RCA connector

Phono (RCA ) [ kɪntʃ or sɪntʃ ] is a widely used slang term for non-standard connectors for asymmetric transmission of electrical signals, especially with lines with coaxial arrangement for transfer of low and high frequency signals ( shielded cable or coaxial cable ). The use of different cable types is rather rare.

This type of connector has been increasingly used in the U.S. since the 1940s, as in German-speaking nor banana plug or DIN connector ( square plug, Tuchel, and others) were common.

The electrical rating of the plug connection is usually 30 VAC / 0.5A, whereby high-load variations are offered to 250 VAC/10 A with a dielectric strength of 1 kV.

Term

The international and correct name is RCA jack, because the plug-in was developed at the time of the Radio Corporation of America, but in the U.S. are also phono jack or phono plug (actually turntable connection) Common Names.

The usual designation in Germany RCA could be found on the U.S. company " RCA connectors" to go back (to have this plug and socket type initially mainly produced, the names creation does not take claim for themselves ). The English noun cinch means, among other things, " tight grip " ( which is also correct translation "no-brainer " - meaning " with ease " - seems to derive less obvious ); the verb to cinch means " lash " among others. An original primary meaning of the word stands for belt / girth, which at least has a certain similarity with the outer grip of the socket by the plug.

In German-speaking various other spellings are not correct next to the correct spelling RCA often used, for example, " RCA " (pronounced "chee -friction "), " Cynch " or " Chynch ".

Areas of application

Use this connector is mainly in home audio and video range ( audiovisual). As a separate connector is used for each signal, a color coding of the function offers. In return, (largely) consistent color codings have naturalized:

Audio

White: left analogue channel (sometimes black or gray or yellow, the latter because of the common L in left and yellow)
Red: Right analog channel
Orange: Digital Audio ( S / PDIF)
Black: subwoofer or center channel
Gray: speaker plug (rare)

Occasionally used for the connection of audio recording equipment cables that same bundle four ports and can thus cover both the inputs and the outputs of the device in stereo. In these cables the colors red, white, yellow and black are used:

White left channel for playback
Red: right channel for playback
Black: left channel for recording
Yellow: right channel for recording

This color combination is also used for some adapters from RCA to five pin DIN connectors and SCART adapter.

Reminder: The " colorful " connections are right, the " achromatic " left. The most famous pairing of white and red is used for playback.

The typical line- AF level is about -6 to 6 dBV ( 0.5 to 2 Vrms ). The resistance at signal outputs is about 200 ohms to 2 ohms, with signal inputs from 10 kOhm to 1 MOhm. The CCITT standard = 600 ohms only meaningful applications in metrology.

Video

Composite Video Yellow: Composite Video

Green: Yy (Component Video, brightness)
Blue: Pb (Component Video, color difference )

Pros and Cons

RCA plugs usually come with coaxial cables are used. Disorder Poorer differential signal transmission methods are usually not realized with RCA connections, since they would require a paired connection per signal. Form via the coax outer conductor may be incurred earth loops - as well as other coaxial connections - a source of interference. RCA coax combinations are suitable, because the contact is not secure due to much larger deviations also not for metrology, high-end audio or microphones.

RCA plug should be plugged for safety's sake only when the equipment is switched, since the inner contact " voreilend " is - the inner " hot" pin protrudes further out and thus gets from the external ground shield contact. This can damage sensitive equipment when they are during insertion into operation.

Although RCA connectors are the standard for consumer devices, they have many weaknesses, why be used for studio equipment or balanced XLR connector plug. The two-pole asymmetric design of the RCA connector to the shield as a return conductor for the signal makes the transmission more vulnerable to disruption than the balanced signal transmission used in the studio technology. This has two signal contacts for signal and phase-inverted signal and a third contact for the bulk, although the shield and the equipotential bonding is used, but does not execute even when ground loops interference.

The manufacturing accuracy of RCA connectors is often insufficient because an accurate standardization is lacking, why put some plugs either too loose or too tight on the sleeves. In the first case, the contact is unreliable in the last socket or its attachment may be damaged. Especially with directly soldered onto printed circuit boards sockets this can lead to failure of the device.

Another weak point is the poor handling. So must be connected in contrast to the DIN connectors for a stereophonic recording device per connector two couples (both left and right channels for recording and playback, a total of four plug).

The impedances and levels are not uniform for analog audio, so that it can occasionally occur even in devices from different series from the same manufacturer to loudness to distorting mismatches in devices from different manufacturers. The digital audio transfer via S / PDIF ( Sony / Philips Digital InterFace ), however, is standardized. These have the usual consumer devices for S / PDIF level of 0.5 Vpp concluded at its output with a resistance of 75 ohms ( the wave impedance) output. Video signals have - regardless of the type of connector - a level of 1.0 Vpp into 75 ohms.

Advantage of the RCA connector is that due to the separate plug for each individual signal to easily adjust to the desired connection between two devices is possible, for example, crossed connections for direct dubbing between two tape devices - what with DIN cabling a special cable (similar to is a null modem cable) needed, which swaps the pins and adjust the level by resistors. In general, however, the dubbing is performed via an amplifier whose circuit makes this adaptation so then suffice two ordinary 1:1 wired cable.

Because of the continuous individual screening of each individual line, the crosstalk between left and right channels of a stereo signal or between front and rear band signal of a recording device is theoretically lower with RCA plugs. But for this opposite effect the common ground connection, albeit split across multiple lines, and their contact and line resistance. Especially at low input impedances ( non-negligible currents) affects the negative impact on the crosstalk.

Cable

For RCA coaxial cable connections are usually used. This is necessary to shield signal voltages to small disturbances caused by electrical fields from the outside. Magnetic fields have no disturbing effect here as with twisted twin cable.

In cases with high signal levels shielding is not necessary. Examples are the power supply or connections between the amplifier ( audio amplifier ) and speakers or headphones. Then can also be used a symmetrical pair of wires ( twisted pair),.