The Moreland Magnetics 202a Harmonic Percolator is a distortion/fuzz pedal with slight octaving effects, and it is Moreland Magnetics' take on the inimitable Interfax Harmonic Percolator, an unruly tone machine1. It sits in the same family as other distortion pedals and fuzz pedals built around this circuit.
What it does
The crucial components in the 202a are the vintage Si & Ge transistors, along with a pair of specific and hard-to-find germanium diodes1. Each set of NOS (new old stock) components is measured for gain and then audited by ear before it goes into a pedal. As Pedal of the Day put it, the parts are checked "to make sure they do The Thing"1.
The pedal carries two knobs. Dialing them back transitions unruly, mangled chaos into a surprisingly usable overdrive tone, the kind of range you might otherwise spread across separate overdrive pedals and fuzz boxes1.
On the sound itself, Pedal of the Day's reviewer described it this way1:
"At once you'll notice a fierce, unforgiving upper midrange bite, with a lower octave undertone supporting your notes as you move up the fretboard."
That lower octave undertone is described as almost like an Octavia tone but inverted, which places the 202a near the territory of octave and pitch pedals as well as straight distortion1.
The circuit it comes from
The Harmonic Percolator circuit has a long history of being modified by builders. Premier Guitar's 2014 press coverage described it as "a simple yet fascinating circuit which readily lends itself to tweaking and improvement"2. The original Interfax HP-1 used a Harmonics control for input gain, one of its defining features3. Builders such as Fredric Effects have worked from the same starting point, describing their version as "an improved version of that hybrid Silicon/Germanium circuit"4.
The 202a adds its own twist to the format: an internal trimpot lets you adjust a variable resistor that changes the frequencies where the octave effect happens1.
What reviewers said
Pedal of the Day's reviewer came away positive, noting that "It's always impressed me how two knobs are capable of doing so much" and that they were excited to have another Harmonic Percolator example to cover, with the 202a continuing a streak of enjoying every one they had played1.
Videos
collector//emitter
Pedal of the Day
Sources (4)
- Moreland Magnetics 202a Harmonic Percolator, Pedal of the Day, 2026-08-10
- Fredric Effects Releases the Utility Perkolator, Premier Guitar, 2014-09-09
- Guitar Pedal X, Guitar Pedal X, 2024-05-13
- Silicon Harmonic Percolator, fredric.co.uk
