Tone control is a type of equalization used to make specific pitches or " frequencies" in an audio

signal In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The '' IEEE Transactions on Signal Processing' ...

softer or louder. It allows a listener to adjust the tone of the sound produced by an

audio system Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording te ...

to their liking, for example to compensate for inadequate bass response of loudspeakers or earphones, tonal qualities of the room, or hearing impairment. A tone control circuit is an electronic circuit that consists of a network of filters which modify the signal before it is fed to

speakers Speaker may refer to: Society and politics * Speaker (politics), the presiding officer in a legislative assembly * Public speaker, one who gives a speech or lecture * A person producing speech: the producer of a given utterance, especially: ** I ...

, headphones or recording devices by way of an amplifier. Tone controls are found on many sound systems: radios, portable music players, boomboxes,

public address system A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...

s, and musical instrument amplifiers.

Uses

Tone control allows listeners to adjust sound to their liking. It also enables them to compensate for recording deficiencies, hearing impairments, room acoustics or shortcomings with playback equipment. For example, older people with hearing problems may want to increase the loudness of high pitch sounds they have difficulty hearing. Tone control is also used to adjust an audio signal during recording. For instance, if the acoustics of the recording site cause it to absorb some frequencies more than others, tone control can be used to amplify or "boost" the frequencies the room dampens.

Types

In their most basic form, tone control circuits

attenuate In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at vari ...

the high or low frequencies of the signal. This is called treble or bass "cut". The simplest tone control circuits are passive circuits which utilize only resistors and capacitors or

inductors An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a c ...

. They rely on the property of

capacitive reactance In electrical circuits, reactance is the opposition presented to alternating current by inductance or capacitance. Greater reactance gives smaller current for the same applied voltage. Reactance is similar to resistance in this respect, but does ...

or inductive reactance to inhibit or enhance an AC signal, in a frequency-dependent manner. Active tone controls may also amplify or "boost" certain frequencies. More elaborate tone control circuits can boost or attenuate the middle range of frequencies. The simplest tone control is a single knob that when turned in one direction enhances treble frequencies and the other direction enhances bass frequencies. This was the first type of tone control, typically found on radios and

record player A phonograph, in its later forms also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or since the 1940s called a record player, or more recently a turntable, is a device for the mechanical and analogu ...

s from the 1930s to the 1970s.

Graphic equalizer Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer. Most hi-fi eq ...

s used for tone control provide independent elevation or attenuation of individual bands of frequencies. Wide frequency range graphic equalizers of high resolution can provide elevation or attenuation in 1/3 octave bands spanning from approximately 30 Hz to 18 kHz.

Parametric equalizer Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer. Most hi-fi eq ...

s can control not only the amount of boost and cut but also the specific frequency at which the boost and cut takes place and the range of frequencies (

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

) affected. Elaborate circuits may also use amplifiers. The most modern analog units use operational amplifiers, resistors and capacitors, abandoning inductors because of their size and sensitivity to ubiquitous electromagnetic interference. Historically, tone control was achieved via

analog electronics Analogue electronics ( en-US, analog electronics) are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two levels. The term "analogue" describes the proportional relat ...

, and most tone control circuits produced today still use the analog process. Nonetheless, digital approaches are increasingly being implemented through the use of digital signal processing.

External links

{{Commonscat, Tone control
The James-Baxandall Passive Tone-Control NetworkNegative-Feedback Tone Control - Independent Variation of Bass and Treble Without Switches by P. J. Baxandall -pdfTone control for DJs
NB. The above mentioned file should now be downloaded fro

Also, an article referenced by it entitled "Simple Tone Control Circuit: Bass and Treble, Cut and Lift, by E.J.James" may be downloaded from there as well.

Analog circuits Tone, EQ and filter

Uses

Types

See also

External links