Fuzz Face third knob?

[TheWaker43]

I have a Fuzz Face board and a pre-drilled enclosure with three holes.  Two will be fuzz and volume.  But I was hoping to use the third hole.  Would a bias pot be a good option (Sundial)?  If so, how would I go about wiring it?  Or any other suggestions please.  Thanks,
casey

btw
this is the board I have http://www.pigeonfx.com/layouts/layoutff.html

[LucifersTrip]

I have a Fuzz Face board and a pre-drilled enclosure with three holes.  Two will be fuzz and volume.  But I was hoping to use the third hole.  Would a bias pot be a good option (Sundial)?  If so, how would I go about wiring it?  Or any other suggestions please.  Thanks,
casey

btw
this is the board I have http://www.pigeonfx.com/layouts/layoutff.html

Yes, A pot substituting for the 8.2K would be cool. Just wire it (10K pot) using the middle & right lugs (looking down), and a 3K-5K resistor (cutoff) in series with one of those lug connections


good luck

[TheWaker43]

that would be a 10k linear pot?

[joegagan]

i have found a variable input cap pot to be more useful in real life than a bias knob. nice to have it as a trimmer inside tho.

i go with Si q1, ge Q2, (easyface!) do a google search for easyface with input cap blend.

nice to go with a hotter fuzz circ ( higher gain Q2 ie 120 or higher) so that the thinner trebly input cap sounds don't lose their balls too much.

[CynicalMan]

I haven't tried out a bias knob, but here are two I'd suggest:

Pregain: A 500k log pot in series with the input. This is a really effective distortion control, IMO better than the Fuzz knob. Wire it like the Distortion pot here:
http://sites.google.com/site/distorque/home/projects/modded-electra-distortion/Modded%20Electra.JPG

Tone: From the Wiki:
"Add a lowpass filter


A lot of distortions don't have tone controls. Here is an easy lowpass filter you can add. It will reduce your output a little but if your distortion pedal has lots of gain, this shouldn't be a big problem. If you think about it, this can go right on the lugs of the output volume pot. Use a small trimmer mounted on the lugs of the output pot along with the capacitor.

"

[Steben]

I haven't tried out a bias knob, but here are two I'd suggest:

Pregain: A 500k log pot in series with the input. This is a really effective distortion control, IMO better than the Fuzz knob. Wire it like the Distortion pot here:
http://sites.google.com/site/distorque/home/projects/modded-electra-distortion/Modded%20Electra.JPG

Tone: From the Wiki:
"Add a lowpass filter


A lot of distortions don't have tone controls. Here is an easy lowpass filter you can add. It will reduce your output a little but if your distortion pedal has lots of gain, this shouldn't be a big problem. If you think about it, this can go right on the lugs of the output volume pot. Use a small trimmer mounted on the lugs of the output pot along with the capacitor.

"

500k sounds a lot IMHO ... 100k will do fine.

[CynicalMan]

Depends how clean you want it to get. In fuzzes, I like having it at 500k because it's easier to cet cleanish sounds than with a 100k. Also, this is a logarithmic scale so 500k isn't really a huge increase from 100k.

[tubelectron]

Hi TheWaker43,

My Saupiquet Fuzz Face (TinBox series) has this third control : sensivity. It adds smoothness to the Fuzz control and give a better fuzz decay at low settings :





A+!

[R.G.]

Put 100K in series with the volume control and label the control "MORE".

[CynicalMan]

Put 100K in series with the volume control and label the control "MORE".

Have a 100k pot that's not connected to anything in the circuit and label it "Colour". 

[petemoore]

  Input gain pot for the FF was originally [and nothing wrong with it] the guitar volume pot. Another pot in series to adjust the guitar volume pot so that the potrange: 1-10 = 1-'8' or whatever, adjustable max gain.
   A fixed resistor inside the FF input switch does this, the same position exists as insertion point inside the guitar at output jack or VC pot output.
  this one votes for the treble control knob, then 'doctored' bias pot as the third knob assignment when V and G knobs are already there. 
  'Doctored bias pot would be maybe 5k6 + 10pot, starts at 5k6, ends at 15k6, biases most usable GE's nice range as starting R range for compromise between 'touchy=too fast a sweep' to 'dials in precisely' which might not cover the range if you want sputter-gating.

[LucifersTrip]

that would be a 10k linear pot?

yes, that'd work...

[zombiwoof]

On my FF, I've got a 50k trimmer inside in series with a small resistor in place of the 33k resistor, and I'm planning on putting a 10k linear pot with a small resistor on the outside of the pedal.   To set it, I would put the external bias pot right in the center position, and set the internal trimmer to get the 4.5 volts bias (or whatever you like it to bias at), that way when the external pot is in the center it's close to bias with the stock resistors, and you have leeway in either direction on the external bias pot to make up for temperature differences.   I'm also contemplating putting external bias jacks for my meter, so I can hook up my meter and bias quickly to whatever bias voltage I prefer using the external bias pot.   With germanium trannies, they are really sensitive to temperature differences, so I think the ability to bias for whatever temperature the environment is experiencing is a real plus.  I hope I've explained this clearly, but I would definitely make the third pot a bias pot if you are using germanium trannies.

Al

[MrTonesNZ]

I've added a clean blend knob to my fuzz face. I find you can use it to just add a lot of warmth from the clean signal. I did it by wiring a 500k log pot between to the input and output. Much bigger range in tones now, and so simple 

[rugeb]

Third knob: FACE MUFF (fuzz face + Big Muff tone control)

Link: http://www.fuzzface.es/fuzzpedal/especiales/index.htm

Kind regards.

[Bananas]

My Saupiquet Fuzz Face (TinBox series) has this third control : sensivity. It adds smoothness to the Fuzz control and give a better fuzz decay at low settings

Hello! Thank you very much for the schematic of it!!! It real awesome, it sounds even better than classical Fuzz Face (i hope my broken English is understandable).

May be you can answer on some question about?

1. On your schematic 10u capacitor "-" look to the ground. Is it necessary?
I'd put it on such way:

(see C4. I`T402 - it is old soviet germanium transistor. Q2 is same)

2. I made some pics of wave form

Clear:


Fuzz on, Sensitivity Knob on min, Fuzz Knob on min


Sensitivity Knob on min, Fuzz Knob on max


and at last  Sensitivity Knob on max, Fuzz Knob on min:


and Sensitivity Knob on max, Fuzz Knob on max:


Can you tell my why the Sensitivity Knob changes "duty cycle" of signal but not the amplitude? It work real awesome. I mean even "Sensitivity Knob on max, Fuzz Knob on min" settings sounds real fuzzy and much better then "Sensitivity Knob on min, Fuzz Knob on max", more "wet", more powerful.

Is it some way to do such thing, I mean changes "duty cycle" for clear sin?

[PRR]

> why the Sensitivity Knob changes "duty cycle" of signal but not the amplitude?

The *output* amplitude is fixed by the output circuit. The collector swings nearly 9 Volts peak to peak. 33K and 6.8K cut this down to about 1.5V p-p. The output pot cuts this down more, as desired.

The "duty cycle" is influenced by what happens at the *input*. Put your oscilloscope on the Base, DC coupled. At idle it sits about 0.6V for Silicon, maybe 0.2V for Germanium. Call this "Vbe". Now apply BIG signal. The Base can not go much higher than Vbe, it is a forward-conducting diode and will conduct very-very well to hold the voltage near Vbe. But the Base can go lower than Vbe. It can go a lot lower, because in this direction it is a reverse-biased diode, infinite impedance. With a BIG input, the average Base voltage will be lower than Vbe, and even lower than Ground. Your C1 will charge-up to this average voltage. When that happens, Q1 will only conduct on the highest peaks of the input signal. For sine, triangle, and most musical waveforms, this will be less than 50% duty cycle.

This effect is not desired in "clean" amplifiers.

It is very useful in the hands of a skilled musician, because it adds different harmonics and different harmonic balance with change of level. The same happens in human voice, flute, violin, when sung/played hard. Naked steel strings do not do this (much). The fuzzbox gives the guitarist timbre changes similar to other instruments, for musical emphasis.

The direction of the capacitors' + and - depends on the circuit polarity. Old fuzzes used PNP transistors and your capacitor polarity is correct. Around 1970, NPN (as Silicon) became cheaper, so you see many FFs re-drawn opposite polarity (and different bias for Si versus Ge).

[Bananas]

@PRR: thank-you very much!!! It was real-real helpful!
And thanks again for the "hard sung/play". Now I know what happens with signal. I mean it was clear that something happens with signal and it is not compression or tone/EQ like. It was not exactly "duty cycle", but something like.
Thank you very much.