RC pad corner frequency cutoff calculation calculate filter time constant RC

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• R-C Filter and Cutoff frequency •

Calculation: R and C → Corner frequency f_c
R × C → Time constant τ

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	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.
	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.

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.

Short conditional equations:
f_c in Hz = 159155 / τ in µs
τ in µs = 159155 / f_c 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 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.

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