scratch and rumble filter - audio extremes filter

audio extremes filter The purpose of this filter is to at- tenuate very low and very high audio frequencies as signals in these fre- quency ranges generally do more harm than good for the total audio signal. Another way of considering this circuit is to see it as a very wide band-pass filter for the band contain- ingthemostimportantpartofthe Ton Toon audio spectrum. The layout is quite simple as it con- 15 V VAn II 1,.13 330n , R2 C8 11.8 H 3 dB C3 I C4 I I I I 330n 330n 5 sists of two filters in series, a Iow- reject followed by a high-reject. Each filter consists of a pair of cascaded second-order filter stages to achieve a very steep characteristic of 24 dB/octave. The cut-off frequencies are at 11.8 Hz and 10.7 kHz with the component values given here. The suitability of these points depends on the application and it is not at all dif- ficult to change them. The 11.8 Hz can be increased by reducing the value of capacitors C1 . . . C4, or it can be lowered by increasing the cap...