 7.9, B 7.97, E 0.00

Thanks

[LucifersTrip]

Here are the current voltages (which none are 9v)

Trans 1: C 7.9, B 7.9, E 7.72
Trans 2: C 7.9, B 7.97, E 0.00

hey...

those are so far off, I'd first remeasure...remember, black on ground and red on the lugs you're measuring

here's an example from another thread that are around what you should have. Q2C is the first thing you look at.

Q1:
C -> .8 - 1.4
B -> .4 - .7
E ->  0

Q2:
C -> 4.5
B -> .8 - 1.4
E -> .4 - .7

I'll have to pull out one of mine to check...