Guyatone HD-2 Harmonic Distortion

The Guyatone HD-2 Harmonic Distortion is an analog distortion pedal built around one of the most storied circuits in effects: the first-series Big Muff. RockBoard's PedalPedia describes it as a transistor distortion based on the most popular vintage designs, whose dual clipping stages provide considerable sustain, and says it offers a faithful replication of that classic tone with some added benefits¹. For a player, that means a Big Muff-style distortion and sustain voice in a modern pedal, without hunting down a vintage original, which RockBoard's PedalPedia notes is an expensive proposition¹.

Controls and how it works

The HD-2 keeps things simple with two controls:

Underneath, it is a transistor distortion with dual clipping stages, the arrangement Guyatone points to for its sustain¹. There is no tone control, and that is a deliberate choice: RockBoard's PedalPedia says that, as on its OD-2, it has "foregone a tone control in order to reproduce the instrument's tonal characteristics more accurately"¹. In practice, the pedal passes more of your guitar's own voice through the distortion than a design with an active tone stage would.

The Big Muff connection

The circuit the HD-2 draws on is the first-series Big Muff, which RockBoard's PedalPedia calls one of the indisputable classics, while noting the trouble of finding one that works nowadays at a reasonable cost¹. The Big Muff itself is an Electro-Harmonix design, described in a MusicRadar interview with founder Mike Matthews as "the Big Muff distortion/sustainer"². The HD-2 is Guyatone's own take on that first-series voicing rather than an Electro-Harmonix product.

Power

The HD-2 runs on 9V DC with a center negative plug and draws 5mA¹. That low draw means it sits comfortably on a pedalboard supply alongside other distortion pedals.

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