Recording Industry Association of America
The RIAA’S recording equalization
The RIAA recording equalization curve was adopted in 1954.
Before that date 100 + different turnover points were used within the industry.
What the RIAA EQ curve accomplishes is:
1 Allows more recording time.
(approximately 22 minutes per side)
2 Reduces the vinyl noise.
At the time of recording the low frequencies are cut (more space = more time) and the high frequencies are boosted.
At playback the low frequencies are boosted and the high frequencies are cut (lowering the noise floor of the vinyl).
The turnover points are: 50 - 500 - 2122 HZ