The Nine Volt Nirvana Nitroburner Fuzz is a fuzz circuit designed by Joe Gagan, described by the Guitar FX Layouts technical write-up as "another fuzz, based on the fuzzface with a bunch of tweaks"1. It belongs to the broader family of fuzz pedals, and it is a circuit that DIY builders know well: the published layout and the discussion around it are the main record of how the pedal works and how to build one that sounds right.
A Fuzz Face with modifications
The Nitroburner takes the Fuzz Face topology, the two-transistor fuzz circuit that sits behind many classic fuzz sounds, and modifies it. The Guitar FX Layouts analysis, written by Zach, describes the design as coming from "the man, the myth, the legend Joe Gagan"1. Because it is a Fuzz Face derivative, transistor choice and biasing matter more than they do in most pedals: the character of the fuzz depends on the gain and type of the transistors fitted and on where the bias is set.
One builder, EddieB, reported building a variation of the circuit without Q3 and described it as "a great sounding Fuzzface"1. EddieB also suggested that Q3 may do nothing in the circuit and could be removed along with the 2.7k resistor that biases it, using that lane on the board to add the Q1 to Q2 jumper instead1.
The Q1 to Q2 jumper
A build note that matters to anyone assembling the circuit: there needs to be a jumper between the base of Q2 and the collector of Q11. The layout author confirmed that this connection was missing from the published layout by accident, saying "while i was moving things around I must have removed it by accident"1. A build that follows the original layout as drawn will not pass signal correctly between the two stages until that jumper is added.
If you build from the original layout, add the jumper between the base of Q2 and the collector of Q1. The layout author confirmed the connection was dropped by accident1.
Transistors and biasing
The stock circuit calls for a high gain PNP germanium transistor at Q21. Setup is a two-step affair:
Builders have reported results with other transistor choices:
| Build | Transistors | Result | Reported by |
|---|---|---|---|
| Stock circuit | High gain PNP germanium at Q2 | As designed | Guitar FX Layouts1 |
| Gavin's build | Germanium transistor with around 100 hfe | "it sounded good" | Zach1 |
| NPN version | 2n3904 and a GT404, hfe around 100, caps swapped around | "it sounds awesome" | Hozy311 |
| Suggested option | 2n1307 transistors, hfe around 180 | "should be enough gain", sound untested | Zach1 |
On the NPN route, Hozy31 reported: "I built an NPN version by swapping the caps around and used 2n3904 and a GT404 Hfe ~100 and it sounds awesome"1. Zach also suggested that 2n1307 transistors with hfe around 180 should be enough gain for the circuit, while adding "no idea if they will sound good, but that should be enough gain"1.
Related Nine Volt Nirvana circuits
Guitar FX Layouts has published layouts for other Nine Volt Nirvana designs, including the Nine Volt Nirvana Tone Dog fuzz and the Nine Volt Nirvana Dino Drive fuzz, alongside the Nine Volt Nirvana BrontoBoost1.
Questions
Who designed the Nine Volt Nirvana Nitroburner Fuzz?
The Nitroburner comes from Joe Gagan, the designer behind Nine Volt Nirvana. The Guitar FX Layouts write-up of the circuit introduces it as another design from Gagan, whom the author calls "the man, the myth, the legend". The circuit is described as a fuzz based on the Fuzz Face with a bunch of tweaks.
What should Q2 be in the Nitroburner Fuzz?
Q2 should be a high gain PNP germanium transistor, according to the Guitar FX Layouts analysis of the circuit. Builders have also reported good results with germanium parts of around 100 hfe, and one builder reported an NPN version using a 2n3904 and a GT404 with hfe around 100.
What voltage should Q2 be biased to?
Bias Q2 using the trimmer to -4.2V. The Guitar FX Layouts notes also suggest setting the bias pot to 0 to start setup. The negative voltage reflects the PNP germanium transistor at Q2 in the stock circuit.
Does the Nitroburner need a jumper between Q1 and Q2?
Yes. There needs to be a jumper between the base of Q2 and the collector of Q1. The layout author confirmed the missing connection was removed by accident while moving things around, so a corrected build adds that jumper.
Can the Nitroburner be built with NPN transistors?
A builder named Hozy31 reported building an NPN version by swapping the caps around, using a 2n3904 and a GT404 with hfe around 100, and said it sounds awesome. The stock circuit, however, calls for a high gain PNP germanium transistor at Q2.
Sources (1)
- Guitar FX Layouts: Nine Volt Nirvana Nitroburner Fuzz, Guitar FX Layouts (tagboardeffects.blogspot.com), 2017-10-14
