Deutsche Version

	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 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 = U²/R; P~ U².

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

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

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 (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.

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