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Electro-Harmonix Operation Overlord Allied Overdrive review

Keep your options open with this versatile pedal ideal for any electronic instrument of your choice

  • £140
  • €165
  • $147

Our Verdict

A practical overdrive/distortion suitable for both guitar and studio applications.


  • Versatile.


  • Very few.

There are many things about this overdrive that set it apart. 

First, it works with a variety of instruments so has three selectable input levels and full stereo operation plus mono in/stereo out (besides standard mono), should you find a way to use that in your guitar chain. 

It also has a Dry knob to blend in any amount of drive - useful for adding edge to a clean sound or keeping a certain amount of note clarity with a dirty sound. 

The drive sound, based on three JFET gain stages, is amp-like from a touch of grit through to cranked stack, but you can go further with the ‘Boost’ footswitch, which engages an extra overdrive circuit to push the drive sounds harder, adding saturation and ultimately edging it into fuzz territory, all with active tone knobs delivering sonic shaping from mild to brutal.