RIAAequalisering

RIAA equalization, or the RIAA equalization curve, is a standard pre-emphasis used in vinyl recording and playback. Developed in the 1950s by the Recording Industry Association of America, it specifies how audio signals are shaped when cutting records and how they should be de-emphasized during playback. The goal is to improve signal-to-noise ratio, reduce groove width for longer playing times, and minimize rumble and distortion, while restoring a flat frequency response when the record is played back on a properly calibrated system.

The curve is built from three interacting frequency regions defined by time constants and breakpoints. The typical breakpoints are around 50 Hz, 500 Hz, and 2,122 Hz, corresponding to time constants of about 3180 µs, 318 µs, and 75 µs. In recording, the curve applies a pre-emphasis that alters bass and treble relative to a reference, and in playback the inverse de-emphasis is applied by the phono stage. When the two curves are combined with the cartridge, tonearm, and amplifier chain, the intended flat response is recovered and noise and distortion introduced by the vinyl format are reduced.

RIAA equalization remains the de facto standard for most vinyl mastered material and consumer turntables. Variants and competing curves (such as NAB, CCIR/IEC) exist but are less common in modern mastering. Proper implementation—whether in RIAA-compliant phono preamps or in digital decoding of vinyl rips—is essential for accurate reproduction of the original recording.