The Idea

The idea behind the design was to create a 'vintage' fuzz, but with all the parameters adjustable. Bear with me whilst I explain...

After doing an analysis of fuzz pedals, I came to the conclusion that fuzz pedals were in fact very complex devices, despite the deceptive sparseness of their circuit designs. In fact, there are many more parameters to control in a fuzz pedal compared to an overdrive pedal, but for some reason, overdrive pedals often come with a plethora of controls, whilst fuzz pedals often just have fuzz and volume.

I identified the following 'parameters', and set about designing the Neo (germanium oriented) and GI (silicon oriented) with controls to control the following:

Input Impedance - Fuzz pedals typically have a low input impedance. The value of this impedance 'loads' different pickups in different ways, and is often the reason why fuzz pedals sound magical with some guitars, and very dull with others. With variable input impedance, it would be possible to 'tune' the fuzz pedal to different guitars... and even make them useable with humbuckers (shock horror!)!

Fuzz Amount - Fuzz pedals tend to have a very limited range. I want to create something which could go from completely clean to over the top.

Tone Controls - Why are there rarely tone controls on Fuzz pedals?

Bias - Many 'classic' fuzz pedals were in fact very variable, both with respect to temperature, as well as from pedal to pedal. Often, this was a result of the transistor working at different point. A bias control would allow the user to adjust the operating point of the transistors and capture any sound from asymmetrical synth-like sounds to smooth vintage fuzz.

Output volume - traditional designs often aren't loud enough.

The circuit concept for the Neo Fuzz is the same as that of the GI Fuzz, but instead of NPN high gain silicon transistors, the Neo Fuzz is built around a pair of hand selected early 70s NOS AC128 germanium transistors. There's also a third silicon transistor which is not involved in the fuzz tone generation. The tone is pure germanium. Each germanium transistor is tested for leakage current and gain, and only the best of these transistors is used in the Neo Fuzz.

The Features

The tone of the Neo Fuzz is remarkably different to the G.I. The Neo is much more vintage sounding, a lot smoother, with less bite and buzz. Its gain is also a lot tamer, but don't worry, there's still plenty on tap.

The other features of the Neo Fuzz are the same as the GI Fuzz, namely:

A huge gain range, from nothing to sustain-for-days

It can be used as a low gain device (for a fat bluesy bite), which is fairly unique for a fuzz pedal, since fuzz pedals tend to have a very narrow range of gain.

To tame this pedal, there's an internal gain trimmer to wind things back (which I recommend)

A load control, which is a variable input impedance. This can be used to match the Neo Fuzz to humbuckers as well as single coils (Fuzz pedals tend to have low input impedance which is a better match for single coils. Now you can also use humbuckers without any problems). You can also use it to go from a tradition fuzz sound (low input impedance) to a more articulate sound with detailed highs (high impedance)

A bias control to set up the operating point of the transistors, from a fat symmetrical fuzz, to an asymmetrical 'mosquito' buzz, and beyond, to a gated synth-like sound (almost sounds like your amp is about to die!)

A body control, which full range mid range control. The mids, of course, are the most important frequencies for determining how your guitar tone sits in with the rest of the band.

A tone control, which controls both lows and highs, as opposed to simply a high cut filter. This is like bass and treble controls rolled into one. The combination of the tone and the body controls is like having a low/mid/high EQ

A volume control with output to spare. You can use the Neo fuzz to overdrive your amp.

A 3 position bright switch to help tame the top end. This is useful if you're going to use your Neo Fuzz with a bright 'modern' voiced clean channel, or if you're going to use the Neo with overdrive pedals (which tend to be darker, and by comparison, make a normal fuzz sound shrill)

One thing to note is the fact that this pedal will need its own independent power supply. Even though the pedal can be powered using a standard power supply, the internal polarity is reversed since the germanium transistors requires a negative supply voltage. This means that you cannot use the same power supply to power normal pedals as well. Alternatively you can use batteries to power the Neo Fuzz.