Definição do conceito
SOURCE: https://en.wikipedia.org/wiki/Phonograph_record
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[POR] quadrifônico : Som Quadrifônico também conhecido como estéreo 4.0 usa quatro canais de áudio onde os alto-falantes são posicionados em quatro cantos de um ambiente reproduzindo sons inteiramente ou parcialmente independentes em cada caixa de som. Foi um fracasso de mercado devido a sua complexidade técnica para instalação e alto custo de implantação. Atualmente é substituído pelo Surround sound. | Compatible Discrete 4 (CD-4) ou Quadradisc (não fazer confusão com o disco compacto) foi criado em 1971 com o sistema quadrifônico pela JVC. Algumas empresas que adotaram este padrão foram Arista, CTI Records, Atlantic, Capricorn, Elektra, Fantasy, JVC, Nonesuch, RCA, Reprise and Warner. | A matriz de codificação/decodificação do CD-4 | (LF+LB)+(LF-LB)=2LF ou Esquerda frontal | (LF+LB)-(LF-LB)=2LB ou Esquerda traseira | (RF+RB)+(RF-RB)=2RF ou Direita frontal
(RF+RB)-(RF-RB)=2RB ou Direita traseira | Mesmo com o fracasso do CD-4, em parte pelo atraso na aprovação pelo FCC, a sua tecnologia foi responsável pelo avanço substancial das gravações em LP. | FONTE : quadrifônico. in: Wikipedia. Disponível em : https://pt.wikipedia.org/wiki/Quadrif%C3%B4nico / Acessade em : 25 set. 2022
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[ENG] Quadradisc ; Compatible Discrete 4 (CD-4) : Compatible Discrete 4, also known as Quadradisc or CD-4 (not to be confused with compact disc) was as a discrete four-channel quadraphonic system for phonograph records. The system was created by JVC and RCA in 1971[1] and introduced in May 1972. Hundreds of recordings using this technology were released on LP during the 1970s. | Other major record companies who adopted this format include A&M, Arista, Atlantic, Capricorn, Elektra, Fantasy, Nonesuch, Reprise and Warner Bros. | This was the only discrete quadraphonic phonograph record system to gain major industry acceptance. A competing system, UD-4, was later introduced by Denon (Nippon Columbia). | In discrete quadraphonic systems, all four channels remain fully independent of each other throughout the entire recording and reproduction chain. There is no intermingling of channels as is done in matrix decoder 4-channel systems such as Stereo Quadraphonic (SQ) and QS Regular Matrix. | | Though CD-4 and other quadraphonic technologies were not widely accepted by the public, CD-4 was responsible for major improvements in stereo phonograph technology. These improvements included phono cartridges with higher compliance, lower distortion levels, wider frequency range, and new vinyl compounds for records. Such new compounds included JVC´s "Supervinyl", which was more durable than convention materials, and Q-540, which was highly anti-static. | SOURCE : Compatible Discrete 4. in: Wikipedia. Available at : https://en.wikipedia.org/wiki/Compatible_Discrete_4 Accessed : 25 sep. 2022
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