# Twin Face Question



## JetFixxxer (Feb 13, 2019)

Will this handle a buffer circuit?  Does this "Fuzz" have to be at the beginning of the chain if I was to use some germanium transistors?  
I already have Fuzz Factory clone (with germanium), fuzz face clone (germanium), and dream fuzz (which so far is my favorite). 

The Fuzz Factory and Fuzz Face connected to a loop switch at the beginning of my chain

Why so many fuzz you ask..  Once I find a sound I like I don't make any adjustments. Same goes for my OD's.


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## Robert (Feb 13, 2019)

You can never have too much fuzz.   ?‍♂️??‍♀️

This is essentially two switchable "Face" fuzzes in one....   Aside from the ability to toggle between NPN/PNP operation, play nice in a signal chain,  and run on a standard negative ground power supply everything else is the same.

As such, any transistor sets that work in those respective NPN/PNP circuits will work great in the Twin Face, although you might have to tweak some resistor values to better match the pairs used.  (this was mentioned in the other thread, but has better context here)

Popular opinion is that it should be run with no buffer and first in the chain, but of course that's totally up to you...   The BOG is another Fuzz Face-style circuit with input and output buffers and sounds excellent to my ears.


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## jjjimi84 (Feb 14, 2019)

From one fuzz fiend to another, I will say the twin face is pretty great and is super fun to swap trannies out until you get the magic ones. Using a peak DCA 55 really helps narrowing it done for gain staging, but as mentioned above it is a fuzz face and needs to be first in line.

I agree the BOG is a great circuit (Marsh Fuzz) and is great to put anywhere in the single chain. I personally have been loving the kazoo fuzz lately, when you turn the fuzz way down on it it sounds like a fuzz face but with some tonal options and then you turn it up to get weird.


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## JetFixxxer (Feb 14, 2019)

Will 22uF work instead of 20uf? Tadya doesn't have 20uF.


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## Robert (Feb 14, 2019)

Yes 22uF is perfectly fine.


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## JetFixxxer (Feb 24, 2019)

Toggle switch to the left = PNP correct?


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## Robert (Feb 24, 2019)

It's actually Up / Down, not Left / Right.

Up - NPN  (Middle row of pads connected to Bottom row of pads)
Down - PNP (Middle row of pads connected to Top row of pads)


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## Hirti (Feb 25, 2019)

Is there a way to modifiy the PCB so NPN and PNP are reversed? I already created an decal with NPN down and PNP up. Not a big problem if not.


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## zgrav (Feb 25, 2019)

changing a pcb board to match a decal would be a case of the tail wagging the dog.  no question it would be easier to redo your decal, compared to not mounting any parts to your pcb and hard-wiring them to the board instead.


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## JetFixxxer (Feb 26, 2019)

Hirti said:


> Is there a way to modifiy the PCB so NPN and PNP are reversed? I already created an decal with NPN down and PNP up. Not a big problem if not.


That's why I asked


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## JetFixxxer (Feb 27, 2019)

You bias this by ear?


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## jjjimi84 (Feb 28, 2019)

You can bias by ear but the some what standard is to get the collector of the second transistor to around 4.5v. Some signature fuzzes intentionally bias them lower or higher to get the preferred setting. I believe the eric johnson fuzz is at like 3 volts.


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## zgrav (Feb 28, 2019)

most fuzz face designs have you use the trimmer to set the voltage on the Q2 lead (maybe the collector, I don't recall, but only one of the leads will have the voltage change when you turn the trimmer) to about 4.5v.    but then you are welcome to use your ear since it does change the "squishiness" of the fuzz.  and you can always open up the box and tweak that setting if you want to try something a bit different.


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## JetFixxxer (Feb 28, 2019)

Thank you.   

My other Fuzz Face clone has bias points where I could put my meter.  Wasn't too sure where to check for the voltage on this circuit. 

I guess Op-Amp fuzz don't need to simulate a weak battery because it has a set value?  Would you be able to change the fuzz if you varied the input voltage of an 4558?


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## zgrav (Feb 28, 2019)

Op-amps don't behave like transistors in that regard.  The op-amp is driving the audio signal through diodes to clip the sound, it is not the source of the fuzz.


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## jjjimi84 (Feb 28, 2019)

To bias the twin face put your black probe into the screw holes of your enclosure and put the red probe to the collector of q2 and then turn the trimmer until you get 4.5v.


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