In 1960, Leo Fender introduced a circuit in his Bandmaster and Vibrasonic amps called the “Harmonic Tremolo” (which proved to be a misnomer, since it was a volume effect, not a pitch effect). Essentially, the amp’s signal was split into high frequency and low frequency components, with the output switching back and forth between the two, resulting in a dreamy effect similar to the Uni-Vibe. The 3 Series Harmonic Trem allows you to utilize Leo Fender’s revolutionary effect in a package much easier to tote than a vintage amplifier. Toggle up is a great sounding amp trem, while toggle down is our take on harmonic trem effect.