February 1978

The MXR Thirty-One Band EQ is a professional-grade graphic EQ introduced in the late 1970s, offering precise tonal control for studio, live sound, and broadcast applications. With 31 frequency bands spaced one-third of an octave apart and a ±12 dB adjustment range, it allows for detailed sound shaping, feedback reduction, and room correction. Its rugged 19-inch rackmount design, high-quality faders, and connectivity options – including 6.35 mm jacks and XLRs – ensure durability and compatibility.

The MXR Dual Fifteen Band EQ offered precise two-channel frequency control with bands set two-thirds of an octave apart for greater accuracy, particularly in the midrange. Each channel had its own level control, with a ±12dB range per band, housed in a rugged 19-inch rackmount design with quarter-inch connections.