Conversion - time constant and cut-off frequency RIAA frequency response calculator upper and lower corner frequency RC pad filter emphasis Pre-Emphasis De-Emphasis preemphasis deemphasis - sengpielaudio
 
Deutsche Version UK-flag s/w - sengpielaudio D-flag - sengpielaudio
 
Frequency response and equalization (EQ filter) ●
 
Preemphasis and deemphasis - Frequency and angular frequency
 
Conversion: time constant τ to cut-off frequency  fc and
cut-off frequency (corner frequency) fc to time constant τ
 
cut-off frequency = corner frequency = break frequency

 
Time constant  µs   |   Cut-off frequency  Hz 
   |   
       |       
   |   
 Cut-off frequency  Hz   |  Time constant  µs 
   |   
 
Fill 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: Conversion: cutoff frequency - sengpielaudio

Time constant: Conversion: time constant - sengpielaudio

Conditional equations:
Cut-off frequency fc in Hz = 159155 / τ in µs
Time constant τ in µs = 159155 / fc in Hz

PCM Timeconstants

The possible pre-emphasis/de-emphasis of a PCM recording for DAT or CD (15/50 s EIAJ DAT/CD).

Cut-off frequency: Umrechnung: Zeitkonstante und Übergangsfrequenz - sengpielaudio

Time constant: Umrechnung: Zeitkonstante und Übergangsfrequenz - sengpielaudio

Conditional equations:
Cut-off frequency fc in Hz = 159155 / τ in µs
Time constant τ in µs = 159155 / fc in Hz

Aha!
 
At the cut-off frequency fc of a drop, the voltage V is always fallen to the value of 1/√2 and the voltage level is damped to 20 × log(1/√2) = (−)3,0103 dB.
 

Time constant and cut-off frequency

AME - Ampex Master Equalization Curve
Pre-Emphasis and De-Emphasis or preemphasis and deemphasis

There was also an "Ampex Master Equalization" around the year 1958, called AME. It was based on modifying the NAB response with an auditory (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; see the AME curve:

http://home.comcast.net/~mrltapes/pubame.pdf
http://www.richardhess.com/tape/ame_equalizer_20040412.pdf

In USA FM radio has a time constant of 75 µs, but also in Korea, Taiwan, Thailand, AFN worldwide and the rest of America.
In Europe FM radio has a time constant of 50 µs,
but also in Africa, Asia (without Korea, Taiwan, Thailand), Pacific.

Record RIAA cutting equalization
 
Record RIAA cutting equalization

Conversion
 
To use the calculator, simply enter a value.
The calculator works in both directions of the
sign.

 
Cut-off frequency fc 
Hz
 ↔  Time constant τ  
µs
Corner frequency and time constant - sengpielaudio   Time constant and corner frequency - sengpielaudio
1 microsecond = 10−6 second = 0.000001 second

Time constant τ = R × C            R = τ / C            C = τ / R

Time constant in seconds = Resistance in ohms × Capacitance in Farad

Please enter two values, the third value will be calculated.

 Time constant τ  microseconds  Time Constant R C
Resistance R  ohms
Capacitance C  microfarad
Corner angular frequency ωc = Angular frequency ωc
The corner angular frequency ωc is developed from the corner frequency fc:
ωc = 2 π × fc


Corner frequency fc = Cut-off frequency fc

For systems that correspond to a differential equation of first grades the cutoff point is the intersection of the horizontal asymptote with the asymptote of the falling branch of the Bode diagram. At this point, the level is −3 dB and the phase shift is 45. This means that the amplitude drop of the output value reached 30% of the input size. At the same time the time constant τ of such system is: τ = 1 / ωc = 1 / 2 π × fc

Cut-off frequency to corner angular frequency and vice versa
 
To use the calculator, simply enter a value.
The calculator works in both directions of the
sign.

rad = radiant
Cut-off frequency fc 
Hz
 ↔  Corner angular frequency ωc 
rad/s
Übergangsfrequenz und Zeitkonstante - sengpielaudio   Zeitkonstante und Eckfrequenz - sengpielaudio
 
Conversion of dB/octave to dB/decade
dB/oct to dB/dec

The increase of 20 dB per decade is equivalent to the increase of 6 dB per octave

  6 dB/octave = 20 dB/decade
12 dB/octave = 40 dB/decade
18 dB/octave = 60 dB/decade
24 dB/octave = 80 dB/decade
20/6.0206 = 3.3219
There are 3.322 octaves in 1 decade,
so 1 dB/decade = 3.322 × dB/octave.
 
To use the calculator, simply enter a value.
The calculator works in both directions of the
sign.

 
dB/octave 
 ↔  dB/decade 
acoustics   physics
 
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