FUZZ FACE PROBLEM... HELP PLEASE...

[DARK_ANGEL]

Hey guys!!!

I have a question for you. I build a fuzz face clone. It works great but it have a problem... The tone pot on guitar works reversal...

When the pot is at 0 and fuzz is on, sounds like tone at 10.
When the pot is at 10 and fuzz is on, sounds like tone at 0.
When pedal is off, tone works fine.

Happens with several quitars...
WHY...

Transistors i use: bc109c

[zombiwoof]

I'd say you wired the tone pot backwords, reverse the connections and it will work the way you want.  However, you say the tone pot works fine when the pedal is switched off?.  The tone pot shouldn't work at all in a Fuzz Face when the effect is switched off.

Al

[artsinbloodshed]

yes, the tone should work normally but isn't that noticeable with a "face"...
It's kind of mysterious...
let's try two 5088 trans to see what happens but I doubt that could do the trick...
Did you mod the circuit?

[DARK_ANGEL]

Hi again!!!

zombiwoof
The problem is at the guitar tone pot, not on the pedal. The problem is on the guitar when i use fuzz face.

With other diy pedals the tone pot on the guitar doesn't have any problem. Only with fuzz face my guitar and others make that problem.

Thanks for your advice!!!


artsinbloodshed
It's really mysterious. I don't mod the pedal.
I asked and other diy pedal makers but i don't have answers...

I finally found 5088 trans but same with you i don't think that trick will work... I will try and i hope to post a "happy face" in my fuzz face...

Also, thank you!!!

[Jhouse]

Are you saying that the tone pot affects the tone when the pedal is bypassed?

[DARK_ANGEL]

Hi Jhouse!

Affects the guitar tone pot when the pedal is on...

Any advice???

[Jhouse]

Try switching the wires on you tone pot. Switch the wire you have on lug 3 to lug 1 and the wire on luge 1 to lug 3

[jefe]

Try switching the wires on you tone pot. Switch the wire you have on lug 3 to lug 1 and the wire on luge 1 to lug 3

It's the tone pot on his guitar, not on the pedal.

I dunno, dark_angel.. something wierd is happening when the pedal is loaded with a guitar signal.

I wonder if this is normal for a fuzz face?

[petemoore]

  Put a tone pot after the FF, with Si FF gain G-speaking, getting a little more than adequate treble response is can do, then taper it at the end.
 If it's biased and the capactiros are 'correct' or anywhere close...
 Never heard of this one and I've followed through quite a few "FF challenges".
 Seems near beyond the possibility of coincidence that every one of the guitars does reverse tone with this FF, and they all work fine otherwise.
 That said, the impedance interaction of guitar out/FF input may still somehow help explain it.
 

[DARK_ANGEL]

Hi once again,

jefe
I don't know if this is normal for a fuzz face but I've seen fuzz face clones in which the guitar tone pot worked normally.

But... I'm not sure that they use the same circuit or modified.


petemoore

I'm not sure I understand your answer... 

What exactly do you mean by telling me to put a pot after FF???
And what is Si FF gain G-speaking???

Also, it would be very helpful to post me a scheme for better understanding...

[mth5044]

A lot of people are misunderstanding the problem.

He's got a fuzz face, a supposed-to-be normal one. Fuzz control, volume control.

When it's engaged, the GUITAR's tone pot works in reverse, not anything on the pedal. So when the effect is on and the guitars tone pot all the way, it sounds like the guitars tone pot is all the way down. When the guitars tone pot is all the way down, it sounds like it's all the way up.

I can't give you any answers, but hopefully this re-explanation will help someone else guide you.

[jefe]

Also, it would be very helpful to post me a scheme for better understanding...

Not to be a jerk or anything, but YOU should be the first one posting a schematic here. Exactly which circuit did you build? Which schematic? We can't really help you until you give us more info. Follow the instructions in this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

[DARK_ANGEL]

This is the schematic i used to build the fuzzface.
BUT
Instead of 20uF capacitor i used 22μF.

Also, at the input of fuzz pot (note 2 in the scheme) i put a 120R resistor, because when i turn the fuzz knob to max there was a LOT of noise.

[petemoore]

Also, at the input of fuzz pot (note 2 in the scheme) i put a 120R resistor, because when i turn the fuzz knob to max there was a LOT of noise.
  Better off with the 'low noise' values.,,probably, when gain is max, the potwafer is connected at both ends, cap+ and into circuit feedback loop at one end, Gnd. on the other. It's just a fixed resistor value of potwafer there.
  It isn't until the pot is backed from full that the gainpot becomes a divider with the cap in the middle.
  But the overall gain, set super high, might somehow overload bass and make treble hard for the amp to amp...long story aside...try setting the gain lower and see if the treble knob function changes.
  ie...the FF cleans up, could be the highs are 'saturated-squelched' and come in when the input or gain brings the output swings more into linear range [ie cleans up and the treble starts being amplifiable at X gain.
  Because you've maybe already tried this easy/worth a try thing.
  not being there it's kinda hard to tell...either something with the gain structure, or the input impedance [less likely after having done multi-gutiar-tests]..or something else.
  Did you tune the value of the 8k2/Q2C...circuit bias reisistor, around 1/2 supply V or a little more allows more even +/- swings, equal-ish AC signal Voltage swing-headroom on both sides of bias means the signal doesn't clip hard on one *side of bias [+ or - depending on where bias is sitting] before the other.
   

[jefe]

Yeah, DARK_ANGEL, can you measure the Q1 & Q2 voltages?

[LucifersTrip]

Also, at the input of fuzz pot (note 2 in the scheme) i put a 120R resistor, because when i turn the fuzz knob to max there was a LOT of noise.

Try a small cap (~47-300pf) across collector & base of Q1 to eliminate noise instead of 120R

[Earthscum]

I stumbled onto something like this before... try putting a 100R or so at the input of the FF and see if that dampens the 'reverse tone' effect you're getting. The second stage has a ton more output than your guitar, and it may be feeding signal back into your guitars. When the tone pot is up, the loop is working to cut the tone, but when the tone pot is down, it may be dampening that feedback. I'm more of the McGuyver type, so I really don't know how to explain it very well.

[DARK_ANGEL]

jefe
Can you tell me how to measure the voltages with my multimeter?

LucifersTrip
very interesting! thanks!

Earthscum
i will try this! thanks a lot!

[jefe]

jefe
Can you tell me how to measure the voltages with my multimeter?

Did you read the link I provided earlier? The thread is titled "DEBUGGING - What to do when it doesn't work ". Here is the link again:
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Read that thread, the instructions on how to measure the voltages are there. However, you would be wise to read the entire thread, and follow all of the instructions there. 

[DARK_ANGEL]

at last ! ! !

the tone pot works normally thanks to the Earthscum's advice ! ! !
i put a 68k resistor at the input of fuzz face after lot of experimentation . . .

THANKS GUYS ! ! !