RCA / Phono Connector Symbol
Definition: The RCA / Phono Connector symbol represents a coaxial audio/video connector — standardised informally as the RCA plug — consisting of a central signal pin (Signal Centre) and a surrounding shield (GND Shield), used in circuit diagrams and wiring schematics to show analogue audio, composite video, or low-frequency signal interconnections.
Also known as: phono connector, cinch connector, RCA plug, RCA jack, composite connector, phono jack.
What the RCA / Phono Connector symbol means
The RCA / Phono Connector symbol denotes an unbalanced coaxial signal interface widely used in consumer electronics. The inner contact carries the signal (hot), while the outer cylindrical shield is connected to ground, providing basic electromagnetic shielding for analogue signals.
In wiring diagrams and schematics, the RCA connector symbol marks the physical interface point between source devices (turntables, disc players, cameras) and destination equipment (amplifiers, televisions, mixers). Two pins are modelled: Signal (Centre) for the hot conductor and GND (Shield) for the return/ground path.
How to identify the RCA / Phono Connector symbol
The RCA connector symbol is typically drawn as a small rectangle or plug-outline shape with a centre-pin line (Signal) exiting from the right and a shield/ground line exiting from the left or bottom. Some schematic styles render it as a circle with a central dot for the signal contact and a surrounding ring for the ground shell, mirroring the physical plug cross-section.
Function in a circuit
An RCA connector provides an unbalanced coaxial signal path between two pieces of equipment; the centre conductor carries the audio or video signal at line level (nominally −10 dBV for consumer audio, 1 Vp-p for composite video), while the shield conductor serves as both signal return and ground reference, completing the circuit and partially rejecting interference.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60169-24 defines the RCA / phono coaxial RF connector; the standard specifies the 3.175 mm centre pin, the 8.25 mm outer diameter shell, and impedance characteristics for audio and video use. |
|---|---|
| ANSI/IEEE 315 | No dedicated ANSI Y32.2 / IEEE 315 symbol exists specifically for the RCA connector; it is typically represented in North American schematics as a generic coaxial connector (IEEE 315 Section 15) or labelled RCA/phono within a box connector symbol. |
| Key difference | IEC 60169-24 provides the mechanical specification; schematic representation varies by CAD tool rather than a single mandated glyph. Both regions use equivalent functional symbols showing centre-signal and outer-shield pins. |
Terminals / pins
| Pin | Name |
|---|---|
| signal | Signal (Centre) |
| gnd | GND (Shield) |
Typical values
Impedance: unspecified for audio (typically 10 kΩ load); 75 Ω for composite video (IEC). Signal level: −10 dBV (consumer audio), 1 Vp-p (composite video NTSC/PAL). Frequency range: DC to ~10 MHz for video; DC to ~20 kHz audio.
Where the RCA / Phono Connector symbol is used
- Consumer hi-fi audio connections between amplifiers, CD players, and preamplifiers
- Composite video connections between cameras, VCRs, DVD players, and televisions
- Subwoofer output connections from AV receivers to powered subwoofers
- Analogue audio patch bays in recording studios and broadcast environments
- Turntable phono cartridge output to phono preamplifier input
- S/PDIF digital audio coaxial connections (75 Ω RCA variant)
Example
In a home theatre wiring diagram, two RCA connector symbols appear at the subwoofer pre-out terminals of an AV receiver: the Signal (Centre) pin connects to the subwoofer amplifier input, and the GND (Shield) pin ties to chassis ground at both ends, completing the unbalanced mono bass signal path.
Key facts
- The RCA / Phono Connector has two pins: Signal (Centre) carries the hot signal and GND (Shield) provides the return ground path.
- Mechanically specified by IEC 60169-24; the centre pin diameter is 3.175 mm and the outer shell diameter is 8.25 mm.
- The connector is inherently unbalanced — the shield acts as both return conductor and ground, making it susceptible to ground-loop hum in long cable runs.
- For composite video the characteristic impedance is 75 Ω and signal amplitude is 1 Vp-p; for consumer audio the impedance is high (10 kΩ load typical) and nominal level is −10 dBV.
- S/PDIF digital coaxial audio uses an RCA connector wired for 75 Ω to carry IEC 60958 format digital audio streams.
- RCA connectors are not hot-pluggable in the sense of being rated for repetitive connection under power; connecting/disconnecting while signal is present can cause audible pops or ground-loop transients.
- Colour coding is standardised in consumer equipment: white or black for left audio channel, red for right audio channel, yellow for composite video.
Diagrams that use this symbol
Frequently asked questions
What does the RCA connector symbol look like in a wiring diagram?
The RCA connector symbol is drawn as a plug or box outline with two pins: a centre line labelled Signal (Centre) representing the inner conductor, and a second line labelled GND (Shield) representing the outer metal shell. Some tools use a circle-with-dot cross-section representation.
What does the RCA / Phono Connector symbol mean in a circuit diagram?
The symbol marks a physical coaxial interface point for analogue audio, composite video, or S/PDIF digital audio signals. The centre pin carries the signal; the shield pin is grounded, completing the unbalanced signal circuit.
What standard defines the RCA connector?
IEC 60169-24 defines the mechanical and electrical specification of the RCA phono coaxial connector. There is no dedicated ANSI Y32.2 or IEEE 315 schematic symbol; it is represented as a generic coaxial connector in North American schematics.
What is the difference between an RCA connector and a phono connector?
RCA connector and phono connector are the same component — 'phono' is the European common name (from 'phonograph'), while 'RCA' comes from Radio Corporation of America, which popularised the design in the 1930s. Cinch and chinch are additional regional synonyms.
How many pins does an RCA connector have?
An RCA connector has two conductors: pin Signal (Centre) for the hot signal path and pin GND (Shield) for the return/ground path, making it a two-terminal unbalanced connection.
Can I use an RCA connector for digital audio?
Yes. S/PDIF coaxial digital audio uses a standard RCA connector and cable, but the cable must be 75 Ω impedance-matched (per IEC 60958) rather than a generic audio cable, to preserve signal integrity at the 3–6 MHz frequencies involved.
What is the impedance of an RCA video connection?
Composite video over an RCA connector uses 75 Ω characteristic impedance as specified by IEC 60169-24 and broadcast practice, with a signal amplitude of 1 Vp-p. Consumer audio RCA connections are unmatched (high impedance, nominally −10 dBV signal level).
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