The Supro Tremolo is an analog stompbox designed to recreate two of the most desirable vacuum tube based modulation effects found in American amplifiers of the 1960’s. The Supro Tremolo pedal’s AMPLITUDE / HARMONIC switch allows the musician to choose between these distinctly different, vintage effects. AMPLITUDE mode provides the traditional swampy, tremolo sounds generated by bias modulating the power tubes in the original Supro amps. HARMONIC mode provides the psychedelic tones of Leo Fender's brownface and blonde amps from the early 60's. We've implemented Leo’s unique "harmonic tremolo" effect within the output stage of the pedal to create an "amp-like" modulation experience.