RC pad corner frequency cutoff calculation calculate filter time constant RC voltage power calculator - sengpielaudio Checker
 
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• RC Filter and Cutoff  frequency

Calculation: R and CCorner frequency fc
R × C Time constant τ

CR pad Bass cut - High pass - CR filter:
 
This CR filter rolls off the frequency response at 6 dB per octave below the cutoff frequency.
The same calculation applies to both filters. The calculator assumes a low source impedance, which usually is small enough that it does not change the cutoff frequency.
RC pad

Treble cut -
Low pass - RC filter:
 
This RC filter rolls off the frequency response at a ratio of 6 dB per octave above the cutoff frequency (corner frequency). The same calculation applies to both filters.

Aha!
At the cut-off frequency fc of a drop the voltage V is always fallen to the value
1/√2 = 0.7071 ≡ 70.71 % and the voltage level is damped by
20 · log (1/√2) = (−)3.0103 dB.


At the cut-off frequency the less interesting power P is always fallen to
1/2 = 0.5 ≡ 50 % and the power level is damped by
10 · log (1/2) = (−)3.0103 dB − that is the same dB value.

This is often confusing. 0.7071 × 0.7071 is 0.5 and P = UČ/R; P~ UČ.

RC filter: resistor R and capacitor C
Searched: corner frequency fc and timeconstant τ

Enter the value for resistor and capacitor, then press "calculate".

Resistor
(Ω)




Capacitor
(μF)




Cutoff frequency
(Hz)




Time constant
(s)




Formula fc - sengpielaudio

Formula tc - sengpielaudio

Short conditional equations:
fc in Hz = 159155 /
τ in µs
τ in µs = 159155 / fc in Hz

The Greek letter for time constant is tau = τ, and 1 microsecond is 10-6 seconds.
The cutoff frequency is also called corner frequency.
More formulas you find here "Zeitkonstante und Übergangsfrequenz"

Frequency response and equalization - Conversion: time constant to cut-off frequency

For a sound designer (aural architect) it is strange to cut off
high frequencies with a low-pass filter and to cut off
bass frequencies with a high-pass filter. Filters change the
sound in special frequency regions.
Filters changing the bass frequencies are application-oriented
called low cut filter, bass cut filter, or rumble filter.
Filters changing the treble frequencies are better called treble
cut filter, high cut filter, or noise filter.
Aha!

Notice: A low-pass lets pass voltages / amplitudes with low frequencies.
A high-pass lets pass voltages / amplitudes with high frequencies.
These words do not help the practitioners in sound mixing, because it is
unimportant, what will theoretically pass through, it is a lot more interesting,
what frequencies are practically audibly filtered out (cut off).

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