IC_PREAMPLIFIER_TONE_CONTROL

Published:2009/7/8 3:12:00 Author:May | From:SeekIC

The circuit is a form of the so-called Americanized version of the Baxandall negative-feedback tone control. At very low frequencies, the reactance of the capacitor is large enough that they might be considered open circuits, and the gain is controlled by the bass potentiometer. At low to middle frequencies, the reactance of the 0.03-μF capacitors decreases at the rate of 6 dB/octave, and is in parallel with the 200-KΩ potentiometer; so the effective impedance is reduced correspondingly, thereby reducing the gain. This process continues until the 10-KΩ resistors, which are in series with the bass pot, become dominant and the gain levels off at unity. The action of treble circuit is smaller and becomes effective when the reactance of the 0.003- μF capacitors becomes minimal. This complete tone control is in the negative feedback loop of the TL080. Figure B shows the bass and treble tone control response.



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