Time constant and cutoff frequency corner calculator RC tau and f RIAA NAB CCIR DIN FM conversion cut-off cut off EQ emphasis preemphasis deemphasis

time constant tau RC cut-off cutoff cut off frequency corner frequency response Hz hertz EQ filter calculator calculation calculate calcating converter convert Compute translate acoustics studio technique techniques audio video level levels resistor resistanceaudio value values unit units micro seconds equalizer ratio corner frequency conversion engine RIAA AES DIN PCM FM AM MC NAB digital reverse emphasis preemphasis deemphasis equalization high pass low pass filter Sengpiel Berlin sengpielaudio

Deutsche Version

• Frequency response and equalization EQ •

Preemphasis and deemphasis

Conversion: time constant τ → cut-off frequency f_c and
cut-off frequency (corner frequency) f_c→ time constant τ

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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 f_c 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 f_c in Hz = 159155 / τ in µs
Time constant τ in µs = 159155 / f_c in Hz

PCM Timeconstants

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.

At the cut-off frequency f_c the voltage is always damped to the value of 1/√2
and the voltage level is damped to 20 · log(1/√2) = (−)3,0103 dB.

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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