Time constant ↔ corner frequency
Convert time constants (µs) to corner frequencies, with FM, RIAA and CD emphasis values.
µs
ms
Hz
| Standard | τ | Corner frequency |
|---|---|---|
| FM pre-emphasis, Europe | 50 µs | 3183.1 Hz |
| FM pre-emphasis, Americas | 75 µs | 2122.1 Hz |
| RIAA vinyl: bass turnover | 3180 µs | 50.049 Hz |
| RIAA vinyl: mid shelf | 318 µs | 500.49 Hz |
| RIAA vinyl: treble | 75 µs | 2122.1 Hz |
| CD pre-emphasis (shelf start) | 50 µs | 3183.1 Hz |
| CD pre-emphasis (shelf end) | 15 µs | 10610 Hz |
Equalisation curves for broadcast, vinyl and tape are specified as time constants; each corresponds to a first-order corner at f = 1 / (2πτ).
How it works
A first-order RC network is fully described by its time constant τ. Emphasis and de-emphasis curves in broadcasting, vinyl and tape are therefore specified in microseconds rather than hertz.
Formulas
- f = 1 / (2π · τ)
- τ = R · C
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