The Gigahearts Siliface MKII is a silicon fuzz pedal built on the Fuzz Face circuit. Gigahearts took the classic Fuzz Face schematic and added a set of adaptations: a Vintage/Modern mode switch, a reversed Bias control that can starve the circuit down to 0.7V, and Body and IN controls. The silicon "Fuzz Face" is a design used on countless recordings for over 50 years, as the maker's product page puts it12.
Guitar Pedal X's Stefan Karlsson reviewed the MKII in May 2026 and called it "the perfect everyday all-rounder Fuzz Face - likely my favourite Silicon variety to-date!"2. It was listed at $155 USD on the Gigahearts Webstore at that date, which the same review gives as £1152.
Controls
| Control | What it does |
|---|---|
| Fuzz (Gain) | Sets the amount of fuzz2 |
| Mode | Vintage (Classic) or Modern (Louder) output profile2 |
| Volume | Output level2 |
| Bias | Reversed, running 7V down to 0.7V, for starved and gated sounds2 |
| IN | Part of Ian's circuit layout alongside the other controls2 |
| Body | Bass contour2 |
The designer is named as Ian in Guitar Pedal X's review, which describes the circuit as including "Fuzz, Vintage/Modern Mode, Volume, reversed Bias and IN controls, plus Body bass contour"2.
Vintage and Modern modes
The two modes are not simply a softer and a louder output. Guitar Pedal X found they interact with the other controls for a somewhat different character, covering both Type II and Type III style Fuzz Face tones, which the review frames as vintage and modern voicings2.
For a reference point, the reviewer described one setting in detail: Vintage mode with Fuzz and Volume fully cranked, Bias just before 9 o'clock, and IN and Body fully off. "with those settings I get the perfect cutting / searing Silicon Type II tones"2.
The Bias / Starve control goes beyond a single Volt, down to 0.7V, for extreme dying battery, starved, sputtery and gated sounds2. Guitar Pedal X also notes the pedal can get extremely loud on Modern Mode, where 2 o'clock on the Volume is already really loud2.
Where it sits in the Gigahearts range
Gigahearts builds a family of fuzz designs around Ian's circuits. The same outlet has covered the Gigahearts MK2 Small Cheese, a Lovetone Big Cheese derivative, and the Full Moon, a seven-control take on the Moonrock Fuzz available as a PCB and as a Custom Shop Imbrium edition3. The Siliface MKII is the Fuzz Face branch of that range.
Videos
GIGAHEARTS FX
Questions
Is the Gigahearts Siliface MKII a germanium or silicon fuzz?
It is a silicon fuzz. Guitar Pedal X's review describes the circuit as built around unique lower-gain TO-92 style silicon transistors, with the transistor identity kept private and both devices masked inside the pedal. The circuit is based on the classic Fuzz Face schematic with a range of adaptations.
What Fuzz Face tones does the Siliface MKII cover?
Guitar Pedal X describes the Siliface MKII as delivering both Type II and Type III style Fuzz Face tones, straddling vintage and modern voicings. The Vintage and Modern modes are not just about a softer or louder output profile: the reviewer found they interact with the other controls for a somewhat different character.
How much does the Gigahearts Siliface MKII cost in the US?
Guitar Pedal X's May 2026 review lists the Siliface MKII at $155 USD on the Gigahearts Webstore, which the same review gives as £115 in the UK.
What does the Bias / Starve control do?
The Bias control is reversed and runs from 7V down to 0.7V. At the bottom of its range it starves the circuit for extreme dying battery, sputtery and gated sounds, the kind of behavior a Fuzz Face shows as its battery dies. Guitar Pedal X notes the control is reversed, so the starved sounds sit at the low end of the sweep.
Sources (3)
- Siliface by Gigahearts, RockBoard PedalPedia, 2026
- Guitar Pedal X, Guitar Pedal X, 2026-05-19
- Guitar Pedal X, Guitar Pedal X
