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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Audio equalizer</span></span>

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</style><div role="note" class="hatnote navigation-not-searchable">This article is about frequency-dependent processing of audio signals. For other uses, see <a href="Equalization_(disambiguation)" class="mw-redirect mw-disambig" title="Equalization (disambiguation)">Equalization (disambiguation)</a>.</div>

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<p><b>Equalization</b>, or simply <b>EQ</b>, in <a href="Sound_recording_and_reproduction" title="Sound recording and reproduction">sound recording and reproduction</a> is the process of adjusting the volume of different frequency bands within an <a href="Audio_signal" title="Audio signal">audio signal</a>. The circuit or equipment used to achieve this is called an <b>equalizer</b>.<sup id="cite_ref-Strong_2005_25_1-0" class="reference"><a href="#cite_note-Strong_2005_25-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-The_Audio_Dictionary_2-0" class="reference"><a href="#cite_note-The_Audio_Dictionary-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Most <a href="Hi-fi" class="mw-redirect" title="Hi-fi">hi-fi</a> equipment uses relatively simple <a href="Electronic_filter" title="Electronic filter">filters</a> to make <a href="Bass_(sound)" title="Bass (sound)">bass</a> and <a href="Treble_(sound)" title="Treble (sound)">treble</a> adjustments. Graphic and parametric equalizers have much more flexibility in tailoring the frequency content of an audio signal. Broadcast and recording studios use sophisticated equalizers capable of much more detailed adjustments, such as eliminating unwanted sounds or making certain instruments or voices more prominent. Because of this ability, they can be aptly described as "frequency-specific volume knobs."<sup id="cite_ref-Hodgson_3-0" class="reference"><a href="#cite_note-Hodgson-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 73">: 73 </span></sup>

</p><p>Equalizers are used in <a href="Recording_studio" title="Recording studio">recording and radio studios</a>, <a href="Production_control_room" title="Production control room">production control rooms</a>, and live <a href="Sound_reinforcement" class="mw-redirect" title="Sound reinforcement">sound reinforcement</a> and in <a href="Instrument_amplifier" title="Instrument amplifier">instrument amplifiers</a>, such as <a href="Guitar_amplifier" title="Guitar amplifier">guitar amplifiers</a>, to correct or adjust the response of <a href="Microphone" title="Microphone">microphones</a>, <a href="Pickup_(music_technology)" title="Pickup (music technology)">instrument pickups</a>, <a href="Loudspeakers" class="mw-redirect" title="Loudspeakers">loudspeakers</a>, and <a href="Room_acoustics" title="Room acoustics">hall acoustics</a>.<sup id="cite_ref-The_Audio_Dictionary_2-1" class="reference"><a href="#cite_note-The_Audio_Dictionary-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Equalization may also be used to eliminate or reduce unwanted sounds (e.g., low-frequency hum coming from a guitar amplifier), make certain instruments or voices more (or less) prominent, enhance particular aspects of an instrument's tone, or combat <a href="Audio_feedback" title="Audio feedback">feedback</a> (howling) in a <a href="Public_address" class="mw-redirect" title="Public address">public address</a> system.<sup id="cite_ref-Strong_2005_25_1-1" class="reference"><a href="#cite_note-Strong_2005_25-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-The_Audio_Dictionary_2-2" class="reference"><a href="#cite_note-The_Audio_Dictionary-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> Equalizers are also used in <a href="Music_production" class="mw-redirect" title="Music production">music production</a> to adjust the <a href="Timbre" title="Timbre">timbre</a> of individual instruments and voices by adjusting their frequency content and to fit individual instruments within the overall frequency spectrum of the <a href="Audio_mixing_(recorded_music)" title="Audio mixing (recorded music)">mix</a>.<sup id="cite_ref-Hodgson_3-1" class="reference"><a href="#cite_note-Hodgson-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 73–74">: 73–74 </span></sup>

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<div class="mw-heading mw-heading2"><h2 id="Terminology">Terminology</h2></div>

<p>The concept of equalization was first applied in correcting the <a href="Frequency_response" title="Frequency response">frequency response</a> of <a href="Equalization_(communications)#Analog_telecommunications" title="Equalization (communications)">telephone lines</a> using <a href="Passive_filter" class="mw-redirect" title="Passive filter">passive filters</a>; this was prior to the invention of electronic amplification. Initially, equalization was used to compensate for the uneven frequency response of an electric system by applying a filter having the opposite response, thus restoring the fidelity of the <a href="Transmission_(telecommunications)" class="mw-redirect" title="Transmission (telecommunications)">transmission</a>. A plot of the system's net frequency response would be a flat line, as its response at any frequency would be equal to its response at any other frequency. Hence the term <i>equalization</i>.

</p><p>Later the concept was applied in <a href="Audio_engineering" class="mw-redirect" title="Audio engineering">audio engineering</a> to adjust the frequency response in recording, reproduction, and live <a href="Sound_reinforcement_system" title="Sound reinforcement system">sound reinforcement systems</a>. Sound engineers correct the frequency response of a sound system so that the frequency balance of the music as heard through speakers better matches the original performance picked up by a <a href="Microphone" title="Microphone">microphone</a>. <a href="Amplifier" title="Amplifier">Audio amplifiers</a> have long had filters or controls to modify their frequency response. These are most often in the form of variable <a href="Bass_(sound)" title="Bass (sound)">bass</a> and <a href="Treble_(sound)" title="Treble (sound)">treble</a> controls, and switches to apply low-cut or high-cut filters for elimination of low-frequency <i>rumble</i> and high-frequency <i>hiss</i> respectively.

</p><p><a href="#Graphic_equalizer">Graphic equalizers</a> and other equipment developed for improving fidelity have since been used by <a href="Recording_engineer" class="mw-redirect" title="Recording engineer">recording engineers</a> to modify frequency responses for aesthetic reasons. Hence in the field of audio electronics the term <i>equalization</i> is now broadly used to describe the application of such filters regardless of intent. This broad definition, therefore, includes all <a href="Linear_filter" title="Linear filter">linear filters</a> at the disposal of a listener or engineer.

</p><p>A <b>British EQ</b> or <b>British style equalizer</b> is one with similar properties to those on <a href="Mixing_console" title="Mixing console">mixing consoles</a> made in the UK by companies such as Amek, <a href="Neve_Electronics" title="Neve Electronics">Neve</a> and <a href="Soundcraft" title="Soundcraft">Soundcraft</a><sup id="cite_ref-Glossary_4-0" class="reference"><a href="#cite_note-Glossary-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> from the 1950s through to the 1970s. Later on, as other manufacturers started to market their products, these British companies began touting their equalizers as being a cut above the rest. Today, many non-British companies such as <a href="Behringer" title="Behringer">Behringer</a> and <a href="Mackie_(company)" title="Mackie (company)">Mackie</a><sup id="cite_ref-Perkins_5-0" class="reference"><a href="#cite_note-Perkins-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> advertise British EQ on their equipment. A British style EQ seeks to replicate the qualities of the expensive British mixing consoles.

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<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>

<p>Filtering audio frequencies dates back at least to <a href="Acoustic_telegraphy" title="Acoustic telegraphy">acoustic telegraphy</a><sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> and <a href="Multiplexing" title="Multiplexing">multiplexing</a> in general. Audio electronic equipment evolved to incorporate filtering elements as consoles in radio stations began to be used for recording as much as broadcast. Early filters included basic bass and treble controls featuring fixed frequency centers, and fixed levels of cut or boost. These filters worked over broad frequency ranges. Variable equalization in audio reproduction was first used by <a href="John_Volkman" class="mw-redirect" title="John Volkman">John Volkman</a> working at <a href="RCA" title="RCA">RCA</a> in the 1920s. That system was used to equalize a motion picture theater sound playback system.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-note122_8-0" class="reference"><a href="#cite_note-note122-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p><p>The Langevin EQ-251-A, designed by Art Davis, was the first equalizer to use slide controls. It featured two passive equalization sections, a bass shelving filter, and a pass band filter. Each filter had switchable frequencies and used a 15-position slide switch to adjust cut or boost. The passive design required 14 dB of make-up gain.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> Born in Salt Lake City, Davis worked in Southern California most of his life for a series of companies including Cinema Engineering (from 1938), Langevin, Electrodyne, Cetec and Altec.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> The first true graphic equalizer was the type 7080, an active tube device developed in the 1950s by Davis's Cinema Engineering company. It featured six bands, each 1.5 octaves wide, with a boost or cut range of 8 dB. It used a slide switch to adjust each band in 1 dB steps. Three summing amps smoothly restored the gain lost in the filter circuits. Davis followed this in 1961 with the Langevin EQ-252-A having seven sliders, then reworked it for <a href="Altec_Lansing" title="Altec Lansing">Altec Lansing</a> to create the Model 9062A EQ which sold well into the 1970s.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> In 1967 Davis developed the first 1/3 octave variable notch filter set, the Altec-Lansing "Acousta-Voice" system.<sup id="cite_ref-note122_8-1" class="reference"><a href="#cite_note-note122-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p><p>In 1966, Burgess Macneal and <a href="George_Massenburg" title="George Massenburg">George Massenburg</a> envisioned a tunable EQ for a new recording console. Bob Meushaw, a friend of Massenburg, built the equalizer. According to Massenburg, "Four people could possibly lay claim to the modern concept: Bob Meushaw, Burgess Macneal, Daniel Flickinger, and myself… Our (Bob’s, Burgess’ and my) sweep-tunable EQ was borne, more or less, out of an idea that Burgess and I had around 1966 or 1967 for an EQ… three controls adjusting, independently, the parameters for each of three bands for a recording console… I wrote and delivered the AES paper on Parametrics at the Los Angeles show in 1972… It’s the first mention of 'Parametric' associated with sweep-tunable EQ."<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup>

</p><p><a href="Daniel_Flickinger" title="Daniel Flickinger">Daniel N. Flickinger</a> introduced the first parametric equalizer in early 1971. His design leveraged a high-performance op-amp of his own design, the 535 series<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> to achieve filtering circuits that were before impossible. Flickinger's patent from early in 1971<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> showed the circuit topology that would come to dominate audio equalization until the present day, as well as the theoretical underpinnings of the elegant circuit. Instead of slide potentiometers working on individual bands of frequency, or rotary switches, Flickinger's circuit allowed arbitrary selection of frequency and cut or boost level in three overlapping bands over the entire audio spectrum. Six knobs on his early EQs would control these sweepable filters. Up to six switches were incorporated to select shelving on the high and low bands, and bypassing for any unused band for the purest signal path.

</p><p>Similar designs appeared soon thereafter from <a href="George_Massenburg" title="George Massenburg">George Massenburg</a> (in 1972) and Burgess McNeal from ITI corp. In May 1972 Massenburg used the term <i>parametric equalization</i> in a paper presented at the 42nd convention of the <a href="Audio_Engineering_Society" title="Audio Engineering Society">Audio Engineering Society</a>.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> Most channel equalization on <a href="Mixing_console" title="Mixing console">mixing consoles</a> made from 1971 to the present day rely upon the designs of Flickinger, Massenburg and McNeal in either semi or fully-parametric topology. In the late 1990s and in the 2000s, parametric equalizers became increasingly available as <a href="Digital_signal_processing" title="Digital signal processing">digital signal processing</a> (DSP) equipment, usually in the form of plug-ins for various digital audio workstations. Standalone <a href="Outboard_gear" title="Outboard gear">outboard gear</a> versions of DSP parametric equalizers were also quickly introduced after the software versions.

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<div class="mw-heading mw-heading2"><h2 id="Filter_types">Filter types</h2></div>

<p>Although the range of equalization functions is governed by the theory of <a href="Linear_filter" title="Linear filter">linear filters</a>, the adjustment of those functions and the flexibility with which they can be adjusted varies according to the topology of the circuitry and controls presented to the user.

</p><p>Shelving controls are usually simple first-order filter functions that alter the relative gains between frequencies much higher and much lower than the <a href="Cutoff_frequency" title="Cutoff frequency">cutoff frequencies</a>. A <i>low shelf</i>, such as the bass control on most <a href="Hi-fi" class="mw-redirect" title="Hi-fi">hi-fi</a> equipment, is adjusted to affect the gain of lower frequencies while having no effect well above its cutoff frequency. A <i>high shelf</i>, such as a treble control, adjusts the gain of higher frequencies only. These are broad adjustments designed more to increase the listener's satisfaction than to provide actual equalization in the strict sense of the term.

</p><p>A parametric equalizer has one or more sections each of which implements a second-order filter function. This involves three adjustments: selection of the center frequency (in <a href="Hertz" title="Hertz">Hz</a>), adjustment of the <a href="Q_factor" title="Q factor">Q</a> which determines the sharpness of the <a href="Bandwidth_(signal_processing)" title="Bandwidth (signal processing)">bandwidth</a>, and the level or gain control which determines how much those frequencies are boosted or cut relative to frequencies much above or below the center frequency selected. In a <i>semi-parametric</i> equalizer the bandwidth is preset by the designer. In a <i>quasi-parametric</i> equalizer, the user is given limited switchable options for bandwidth.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup>

</p><p>A graphic equalizer also implements second-order filter functions in a more user-friendly manner but with somewhat less flexibility. This equipment is based on a <a href="Filter_bank" title="Filter bank">bank of filters</a> covering the audio spectrum in up to 31 <a href="Frequency_band" class="mw-redirect" title="Frequency band">frequency bands</a>. Each second-order filter has a fixed center frequency and <a href="Q_factor" title="Q factor">Q factor</a>, but an adjustable level. The user can raise or lower each slider in order to visually approximate a <i>graph</i> of the intended frequency response.

</p><p><i>Equalization</i> in the context of audio reproduction is not used strictly to compensate for the deficiency of equipment and transmission channels. A <a href="High-pass_filter" title="High-pass filter">high-pass filter</a> modifies a signal by eliminating only lower frequencies. An example of this is a low-cut or <a href="Rumble_(noise)#Rumble_filters" title="Rumble (noise)">rumble filter</a>, which is used to remove <a href="Infrasonic" class="mw-redirect" title="Infrasonic">infrasonic</a> energy from a program that may consume undue amplifier power and cause excessive diaphragm excursions in (or even damage to) loudspeakers. A <a href="Low-pass_filter" title="Low-pass filter">low-pass filter</a> only modifies the audio signal by removing high frequencies. An example of this is a high-cut or <a href="Tape_hiss" title="Tape hiss">hiss filter</a>, which is used to remove annoying white noise at the expense of the crispness of the program material.

</p><p>A first-order low-pass or high-pass filter has a standard response curve that reduces the unwanted frequencies well above or below the cutoff frequency with a slope of 6 dB per octave.<sup id="cite_ref-6dB_17-0" class="reference"><a href="#cite_note-6dB-17"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> A second-order filter will reduce those frequencies with a slope of 12 dB per octave and moreover may be designed with a higher Q or finite <a href="Pole%E2%80%93zero_plot" title="Pole–zero plot">zeros</a> in order to effect an even steeper response around the <a href="Cutoff_frequency" title="Cutoff frequency">cutoff frequency</a>. For instance, a second-order <i>low-pass notch</i> filter section only reduces (rather than eliminates) very high frequencies, but has a steep response falling to zero at a specific frequency (the so-called <i>notch frequency</i>). Such a filter might be ideal, for instance, in completely removing the 19 kHz <a href="Subcarrier#FM_stereo" title="Subcarrier">FM stereo subcarrier</a> <a href="Pilot_signal" title="Pilot signal">pilot signal</a> while helping to cut even higher frequency subcarrier components remaining from the stereo <a href="FM_broadcasting#FM_stereo" title="FM broadcasting">demultiplexer</a>.

</p><p>In addition to adjusting the relative amplitude of frequency bands, an audio equalizer usually alters the relative <a href="Phase_(waves)" title="Phase (waves)">phases</a> of those frequencies. While the human ear is not as sensitive to the phase of audio frequencies,<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> music professionals may favor certain equalizers because of how they affect the timbre of the musical content by way of audible phase artifacts.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup>

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<div class="mw-heading mw-heading3"><h3 id="High-pass_and_low-pass_filters">High-pass and low-pass filters</h3></div>

<p>A <a href="High-pass_filter" title="High-pass filter">high-pass filter</a> is a filter, an electronic circuit or device, that passes higher <a href="Audio_frequency" title="Audio frequency">frequencies</a> well but <a href="Attenuation" title="Attenuation">attenuates</a> lower-frequency components. A <a href="Low-pass_filter" title="Low-pass filter">low-pass filter</a> passes low-frequency components of signals while attenuating higher frequencies. In audio applications these high-pass and low-pass filters are frequently termed <i>low cut</i> and <i>high cut</i>, respectively, to emphasize their effect on the original signal. For instance, sometimes audio equipment will include a switch labeled <i>high cut</i> or described as a <i>hiss filter</i> (hiss being <a href="Colors_of_noise" title="Colors of noise">high-frequency noise</a>). In the <a href="Phonograph" title="Phonograph">phonograph</a> era, many stereos would include a switch to introduce a high-pass (low cut) filter, often called a <i>rumble filter</i>, to eliminate <a href="Infrasonic" class="mw-redirect" title="Infrasonic">infrasonic</a> frequencies. High and low-pass filters are used in <a href="Audio_crossover" title="Audio crossover">audio crossovers</a> to direct energy to the <a href="Speaker_driver" class="mw-redirect" title="Speaker driver">speaker drivers</a> capable of reproducing it. For instance, a low-pass filter is used in the signal chain before a <a href="Subwoofer" title="Subwoofer">subwoofer</a> to ensure that only deep bass frequencies reach the subwoofer.

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<div class="mw-heading mw-heading3"><h3 id="Shelving_filter">Shelving filter</h3></div>

<p>While high-pass and low-pass filters are useful for removing unwanted signal above or below a set frequency, shelving filters can be used to reduce or increase signals above or below a set frequency.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> Shelving filters are used as common <a href="Tone_control" class="mw-redirect" title="Tone control">tone controls</a> (bass and treble) found in consumer audio equipment such as home stereos, and on <a href="Guitar_amplifier" title="Guitar amplifier">guitar amplifiers</a> and <a href="Bass_amplifier" title="Bass amplifier">bass amplifiers</a>. These implement a first-order response and provide an adjustable boost or cut to frequencies above or below a certain point.

</p><p>A <i>high shelf</i> or <i>treble control</i> will have a frequency response |<i>H</i>(<i>f</i>)| whose square is given by:

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<annotation encoding="application/x-tex">{\displaystyle |H(f)|^{2}={{1+(f/f_{z})^{2}} \over {1+(f/f_{p})^{2}}}}</annotation>

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</math></span><img src="./e81341c1c0688a83d0934d9445b10ff0bcafdb9a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:22.94ex; height:6.676ex;" alt="{\displaystyle |H(f)|^{2}={{1+(f/f_{z})^{2}} \over {1+(f/f_{p})^{2}}}}" loading="lazy"></span></dd></dl>

<p>where <i>f<sub>p</sub></i> and <i>f<sub>z</sub></i> are called the pole and zero frequencies, respectively. Turning down the treble control increases <i>f<sub>z</sub></i> and decreases <i>f<sub>p</sub></i> so that frequencies higher than <i>f<sub>p</sub></i> are attenuated. Turning up the treble control increases <i>f<sub>p</sub></i> and decreases <i>f<sub>z</sub></i> so that frequencies higher than <i>f<sub>z</sub></i> are boosted. Setting the treble control at the center sets <i>f<sub>z</sub></i> = <i>f<sub>p</sub></i> so that |<i>H</i>(<i>f</i>)|<sup>2</sup> = 1 and the circuit has no effect. At most, the slope of the filter response in the transition region will be 6 dB per octave.<sup id="cite_ref-6dB_17-1" class="reference"><a href="#cite_note-6dB-17"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup>

</p><p>Similarly the response of a <i>low shelf</i> or <i>bass control</i> can be represented as:

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<annotation encoding="application/x-tex">{\displaystyle |H(f)|^{2}=(f_{z}/f_{p})^{2}\;{{1+(f/f_{z})^{2}} \over {1+(f/f_{p})^{2}}}.}</annotation>

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</math></span><img src="./f5254129b2960ee7223dbd144d812eccfdafd681.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:32.597ex; height:6.676ex;" alt="{\displaystyle |H(f)|^{2}=(f_{z}/f_{p})^{2}\;{{1+(f/f_{z})^{2}} \over {1+(f/f_{p})^{2}}}.}" loading="lazy"></span></dd></dl>

<p>In this case, the inclusion of the leading factor simply indicates that the response at frequencies much higher than <i>f<sub>z</sub></i> or <i>f<sub>p</sub></i> is unity and that only bass frequencies are affected.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup>

</p><p>A high shelving control in which <i>f<sub>z</sub></i> is set to infinity, or a low shelving response in which <i>f<sub>z</sub></i> is set to zero, implements a first-order low-pass or high-pass filter, respectively. However, the usual tone controls have a more limited range, since their purpose is not to eliminate any frequencies but only to achieve a greater balance when, for instance, the treble is lacking and the sound is not crisp. Since the range of possible responses from shelving filters is so limited, some audio engineers considered shelving controls inadequate for equalization tasks. On some <a href="Bass_amp" class="mw-redirect" title="Bass amp">bass amps</a> and <a href="DI_box" class="mw-redirect" title="DI box">DI boxes</a>, the units provide both low and high shelving controls and additional equalization controls.

</p>

<div class="mw-heading mw-heading3"><h3 id="Graphic_equalizer">Graphic equalizer</h3></div>

<p>In the <b>graphic equalizer</b>, the input signal is sent to a <a href="Filter_bank" title="Filter bank">bank of filters</a>. Each filter passes the portion of the signal present in its own frequency range or <i>band</i>. The amplitude passed by each filter is adjusted using a slide control to boost or cut frequency components passed by that filter. The vertical position of each slider thus indicates the gain applied to that frequency band, so that the sliders resemble a <i>graph</i> of the equalizer's response plotted versus frequency.

</p><p>The number of frequency channels may be matched to the requirements of the intended application. A <a href="Car_audio" class="mw-redirect" title="Car audio">car audio</a> equalizer might have a total of five to ten frequency bands. An equalizer for professional <a href="Live_sound_reproduction" class="mw-redirect" title="Live sound reproduction">live sound reinforcement</a> typically has some 25 to 31 bands, for more precise control of feedback problems and equalization of <a href="Room_modes" title="Room modes">room modes</a>. Such an equalizer is called a 1/3-octave equalizer (spoken informally as "<i>third-octave</i> EQ") because the center frequencies of its filters are spaced one third of an <a href="Octave" title="Octave">octave</a> apart, three filters to an octave. Equalizers with half as many filters per octave are common where less precise control is required—this design is called a 2/3-octave equalizer.

</p>

<div class="mw-heading mw-heading3"><h3 id="Parametric_equalizer">Parametric equalizer</h3></div>

<p><b>Parametric equalizers</b> are multi-band variable equalizers that allow users to control the three primary filter parameters: <a href="Gain_(electronics)" title="Gain (electronics)">gain</a>, <a href="Center_frequency" title="Center frequency">center frequency</a> and <a href="Bandwidth_(signal_processing)" title="Bandwidth (signal processing)">bandwidth</a>. Gain allows adjustment of boost or cut produced. The center frequency controls the frequencies affected. The bandwidth (which is inversely related to <a href="Q_factor" title="Q factor">Q</a>) the range of frequencies affected. Parametric equalizers are capable of making much more precise adjustments to the sound than other equalizers and are commonly used in sound recording and <a href="Live_sound_reinforcement" class="mw-redirect" title="Live sound reinforcement">live sound reinforcement</a>.

</p><p>A variant of the parametric equalizer is the semi-parametric equalizer, a sweepable filter. It allows users to control the gain and frequency but uses a pre-set bandwidth. In some cases, semi-parametric equalizers allow the user to select between a wide and a narrow preset bandwidth.

</p>

<div class="mw-heading mw-heading2"><h2 id="Filter_functions">Filter functions</h2></div>

<p>The responses of <a href="Linear_filter" title="Linear filter">linear filters</a> are mathematically described in terms of their <a href="Transfer_function" title="Transfer function">transfer function</a> or, in layman's terms, <a href="Frequency_response" title="Frequency response">frequency response</a>. A transfer function can be decomposed as a combination of <i>first-order</i> responses and <i>second-order</i> responses (implemented as <i><a href="Biquad" class="mw-redirect" title="Biquad">biquad</a></i> sections). These can be described according to their <i><a href="Pole%E2%80%93zero_plot" title="Pole–zero plot">pole</a></i> and <i><a href="Pole%E2%80%93zero_plot" title="Pole–zero plot">zero</a></i> frequencies, which are <a href="Complex_numbers" class="mw-redirect" title="Complex numbers">complex numbers</a> in the case of second-order responses.

</p>

<div class="mw-heading mw-heading3"><h3 id="First-order_filters">First-order filters</h3></div>

<p>A first-order filter can alter the response of frequencies above and below a point. In the transition region the filter response will have a slope of up to 6 <a href="Decibel" title="Decibel">dB</a> per <a href="Octave" title="Octave">octave</a>.<sup id="cite_ref-6dB_17-2" class="reference"><a href="#cite_note-6dB-17"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> The bass and treble controls in a hi-fi system are each a first-order filter in which the balance of frequencies above and below a point are varied using a single knob. A special case of first-order filters is a first-order high-pass or low-pass filter in which the 6 dB per octave cut of low or high frequencies extends indefinitely. These are the simplest of all filters to implement individually, requiring only a capacitor and resistor.

</p>

<div class="mw-heading mw-heading3"><h3 id="Second-order_filters">Second-order filters</h3></div>

<p>Second-order filters are capable of <a href="Resonance" title="Resonance">resonance</a> (or anti-resonance) around a particular frequency. The response of a second-order filter is specified not only by its frequency but also its <a href="Q_factor" title="Q factor">Q</a>; a higher Q corresponds to a sharper response (smaller bandwidth) around a particular center frequency. For instance, the red response in the accompanying image cuts frequencies around 100 Hz with a higher Q than the blue response, which boosts frequencies around 1000 Hz. Higher Q's correspond to resonant behaviour in which the half-power or −3 dB bandwidth, <i>BW</i>, is given by:

</p>

<msub>

</mrow>

</msub>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle BW\ =\ F_{0}/Q}</annotation>

</semantics>

</math></span><img src="./b2879bcfd3809e5ed3d3a12d9e3ad246cf24aefe.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:14.009ex; height:2.843ex;" alt="{\displaystyle BW\ =\ F_{0}/Q}" loading="lazy"></span></dd></dl>

<p>where <i>F</i><sub>0</sub> is the resonant frequency of the second-order filter. <i>BW</i> is the bandwidth expressed in the same frequency unit that <i>F</i><sub>0</sub> is. Low Q filter responses (where <i>Q</i> < <style data-mw-deduplicate="TemplateStyles:r1154941027">

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</style><span class="frac"><span class="num">1</span>⁄<span class="den">2</span></span>) are not said to be resonant and the above formula for bandwidth does not apply.

</p><p>It is also possible to define the Q of a band-pass function as:

</p>

<mfrac>

<msqrt>

<msup>

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<mfrac>

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<mrow>

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<annotation encoding="application/x-tex">{\displaystyle Q\ =\ {\frac {\sqrt {2^{N}}}{2^{N}-1}}\ =\ {\frac {1}{2\sinh \left({\frac {\ln(2)}{2}}N\right)}},}</annotation>

</semantics>

</math></span><img src="./6c2aed9b030d2fe677a774c911fb6d2c59d25418.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -4.505ex; width:34.379ex; height:8.843ex;" alt="{\displaystyle Q\ =\ {\frac {\sqrt {2^{N}}}{2^{N}-1}}\ =\ {\frac {1}{2\sinh \left({\frac {\ln(2)}{2}}N\right)}},}" loading="lazy"></span></dd></dl>

<p>where <i>N</i> is the bandwidth in octaves. The reverse mapping is:

</p>

<msub>

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<mrow>

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</msqrt>

</mrow>

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<mfrac>

<mrow>

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</mrow>

<mi>arsinh</mi>

<mrow>

<mfrac>

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</mrow>

</mfrac>

</mrow>

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</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle N\ =\ 2\log _{2}\left({\frac {1}{2Q}}+{\sqrt {{\frac {1}{4Q^{2}}}+1}}\right)\ =\ {\frac {2}{\ln(2)}}\operatorname {arsinh} \left({\frac {1}{2Q}}\right).}</annotation>

</semantics>

</math></span><img src="./7c008c72b3899e67470d8d9e28b3de0ea2e8dad8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -3.338ex; width:57.997ex; height:7.676ex;" alt="{\displaystyle N\ =\ 2\log _{2}\left({\frac {1}{2Q}}+{\sqrt {{\frac {1}{4Q^{2}}}+1}}\right)\ =\ {\frac {2}{\ln(2)}}\operatorname {arsinh} \left({\frac {1}{2Q}}\right).}" loading="lazy"></span></dd></dl>

<p>A second-order filter response with <i>Q</i> of less than 1/2 can be decomposed into two first-order filter functions, a low-cut and a high-cut (or boost). Of more interest are <a href="Resonant" class="mw-redirect" title="Resonant">resonant</a> filter functions which can boost (or cut) a narrow range of frequencies. In addition to specifying the center frequency <i>F</i><sub>0</sub> and the Q, the specification of the filter's <a href="Pole%E2%80%93zero_plot" title="Pole–zero plot">zeros</a> determines how much that frequency band will be boosted (or cut). Thus a <a href="Parametric_equalizer" class="mw-redirect" title="Parametric equalizer">parametric equalizer</a> section will have three controls for its center frequency <i>F</i><sub>0</sub>, bandwidth or Q, and the amount of boost or cut usually expressed in <a href="Decibel" title="Decibel">dB</a>.

</p><p>The range of second-order filter functions is important because any analog filter function can be decomposed into a (usually small) number of these (plus, perhaps, simpler first-order responses). These are implemented directly by each section of a parametric equalizer, where they are explicitly adjusted. And each element of a graphic equalizer based on a <a href="Filter_bank" title="Filter bank">filter bank</a> includes one such element per band whose Q and <i>F</i><sub>0</sub> is not adjustable by the user.

</p>

<p>In <a href="Sound_recording" class="mw-redirect" title="Sound recording">sound recording</a>, equalization may be used to adjust frequency responses for practical or aesthetic reasons, where the end result typically is intentionally <i>unequal</i> volume levels for the different frequencies.<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> For example, equalization is used to modify an instrument's sound or make certain instruments and sounds more prominent. A <a href="Recording_engineer" class="mw-redirect" title="Recording engineer">recording engineer</a> may use an equalizer to make some high-pitches in a vocal part louder while making low-pitches in a drum part quieter.<sup id="cite_ref-Strong_2005_25_1-2" class="reference"><a href="#cite_note-Strong_2005_25-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-The_Audio_Dictionary_2-3" class="reference"><a href="#cite_note-The_Audio_Dictionary-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Equalization is commonly used to increase the <i>depth</i> of a mix, creating the impression that some sounds in a mono or stereo mix are farther away or closer than others.<sup id="cite_ref-Hodgson_3-2" class="reference"><a href="#cite_note-Hodgson-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 75–76">: 75–76 </span></sup> Equalization is also commonly used to give tracks with similar frequency components complementary spectral contours, known as <b><style data-mw-deduplicate="TemplateStyles:r1238216509">

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</style><span class="vanchor"><span class="vanchor-text">mirrored equalization</span></span></b>. Selected components of parts that would otherwise compete, such as bass guitar and kick drum, are boosted in one part and cut in the other, and vice versa, so that they both stand out.<sup id="cite_ref-Hodgson_3-3" class="reference"><a href="#cite_note-Hodgson-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: 76–77">: 76–77 </span></sup>

</p><p>Equalizers can correct problems posed by a room's <a href="Acoustics" title="Acoustics">acoustics</a>, as an auditorium will generally have an uneven frequency response, especially due to <a href="Standing_waves" class="mw-redirect" title="Standing waves">standing waves</a> and <a href="Acoustic_dampening" class="mw-redirect" title="Acoustic dampening">acoustic dampening</a>. For instance, the <a href="Frequency_response" title="Frequency response">frequency response</a> of a room may be analyzed using a <a href="Spectrum_analyzer" title="Spectrum analyzer">spectrum analyzer</a> and a <a href="Pink_noise" title="Pink noise">pink noise</a> generator. Then a graphic equalizer can be adjusted to compensate for the room's acoustics. Such compensation can also be applied to tweak the sound quality of a <a href="Recording_studio" title="Recording studio">recording studio</a> in addition to its use in live <a href="Sound_reinforcement_system" title="Sound reinforcement system">sound reinforcement systems</a> and even home <a href="Hi-fi" class="mw-redirect" title="Hi-fi">hi-fi</a> systems.

</p><p>During live events where signals from microphones are amplified and sent to <a href="Loudspeaker" title="Loudspeaker">speaker</a> systems, equalization is not only used to "flatten" the frequency response but may also be useful in eliminating <a href="Audio_feedback" title="Audio feedback">feedback</a>. When the sound produced by the speakers is picked up by a microphone, it is further reamplified; this recirculation of sound can lead to "howling", requiring the sound technician to reduce the <a href="Gain_(electronics)" title="Gain (electronics)">gain</a> for that microphone, perhaps sacrificing the contribution of a singer's voice, for instance. Even at a slightly reduced gain, the feedback will still cause an unpleasant resonant sound around the frequency at which it would howl. But because the feedback is troublesome at a particular frequency, it is possible to cut the gain only around that frequency while preserving the gain at most other frequencies. This can best be done using a parametric equalizer tuned to that very frequency with its amplitude control sharply reduced. By adjusting the equalizer for a narrow bandwidth (high Q), most other frequency components will not be affected. The extreme case when the signal at the filter's center frequency is completely eliminated is known as a <a href="Notch_filter" class="mw-redirect" title="Notch filter">notch filter</a>.

</p><p>An equalizer can be used to correct or modify the frequency response of a loudspeaker system rather than designing the speaker itself to have the desired response. For instance, the Bose 901 speaker system does not use separate larger and smaller drivers to cover the bass and treble frequencies. Instead it uses nine drivers all of the same four-inch diameter, more akin to what one would find in a table radio. However, this speaker system is sold with an active equalizer. That equalizer must be inserted into the amplifier system so that the amplified signal that is finally sent to the speakers has its response increased at the frequencies where the response of these drivers falls off, and vice versa, producing the response intended by the manufacturer.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup>

</p><p><a href="Tone_control_circuit" title="Tone control circuit">Tone controls</a> (usually designated "bass" and "treble") are simple shelving filters included in most <a href="Hi-fi" class="mw-redirect" title="Hi-fi">hi-fi</a> equipment for gross adjustment of the frequency balance. The bass control may be used, for instance, to increase the drum and bass parts at a dance party, or to reduce annoying bass sounds when listening to a person speaking. The treble control might be used to give the percussion a sharper or more "brilliant" sound, or can be used to cut such high frequencies when they have been overemphasized in the program material or simply to accommodate a listener's preference.

</p><p>A "rumble filter" is a high-pass (low cut) filter with a cutoff typically in the 20 to 40 Hz range; this is the low frequency end of <a href="Audible_range" class="mw-redirect" title="Audible range">human hearing</a>. "Rumble" is a type of low-frequency noise produced in record players and turntables, particularly older or low quality models. The rumble filter prevents this noise from being amplified and sent to the loudspeakers. Some cassette decks have a switchable "subsonic filter" feature that does the same thing for recordings.

</p><p>A <a href="Audio_crossover" title="Audio crossover">crossover network</a> is a system of filters designed to direct electrical energy separately to the <a href="Woofer" title="Woofer">woofer</a> and <a href="Tweeter" title="Tweeter">tweeter</a> of a <a href="2-way_speaker" class="mw-redirect" title="2-way speaker">2-way speaker</a> system (and also to the <a href="Mid-range_speaker" title="Mid-range speaker">mid-range speaker</a> of a 3-way system). This is most often built into the speaker enclosure and hidden from the user. However, in <a href="Bi-amplification" class="mw-redirect" title="Bi-amplification">bi-amplification</a>, these filters operate on the low level audio signals, sending the low-frequency and high-frequency signal components to separate amplifiers, which connect to the woofers and tweeters, respectively.

</p><p>Equalization is used in a reciprocal manner in certain communication channels and recording technologies. The original music is passed through a particular filter to alter its frequency balance, followed by the channel or recording process. At the end of the channel or when the recording is played, a complementary filter is inserted which precisely compensates for the original filter and recovers the original waveform. For instance, FM broadcasting uses a <a href="Pre-emphasis" class="mw-redirect" title="Pre-emphasis">pre-emphasis</a> filter to boost the high frequencies before transmission, and every receiver includes a matching <a href="De-emphasis" class="mw-redirect" title="De-emphasis">de-emphasis</a> filter to restore it. The <a href="White_noise" title="White noise">white noise</a> that is introduced by the radio is then also de-emphasized at the higher frequencies (where it is most noticeable) along with the pre-emphasized program, making the noise less audible. <a href="Tape_recorder" title="Tape recorder">Tape recorders</a> used the same approach to reduce "<a href="Tape_hiss" title="Tape hiss">tape hiss</a>" while maintaining fidelity. On the other hand, in the production of <a href="Phonograph" title="Phonograph">vinyl records</a>, a filter is used to reduce the amplitude of low frequencies which otherwise produce large amplitudes on the tracks of a record. Then the groove can take up less physical space, fitting more music on the record. The preamplifier attached to the <a href="Phono_cartridge" class="mw-redirect" title="Phono cartridge">phono cartridge</a> has a complementary filter boosting those low frequencies, following the standard <a href="RIAA_equalization" title="RIAA equalization">RIAA equalization</a> curve.

</p>

<ul><li><a href="Electronic_filter" title="Electronic filter">Electronic filter</a></li>

<li><a href="Loudness_compensation" title="Loudness compensation">Loudness compensation</a></li>

<li><a href="Weighting_filter" title="Weighting filter">Weighting filter</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2></div>

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</style><div class="reflist reflist-lower-alpha">

<li id="cite_note-6dB-17"><span class="mw-cite-backlink">^ <a href="#cite_ref-6dB_17-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-6dB_17-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-6dB_17-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text">A doubling of signal voltage and a consequent quadrupling of signal power for every doubling of frequency.</span>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="Citations">Citations</h2></div>

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</style><cite id="CITEREFStrong2005" class="citation book cs1">Strong, Jeff (2005). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=4-2SfnghnYwC&q=pc+recording+studios+for+dummies"><i>PC Recording Studios for Dummies</i></a>. Wiley. p. 25. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9780764577079</bdi>.</cite></span>

</li>

<li id="cite_note-The_Audio_Dictionary-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-The_Audio_Dictionary_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-The_Audio_Dictionary_2-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-The_Audio_Dictionary_2-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-The_Audio_Dictionary_2-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFLouieWhite2005" class="citation book cs1">Louie, Gary; White, Glenn (2005). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=DulVm8t88QkC&q=the+audio+dictionary"><i>The Audio Dictionary</i></a>. University of Washington Press. p. 140. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9780295984988</bdi>.</cite></span>

</li>

<li id="cite_note-Hodgson-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-Hodgson_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Hodgson_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-Hodgson_3-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-Hodgson_3-3"><sup><i><b>d</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFHodgson,_Jay2010" class="citation book cs1">Hodgson, Jay (2010). <i>Understanding Records</i>. Bloomsbury Publishing USA. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-4411-5607-5</bdi>.</cite></span>

</li>

<li id="cite_note-Glossary-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-Glossary_4-0">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20120820194319/http://www.sweetwater.com/expert-center/glossary/t--BritishEQ">"British EQ"</a>. Sweetwater. December 20, 1999. Archived from <a rel="nofollow" class="external text" href="http://www.sweetwater.com/expert-center/glossary/t--BritishEQ">the original</a> on August 20, 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">November 25,</span> 2013</span>.</cite></span>

</li>

<li id="cite_note-Perkins-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-Perkins_5-0">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131202221704/http://www.mackie.com/technology/perkinseq.html">"Extraordinary EQ from Extraordinary Engineers"</a>. Mackie. Archived from <a rel="nofollow" class="external text" href="http://www.mackie.com/technology/perkinseq.html">the original</a> on December 2, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">November 25,</span> 2013</span>.</cite></span>

</li>

<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><cite class="citation cs2"><a rel="nofollow" class="external text" href="https://www.loc.gov/collections/alexander-graham-bell-papers/articles-and-essays/telephone-and-multiple-telegraph/"><i>The Telephone and the Multiple Telegraph</i></a><span class="reference-accessdate">, retrieved <span class="nowrap">March 3,</span> 2016</span></cite></span>

</li>

<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">H. Tremaine, Audio Cyclopedia, 2nd. Ed., (H.W. Sams, Indianapolis, 1973)</span>

</li>

<li id="cite_note-note122-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-note122_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-note122_8-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFDennis_Bohn1997" class="citation web cs1">Dennis Bohn (August 1997). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140402040654/http://www.rane.com/note122.html">"Operator Adjustable Equalizers: An Overview"</a>. <a href="Rane_Corporation" title="Rane Corporation">Rane Corporation</a>. Archived from <a rel="nofollow" class="external text" href="http://www.rane.com/note122.html">the original</a> on April 2, 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">November 25,</span> 2013</span>.</cite></span>

</li>

<li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><cite id="CITEREFRick_Chinn" class="citation web cs1">Rick Chinn. <a rel="nofollow" class="external text" href="http://www.gyraf.dk/schematics/Langevin_EQ251A.GIF">"Langevin EQ-251A Schematic"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">November 25,</span> 2013</span>.</cite></span>

</li>

<li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><cite id="CITEREFFrank_Hoffman2005" class="citation book cs1">Frank Hoffman, ed. (2005). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=-FOSAgAAQBAJ&pg=PA550">"Davis, Arthur C. (11 Mar 1908 – 7 Nov 1970)"</a>. <i>Encyclopedia of Recorded Sound</i> (2 ed.). Routledge. p. 550. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9781135949501</bdi>.</cite></span>

</li>

<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text">Tremaine 1973, pp. 312–313</span>

</li>

<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://intelligentsoundengineering.wordpress.com/2016/02/22/a-short-history-of-graphic-and-parametric-equalization.html">"A short history of graphic and parametric equalization"</a>. February 22, 2016.</cite></span>

</li>

/* start https://en.wikipedia.org/ */

.mw-parser-output .citation{word-wrap:break-word}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}

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</style><span class="citation patent"><a rel="nofollow" class="external text" href="https://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US3727896">US 3727896</a></span><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Apatent&rft.number=3727896&rft.cc=US&rft.title="><span style="display: none;"> </span></span></span>

</li>

</li>

<li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><cite id="CITEREFGeorge_Massenburg1972" class="citation conference cs1"><a href="George_Massenburg" title="George Massenburg">George Massenburg</a> (May 1972). <a rel="nofollow" class="external text" href="https://www.aes.org/e-lib/download.cfm/16171.pdf?ID=16171"><i>Parametric Equalization</i></a> <span class="cs1-format">(PDF)</span>. 42nd AES Convention. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20240418064302/https://www.aes.org/tmpFiles/elib/20240418/16171.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on April 18, 2024.</cite>

(<a rel="nofollow" class="external text" href="https://www.aes.org/e-lib/browse.cfm?elib=16171">AES E-Library description page</a>)

<ul><li>Author's copy: <cite id="CITEREFGeorge_Massenburg1972" class="citation web cs1"><a href="George_Massenburg" title="George Massenburg">George Massenburg</a> (May 1972). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110714044154/http://www.massenburg.com/gml/downloads/parametric_paper.pdf">"Parametric Equalization"</a> <span class="cs1-format">(PDF)</span>. Archived from <a rel="nofollow" class="external text" href="http://www.massenburg.com/gml/downloads/parametric_paper.pdf">the original</a> <span class="cs1-format">(PDF)</span> on July 14, 2011<span class="reference-accessdate">. Retrieved <span class="nowrap">April 23,</span> 2011</span>.</cite></li></ul>

</span></li>

<li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://legacy.presonus.com/learn/technical-articles/What-Is-a-Parametric-Eq">"What is a Parametric EQ?"</a>. <a href="PreSonus" title="PreSonus">PreSonus</a><span class="reference-accessdate">. Retrieved <span class="nowrap">February 17,</span> 2024</span>.</cite></span>

</li>

<li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><cite id="CITEREFPreisBloom1984" class="citation cs2">Preis, Douglas; Bloom, P. J. (November 1984), <a rel="nofollow" class="external text" href="https://aes2.org/publications/elibrary-page/?id4476">"Perception of Phase Distortion in Anti-Alias Filters"</a>, <i>Journal of the Audio Engineering Society</i>, <b>32</b> (11): <span class="nowrap">842–</span>848</cite></span>

</li>

<li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20150716031431/http://www.emusician.com/tutorials/square-one-phase/">"Linear Phase EQ, <i>Electronic Musician</i>"</a>. Archived from <a rel="nofollow" class="external text" href="http://emusician.com/tutorials/square-one-phase/">the original</a> on July 16, 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">July 15,</span> 2015</span>.</cite></span>

</li>

<li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><cite class="citation magazine cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131203021159/http://www.soundonsound.com/sos/jul01/articles/equalisers1.asp">"Equalisers Explained"</a>. <i><a href="Sound_on_Sound" title="Sound on Sound">Sound on Sound</a></i>. July 2001. Archived from <a rel="nofollow" class="external text" href="http://www.soundonsound.com/sos/jul01/articles/equalisers1.asp">the original</a> on December 3, 2013<span class="reference-accessdate">. Retrieved <span class="nowrap">November 25,</span> 2013</span>.</cite></span>

</li>

<li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><cite id="CITEREFMiller_Puckette2006" class="citation book cs1">Miller Puckette (December 30, 2006). <a rel="nofollow" class="external text" href="http://msp.ucsd.edu/techniques/latest/book-html/node142.html"><i>The Theory and Technique of Electronic Music</i></a>. World Scientific. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>9789812700773</bdi>.</cite></span>

</li>

<li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">Ballou, pp.875-876.</span>

</li>

<li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><a href="Stereophile" title="Stereophile">Stereophile</a> magazine, <a rel="nofollow" class="external text" href="https://www.stereophile.com/content/bose-901-loudspeaker-page-4">Bose 901 Loudspeaker Review</a>, 1995.</span>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="General_sources">General sources</h2></div>

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.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}

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<ul><li>Glen Ballou, "Filters and equalizers", <i>Handbook for Sound Engineers</i>, Fourth edition, Focal Press, 2008 <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-240-80969-6</bdi>.</li></ul>

</div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

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</style>

<div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/equalisation" class="extiw external" title="wiktionary:equalisation">equalisation</a></b></i> or <i><b><a href="https://en.wiktionary.org/wiki/equalization" class="extiw external" title="wiktionary:equalization">equalization</a></b></i> in Wiktionary, the free dictionary.</div></div>

</div>

<ul><li><a rel="nofollow" class="external text" href="http://www.audiocheck.net/engineertraining_bands_difficult.php">Discriminating EQ frequencies by ear</a></li>

<li><a rel="nofollow" class="external text" href="http://www.sengpielaudio.com/calculator-bandwidth.htm">Calculator: bandwidth per octave <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle N}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle N}</annotation>

</semantics>

</math></span><img src="./f5e3890c981ae85503089652feb48b191b57aae3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:2.064ex; height:2.176ex;" alt="{\displaystyle N}" loading="lazy"></span> to quality factor <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Q}">

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle Q}</annotation>

</semantics>

</math></span><img src="./8752c7023b4b3286800fe3238271bbca681219ed.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:1.838ex; height:2.509ex;" alt="{\displaystyle Q}" loading="lazy"></span> and back</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110721132848/http://www.idc.ul.ie/idcwiki/index.php/Equalisation">EQ Condensed Overview</a></li>

<li><a rel="nofollow" class="external text" href="https://archive.today/20121220231853/http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt">Audio EQ Cookbook</a></li>

<li><a rel="nofollow" class="external text" href="http://www.presonus.com/community/learn/equalizer-terms-and-tips">PreSonus Equalizer Terms and Tips</a></li>

<li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100131065338/http://www.wikirecording.org/EQ">WikiRecording's Guide to Equalization</a></li></ul>

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</style><div id="Music_production505" style="font-size:114%;margin:0 4em"><a href="Record_producer" title="Record producer">Music production</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Audio_engineer" title="Audio engineer">Engineering</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Audio_filter" title="Audio filter">Audio filter</a></li>

<li><a href="Mastering_(audio)" title="Mastering (audio)">Audio mastering</a></li>

<li><a href="Audio_mixing_(recorded_music)" title="Audio mixing (recorded music)">Audio mixing</a></li>

<li><a href="Critical_distance" title="Critical distance">Critical distance</a></li>

<li><a href="Effects_loop" title="Effects loop">Effects loop</a></li>

<li><a href="Effects_unit" title="Effects unit">Effects unit</a>

<li><a href="Wah-wah_pedal" title="Wah-wah pedal">Wah-wah pedal</a></li></ul></li>

<li><a href="Diffusion_(acoustics)" title="Diffusion (acoustics)">Diffusion</a></li>

<li><a href="Microphone" title="Microphone">Microphone</a></li>

<li><a href="Overdubbing" title="Overdubbing">Overdubbing</a></li>

<li><a href="Ping-pong_recording" title="Ping-pong recording">Ping-ponging</a></li>

<li><a href="Punch_in/out" title="Punch in/out">Punch in/out</a></li>

<li><a href="Sound_recording" class="mw-redirect" title="Sound recording">Sound recording</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Audio_signal_processing" title="Audio signal processing">Signal <br> processing</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Audio_time_stretching_and_pitch_scaling" title="Audio time stretching and pitch scaling">Pitch shift</a></li>

<li><a href="Chorus_(audio_effect)" title="Chorus (audio effect)">Chorus effect</a></li>

<li><a href="Dynamic_range_compression" title="Dynamic range compression">Compression</a></li>

<li><a href="Delay_(audio_effect)" title="Delay (audio effect)">Delay effect</a> (<a href="Send_tape_echo_echo_delay" title="Send tape echo echo delay">STEED</a>)</li>

<li><a href="Distortion_(music)" title="Distortion (music)">Distortion</a></li>

<li><a href="Double_tracking" title="Double tracking">Double tracking</a> (<a href="Automatic_double_tracking" title="Automatic double tracking">ADT</a>)</li>

<li><a href="Ducking" title="Ducking">Ducking</a></li>

<li><a href="Equalization_(audio)" class="mw-redirect" title="Equalization (audio)">Equalization</a></li>

<li><a href="Exciter_(effect)" title="Exciter (effect)">Exciter effect</a></li>

<li><a href="Flanging" title="Flanging">Flanging</a></li>

<li><a href="Octave_effect" title="Octave effect">Octave effect</a></li>

<li><a href="Noise_gate" title="Noise gate">Noise gate</a></li>

<li><a href="Phaser_(effect)" title="Phaser (effect)">Phaser</a></li>

<li><a href="Pumping_(audio)" title="Pumping (audio)">Pumping</a></li>

<li><a href="Reverb_effect" title="Reverb effect">Reverb</a></li>

<li><a href="Reverse_echo" title="Reverse echo">Reverse echo</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div class="hlist"><ul><li>Practices</li><li><br>aesthetics</li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Hip_hop_production" class="mw-redirect" title="Hip hop production">Hip hop production</a></li>

<li><a href="Overproduction_(music)" title="Overproduction (music)">Overproduction</a></li>

<li><a href="Recording_studio_as_an_instrument" title="Recording studio as an instrument">Recording studio as an instrument</a></li>

<li><a href="Sampling_(music)" title="Sampling (music)">Sampling</a></li>

<li><a href="Turntablism" title="Turntablism">Turntablism</a></li>

<li><a href="Wall_of_Sound" title="Wall of Sound">Wall of Sound</a></li>

<li><a href="Xenochrony" title="Xenochrony">Xenochrony</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div class="hlist"><ul><li>Roles</li><li><br> professions</li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Arrangement" title="Arrangement">Arranger</a></li>

<li><a href="Audio_engineer" title="Audio engineer">Audio engineer</a></li>

<li><a href="Backup_band" title="Backup band">Backup band</a></li>

<li><a href="Bandleader" title="Bandleader">Bandleader</a></li>

<li><a href="Ghostwriter#Music" title="Ghostwriter">Ghostwriters in music</a></li>

<li><a href="Horn_section" title="Horn section">Horn section</a></li>

<li><a href="Orchestrator" class="mw-redirect" title="Orchestrator">Orchestrator</a></li>

<li><a href="Record_producer" title="Record producer">Record producer</a></li>

<li><a href="Rhythm_section" title="Rhythm section">Rhythm section</a></li>

<li><a href="Session_musician" title="Session musician">Session musician</a></li>

<li><a href="Backup_singer" class="mw-redirect" title="Backup singer">Backup singer</a>

<ul><li><a href="Ghost_singer" class="mw-redirect" title="Ghost singer">Ghost singer</a></li></ul></li>

<li><a href="Vocal_coach" title="Vocal coach">Vocal coach</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Click_track" title="Click track">Click track</a></li>

<li><a href="Interpolation_(popular_music)" title="Interpolation (popular music)">Interpolation</a></li>

<li><a href="Loudness_war" title="Loudness war">Loudness war</a></li>

<li><a href="Mashup_(music)" title="Mashup (music)">Mashup</a></li>

<li><a href="Medley_(music)" title="Medley (music)">Medley</a></li>

<li><a href="Music_technology_(electric)" title="Music technology (electric)">Music technology (electric)</a></li>

<li><a href="Music_technology_(electronic_and_digital)" title="Music technology (electronic and digital)">Music technology (electronic and digital)</a></li>

<li><a href="Remix" title="Remix">Remix</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div><b><span class="nowrap"><span class="noviewer" typeof="mw:File"><span></span></span> </span><a href="Portal%3ARecord_production" title="Portal:Record production">Record production portal</a></b></div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Music_technology445" style="padding:3px"><table class="nowraplinks mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Music_technology445" style="font-size:114%;margin:0 4em"><a href="Music_technology" title="Music technology">Music technology</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Music_technology" title="Music technology">Music technology</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Music_technology_(mechanical)" title="Music technology (mechanical)">Mechanical</a></li>

<li><a href="Music_technology_(electric)" title="Music technology (electric)">Electrical</a></li>

<li><a href="Music_technology_(electronic_and_digital)" title="Music technology (electronic and digital)">Electronic and digital</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Sound_recording_and_reproduction" title="Sound recording and reproduction">Sound recording</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Audio_channel" class="mw-redirect" title="Audio channel">Audio channel</a></li>

<li><a href="Mixing_console" title="Mixing console">Mixing console</a></li>

<li><a href="Binaural_recording" title="Binaural recording">Binaural recording</a></li>

<li><a href="Digital_audio_workstation" title="Digital audio workstation">Digital audio workstation</a> (DAW)</li>

<li><a href="Effects_unit" title="Effects unit">Effects unit</a></li>

<li><a href="Equalization_(audio)" class="mw-redirect" title="Equalization (audio)">Equalizer</a></li>

<li><a href="Headphones" title="Headphones">Headphones</a></li>

<li><a href="Microphone" title="Microphone">Microphone</a></li>

<li><a href="Microphone_preamplifier" title="Microphone preamplifier">Microphone preamplifier</a></li>

<li><a href="Foldback_(sound_engineering)" class="mw-redirect" title="Foldback (sound engineering)">Monitor speaker</a></li>

<li><a href="Multitrack_recording" title="Multitrack recording">Multitrack recording</a></li>

<li><a href="Record_producer" title="Record producer">Music production</a></li>

<li><a href="Music_sequencer" title="Music sequencer">Music sequencer</a></li>

<li><a href="Outboard_gear" title="Outboard gear">Outboard gear</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Timeline_of_audio_formats" title="Timeline of audio formats">Recording media</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Phonograph_record" title="Phonograph record">Phonograph record</a></li>

<li><a href="Magnetic_tape" title="Magnetic tape">Magnetic tape</a></li>

<li><a href="Compact_Cassette" class="mw-redirect" title="Compact Cassette">Compact Cassette</a></li>

<li><a href="Compact_disc" title="Compact disc">Compact disc</a></li>

<li><a href="MiniDisc" title="MiniDisc">MiniDisc</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Analog_recording" title="Analog recording">Analog recording</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="8-track_tape" class="mw-redirect" title="8-track tape">8-track cartridge</a></li>

<li><a href="Amplifier" title="Amplifier">Amplifier</a></li>

<li><a href="Cassette_deck" title="Cassette deck">Cassette deck</a></li>

<li><a href="Comparison_of_analog_and_digital_recording" title="Comparison of analog and digital recording">Comparison of analog and digital recording</a></li>

<li><a href="Experimental_musical_instrument" title="Experimental musical instrument">Experimental musical instrument</a></li>

<li><a href="Phonograph" title="Phonograph">Phonograph</a></li>

<li><a href="Player_piano" title="Player piano">Player piano</a></li>

<li><a href="Reel-to-reel_audio_tape_recording" title="Reel-to-reel audio tape recording">Reel-to-reel audio tape recording</a></li>

<li><a href="Tape_recorder" title="Tape recorder">Tape recorder</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Playback transducers</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Loudspeaker" title="Loudspeaker">Loudspeaker</a></li>

<li><a href="Headphones" title="Headphones">Headphones</a></li>

<li><a href="Foldback_(sound_engineering)" class="mw-redirect" title="Foldback (sound engineering)">Monitor speaker</a></li>

<li><a href="Public_address_system" title="Public address system">PA system</a></li>

<li><a href="Sound_reinforcement_system" title="Sound reinforcement system">Sound reinforcement system</a></li>

<li><a href="Speaker_enclosure" class="mw-redirect" title="Speaker enclosure">Speaker enclosure</a></li>

<li><a href="Subwoofer" title="Subwoofer">Subwoofer</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Digital_audio" title="Digital audio">Digital audio</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Digital_recording" title="Digital recording">Digital recording</a></li>

<li><a href="Digital_signal_processing" title="Digital signal processing">Digital signal processing</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Concert" title="Concert">Live music</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Mixing_console" title="Mixing console">Mixing console</a></li>

<li><a href="Bass_amplifier" title="Bass amplifier">Bass amplifier</a></li>

<li><a href="Effects_unit" title="Effects unit">Effects unit</a></li>

<li><a href="Foldback_(sound_engineering)" class="mw-redirect" title="Foldback (sound engineering)">Foldback</a></li>

<li><a href="Guitar_amplifier" title="Guitar amplifier">Guitar amplifier</a></li>

<li><a href="Keyboard_amplifier" title="Keyboard amplifier">Keyboard amplifier</a></li>

<li><a href="Public_address_system" title="Public address system">PA system</a></li>

<li><a href="Reverb_effect" title="Reverb effect">Reverb</a></li>

<li><a href="Sound_reinforcement_system" title="Sound reinforcement system">Sound reinforcement system</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Electronic_music" title="Electronic music">Electronic music</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Chiptune" title="Chiptune">Chiptune</a></li>

<li><a href="Circuit_bending" title="Circuit bending">Circuit bending</a></li>

<li><a href="Drum_machine" title="Drum machine">Drum machine</a></li>

<li><a href="Electronic_drums" class="mw-redirect" title="Electronic drums">Electronic drums</a></li>

<li><a href="Electronic_musical_instrument" title="Electronic musical instrument">Electronic musical instrument</a></li>

<li><a href="MIDI_controller" title="MIDI controller">MIDI controller</a></li>

<li><a href="Music_workstation" title="Music workstation">Music workstation</a></li>

<li><a href="Sampler_(musical_instrument)" title="Sampler (musical instrument)">Sampler</a></li>

<li><a href="Music_sequencer" title="Music sequencer">Sequencer</a></li>

<li><a href="Sound_module" title="Sound module">Sound module</a></li>

<li><a href="Synthesizer" title="Synthesizer">Synthesizer</a></li>

<li><a href="Theremin" title="Theremin">Theremin</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Software" title="Software">Software</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Digital_audio_editor" class="mw-redirect" title="Digital audio editor">Digital audio editor</a></li>

<li><a href="Digital_audio_workstation" title="Digital audio workstation">Digital audio workstation</a></li>

<li><a href="GarageBand" title="GarageBand">GarageBand</a></li>

<li><a href="ProTools" class="mw-redirect" title="ProTools">ProTools</a></li>

<li><a href="Scorewriter" title="Scorewriter">Scorewriter</a></li>

<li><a href="Software_effect_processor" title="Software effect processor">Software effect processor</a></li>

<li><a href="Software_sampler" class="mw-redirect" title="Software sampler">Software sampler</a></li>

<li><a href="Software_synthesizer" title="Software synthesizer">Software synthesizer</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Professions</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Audio_engineer" title="Audio engineer">Audio engineer</a></li>

<li><a href="Guitar_tech" title="Guitar tech">Guitar technician</a></li>

<li><a href="Mixing_engineer" title="Mixing engineer">Mixing engineer</a></li>

<li><a href="Monitor_engineer" class="mw-redirect" title="Monitor engineer">Monitor engineer</a></li>

<li><a href="Piano_tuner" class="mw-redirect" title="Piano tuner">Piano tuner</a></li>

<li><a href="Record_producer" title="Record producer">Record producer</a></li>

<li><a href="Re-recording_mixer" title="Re-recording mixer">Re-recording mixer</a></li>

<li><a href="Sound_designer" class="mw-redirect" title="Sound designer">Sound designer</a></li>

<li><a href="Sound_follower" title="Sound follower">Sound follower</a></li>

<li><a href="Sound_operator" class="mw-redirect" title="Sound operator">Sound operator</a></li>

<li><a href="Sound_recording" class="mw-redirect" title="Sound recording">Sound recording engineer</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People and organizations</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Audio_Engineering_Society" title="Audio Engineering Society">Audio Engineering Society</a></li>

<li><a href="Goji_Electronics" title="Goji Electronics">Goji Electronics</a></li>

<li><a href="Institute_of_Broadcast_Sound" class="mw-redirect" title="Institute of Broadcast Sound">Institute of Broadcast Sound</a></li>

<li><a href="Lejaren_Hiller" title="Lejaren Hiller">Lejaren Hiller</a></li>

<li><a href="IRCAM" title="IRCAM">IRCAM</a></li>

<li><a href="Max_Mathews" title="Max Mathews">Max Mathews</a></li>

<li><a href="Musical_Electronics_Library" title="Musical Electronics Library">Musical Electronics Library</a></li>

<li><a href="Professional_Lighting_and_Sound_Association" title="Professional Lighting and Sound Association">Professional Lighting and Sound Association</a></li>

<li><a href="Robert_Moog" title="Robert Moog">Robert Moog</a></li>

<li><a href="Society_of_Motion_Picture_and_Television_Engineers" title="Society of Motion Picture and Television Engineers">SMPTE</a></li>

<li><a href="STEIM" title="STEIM">STEIM</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related topics</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Audiophile" title="Audiophile">Audiophile</a></li>

<li><a href="High_fidelity" title="High fidelity">High fidelity</a></li>

<li><a href="Home_audio" title="Home audio">Home audio</a></li>

<li><a href="Home_cinema" title="Home cinema">Home cinema</a></li>

<li><a href="Music_store" title="Music store">Music store</a></li>

<li><a href="Professional_audio_store" title="Professional audio store">Professional audio store</a></li>

<li><a href="New_Interfaces_for_Musical_Expression" title="New Interfaces for Musical Expression">New Interfaces for Musical Expression</a> (NIME)</li>

<li><a href="Media_control_symbols" title="Media control symbols">Symbols of control</a></li>

<li><a href="Vehicle_audio" title="Vehicle audio">Vehicle audio</a></li></ul>

This article is issued from <a class="external text" title="Last edited on 2025-07-21" href="https://en.wikipedia.org/wiki/?title=Audio_equalizer&oldid=1301680960">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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