# Fuzz control on the Pacifier?



## bifurcation (Dec 4, 2019)

Since the Punkifier/Pacifier is basically a blend of a full-on fuzz with an overdrive, is there an easy way to throw on an extra pot to control the fuzz?


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## DGWVI (Dec 4, 2019)

You could place a voltage divider between the connection of C3 and the buffer, Big Muff Style. Or, replace R6 with a pot wired as a variable resistor


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## Chuck D. Bones (Dec 4, 2019)

The pot between C3 and IC1.1 that DGWVI suggests will work well.  Like a BMP, you'll want a resistor at the bottom end of the pot to make the bottom end of the adjustment range useful. If you return the bottom end of the pot to GND, it will be scratchy like the Fuzz pot on a Fuzz Face.  If you return the bottom end to VREF, then it won't scratch.  Not a big deal either way.

I wouldn't put a pot in place of R6, it will mess up Q1's biasing.

If you want to reduce Q1's gain, then put a pot in series with Q1's emitter.  I'd start with C1K, wired so that you get zero resistance at full CW.  It will be scratchy, but that's not really a big deal.  You could do the same thing with Q2, but I'd try Q1 first.


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## eh là bas ma (Oct 25, 2021)

Hello,

This mod can be interesting...

I would like to try to add a pot between C3 and IC1.1, as suggested.

What values can I try for the pot and the resistor ?


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## Chuck D. Bones (Oct 25, 2021)

Try B10K.  Pin 3 to IC1-1, pin 2 to C3, pin 1 to 470Ω and the other end of the 470Ω to Vref.

Or put a C5K between Q1-E and GND.  Pin 3 to Q1-E, pins 1 & 2 to GND.

I have not tried these mods, but I think they will work and maybe even do something sonically useful.


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## eh là bas ma (Dec 9, 2021)

It took me some time, but i am finally trying the B10K mod. I only have B25K right now so I am using it. 

For the C3 wire, i soldered it on the pad that isn't connected to R3 (schematics side "1").

So far I only have a leaking sound much like the fuzz factory. The whistling pitch change through the B25k rotation. At some positions there isn't any signal at all. I noticed the pot is microphonic (i don't know if it's the right word, there is a subtle noise when i touch it).

I wonder if I should unsolder a leg of some component like R22 or C3 ?
I just soldered the pot's wires on the suggested locations directly without any change. 

I should mention that i have 2n2369 at Q1 and Q2 instead of 2n5088.


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## Chuck D. Bones (Dec 10, 2021)

You have to disconnect C3 from IC1-1.  Is the bottom end of the pot connected to Vref?


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## eh là bas ma (Dec 10, 2021)

Thank you very much !

Now it's working perfectly. I made a mistake on C3 (I was on C7). I can feel a variation in the fuzz texture as i turn the pot.

 It's quite subtle but I can really hear a difference CW and CCW. I am not sure that it sounds very differently from turning the OD/Fuzz blend pot, though.   I need more tests.

 What are we doing here ? Is the extra pot biasing Q1 ? Like a battery starvation effect ? It sounds a lot like that.

I will play a few hours. Then, I will try the C5K mod to compare...


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## Chuck D. Bones (Dec 11, 2021)

Putting a pot in series with Q1's emitter (you have to lift the Q1-E lead off of the board) affects the bias a little bit but mostly it lowers Q1's gain.  Use C1K wired so you get minimum resistance at full CW. C5K will probably be too touchy at the CW end.  This pot will scratch when turned, that's normal.


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