The MXR Thirty-One Band EQ is a professional-grade graphic EQ designed for precision tonal control in studio, live sound, and broadcast applications. Introduced in the late 1970s, it was part of MXR’s Professional Products range and remained in production until MXR ceased operations in 1984. This single-channel unit divides the frequency spectrum into 31 bands, each spaced one-third of an octave apart, which is widely considered the optimal resolution for detailed frequency shaping.
Each band of the MXR Thirty-One Band EQ provides a ±12 dB adjustment range, allowing for fine-tuned control over the audio spectrum. This level of precision makes it ideal for eliminating unwanted resonances, compensating for room acoustics, reducing feedback in PA systems, or sculpting an instrument’s tonal balance. Unlike parametric equalisers, which require careful setting of bandwidth and centre frequency, the MXR Thirty-One Band EQ provides immediate and visible response adjustments, making it an intuitive tool for engineers and musicians.
Built for professional use, the unit features a rugged metal chassis and a standard 19-inch rackmount format, ensuring durability in both studio and live environments. The high-quality faders are designed to withstand repeated adjustments without signal degradation. Connectivity options include standard 6.35 mm (¼-inch) input and output jacks, as well as XLR connectors, offering compatibility with a wide range of professional audio systems.
Performance specifications include a high slew rate of 1V per microsecond, allowing it to handle fast transient signals without introducing distortion. Its noise floor is rated at better than -90 dBm, ensuring a clean and transparent signal path, even when applying significant EQ adjustments. This makes it particularly useful in critical audio applications where maintaining signal integrity is essential.
During its time in production, the MXR Thirty-One Band EQ was recognised for its reliability, precision, and robust build quality. It was widely used in live sound reinforcement to optimise PA system performance, in studio environments for mix refinement and mastering adjustments, and in broadcast settings to maintain balanced audio output. Its ability to provide detailed tonal control while remaining simple to use made it a favourite among engineers who needed a dependable and effective equalisation solution.
The MXR Thirty-One Band EQ remains a respected piece of equipment for those who seek high-quality analogue equalisation. Its combination of precision, durability, and ease of use ensures its continued appreciation by audio professionals who value hands-on control over their sound.
