S/PDIF (optical digital audio) – HDfury Vertex glossary
S/PDIF is an older digital audio link over optical or coax. It carries stereo PCM or compressed 5.1, not lossless surround.
S/PDIF is a way to send digital sound from one device to another over a single cable. The optical version uses light instead of electricity.
It is like a narrow pipe: plenty for stereo music or normal 5.1 movie sound, but too narrow for the big lossless formats.
Does the HDfury Vertex have an optical (S/PDIF) audio output?
YESYes. The D/A jack takes a mini-TOSLINK cable for optical sound up to 5.1 Dolby/DTS, or a 3.5 mm cable for analog stereo. Lossless formats such as TrueHD or DTS-HD MA go over HDMI only, not optical.
How to use it with the Vertex:
- Plug a 3.5 mm mini-TOSLINK cable into the D/A jack, or use a mini-TOSLINK to TOSLINK adapter (p.105).
- No sound? Select a preloaded EDID ending in 'SPDIF' so the source sends a format that fits (p.15).
- For stereo speakers without an AVR, use a 3.5 mm analog cable in the same jack (p.105).
- With ARC set up, TV sound can come out of the optical output too (p.39).
What it is
S/PDIF (Sony/Philips Digital Interface) is standardised as IEC 60958. It comes as a coaxial cable with RCA plugs or as an optical cable called TOSLINK. It carries two channels of uncompressed PCM, or compressed surround such as Dolby Digital or DTS up to 5.1 (sent using IEC 61937).
S/PDIF does not have enough room for lossless multichannel formats like Dolby TrueHD or DTS-HD Master Audio, and so not for the Atmos or DTS:X versions on Blu-ray either. For those you need HDMI or eARC. Many older AV receivers and soundbars still have an optical input, which is why S/PDIF is still useful.
On the Vertex
The Vertex has a 3.5 mm combo jack labelled 'D/A'. Plug in a 3.5 mm analog cable for stereo, or a mini-TOSLINK cable for optical digital audio up to 5.1 Dolby/DTS (p.104-105). With an adapter you can use a regular TOSLINK cable (p.105). Analog stereo and optical come out of the same connector at the same time (p.108).
Lossless audio is only sent over HDMI; the Vertex does not squeeze it down to fit S/PDIF (p.104). If your source sends TrueHD or DTS-HD, the optical output will not give you that. Several preloaded EDIDs end in 'SPDIF' (for example no. 12, p.15). They limit the sound the source is told it may send, so the source picks a format that fits the optical link.
With ARC set up, sound from the TV can come out of the optical output too (p.39).
Common questions
Why do I get no sound from the optical output?
The source may be sending a lossless format such as TrueHD, or multichannel PCM, which S/PDIF cannot carry. Pick an EDID ending in 'SPDIF' so the source sends a format that fits (p.15-17).
Can the Vertex optical output give 7.1 or Atmos?
No, stereo or 5.1 only (p.104). The one exception is DD+/Atmos from TV apps via ARC to an AVR that accepts 192 kHz over optical (p.39).
Do I need a special cable?
Yes: a 3.5 mm mini-TOSLINK plug, or a mini-TOSLINK to TOSLINK adapter for a regular optical cable (p.105).
- https://en.wikipedia.org/wiki/S/PDIF
- https://monopricesupport.kayako.com/article/121-what-audio-formats-does-s-pdif-support
- manual p.15
- manual p.104
- manual p.105