is a specification for the correct playback of gramophone records
, established by the Recording Industry Association of America
(RIAA). The purpose of the equalization
is to permit greater playback times, improve sound quality, and to limit the vinyl damages that would otherwise arise from recording analog records without such equalization.
equalization curve was intended to operate as a de facto
global industry standard
for the recording and playback of vinyl records since 1954. However, it is almost impossible to say when the change actually took place.
Before then, especially from 1940, each record company applied its own equalization; there were over 100 combinations of turnover and rolloff
frequencies in use, the main ones being Columbia-78, Decca-U.S., European (various), Victor-78 (various), Associated, BBC, NAB, Orthacoustic, World, Columbia LP, FFRR-78 and microgroove, and AES.
The RIAA curve
RIAA equalization is a form of preemphasis
on recording, and deemphasis
on playback. A record is cut with the low frequencies
reduced and the high frequencies boosted, and on playback the opposite occurs. The result is a flat frequency response, but with noise such as hiss and clicks arising from the surface of the medium itself much attenuated
. The other main benefit of the system is that low frequencies, which would otherwise cause the cutter to make large excursions when cutting a groove, are much... Read More