The Fredric Effects Utility Perkolator MKII is a distortion pedal built on the Interfax Harmonic Percolator circuit from the 1970s. Fredric Effects calls the original "the fabled Interfax Harmonic Percolator from the 1970s," and the Utility Perkolator is the company's own improved version of that hybrid silicon and germanium design, which it has built "for almost as long" as the maker has existed12. The MKII adds a switchable ring modulation circuit on top of the Percolator formula, and Fredric Effects also builds a faithfully vintage-correct Harmonic Percolator version alongside it1.
What it does to your signal
The Utility Perkolator takes the Harmonic Percolator circuit and modifies it in two ways. First, it uses higher gain, lower leakage Russian germanium transistors. Second, it adds a low pass filter which, in Fredric Effects' words, "only removes the high-end hisses and glitches associated with the HP." The company says the result is "a tighter and more controllable effect which is still capable of producing the classic Harmonic Percolator sound," with "a considerably lower noise floor and more predictable note decay"14.
Beyond the core circuit, the pedal carries extra clipping options and a selectable ring mod circuit. Guitar Pedal X's Stefan Karlsson listed the controls as "Harmonics, Balance, Clipping : Si / Ge, Ring Mod : On/Off"5. On Delicious Audio, Paolo De Gregorio noted that "a toggle switch lets you choose between Silicon and Germanium diodes"7.
The ring modulation switch
The MKII's headline addition is a switchable ring modulation circuit. Fredric Effects says it was added "for splattery octave effects"1. On gearnews.com, Jef wrote: "This one has that added ring modulation circuit for extra splattery and octave overtones, so purists will probably moan."8 That framing is useful for a buyer deciding between versions: the ring mod is an extension of the Percolator sound rather than a faithful reproduction of it, and players who want the original circuit untouched can look to the maker's vintage-correct version instead1.
History and versions
The Utility Perkolator MKII is Fredric Effects' latest version of what the maker calls "the fabled Interfax Harmonic Percolator from the 1970s"13. The original Utility Perkolator was fitted with Cliff jacks3. The MKII adds a low pass filter which, according to Fredric Effects, only removes the high-end hisses and glitches associated with the Harmonic Percolator, giving it a considerably lower noise floor4. The maker's own page lists the MKII at £1751, while a UK press report on the new wedge-enclosure pedals gave the price as £140, so the two sources disagree6.
| Version | Year | Notable details |
|---|---|---|
| Utility Perkolator (MKI) | 2014 | Cliff jacks3 |
| Utility Perkolator MKII | 2019 | Ring modulation switch, wedge enclosure with top-mounted jacks, £140 at launch486 |
| Vintage-correct Harmonic Percolator | also built | Fredric Effects' faithful version of the original circuit1 |
As of the maker's product page dated 2026-10-26, the Utility Perkolator MKII is listed at £175 GBP, up from the £140 GBP launch price of 201916.
Videos
Jackson Brooksby
Regent Sounds
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Sources (8)
- Utility Perkolator, an improved Harmonic Percolator, Fredric Effects
- Fredric Effects Silicon Harmonic Perc, Premier Guitar, 2025-07-25
- Fredric Effects Releases the Utility Perkolator, Premier Guitar, 2014-09-09
- Fredric Effects Launches New Guitar Pedals 2023, Premier Guitar, 2019-03-07
- Guitar Pedal X, Guitar Pedal X, 2024-05-13
- Fredric Effects unveils “unusual” trio of new guitar effects pedals, MusicRadar, 2019-03-07
- 9 Best Harmonic Percolator Fuzz Clones & Evolutions In 2023, Delicious Audio, 2023-05-03
- Fredric Effects Verzerrer, Utility Perkolator MkII & Dresden Synth Fuzz MkII, gearnews.com, 2019-03-10
