Audio

Surround Sound

Surround sound cables and connectors are used to deliver multi-channel audio from source devices (computers, receivers, Blu-ray players) to speaker systems. Multiple technologies exist for carrying surround sound audio, ranging from analog multi-channel connections using color-coded 3.5mm jacks to digital optical and coaxial connections. Understanding these connectors is important for setting up home theater systems and professional audio installations.

Primary Use

Multi-Channel Audio Output

Reference Image

Surround Sound cable and connector

Key Features

  • Multiple connector types serve the surround sound ecosystem
  • Digital options (TOSLINK, HDMI) carry multiple channels over a single cable
  • Analog 3.5mm jacks are color-coded: green (front), black (rear), orange (center/sub)
  • TOSLINK uses light to transmit audio - visible red light when active
  • Digital coaxial uses an RCA-style connector (orange) for digital audio
  • Channel configurations: 2.1, 5.1, 7.1, and newer Dolby Atmos/DTS:X formats
  • HDMI ARC/eARC is increasingly the preferred method for surround sound

Variants & Standards (6)

TOSLINK (Optical/S/PDIF)

Digital optical audio using light through a fiber optic cable

  • - Distinctive square connector with a protective cap
  • - Transmits audio as light pulses through plastic fiber
  • - Supports up to 5.1 surround sound (Dolby Digital, DTS)
  • - Immune to electrical interference
  • - Red/infrared light visible when active
  • - S/PDIF stands for Sony/Philips Digital Interface
  • - Cannot carry Dolby TrueHD or DTS-HD Master Audio (bandwidth limited)
Digital Coaxial (S/PDIF)

Digital audio over an RCA-style coaxial cable

  • - Uses standard RCA connector, typically orange colored
  • - 75-ohm coaxial cable
  • - Same audio formats as TOSLINK (S/PDIF protocol)
  • - Electrical signal (not optical)
  • - Slightly more bandwidth than TOSLINK in practice
3.5mm TRS/TRRS (Analog)

Analog audio jacks, color-coded for surround sound channels

  • - 3.5mm (1/8 inch) round plug - same as headphone jack
  • - Color coding for surround: Green=Front, Black=Rear, Orange=Center+Sub
  • - Blue = Line In, Pink = Microphone
  • - TRS = Tip-Ring-Sleeve (stereo), TRRS = Tip-Ring-Ring-Sleeve (stereo + mic)
  • - Requires one cable per pair of channels for surround
RCA (Analog)

Classic circular audio connectors, color-coded by channel

  • - Circular push-on connectors with center pin
  • - White = Left audio, Red = Right audio
  • - Yellow = Composite video (not audio, but often bundled)
  • - For analog surround: additional colored RCA cables for each channel pair
  • - Widely used in home theater receivers and older equipment
Banana Plugs / Binding Posts

Speaker wire connectors for connecting amplifiers to speakers

  • - Banana plugs: cylindrical plugs that insert into binding post holes
  • - Binding posts: threaded posts that accept bare wire, banana plugs, or spade lugs
  • - Color coded: Red = positive (+), Black = negative (-)
  • - Found on AV receivers, amplifiers, and speakers
  • - Gauge of speaker wire matters: lower gauge = thicker wire = better for long runs
HDMI ARC/eARC

Audio return through HDMI cable - simplifies surround sound setup

  • - Uses standard HDMI cable and connector
  • - ARC supports Dolby Digital and DTS (compressed)
  • - eARC (HDMI 2.1) supports Dolby TrueHD, DTS-HD MA, and Dolby Atmos
  • - Eliminates need for separate audio cable from TV to receiver
  • - Requires both devices to support ARC/eARC on the same HDMI port

Quick ID Tips

1 TOSLINK: Square connector with a distinctive cover/cap - look for red light when connected to active device
2 3.5mm audio jacks: Color coded - GREEN=front/headphones, BLACK=rear, ORANGE=center/sub, BLUE=line in, PINK=mic
3 Digital Coaxial: Looks like an RCA connector but typically ORANGE - carries digital audio
4 RCA (analog): Color-coded circular connectors - RED=right audio, WHITE=left audio
5 Speaker wire/banana plugs: Bare wire or cylindrical plugs that press into binding posts
6 Optical cables are very lightweight and you can see light through the connector tip

A+ Exam Notes

TOSLINK is the square optical connector - remember it uses LIGHT for audio
Know the 3.5mm color coding: Green=Front/Headphones, Black=Rear, Orange=Center+Sub, Blue=Line In, Pink=Mic
S/PDIF is the PROTOCOL - it can run over TOSLINK (optical) OR digital coaxial (electrical)
RCA color coding: White=Left, Red=Right, Yellow=Composite Video
HDMI can carry surround sound audio along with video - this is an advantage over dedicated audio cables
eARC is the enhanced version of ARC available on HDMI 2.1 - supports lossless surround formats
For the A+ exam, focus on identifying connectors by their physical appearance and color coding

At a Glance

Type Audio
Variants 6
Key Features 7
Exam Tips 7