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Optical Audio

TOSLINK / S/PDIF Optical

Standard: IEC 60958, EIAJ CP-1201 (TOSLINK) Last updated: 2025-01-21

TOSLINK was developed by Toshiba in 1983 (Toshiba Link). It uses fiber optic cable to transmit digital audio, eliminating ground loops and electrical interference. While it can't match HDMI's bandwidth for lossless surround formats, it remains popular for TV-to-soundbar connections due to simplicity. The connector has a distinctive square shape, and you can often see red light when the cable is connected and active.

Quick Specifications

Max Speed

12.288 Mbps

Pins

1

Reversible

No

⚠️ Common Confusion Points

  • TOSLINK is the connector, S/PDIF is the protocol - they're often used interchangeably but aren't the same
  • Cannot carry Dolby TrueHD or DTS-HD Master Audio (lossless formats) - bandwidth too low
  • Cannot carry Dolby Atmos or DTS:X (object-based audio) - use HDMI eARC instead
  • Mini-TOSLINK (3.5mm optical) looks like a headphone jack but uses light
  • Some Macs have combo 3.5mm/Mini-TOSLINK ports - you need a Mini-TOSLINK adapter
  • Cable length affects signal quality - keep under 5m for reliability
  • Cheap cables work fine - unlike analog, optical is digital so cable quality matters less
  • The red light should be visible when active - useful for troubleshooting

Protocols & Versions

Protocol Data Rate Power Max Length
S/PDIF (Stereo) (S/PDIF) 3.072 Mbps — 10m typical, 5m recommended
Dolby Digital (Dolby Digital) 640 kbps max — 10m
DTS (DTS) 1.536 Mbps max — 10m
ADAT Lightpipe (ADAT) 12.288 Mbps — 5m recommended

S/PDIF (Stereo) Features

2-channel PCM up to 24-bit/192kHz Dolby Digital (AC-3) DTS

Cable requirements: Standard TOSLINK cable

Dolby Digital Features

5.1 surround (compressed) AC-3 encoding Standard for DVD/Blu-ray

Cable requirements: Standard TOSLINK cable

DTS Features

5.1 surround (compressed) DTS-HD (core only) Higher bitrate than Dolby

Cable requirements: Standard TOSLINK cable

ADAT Lightpipe Features

8 channels at 48kHz/24-bit 4 channels at 96kHz Professional audio

Cable requirements: Standard TOSLINK cable (same connector)

Connector Specifications

Shape
square with rounded top (TOSLINK) or 3.5mm (Mini-TOSLINK)
Pins
1
Width × Height
9 × 9 mm
Depth
10 mm
Reversible
No

Compatibility

Can Adapt To

  • Coaxial S/PDIF (converter)
  • HDMI ARC (via receiver)

Can Adapt From

  • Coaxial S/PDIF (converter)
  • 3.5mm Mini-TOSLINK (adapter)

Common Uses

  • TVs
  • Soundbars
  • AV receivers
  • Game consoles (PS4, Xbox)
  • Blu-ray players
  • CD players
  • DACs
  • Audio interfaces (ADAT)
  • Mac computers (Mini-TOSLINK in headphone jack)

Buying Guide

Any basic TOSLINK cable will work - expensive cables provide no benefit for optical digital audio. Keep cables under 5m for best reliability. If connecting to a Mac's combo jack, you need a Mini-TOSLINK to TOSLINK adapter. For lossless surround sound (Atmos, TrueHD), optical won't work - use HDMI ARC/eARC instead. Optical is still useful for connecting TVs to soundbars when you don't need lossless audio formats.

Also Known As

TOSLINK Optical SPDIF Optical Lightpipe ADAT Lightpipe

Data Sources