fuzz sensibilityto guitar Volume

[Alemastro]

Hi people,

So recently I started moding my pedals, changinging things I dislike and I need help with one of the pedals. I have a fuzz face clone, no mods, I use a fender strat standard. The problem is: whenever I lower the volume on my guitar to anything lower than 9, the pedal looses 70% of its volume, is that suposed to happen? Is there anyway around it?

[GGBB]

Welcome to the forum.

Is the guitar plugged directly into the fuzz pedal?

Opinions will vary on how the fuzz-guitar interaction *should* behave, but they are definitely supposed to interact in a way that causes the fuzz pedal to "clean up" when the guitar volume is turned down. How much knob rotation is necessary is subjective, but one thing you can change is to replace your guitar's volume pot which is most likely audio taper with a linear taper pot. This will cause the guitar volume to change less at the top end of the rotation (between 9 and 10) and spread it out over the rest of the rotation. It's the easiest and best way to fix your problem IMO.

[Alemastro]

Hi GGB, thank you for welcoming me!

Thanks for the the volume pot sugestion, the pedal is connected directly to the fuzz and than directly to the amp, another thing I noticed is the sustain goes away realy fast, even with the fuzz on max. Other important thing to mention, is that thee circuit has a diode and a 100uF capacitor in paralel on the fuzz part of the circuit, I read that it is suposed to smooth the fuzz, I might try to remove this part of the circuit, if anyone has any sugestions I'm open to trying.

Thanks

[GGBB]

Can you post a schematic for what you built?

[antonis]

Hi & Welcome..

We definately need a schematic of your particular circuit 'cause it might be a Jen Fuzz style (asymmetrical clipping) or a Antiquity Fuzz (Joe Davindson style) or even a Bazz Fuss one, so plz proceed as suggested by Gord..

[Alemastro]

Guys, here is the schematic

The two poits circled in blue are connected to each other, its my first schematic, I did not know how to connect them in my drawing lol.

[Alemastro]

Just realized i made a mistake on my drawing, here is the correct one

[antonis]

"Classic" fuzz face with reverse polarity protection diode..

100μF cap is drawn with its polarity reversed (unless it's a positive ground circuit - BJTs can't tell anything without Emitters arrow shown) and LED + CLR shouldn't be connected as per your draw..

http://diy.smallbearelec.com/HowTos/BreadboardSiFF/BreadboardSiFF.htm

In case pf 22μF polarity is correct, it is positive ground circuit so also 100μF polarity is correct BUT Diode polarity shoud be reversed..

[Alemastro]

Antonis, thanks for the tips and the linl (very easy to understand), my drawing was incorrect as you pointed, I even removed the LED, its just to show if its on or not.
Here Is what i thik is the correct schematic:

[antonis]

It sure is the correct schematic except of for input cap polarity..
(and, of course, Level pot wiper grounded  - I suppose it's a drawing error..)

[Alemastro]

Yeah, I'm just really bad at the theory part of it, but one day I'm sure I'll understand it all!

[antonis]

That's the right way of thought process..!!

(till then, just plagiarize - @PRR^copyright)

[ThermionicScott]

The problem is: whenever I lower the volume on my guitar to anything lower than 9, the pedal looses 70% of its volume, is that suposed to happen?

Nope, that doesn't sound right.

[Alemastro]

Hey guys, thanks very much for all the tips. Antonis the link you left was very helpfull, I belive the problem was on the bias of the pedal, the voltage on the colector of Q2 was way of the 4.5V, it was 0.71 lol, i just changed the resistor from the 8.2K to what i beleive is a 3.3K resistor and now it seems to wrok fine, it only looses all the "fuzz" when the guitar volume is on 5 or less. Anyway, thank you guys for all the help, this forum is awesome!

[Steben]

The volume of the out signal must be a lot bigger now as well.

[antonis]

it only looses all the "fuzz" when the guitar volume is on 5 or less.

Thats quite normal according to your modification..
(you altered Q2 total Collector resistance from 330R+8k2 to 33R+3k3..)

Q2 stage gain is set by the (330R+8.2k)/R_{FUZZ pot}, where R_{FUZZ pot} = resistance between Emitter & pot wiper (the unbypassed part of pot), ignoring the feedback network..
Now, present gain is set by (330R+3k3)/R_{FUZZ pot} resulting into lower than half of original circuit gain..

The above results into less global feedback network gain (take as it is for the moment.. ) which means less distortion for a signal of given amplitute..
Signals of low amplitude exhibit NO distortion (output is an undistorted amplified replica of input) due to Q2 Collector failure to hit the supply rails (no waveform clipping..)

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

https://www.electrosmash.com/fuzz-face
(don't mess with formulas in detail, just study conclusions..)

[Steben]

it only looses all the "fuzz" when the guitar volume is on 5 or less.

Thats quite normal according to your modification..
(you altered Q2 total Collector resistance from 330R+8k2 to 33R+3k3..)

Q2 stage gain is set by the (330R+8.2k)/R_{FUZZ pot}, where R_{FUZZ pot} = resistance between Emitter & pot wiper (the unbypassed part of pot), ignoring the feedback network..
Now, present gain is set by (330R+3k3)/R_{FUZZ pot} resulting into lower than half of original circuit gain..

The above results into less global feedback network gain (take as it is for the moment.. ) which means less distortion for a signal of given amplitute..
Signals of low amplitude exhibit NO distortion (output is an undistorted amplified replica of input) due to Q2 Collector failure to hit the supply rails (no waveform clipping..)

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

https://www.electrosmash.com/fuzz-face
(don't mess with formulas in detail, just study conclusions..)

If the collector was a 0.71V it was completely pinched off, with the lower R now it is less misbiased, probably close to mid Vs. This results in more signal to play with, not less.

[Alemastro]

it only looses all the "fuzz" when the guitar volume is on 5 or less.

Thats quite normal according to your modification..
(you altered Q2 total Collector resistance from 330R+8k2 to 33R+3k3..)

Q2 stage gain is set by the (330R+8.2k)/R_{FUZZ pot}, where R_{FUZZ pot} = resistance between Emitter & pot wiper (the unbypassed part of pot), ignoring the feedback network..
Now, present gain is set by (330R+3k3)/R_{FUZZ pot} resulting into lower than half of original circuit gain..

The above results into less global feedback network gain (take as it is for the moment.. ) which means less distortion for a signal of given amplitute..
Signals of low amplitude exhibit NO distortion (output is an undistorted amplified replica of input) due to Q2 Collector failure to hit the supply rails (no waveform clipping..)

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

https://www.electrosmash.com/fuzz-face
(don't mess with formulas in detail, just study conclusions..)

Antonis, tanks for all the information and links, I'm going to study it a bit. The volume is awesome now!

[antonis]

If the collector was a 0.71V it was completely pinched off, with the lower R now it is less misbiased, probably close to mid Vs. This results in more signal to play with, not less.

Your free to reconsider what you said..

[Steben]

The volume is awesome now!

Of course it is, since the 0.71V was well below the balanced bias point. The values of Rc/Rfuzz are futile if your setup is biased out of the efficiency zone drowning the signal.
Do not forget AC gain is controlled by the bypassed signal through the capacitor. In theory mere Rc/Rfuzz will render infinity with max fuzz, which is not the case.
Changing the 3k3 to a trimpot (10k?) will give the option to finetune even more, ideally to 4,5V.