This unit recreates the classic vintage tube amp tremolo effect. Tremolo was popularized in the 1960s, first with Surf Guitar, and later with keyboards, such as the Wurlitzer and Rhodes electric pianos. The blackface Fender amps from that time were considered the best for this kind of “creamy” tremolo.

It was originally (and ingeniously) achieved by using an opto-isolator (opto for short) circuit. The opt sensor detects a light source (often a simple incandescent bulb) which is modulated electrically to flash on and off. It then converts the pulsing light to an electrical impulse which modulates the volume of the audio.

Originally a mono effect, a stereo version was introduced by Fender for their Rhodes electric pianos. The audio alternated from left to right – a really cool effect, especially on stage!


This control sets the speed of the tremolo.


The Depth control adjusts the depth of the amplitude modulation. From all ON and all OFF to just a subtle rise and fall in volume.


As the opto circuits got older, they lost their ability to modulate completely ON or OFF (and that’s actually a good thing!). This made for a smoother ON/OFF or L/R that was not as jarring.

Use this knob to control the modulated amount of ON/OFF or L/R. Higher settings yield a smoother, “older-sounding” tremolo.


This drop-down menu allows you to select different tremolo waveforms: Opto (Square), Sine and Triangle.


Master volume.


Engaging this switch enables alternating left-right panning.