Fuzz Face Pots Question

[Ofek Deitch]

Hey everybody

I'm currently working on my first fuzz face, and by now it's pretty awesome 

After playing and experimenting with it a little I noticed that I get the sound I love most when the Volume knob is cranked all the way up and when the Fuzz pot is at 3-4 o'clock, and the only thing I do in order to change the sound is pretty much play with the volume knob on my strat.

In my opinion the Fuzz Face's knobs aren't very useful so I thought that maybe I'll put a knob instead the A500k Volume knob that will be like a sort of pre-effect volume knob, kind of like what I have on my guitar and it will be a FUZZ/OD pot.
I'm not sure what to put instead of the fuzz knob, but I thought maybe to put a 5k knob to adjust the voltages - instead of using a trim-pot inside the box, to make everything a little more convenience.

I want my fuzz to have two knobs so it would fit the design I made, which in the pedal sort of looks like a face (see below..). So I must have an idea for the second knob...



I would love to here some cool and original ideas for the second knob!
Also, what knob is recommended to be used for a pre-effect knob? and how do I wire one?

Thanks!
Ofek Deitch

[midwayfair]

This is a very common mod. Wire the wiper of a 50K pot to the "in" before the input capacitor. Wire a very small capacitor from the wiper to ground. Wire either of the other two lugs (lug 3 if you want it to get quieter as you turn the pot up) to the input cap.

If you used a PCB with a pulldown resistor, you have some work to do. You need to move the pulldown resistor and the input wire onto the new pot's wiper for the mod to work.

You can make the fuzz knob much more useful by making it a reverse audio taper - this will keep the sound from bunching up in the last area of the sweep. But if you really don't like anything but one setting, then obviously that's not going to help.

You can make the volume a lot more useful by increasing the 470R to something like 1K or 4.7k. If you're using a pregain knob to actually clean up the fuzz enough to be an overdrive and push your amp, you'll want to be able to get all that volume back. 4.7K is LOUD. You can roll the pregain down to absolutely clean and still get a volume boost.

[Ofek Deitch]

Well thanks for the advice!  
But I don't have a 50k pot.. but a 100k one will work, right?

How small should the cap connected between the wiper and ground be?


Thanks again!

[joegagan]

after experimentation, i found i liked a 250k pregain pot, wired just like a guitar volume control at front end of circuit. to keep it from going totally silent when turned down, a 2k R between lug 1 and ground.

midwayfair, nice post,will try your 4.7k mod, sounds cool.

[Ofek Deitch]

Thanks Joe!

I tried playing with the 330r resistor by putting a 5k trim and I like the 2.8k area the most. after 2.8k or so the fuzz face became to buzzy.
How is a guitar volume control is wired? Is wired like the output volume control in the fuzz face, but with a 250k pot?

Thanks

[joegagan]

correct.

this is how i did it when i was on the road with my band in 99.

[Ofek Deitch]

Thanks! 

[GGBB]

This is very timely for me as I am about to build my first FF as well.  I decided on a combination of Joe's easy face and the GGG boutique fuzzes.  Well it's really just an all-silicon NPN easy face with fuzz and mid controls.  The only thing I am unsure about is the pre-gain / bias control.  The easy face pre-gain is 250K wired like a volume control, whereas the boutique bias is a 50K wired like a variable resistor.  Assuming that everything else is the same and ignoring the pot value difference for now, how does the volume style vs. variable resistor wiring affect the circuit?

http://generalguitargadgets.com/pdf/ggg_ff5_sc_easy.pdf
http://generalguitargadgets.com/pdf/ggg_ff5_sc_b69.pdf

[joegagan]

I never tried ezface as si only. Therefore, i cannot comment on how easyfce pregain control works on si fuzzface circs.   Would be very interested in any results when using your stated intentions.

[GGBB]

I never tried ezface as si only. Therefore, i cannot comment on how easyfce pregain control works on si fuzzface circs.   Would be very interested in any results when using your stated intentions.

Just wanted to give an update on my results with the pre-gain in a Si fuzz.  It works reasonably well, but probably not quite as well as with Ge.  My fuzz is BC108C based with hFE in the 500 range.  I used a 250K pot and I have lug 1 on a switch so I can remove the ground connection and turn it into an "input bias" control (variable resistor).  In this pedal at least I like the bias control better than the pre-gain control as it does a nice job of softening the fuzz with losing the amount of fuzz - if that makes any sense.