PEDAL BENCH
by Stompbox Labs
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Overdrive2004· Fulltone (USA)

Fulltone OCD

MOSFET hard-clipping 'amp-like' overdrive — the modern boutique benchmark.

⏳
Schematic pending verification

We don't ship reference schematics until they've been hand-authored against authoritative sources (manufacturer service docs, ElectroSmash analyses, GEOFEX writeups) and reviewed in the simulator. Until then, the BOM, signal chain, controls and mod notes below are accurate, and you can still add this pedal to a project — it just won't include a circuit yet.

About

The Obsessive Compulsive Drive uses an op-amp gain stage feeding MOSFET clippers to ground, with a discrete JFET output stage. Unlike Tube-Screamer-family pedals it has very little mid-hump — the voicing is broader and more 'amp-like', which is why it stacks well in front of any amp.

Signal chain preview

6 stages
Input
Input buffer (JFET)
TL082 op-amp non-inverting gain stage (Drive pot in feedback)
2× 2N7000 MOSFETs as hard clippers to ground
HP/LP voicing switch (input filter)
Passive Tone control
Discrete JFET output booster (gives the OCD its loud, present output)
Output

Quick facts

  • MOSFET clipping (2N7000) gives a harder, more compressed edge than diode clipping but still feels dynamic.
  • The HP/LP switch toggles input filtering — HP rolls off bass for tighter high-gain, LP keeps full range.
  • Counterfeited heavily; genuine units have a Fulltone-stamped enclosure and proper through-hole build.

Controls

  • Volume
  • Tone
  • Drive
  • HP/LP switch

Mod recipes Pro

3 mods
  • Asymmetric MOSFET clipping

    Looser, more open clip with second-harmonic content.

    How: Replace one of the two clipping MOSFETs with a 1N4148 in the same orientation — asymmetric 2N7000 / 1N4148 pair.

  • Bass boost mod

    Restores low end the HP filter removes.

    How: Increase C5 (input AC-coupling) from 0.1 µF to 0.47 µF and bypass the HP filter cap on the toggle.

  • Silicon clipping option

    Adds a third voicing.

    How: Wire a 3-way ON-OFF-ON toggle to select between 2N7000 (stock), 1N4148 silicon (tighter), and LEDs (louder, harder).

References