| Deutsche Version |
• Frequency response and equalization EQ •
Conversion: time constant τ → cut-off frequency fc andFill in the box above and click at the appropriate 'calculate' below.
The Greek letter for the time constant is tau = τ and 1 microsecond is 10-6 seconds.
| Time constant τ in µs |
Cut-off frequency fc in Hz |
Equalization emphasis |
| 7958 | 20 | • (RIAA) |
| 3183 | 50 | • RIAA, NAB |
| 1592 | 100 | |
| 318 | 500 | • RIAA |
| 200 | 796 | |
| 140 | 1137 | |
| 120 | 1326 | MC |
| 100 | 1592 | |
| 90 | 1768 | MC |
| 75 | 2122 | • RIAA, FM |
| 70 | 2274 | |
| 50 | 3183 | NAB, PCM, FM |
| 35 | 4547 | DIN |
| 25 | 6366 | |
| 17,5 | 9095 | AES |
| 15 | 10610 | PCM |
| 12,5 | 12732 | |
| 10 | 15915 |
Cut-off frequency: ![]()
Time constant: ![]()
Conditional equations:
Cut-off frequency fc in Hz = 159155 / τ in µs
Time constant τ in µs = 159155 / fc in Hz

In USA FM radio has a time constant of 75 µs, but also in Korea,
Taiwan, Thailand, AFN worldwide and the rest of Amerika.
In Europe FM radio has a time constant of 50 µs,
but also in Afrika, Asia (without Korea, Taiwan, Thailand), Pacific.
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There was also an "Ampex Master Equalization" around the year 1958, called AME.
It was based on modifying the NAB response with a hearing curve, which resulted
in a recorded flux that had a "hump" (re the NAB EQ) from about +3 dB at 630 Hz
to +8 dB at 2 kHz, back to +3 dB at 5 kHz, and down to −12 dB at 16 kHz.
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