Answer 8—The definition of the RIAA preemphasis curve has poles at 50.05 and 2,122 Hz, and a zero at 500.5 Hz. Expressed in terms of time constants, these frequencies correspond to 3.18 ms, 75 µs, and 318 µs, respectively. The corresponding deemphasis curve swaps the poles and zeros.

Although not part of the preemphasis filter, the RIAA also recommends a high-pass pole at 20 Hz (7.96 ms) to remove rumble from the playback mechanism. The general shape of the playback curve is shown below.

Contributor: David Tweed