 RCA plugs forcomposite video (yellow) andstereo audio (white and red) | |||
| Type | RF coaxial connector | ||
|---|---|---|---|
| Production history | |||
| Designer | Radio Corporation of America | ||
| Designed | 1930s | ||
| General specifications | |||
| Diameter | 0.327 in (8.3 mm) 0.126 in (3.2 mm)contact dia.[1][2] | ||
| Cable | Coaxial | ||
| Passband | Typically 0–100 MHz | ||
TheRCA connector[3] is a type ofelectrical connector commonly used to carry analog audio and video signals. The name refers to the popular name ofRadio Corporation of America, which introduced the design in the 1930s.[4] Typically, the output is aplug type connector and the input ajack type connector. These are referred to asRCA plug andRCA jack respectively.
It is also called aphono connector,[5][6][7] referring to its early use to connect aphonograph turntable to anAM radio receiver.[4] Ashome audio systems became more complex, RCA cables became a standard way to connect components such asradio receivers,amplifiers, turntables,tape decks, andCD players (1980s). Their ubiquity led to them also being used for video: connectingAV receivers,analog televisions,videocassette recorders,DVD players, andgame consoles. They remain in use as a simple, widely supported means of connection.In some European countries such asFrance andGermany, the namecinch is still used as anantonomasia of the Chicago-based manufacturer Cinch,[8] for such a connector and socket.
The following dates were derived from historical RCA documentation.
RCA introduced this connector by 1937, when it was used inside a RCA model U-109radio-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.[10][11] Originally, the concept was intended as an easy method to unhook sources whiletroubleshooting the console during servicing.[citation needed]
By 1938,[4] 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.[7] The connector was labeled on the back of radio with one of the following terms: "Victrola", "Phono", "Pick-up", or "Television".[12][13] RCA later marketed a special turntable for45 RPM records, the model 9JY.[14]
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.[15] 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.[12][16]
In the 1950s, RCA connectors began to replace the older1⁄4 inch (6.35 mm)phone connectors for many other applications in the consumer audio world when componenthigh-fidelity systems started becoming popular during the transistor revolution.[citation needed] Refinement of the RCA connectors came with later designs, although they remained compatible.[citation needed]
In the 1980s, some computer monitors[17][18] and TVs had a RCA jack for composite video input.[19][20][21] These were typically high end TVs for the time, a notable example being the Sony ProFeel line.[22] 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.[23] Later, some televisions had RCA jacks for audio and video out[24] or component video inputs.[25][26]
In the most normal use, cables have a standard plug on each end, consisting of a centralmale 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 asRF connectors, used ceramic).
The RCA connector was initially used foraudio signals. As with many other connectors, it has been adopted for uses other than originally intended, including as aDC power connector, an RF connector, and as a connector forloudspeaker cables. Its use as a connector for composite video signals is extremely common but provides poorimpedance 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.[27] RCA connectors and cable are also commonly used to carryS/PDIF-formatteddigital 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 forcomposite video, red for the right audio channel, and white or black for the left channel ofstereo 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 ofcamcorders, other portable video sources andvideo game consoles.[28] Although nearly all connectors, including analog and S/PDIF audio as well as composite andcomponent 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 adigital signal can only befully received or not received at all. Cables should meet the S/PDIF specification as defined by the international standardIEC 60958-3 for assured performance.
The male plug has a center pin that is1⁄8 inch (3.175 mm) in diameter, and is surrounded by an outer shell that is1⁄3 inch (8.47 mm) in diameter.
When connecting the male into the female, the inner,hot (signal) connection is made before the ground connection has been guaranteed; this often produces a loud buzz if the equipment is active when the connection is made.
The hot signal wire and signal ground provided by an RCA connection implement anunbalanced connection. A true balanced connection is generally preferred in certain applications, particularly professional settings because it allows for the use of long cables while reducing susceptibility to external noise.
Using RCA connectors, each signal requires its own plug. Even the simple case of attaching a cassette deck may need four of them – two for stereo input and two for stereo output. In any common setup this quickly leads to a disarray of cables and confusion in how to connect them. This situation is made worse if one considers more complex signals like component video (a total of three for video and two for analog audio – or one for digital coaxial audio).
Attempts were made to introduce combined audio/video connectors for direct signals - the most successful example was theSCART connector, which was successful inEurope but did not enter widespread use elsewhere.[29] For a time the 5-pinDIN connector was popular for bi-directional stereo connection between A/V equipment, but it has been entirely displaced on modern consumer devices. ThoughRF modulators inherently transmit combined A/V signals in video applications, they depend onbroadcast television systems and RF connectors which are not universal worldwide; RF signals are also generally inferior to direct signals due to protocol conversion and the RF limitations of the three major analog TV systems (NTSC,PAL andSECAM).
Before HD television became a standard, nearly all TV sets,VCRs, andDVD players sold in Europe had SCART connectors,[29] although these were sometimes supplemented by RCA and/or RF connectors. SCART–RCAadapters also exist, which usually allow input of composite video and stereo audio.[30] Outside Europe, separate RCA connectors are usually used,[citation needed] supplemented by RF connectors forbackward compatibility and simplicity. Althoughmini-DIN connectors are used forS-Video connections, composite video, component video, and analog audio (mono or stereo) all use RCA connectors unless the signals are sent via SCART. In the digital realm, however, combined A/V connectors are gaining ground:HDMI is commonly used today for consumer electronics; andDisplayPort, a potential competitor to HDMI, is often found on home computers and peripherals.
%2c_digital_audio_(TOSLINK)%2c_digital_audio_(orange)%2c_analog_stereo_(red%2c_white)%2c_composite_video_(yel.)_and_S-Video_(Mini-DIN)_on_Sony_DVP-NS53P_DVD_player_(2005).jpg)
Plugs and sockets on consumer equipment are conventionally color-coded to aid correct connections. The standard[31] colors for the various signals are shown in the table below; however, beyond 7.1 audio, the standard has degraded to a more general white/yellow, red/blue, and green/yellow color scheme for each cable respectively.
Stereo audio applications use either black and red, grey and red, or white and red RCA connectors; in all three cases, red denotes right. White or purple may also be replaced by black. Some older tape recorders, and equipment like receivers designed to connect to them, use a 5-pin DIN connector to connect left and right for record and playback with a single cable. Adapters between this connector and RCA connectors have used white and red for left and right channel recording, and blue (or sometimes black) and yellow for playback, but this is not universal. Most modern equipment with RCA connectors for recording devices simply uses white and red for all stereo pairs, whether record or playback.
While these are the standard colors found on commercially made products, cables with different-colored connectors may be used, as long as the cable itself is compatible with the application (for example, cables with 75 ohms impedance for video andS/PDIF).
| Composite analog video | Composite | Yellow | |
| Analog audio | Left/Mono (record if 4 connector tape cable) | White | |
| Right (record if 4 connector tape cable) | Red | ||
| Left tape (play if 4 connector tape cable) | Black | ||
| Right tape (play if 4 connector tape cable) | Yellow | ||
| Center | Green | ||
| Leftsurround | Blue | ||
| Right surround | Grey | ||
| Left back surround | Brown | ||
| Right back surround | Tan | ||
| Subwoofer | Purple | ||
| Digital audio | S/PDIF | Orange | |
| Component analog video (YPBPR) | Y | Green | |
| PB/CB | Blue | ||
| PR/CR | Red | ||
| Component analog video/VGA (RGB/HV) | R | Red | |
| G | Green | ||
| B | Blue | ||
| H (Horizontal sync)/S(Composite Sync) | Yellow | ||
| V (Vertical sync) | White |
