The SurfyVibe circuit emulates the mono channel of the Magnatone 280. In "Sweeping" mode, we add a feedback path to create a unique combined phaser/chorus/tremolo effect. The original circuit of the Magnatone 280 used a component called a "varistor", a type of component that was discontinued many years ago. Because of this, modern circuits use other techniques to achieve pitch shifting. To get the sound as close to the original as possible, Surfy Industries found a way to emulate the original circuit. Replacing the vacuum tubes with jFET transistors and the varistors with specialized diode arrays.