Tone control

The amplitude versus frequency characteristics of the high-fidelity sound system can be adjusted by means of a tone control or controls. There are various types of tone controls; some are very simple whereas others are sophisticated.In the simplest form of it, a tone control consists of a single knob or slide device. The counterclockwise, left-hand settings of this control result in strong bass (low- frequency) and weak treble (high-frequency) audio output. The clockwise, upper, or right hand settings result in the weak bass and strong treble. When the control is set to mid position, the audio response of amplifier is more or less flat; which means, the bass, midrange, and treble are in approximately the same proportions as in the received signal.Figure given to us is a simple example of how a single-knob tone control may be incorporated into output of an audio amplifier. The amplifier is itself designed so that the treble output is exaggerated. The potentiometer attenuates treble to a variable extent, so when tone control is at midposition, the frequency versus amplitude audio output curve is flat relatively.

A somewhat more versatile tone control has two capacitors and two potentiometers, as shown in the figure given below. One combination is in series, and other is in parallel. The series connected resistance capacitance (RC) circuit is connected in parallel with audio output; this control attenuates the treble to a variable extent. The parallel RC circuit is in the series with audio path; it attenuates bass to a variable extent. The 2 potentiometers are adjusted separately, although there is some interaction between their effects.

The most sophisticated type of tone control allows independent adjustment of several different frequency ranges within range of human hearing. This device, the graphic equalizer, has several slide potentiometers. By moving these controls to several positions, many different audio response curves are obtained.