The Nine of Swords Headache Harmonic Percolator is a distortion pedal from the builder Nine of Swords, built on the circuit of the rare 1970s Interfax Harmonic Percolator. Pedal of the Day describes it as part overdrive, part distortion and part square-wave noise machine, a pedal that gets down-right filthy when cranked.1
Controls
The pedal keeps the original circuit's two-knob layout.
| Control | What it does |
|---|---|
| Harmonics | Adjusts the level of gain the effect produces, from a low buzz to crazy, glitchy, square-wave territory1 |
| Balance | Attempts to control the overall output volume, although this is more of a suggestion than anything else1 |
The Balance knob is worth understanding before you put the pedal on a board. Because it does not behave like a normal master volume, level changes are best made elsewhere in the signal chain, with the Balance used to shape how the circuit itself sits and responds.1
The circuit it comes from
The original is the Interfax Harmonic Percolator, also known as the Interfax HP-1, built by Ed Giese in the 1970s.3 Pedal of the Day describes the Nine of Swords version as a take on the classic circuit made popular by the rare and ever-elusive original.1
The circuit's design is unusual among distortion pedals. Writing on the AMZ Guitar Effects blog, Jack Orman identified the Harmonic Percolator as another commercial example of PNP transistors operated off a positive supply, and Pedal of the Day notes the classic versions use germanium transistors in the PNP position.45 The circuit is a hybrid silicon and germanium design, and it has proven popular with builders: Premier Guitar has called it a simple yet fascinating circuit which readily lends itself to tweaking and improvement, and Fredric Effects is among the makers who have released their own improved versions of it.6
"The Harmonic Percolator is a simple yet fascinating circuit which readily lends itself to tweaking and improvement."
What reviewers said
Guitar Pedal X's Stefan Karlsson, surveying Harmonic Percolator-format pedals in May 2024, listed the Headache at £80 and gave this verdict2:
"This one has a huge pricing advantage, while there are probably others here that I prefer even at twice the price!"
In other words, the Headache's main appeal is its price against other Percolator-style pedals, though Karlsson personally prefers some of the alternatives even at higher prices.2
Artwork
The enclosure carries artwork that Pedal of the Day describes as an ode to Big Black's album Songs About Fucking, a nod that fits the pedal's abrasive character.1
Videos
Jonathan Wesson
Pedal of the Day
Questions
What is the Interfax Harmonic Percolator?
The Interfax Harmonic Percolator, also known as the Interfax HP-1, is a rare distortion unit built by Ed Giese in the 1970s. It uses a hybrid silicon and germanium design with germanium transistors in the PNP position, and it has become one of the most sought-after and copied fuzz and distortion circuits. Pedal makers including Nine of Swords build their own takes on the circuit.
Does the Balance knob control volume on the Headache Harmonic Percolator?
Only partly. Pedal of the Day notes that the Balance knob attempts to control the overall output volume, although this is described as more of a suggestion than anything else. Players should treat it as a tone and level shaping control within the circuit rather than a precise master volume.
How much gain does the Harmonics knob add?
The Harmonics knob adjusts the level of gain the effect produces, covering a wide sweep from a low buzz at the bottom of its travel to what Pedal of the Day describes as crazy, glitchy, square-wave territory at the top.
Who makes the Headache Harmonic Percolator?
The Headache Harmonic Percolator is made by Nine of Swords, a pedal builder whose version was listed by Guitar Pedal X at £80 in May 2024.
What is the artwork on the Headache Harmonic Percolator based on?
The pedal's enclosure artwork is an ode to Big Black's album Songs About Fucking, according to Pedal of the Day's 2016 review.
Sources (6)
- Nine of Swords Headache Harmonic Percolator, Pedal of the Day, 2016-05-19
- Guitar Pedal X, Guitar Pedal X, 2024-05-13
- Latent Lemon Audio Hurts Fuzz V2, Delicious Audio, 2022-11-28
- Positive Power for the PNP Fuzzface, AMZ Guitar Effects Blog (muzique.com), 2002-03-12
- Vaderin Pedals HP-X Harmonic Percolator, Pedal of the Day, 2021-10-21
- Fredric Effects Releases the Utility Perkolator, Premier Guitar, 2014-09-09
