The Dynamo Reactive Distortion pedal is a unique and versatile drive effect that is loosely based on the RAT distortion pedal. It features an optocoupler that dynamically sets the gain based on the input signal, resulting in a touch-sensitive distortion that is its own unique creature.

The circuit of the Dynamo is derived from an experiment in putting two RAT distortion pedals in series, as evidenced by the two cascaded LM308 gain stages. However, the twist in the Dynamo’s design lies in how the drive level is controlled. A side-chain envelope detector engages an opto-FET, which acts as the op-amp’s gain control. This means that the gain of the pedal varies with the strength of the input signal, resulting in a dynamic and responsive distortion.

The Dynamo is an adaptation of the Bixonic Expandora, a Japanese boutique pedal that was first released in 1995. The Expandora gained popularity among notable musicians such as Billy Gibbons (ZZ Top), Stu G (Delirious?), Thom Yorke, and St. Vincent. The Dynamo is most similar to the third version of the Expandora, known as the “2000R,” but with some tweaks from other versions for added versatility.

One notable modification in the Dynamo is the inclusion of a potentiometer called “Drive,” which covers the full range of resistance of the separate gain toggles found in the Expandora V4. Additionally, the Dynamo features a “Forbidden” mode toggle, which disengages the series resistance in the feedback loop.

The JHS Kilt is a commercial clone of the Expandora, designed in collaboration with Stu G. While the Dynamo has not been traced, it is likely identical to the Kilt, except for the potentiometer modification. The Flat/Bass Cut switch in the Dynamo is the same as the Bass/Guitar switch found in the 2000R version of the Expandora.

Overall, the Dynamo Reactive Distortion pedal offers a unique and untamed drive effect, thanks to its optocoupler-based gain control and its adaptation of the Bixonic Expandora circuit.

Summary created by AI from the original source.