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

audio signal An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals or a series of binary numbers for Digital signal (signal processing), digital signals. Audio signals have frequencies i ...

softer or louder. It allows a listener to adjust the tone of the sound produced by an audio system 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 An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or Conductive trace, traces through which electric current can flow. It is a t ...

that consists of a network of

filters Filtration is a physical process that separates solid matter and fluid from a mixture. Filter, filtering, filters or filtration may also refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Fil ...

which modify the signal before it is fed to

speakers Speaker most commonly refers to: * Speaker, a person who produces speech * Loudspeaker, a device that produces sound ** Computer speakers Speaker, Speakers, or The Speaker may also refer to: Arts and entertainment * Speaker (song), "Speaker" ( ...

headphones Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an ...

or recording devices by way of an

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power su ...

. Tone controls are found on many sound systems:

radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...

s, portable music players, boomboxes, public address systems, 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 Acoustics is a branch of physics that deals with the study of mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician ...

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 the high or low frequencies of the signal. This is called treble or

bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Wood * Bass or basswood, the wood of the tilia americana tree Music * Bass (sound), describing low-frequency sound or one of several instruments in th ...

"cut". The simplest tone control circuits are passive circuits which utilize only resistors and

capacitors In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...

or inductors. They rely on the property of

capacitive reactance In electrical circuits, reactance is the opposition presented to alternating current by inductance and capacitance. It's measured in Ω (Ohms). Along with resistance, it is one of two elements of impedance; however, while both elements involve ...

inductive reactance In electrical circuits, reactance is the opposition presented to alternating current by inductance and capacitance. It's measured in Ω (Ohms). Along with resistance, it is one of two elements of impedance; however, while both elements involve ...

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, later called a gramophone, and since the 1940s a record player, or more recently a turntable, is a device for the mechanical and analogue reproduction of sound. The sound vibration Waveform, waveforms are recorded as correspond ...

s from the 1930s to the 1970s. Graphic equalizers 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 equalizers 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) 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, and most tone control circuits produced today still use the analog process. Nonetheless,

digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

approaches are increasingly being implemented through the use of

digital signal processing Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are a ...

External links

{{Commonscat, Tone control
Simple Tone Control Circuit: Bass and Treble, Cut and Lift, by E.J.James

Negative-Feedback Tone Control - Independent Variation of Bass and Treble Without Switches by P. J. Baxandall -pdfTone control for DJs
Analog circuits Tone, EQ and filter

Uses

Types

See also

External links