An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The name "RCA" derives from the Radio Corporation of America, which introduced the design by the early 1940s for internal connection of the pickup to the chassis in home radio-phonograph consoles. (See Origin, below.) It was originally a low-cost, simple design, intended only for mating and disconnection when servicing the console. Refinement came with later designs, although they remained compatible.
RCA connectors began to replace the older quarter inch phone connectors for many other applications in the consumer audio world when component high fidelity systems started becoming popular in the 1950s. However, quarter inch phone connectors are still common in professional audio, and miniature phone connectors (3.5 mm) are predominant in personal stereo systems.
The connection's plug is called an RCA plug or phono plug, for "phonograph." The name "phono plug" is sometimes confused with a "phone plug" which may refer to a quarter-inch "phone plug" (TS or TRS connector) or to a connector used for a telephone.
Color coding in consumer equipment
Plugs and sockets on consumer equipment are conventionally color-coded to aid correct connections. The standard colors for the various signals are shown below; however, beyond 7.1 audio, there are no standardized colors as of yet
In stereo audio applications there are combinations of either Black+Red,Grey+Red or White+Red RCA connectors; in both cases, Red denotes Right. White or Purple may also be replaced by Black. This is however not true in tape recorder applications with four connectors cables where white is always left channel recording and black or sometimes blue is always left channel playback. Four connector tape recorder cables is mainly used in adaptors between RCA connectors and 5-pin DIN connectors.
While these are the standard colors found on commercially made products, same-colored cables may also be used. For example, a red cable may be used instead of a yellow one, as there is no other difference between them. There are generally two kinds of cables, for video (composite, component YPbPr and RGB) and digital audio 75 ohm impedance coax cable is recommended, for analog audio high impedance cable is recommended. Using high impedance cable for video and digital audio signals degrades signal quality, more noticeable with longer cables and with higher video resolutions. Using a 75 ohm impedance coax cable for analog audio is usually technically not a problem (but those cables are usually more expensive than high impedance cables)