Fuzz Face
A 2-transistor Fuzz Face is the classic first self-planned build: small enough to hold the whole signal path in your head, and a direct application of the transistor clipping and input-loading behavior covered in the Effects book's Fuzz chapter. This guide covers parts selection, the workflow order to build it in, and the bias-check every Fuzz Face needs before it's finished.
The Fuzz Face is the circuit Fuzz uses as its first worked example, and it’s a genuinely good candidate for the “boost or simple fuzz — five to ten components” first self-planned build recommended in From Understanding to Building: two transistors, a small handful of resistors and capacitors, and a circuit small enough to hold the whole signal path in your head at once.
Parts and sourcing
| Part | Notes |
|---|---|
| Q1, Q2 (transistors) | Germanium (e.g. AC128, NKT275-family) for a vintage-correct build, or silicon (e.g. BC108, 2N2222) for a more stable, less temperature-sensitive build — see Transistors and Diodes for what the choice actually changes |
| Resistors, capacitors | Standard 1/4W resistors and film/electrolytic capacitors per the schematic’s values |
| Potentiometers (Fuzz, Volume) | Audio (logarithmic) taper — see Potentiometers for why the taper choice matters here |
| PCB or stripboard | A published PCB kit (PedalPCB and similar vendors carry Fuzz Face-derived designs) or a stripboard layout, per the three build paths in From Understanding to Building |
Germanium transistors specifically, especially matched pairs for the feedback-bias arrangement this circuit depends on, are the one part on this list a general electronics distributor is unlikely to stock — Small Bear Electronics is the supplier this site’s parts catalog specifically flags for obsolete and germanium semiconductors. Tayda Electronics covers everything else on this list at low cost.
Build order
- Read the schematic twice — once for stages only (input, first transistor stage, second transistor stage, output), once for values — per the workflow in From Understanding to Building.
- Breadboard the circuit before committing to stripboard or a PCB, per Breadboarding & Prototyping — a Fuzz Face’s bias-sensitive feedback arrangement is exactly the kind of thing worth confirming behaves as expected while it’s still free to change.
- Populate and solder in signal order, checking each transistor’s bias point against the schematic before moving to the next, using the stage-by-stage approach from Debugging a Circuit.
- Check both transistors’ collector bias voltages once fully assembled — this is the single most useful post-build check for this specific circuit, since the two transistors’ shared feedback bias relationship means a wrong or mismatched part shows up here before it shows up anywhere else.
What to expect, and what’s actually a fuzz-specific quirk rather than a fault
A properly biased Fuzz Face will noticeably clean up in character — not just get quieter — when your guitar’s volume knob is rolled back, because of the low input impedance covered in Fuzz. If that doesn’t happen at all, or the fuzz sounds identical regardless of guitar volume, that’s worth checking against the schematic’s bias points before assuming the circuit itself is at fault.
Build log
This guide is currently the reference/planning layer only. Once this build is actually underway, photos, real component choices, and any deviations from the reference schematic belong here.