Most audio tone controls affect midband gain, and !bey often create booming or hissing sounds when activated. You can avoid tbese problems by using a dual Wien-bridge filter to provide independent control of tbe treble and bass frequencies. Experiments witb equalizers indicate that tbe optimum center frequencies are about 100 Hz and 8 kHz.
Using the relation/= (21fRC)-1, set the Fig. 1 values accordingly: 100Hz: R1 = 15 KO; C1 0.1 p,F 8kHz: R2 = 16 KO; C2 1.3 nF R3 and C3 provide stability. You obtain a Â±9 dB variation of treble and bass by adjusting potentiometers R4 and R5, respectively. The filter"s frequency response is shown in Fig. 2.