Fulltone OCD

The Fulltone OCD is one of the most influential overdrive pedals of the 2000s — a circuit designed by Mike Fuller that helped define the boutique pedal era and earned the kind of widespread adoption usually reserved for Tube Screamers and Klons. Released in 2004 and refined through multiple revisions, the OCD became a near-default "second drive" on countless professional pedalboards, prized for its ability to convincingly mimic the break-up of a cranked amp at any volume.

What sets the OCD apart from most overdrive designs is its use of MOSFET-based clipping rather than the silicon or germanium diodes used in Tube Screamers, RATs, and similar pedals. MOSFET clipping produces a clipping curve that more closely resembles the soft compression of a power tube being driven into saturation, giving the pedal a more amp-like feel — particularly responsive to picking dynamics and guitar volume control. Roll the guitar volume back and the OCD cleans up convincingly; dig in harder and the pedal opens up with the kind of bloom and harmonic content usually associated with a tube amp at the edge of break-up.

The four-control interface is straightforward: Volume sets output level, Drive sets gain, Tone is a low-pass tilt control, and the HP/LP toggle switch selects between two voicings. HP (High Peak) emphasises mids and presence with a slightly compressed feel — well-suited to lead lines and pushing an amp. LP (Low Peak) is more open and full-range with extended low end, working better as a primary rhythm overdrive. The Drive knob has unusually wide range for an overdrive — at lower settings the OCD acts as a transparent boost or light overdrive, and at higher settings it crosses into genuine distortion territory, allowing it to substitute for both an overdrive and a distortion pedal in many rigs.

The current production version is the OCDv2 (around $179 USD / £189), which features true bypass switching and what Fulltone calls a "buffered enhanced bypass" mode selectable internally. Variants include the OCD-Germanium (with germanium components in the signal path for a softer, vintage-flavoured response) and a Custom Shop V1.4 reissue that replicates the early-revision sound. The pedal runs on standard 9V centre-negative power (it can also accept up to 18V for additional headroom and slightly tighter response), and is housed in a die-cast aluminium chassis. Fulltone closed its California facility in 2022 after thirty years, but the company relaunched in 2024 through a partnership with Jackson Audio in Keller, Texas, with OCD production resumed.

Who Is This For? The OCD suits guitarists who want one drive pedal that covers ground from clean boost through to high-gain distortion, with a dynamic, amp-like feel rather than the compressed, narrow-band character of a Tube Screamer. It is particularly well-suited to players using clean or lightly-driven amps who want their drive pedal to provide the break-up — country, indie, classic rock, and modern rock players are all well-served. The HP/LP switch, wide gain range, and dynamic touch response also make it an excellent platform pedal for stacking with other drives, and the strong used market provides good options across all the various V1.x and V2 revisions.