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Distortion1979· DOD Electronics (USA)

DOD 250 Overdrive Preamp

Single op-amp + hard-clipping diodes — the Yngwie Malmsteen / MXR Distortion+ cousin in a yellow box.

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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

Almost identical topology to the MXR Distortion+: a single LM741 (later 1458) op-amp non-inverting gain stage with hard-clipping diodes to ground at the output. Two knobs (Level, Gain) and a famously huge dynamic range — clean boost to fuzzy distortion.

Signal chain preview

5 stages
Input
Input AC-coupling cap
LM741 non-inverting gain stage (Gain pot in feedback)
Hard clipping: 2× 1N914 silicon diodes from output to ground
Level pot
Output buffer
Output

Quick facts

  • The original grey 'LM741' version is the holy grail; later yellow reissues use 1458 / TL081 op-amps.
  • Yngwie Malmsteen's primary boost into his Marshalls for decades.
  • Circuit-wise identical to the MXR Distortion+ apart from the op-amp choice and a few resistor values.

Controls

  • Level (10k audio)
  • Gain (1M audio)

Mod recipes Pro

3 mods
  • LED clipping

    Louder, more open clipping with more headroom.

    How: Replace D1/D2 (1N914) with 2× red LEDs back-to-back — expect ~+6 dB output.

  • Tone control

    Tame the bright top end.

    How: Insert a passive 10k+ tone control (Big Muff style) between the Gain stage output and the Level pot wiper.

  • Asymmetric clipping

    More even-harmonic warmth.

    How: Use one 1N914 one direction and two 1N914 in series the other — SD-1 voicing in the DOD.

References