Editing Quadraphonic sound (section)

== History ==
The first machines used for 4-channel sound recording were [[analog recording|analog]] [[reel-to-reel tape]] recorders. These were developed for use by [[audio engineers]] in professional studios during the 1950s in Germany by [[Telefunken]] and also by [[Ampex]] in the United States. Such machines appeared in some European electronic-music studios by 1954.<ref>Cross, Lowell, "Electronic Music, 1948–1953", ''[[Perspectives of New Music]]'' 7, no. 1 (Autumn–Winter, 1968): 32–65. Citation on 50–51.</ref>

Early attempts to reproduce four channel sound for home playback began with audio laboratory engineers in the late 1960s. Producer Thomas Mowrey,<ref>{{Cite web|url=http://quadraphonic.info/Thomas_Mowrey|title = Thomas Mowrey Archive Quadraphonic.info™ Articles, Manuals and Quadraphonic and Surround Sound Information}}</ref> initially working at the [[Eastman School of Music]], was one of the pioneers of classical quadraphonic recording. He later made quadraphonic productions for [[Deutsche Grammophon]] and other labels in the early 1970s, but many of these were released only as stereo recordings.<ref>{{Cite web|url=https://www.discogs.com/artist/272491-Thomas-Mowrey|title=Thomas Mowrey|website=[[Discogs]]}}</ref>

A small number of quadraphonic recordings were introduced to the American consumer market by [[Vanguard Records]] in June 1969 on reel-to-reel tape. The most popular medium used to market recordings to the public during the 1970s was the vinyl [[LP record|LP]] [[phonograph record]]. Quadraphonic recordings on [[8-track tape]] were also popular in the 1970s, particularly among car audio enthusiasts.

In the 1970s specialized hardware systems were marketed by major electronic manufacturers to the public for decoding 4-channel recordings. These decoders were often sold as separate electronic components. Decoders were also available as built in features of some audio receivers or amplifiers sold during the 1970s.

Many quadraphonic recordings in the 1970s used ''matrix'' technologies to encode and decode four channels of audio information in a 2-channel medium, usually an LP. The poor decoding performance of early matrix formats was the main reason they disappeared once improved matrix systems arrived. The later matrix systems were based on work by [[Peter Scheiber]]. His basic formula used 90° phase-shift circuitry to enable enhanced 4–2–4 matrix systems to be developed, of which the two main leaders were [[Columbia Records|Columbia]]'s SQ and [[Sansui Electric|Sansui]]'s QS systems.

The three most popular quadraphonic LP formats in the 1970s were [[Stereo Quadraphonic|SQ (Stereo Quadraphonic)]], [[QS Regular Matrix|QS (Regular Matrix)]] and [[Compatible Discrete 4|CD-4 (Compatible Discrete 4) / Quadradisc]].

The Japanese governing body and audio hardware manufacturers defined standards for quadraphonic sound. RM (''Regular Matrix'') was used a synonym for QS, QM (''Quadraphonic Matrix''<ref>{{Cite web|url=https://midimagic.sgc-hosting.com/quadrafon.htm|title=Quadraphonic Systems|website=midimagic.sgc-hosting.com}}</ref><ref>{{Cite web|url=https://www.discogs.com/ko/lists/QM+matrix+encoded+Quadraphonic+media/575839|title=QM matrix encoded Quadraphonic media by Afalout &#124; Discogs Lists|website=www.discogs.com}}</ref> was used for [[Stereo-4]] and [[Dynaquad]]) and QX (''QuadXtra'', based on D.H. Cooper "Dual-Triphonic")<ref>{{Cite magazine |last=Eguchi |first=Hideo |date=August 12, 1972 |title=Denon exports to U.S. ended |pages=1, 54 |magazine=Billboard |url=https://books.google.com/books?id=eygEAAAAMBAJ&dq=Nippon+Columbia+QX+QuadXtra+Dual+Triphonic+Matrix+System&pg=PA54}}</ref><ref>{{Cite magazine |last=Eguchi |first=Hideo |date=August 4, 1973 |title='Q' Action in Japan |pages=55 |magazine=Billboard |url=https://worldradiohistory.com/Archive-All-Music/Billboard/70s/1973/Billboard%201973-08-04.pdf}}</ref><ref>{{Cite web |title=Dual Tryphonic QX Adapter |url=https://www.quadraphonicquad.com/forums/attachments/fd2973fc-jpg.17097/}}</ref><ref>{{Cite web |title=Four-Channel Adapter "Dual Triphonic" QX-1A |url=https://www.quadraphonicquad.com/forums/attachments/1-jpg.17098/}}</ref><ref>{{Cite web |title=QX records Japanese advert |url=https://www.quadraphonicquad.com/forums/attachments/nippon-columbia-4-channel-qx-record-jpg.18994/}}</ref> for [[UD4]].<ref>{{Cite web|url=http://pspatialaudio.com/matrix_h.htm|title=BBC Matrix H and Denon UMX (UD-4)|website=pspatialaudio.com}}</ref>

With Scheiber and Martin Willcocks, [[Jim Fosgate]] developed the Tate II 101 SQ decoder, which produced a very accurate sound field by using gain riding and the [[precedence effect|Haas effect]] to mask decoding artifacts. It used custom, hand-assembled and ‑calibrated circuitry with components sorted to 1%, for exact performance. Sansui's QSD-series decoders and QRX-series receivers were very good, even synthesizing left-right stereo into a ⋂ horseshoe topology. However, all these came too late in the game and were too expensive or difficult to procure for public purchase, to rescue matrix quad from obscurity.

By the early 2000s more sophisticated "discrete" multichannel systems had mostly replaced matrix technologies, providing a higher level of performance and full channel independence. Today, [[software]] can be used to take the place of hardware decoding. Modern software algorithms are capable of more accurate decoding performance than the earlier hardware technologies.

All of the multichannel audio systems in common use today are [[digital recording|digital]] systems. Digital multichannel audio has been available for the home since the introduction of surround sound movies in the 1990s using Dolby Digital and DTS. The most common digital media capable of reproducing surround sound music today are Super Audio CD, DVD, and Blu-ray, all of which are capable of playing [[high-resolution audio]] with multiple channels.