Difference between revisions 461353727 and 461357674 on enwiki

{{about|electronic compensation for systems' uneven frequency responses|equalization particularly as used in sound recording and reproduction|Equalization (audio)}}
{{other uses|Equalization (disambiguation)}}

(contracted; show full)aesthetic reasons, often resulting in a net response that is not truly equalized.  The term EQ specifically refers to this variant of the term.<ref>Ballou, pp.875-876.</ref> Stereos typically have adjustable equalizers which boost or cut [[Bass (sound)|bass]] or [[Treble (sound)|treble]] frequencies. 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.


In addition to adjusting the relative amplitude of frequency bands, an equalizer (and the system it is correcting) will alter the relative [[phase (waves)|phase]]s of those frequencies. While the human ear is not as sensitive to the phase of audio frequencies (involving delays of less than 1/30 second), in musical applications technicians frequently favor different equalizers because of how they affect the timbre of the musical content by way of phase artifacts<ref>[http://emusician.com/tutorials/square-one-phase/ Linear Phase EQ, Electronic Muisian]</ref>.  In most non-audio applications the actual [[waveform]] of the transmitted signal must be preserved, not just its frequency content. Thus these equalizing filters must also cancel out any phase shifts (unequal delay) between different frequency components.⏎
⏎
== Uses ==

=== Audio and music ===
{{main|Equalization (audio)}}
[[Image:Shelving-eq.svg|thumb|right|200px|Two first-order shelving filters: a -3&nbsp;dB bass cut (red), and a +9&nbsp;dB treble boost (blue)]]
[[Image:Peaking-eq.svg|thumb|right|200px|Second-order [[linear filter]] functions. Blue: a 9&nbsp;dB boost at 1&nbsp;kHz. Red: a 6&nbsp;dB cut at 100&nbsp;Hz having a higher [[Q factor|Q]] (sharper bandwidth)]]
(contracted; show full)ow-pass notch'' 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 ''notch frequency''). Such a filter might be ideal, for instance, in completely removing the 19&nbsp;kHz [[Subcarrier#FM stereo|FM stereo subcarrier]] [[pilot signal]] while helping to cut even higher frequency subcarrier components remaining from the stereo [[FM broadcasting#FM stereo|demultiplexer]].


In addition to adjusting the relative amplitude of frequency bands, an audio equalizer may alter the relative [[phase (waves)|phase]]s of those frequencies. While the human ear is not as sensitive to the phase of audio frequencies (involving delays of less than 1/30 second), music professionals may favor certain equalizers because of how they affect the timbre of the musical content by way of audible phase artifacts.<ref>[http://emusician.com/tutorials/square-one-phase/ Linear Phase EQ, ''Electronic Musician'']</ref>⏎
⏎
=== Analog telecommunications ===

==== Audio lines ====
Early telephone systems used equalization to correct for the reduced level of high frequencies in long cables, typically using [[Zobel network]]s. These kinds of equalizers can also be used to produce a circuit with a wider bandwidth than the standard telephone band of 300&nbsp;Hz to 3.4&nbsp;kHz.  This was particularly useful for broadcasters who needed "music" quality, not "telephone" quality on landlines carrying program(contracted; show full)[[pl:Korektor (akustyka)]]
[[pt:Equalizador]]
[[ru:Эквалайзер]]
[[fi:Ekvalisaattori]]
[[sv:Equalizer]]
[[tr:Eşitleme (ses)]]
[[uk:Еквалайзер]]
[[zh:等化器]]