Just Four PUFFs

[Cybercow]

Barry’s PUFF (Pumped Up Fuzz Face) is an easy and flexible build. Over the past several months I had acquired four of the PUFF PCBs and finally decided to get them wrapped up. I did one with high-gain silicon PNP transistors and external bias control. One with Barry’s 2N404 germanium transistors. One with NOS Russian MP20B germaniums & external bias pot. And the last one with NOS Tesla AC128s. And for each one, I added a guitar pick-up simulator circuit using the primary side of a 42TL019 transformer and a 330pF cap. The mod itself looks rough, but works nicely to retain a guitar’s dynamic interaction with its volume pot. And while all four builds have nearly identical candy wrappers, (and the silicon version has black knobs instead of chrome), each has unique Fuzz Face qualities. Unfortunately I have no sound samples, but they do definitely range from dark and sputtery to thick and sustaining fuzz tones. OK. Enough of tooting my horn – on with the photos & circuit porn . . . .

 

 

 

 

Thanks for looking. Happy building!

[Chuck]

Very nicely done!  The Fuzz Face is the Lays Potato Chip of the pedal world!   Can you elaborate on “works nicely to retain a guitar’s dynamic interaction with its volume pot” a little?  Are you saying that if I have my Strat’s volume cranked to get the fuzz screaming for mercy and lower the fuzz’s volume so the neighbors don’t complain the character of the fuzz stays the same just quieter?

Chuck

[Cybercow]

Chuck – many dirt circuits work with a guitar’s volume pot by cleaning up the dirt to some degree when the guitar’s volume is turned down – while the volume remains relatively the same. And when the guitar’s volume is turned back up, the fuzz/dirt increases without actually getting a whole lot louder.

Now, when a buffer of any sort is placed between such a dirt circuit and the guitar, (say a wah or most any Boss pedal), that relationship between the dirt circuit and the guitar’s volume pot is lost. The added pickup simulator circuit (X-former & cap) returns that interaction between the dirt circuit and the guitar’s volume. Mind you, the pickup simulator will not extend that relationship beyond one buffer – that I’ve found.

For more info, see this article at AMZ: Pickup Simulator

[Chuck]

Thank you.  Should have figured Jack would have an article on it – will check that out.  Another question along this line – “the pickup simulator will not extend that relationship beyond one buffer” – are you referring to two (or more) buffers before a fuzz or one before and another after?

Noticed you used a simpler deployment of the 5817s on these.

Chuck

[Cybercow]

Chuck – In my experience, the guitar volume control relationship will not extend beyond one buffer before the pickup simulator. What I’ve not tried is adding more simulators after other buffers deeper into a pedal chain. Buffers AFTER a pickup simulator modded fuzz pedal have no bearing.

And the 1N5817 use is just a protection scheme preference. The Schottky diode is faster and exacts a smaller Vfd on the DC supply input than the 1N400x series.

[Chuck]

Ah, that’s sort of what I was thinking.  I may have to experiment with the pickup simulator some.

How did you decide to put the 5817 where you did instead of simply replacing the 4001 on the board?

Chuck

[Cybercow]

Chuck – it’s a personal assembly decision. The 1N4001 is in parallel between the +9v supply and ground – while the 1N5817 is in series. I bring the power in on to the 3PDT Switch PCB (which supplies the indicator LED) and by feeding the +9v thru the 1N5817, the main PCB voltage supply is somewhat isolated from the LED supply.

The story behind it stems from interactions I’ve had with a long-time avionics engineer who shared several current protection circuit schemes with me and boiled basic current/polarity protection down to 4 fundamental approaches – as demonstrated in the attachment below.

Mind you, this no criticism of Barry’s designs. They all work well. I just saw that a simple change yields a better over-current/polarity protection scheme. In some of my digital pedal builds, I will go with a MOSFET protection, (see “Best Design” in the image), daughterboard to place between the DC jack and the internal circuitry.

[Anonymous]

Fantastic work Cybercow!

[Author]

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