Brownface-style tremolo in a stompbox.

If there’s such thing as a cult modulation effect, the “harmonic tremolo” found in certain early-1960s Fender brownface amps certainly qualifies. Unlike most trems, which modulate the entire frequency of your signal, the circuit splits your sound into high and low bands, modulating one with an LFO, and the other with an inverted version of the LFO, alternately emphasizing treble and bass. The result isn’t pure tremolo, but a trippy trem/vibrato/phaser hybrid. Fender soon replaced this complex, three-tube circuit with the simpler (and cheaper) single-tube optical tremolo found in most Fender blackface amps. But for some players, the phasey brownface sound remains the definitive tremolo.

Brownface Reborn
The harmonic tremolo effect is often resurrected in the digital realm, where it’s easy to simulate the two-band effect without tricky, tube-intensive circuitry. But it’s rarely been realized as suavely as in Coldcraft’s Harmonic Tremolo stompbox, which combines an analog preamp stage with a DSP chip and some clever new controls. It’s the company’s second edition of the effect, replacing a discontinued all-analog version.

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