Guyatone Fuzz Monster dissection.

[digi2t]

Hey folks!

Andy and I have been working on the Guyatone Fuzz Monster. I did a thread on some of the Guyatone FLIP series pedals a few weeks back, and one by one, we'll dissect them, and post the traces as we go. I have a Fuzz Monster, and Hell Monster on hand, and a Funky Box on the way from Japan. I'll be cracking them open as we go down this FLIP'd journey (pardon the pun  ).

For now, here is the schematic, courtesy of UKToecutter (Andy);



Please note that the power section has been modified for AC power. Normally, these pedals use a 12VDC wall wart, but I found that even the Guyatone branded wall warts are noisy, especially at high fuzz levels. They are crap, but, by adding a AC to DC scheme directly to a potential clone PCB (see For Sale/Trade section), the noise can be pretty well killed. As for the balance of the schematic, I've gone over it with a fine tooth comb, and it matches the unit.

Go forth, and profuzzinate.

[Gus]

Looks like most of the distortion is from the JFETS to the LED clippers.  You might need to select them I would not adjust the drain resistors I would adjust the source resistors. I still don't understand why people still adjust drain resistor it changes the output resistance.

I don't think the double caps make a difference used for coupling around the JFET section.  This is a distortion and I don't think it matter even with home audio.

Does it have a tube in it just to be a "tube" effect?  I wonder how much the sound would change if you connected the clipping LED section to the opamp and removed the tube.

[bool]

Am I seeing a "clever circuit" that modulates the operating point of a first fet with the source voltage of another (probably modulated by the audio signal)? Quadrants C1, C2..

[Mark Hammer]

The part in C5/C6 had me bamboozled there for a bit until I realized it was a plain vanilla op-amp gyrator circuit.  The way you have the Vref connections is a little confusing.  Maybe have R5 and R15 (100k@) pointing downward so that they are in a more familiar format.

But diligent work!

[digi2t]

There is a correction to be made as well; Q7 is an NPN transistor, and not a fet. I'm just so tied up with the Resonator right now, that I haven't had time to update it.

[digi2t]

PCB's are now for sale in the buy/sell section.