PCB Guitar Mania Volcano Device (EQD Erupter)

[RICHB555]

Build Rating

5.00 star(s)

The PCB Guitar Mania build doc and EQD make the claim that this circuit is the perfect fuzz due to its “classic tone and big low end and biting top.” That’s quite a claim, so I had to find out for myself.

What I can confirm IMHO is Volcano/Erupter is the perfect name for this pedal. The bias control has a tremendous travel from thin to to astoundingly heavy fuzz. For my tastes, I preferred the tone at about 8 o’clock on the singular control.

Under the hood are one 2N5457, two 3904s and a 42TL019 transformer. The bias feeds the voltage into the transistors which results in a very interesting approach to a wide range of fuzz.

Enclosure is Tayda 125b red, volcano graphic is Cricut vinyl. The knob is vintage bakelite that I had been saving in wait for the right use, and this pedal fits the bill. My tip for others is to befriend radio enthusiasts, or attend radio swap meets to find nice vintage knobs for pedal or amp projects.

Great one-knobber project!

 

[owlexifry]

big bakelite knob looks great

how’s it compare to a regular ol silicon FF?

 

[RICHB555]

big bakelite knob looks great

how’s it compare to a regular ol silicon FF?

I think its really its own thing when comparing with silicon fuzz. As the pot is turned, it goes from really thin to thick, low bottom end fuzz. All points in between give you a lot of options. I think it gets a little sputtery at around 3 o’clock but I’m sure that can be useful too if needed.

 

[Aleph Null]

Does the external bias control effect the overall volume much?

 

[RICHB555]

Does the external bias control effect the overall volume much?

There is seemingly a slight level increase but I think it just seems so because there the low end output increase. The doc says the function of the bias control is to run the voltage through the 5457 and the 3904s to vary the high and low end, but doesn’t say anything about acting as a level control.