RCA connector

The RCA connector is a type of electrical connector commonly used to carry analog audio and video signals. The name refers to the popular name of Radio Corporation of America, which introduced the design in the 1930s. Typically, the output is a plug type connector and the input a jack type connector. These are referred to as RCA plug and RCA jack respectively. It is also called a phono connector, referring to its early use to connect a phonograph turntable to an AM radio receiver. As home audio systems became more complex, RCA cables became a standard way to connect components such as radio receivers, amplifiers, turntables, tape decks, and CD players. Their ubiquity led to them also being used for video: connecting AV receivers, analog televisions, videocassette recorders, DVD players, and game consoles. They remain in use as a simple, widely supported means of connection. In some European countries such as France and Germany, the name cinch is still used as an antonomasia of the Chicago-based manufacturer Cinch, for such a connector and socket.

History

The following dates were derived from historical RCA documentation. RCA introduced this connector by 1937, when it was used inside an RCA model U-109 radio-phonograph and model R-97 phonograph. In the U-109, the internal amplifier chassis had female connectors that accepted male cables from the internal radio chassis and built-in phonograph player. Originally, the concept was intended as an easy method to unhook sources while troubleshooting the console during servicing. By 1938, RCA had migrated the female connector to the rear panel of many of their desktop AM radio models to allow customers an easy method to attach an external phonograph or television at a later date. The connector was labeled on the back of radio with one of the following terms: "Victrola", "Phono", "Pick-up", or "Television". RCA later marketed a special turntable for 45 RPM records, the model 9JY. In 1939, RCA introduced two radio-television floor consoles (TRK-9, TRK-12), which used the same internal connection concept, but the audio output of the television chassis was connected to the radio/amplifier chassis via a male-to-male cable. Three lower-cost 1939 television models had an audio output connector on their rear panel instead of an integrated amplifier and speaker: RCA TT-5, Westinghouse WRT-700, GE HM-171. In the 1950s, RCA connectors began to replace the older 1⁄4 inch (6.35 mm) phone connectors for many other applications in the consumer audio world when component high-fidelity systems started becoming popular during the transistor revolution. Refinement of the RCA connectors came with later designs, although they remained compatible. In the 1980s, some computer monitors and TVs had a RCA jack for composite video input. These were typically high end TVs for the time, a notable example being the Sony ProFeel line. While in theory this improved image quality by eliminating the need for an RF modulator, when connecting devices such as VCRs and computers, there was no guarantee for higher image quality. Later, some televisions had RCA jacks for audio and video out or component video inputs.

Other uses

In the most normal use, cables have a standard plug on each end, consisting of a central male connector, surrounded by a ring. The ring is often segmented to provide spring gripping pressure when mated. Devices mount the socket (female jack), consisting of a central hole with a ring of metal around it. The ring on the jack is slightly smaller in diameter and longer than the ring on the plug, allowing the plug's ring to fit tightly over it. The jack has a small area between the outer and inner rings which is filled with an insulator, typically plastic (very early versions, or those made for use as RF connectors, used ceramic). The RCA connector was initially used for audio signals. As with many other connectors, it has been adopted for uses other than originally intended, including as a DC power connector, an RF connector, and as a connector for loudspeaker cables. Its use as a connector for composite video signals is extremely common but provides poor impedance matching: there is neither a standard for plug impedance, nor is it feasible to provide a true match to 75 Ω due to plug dimensions. RCA connectors and cable are also commonly used to carry S/PDIF-formatted digital audio, with plugs colored orange to differentiate them from other typical connections. Connections are made by pushing the cable's plug into the female jack on the device. The signal-carrying pin protrudes from the plug, and often comes into contact with the socket before the grounded rings meet, resulting in loud hum or buzz if the audio components do not share a common ground and are powered while making connections. Continuous noise can occur if the plug partially falls out of the jack, breaking the ground connection but not the signal. Some variants of the plug, especially cheaper versions, also give very poor grip and contact between the ground sheaths due to their lack of spring action. They are often color-coded, yellow for composite video, red for the right audio channel, and white or black for the left channel of stereo audio. This trio (or pair) of jacks can often be found on the back of audio and video equipment. One or more sets are often found on TV sets to facilitate connection of camcorders, other portable video sources and video game consoles. Although nearly all connectors, including analog and S/PDIF audio as well as composite and component video, can use identical 75 Ω cables, sales of special-purpose cables for each use have proliferated. Varying cable quality means that a cheap line-level audio cable might not successfully transfer component video. For digital audio, as long as a connection is successfully made using the cables, the sound will remain faithful to the original signal because a digital signal can only be fully received or not received at all. Cables should meet the S/PDIF specification as defined by the international standard IEC 60958-3 for assured performance. The male plug has a center pin that is 1⁄8 inch (3.175 mm) in diameter, and is surrounded by an outer shell that is 1⁄3 inch (8.47 mm) in diameter.

Disadvantages

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