Boss · OD-1 · 1977–1985

Boss OD-1 OverDrive

The yellow OD-1 is where the word overdrive comes from, at least on a pedal. Boss launched it in November 1977 as one of the first three compacts, alongside the PH-1 and SP-1, and built it until July 1985. It has just two knobs, Level and Over Drive, and an asymmetrical clipping circuit meant to sound like a tube amp breaking up at sane volumes. It was an instant hit. Ibanez's Tube Screamer followed its design, using symmetrical clipping to steer clear of Boss's patent and adding a tone knob. Boss answered with the SD-1 in 1981, and the four-knob OD-2 took over in 1985. Inside, the board went through revisions marked OD-1A to OD-1E. Early ones use a 14-pin op-amp and later ones an 8-pin 4558-type chip, so two OD-1s can sound a little different. If you collect, ask which board revision you're getting and look for the original knobs and screw. If you just want the sound, the SD-1 is its direct descendant.