Bowman Audio Endeavors Harmonic Percolator

The Bowman Audio Endeavors Harmonic Percolator is a distortion and fuzz pedal, described by Pedal of the Day as "a wild and dirty pedal" and the first in the Bowman Audio Endeavors lineup¹. It is a re-creation of the original InterFax Harmonic Percolator, the vintage oddball circuit that has inspired a long line of clones and interpretations². Bowman built it as a strictly limited run: only 4 units were made².

What it does

The Harmonic Percolator design is a simple circuit that produces a distinctive distorted and fuzzy character. Pedal of the Day described the Bowman version's tone as "specific and remarkable distorted/fuzzy tone", crediting the pair of NOS germanium diodes at its heart². Germanium diode clipping is a big part of what gives old fuzz and distortion pedals their particular edge, and using new-old-stock parts is the point of a faithful re-creation.

Bowman aimed the build at players who want the vintage circuit in a modern format. The pedal "keeps that simple enclosure attitude, but makes it smaller and upgrades it a little, for modern aesthetics", according to Pedal of the Day². It uses the same NOS NPN and PNP transistors as the vintage InterFax models².

Controls

Balance and Harmonics are the only controls, but Pedal of the Day found "a wide sonic spectrum just waiting to be explored" between them². The Harmonics control works the same way as the input gain slider on the original InterFax HP-1, which Guitar Pedal X describes as the "Harmonics" or input gain³.

Where it came from

The original InterFax Harmonic Percolator has been described by Premier Guitar as "a simple yet fascinating circuit which readily lends itself to tweaking and improvement"⁴. That openness to modification is one reason the design has drawn so many re-creations, from Bowman's four-unit run to current builds like the Moreland Magnetics 202a Harmonic Percolator, which adds an internal trimpot for adjusting the frequencies where its octave effect happens⁵. For more on the wider family, see Distortion Pedals and Fuzz Pedals.

Videos

Click to load