Cheap Toslink Switch boxes?

kinger8938 · 30 Nov 2019 at 19:56

I'm after a device so I can swap optical from my Sonos Beam to the TV, PS4 And PC without having to manually swap the cable etc.

Are the cheap £15 rainforest ones ok? Can they effect sound quality etc? Just for 5.1 Dolby

lucid · 30 Nov 2019 at 21:19

Dolby 5.1 is a bitstream signal, which means it's all the channels encoded in to a stream of pulses. The only way to affect the quality in such a signal is either to break the stream of pulses (total signal loss) or to decode the DD bitstream audio and then re-encode again doing a bad job on one or both of the steps. A £15 electronic optical just won't contain the hardware for that level of decoding.

What's happening inside these switches is that the light pulses are converted to electrons which makes the signal easier to route through some switching electronics. It's then converted back from electrons to photons which makes it a light pulse signal again. Unlike optical to analogue stereo convertors, the signal shouldn't ever become analogue, and so there isn't an issue with signal degradation in that sense.

Maybe of more interest is the reliability of the switches and whether the remotes are useful at a distance.

jpaul · 30 Nov 2019 at 22:35

not necessarily plain sailing - bandwidth, jitter, latency ?
- can it works at the speed required for the 5.1 sgnal you're pushing through it (like the 18Gb/s premium hdmi lead questions)
- if the signal is converted optical->digital->optical is the timing accuracy preserved (earlier posts on chromecast audio jitter) could get stutter in receiving device
- any latency issues ie, lip-sync that cannot be adjusted for in sending/receiving device

lucid · 1 Dec 2019 at 01:28

The data rates for normally-encoded DD5.1 are nothing like as large as for video data in HDMI. You're looking at just kilobits per second, so it's not even in the full megabit per second range never mind Gigabits.

Normally encoded DD5.1 is a minimum of 192kbps, median 384, and a maximum 448kbps.

If latency was a serious issue then we'd have heard about it already with the small optical to coaxial convertors that have been available cheaply for a number of years. They use the same tech.

Jitter is always a possibility where conversion poses the risk of increasing the rise time. Once again though, measurements of optical to coaxial convertors showed that the before and after signals were functionally identical. If there is an increase in jitter due to the conversion, then it's likely to be at such a low level that it's imperceptible within the compressed audio of a 5.1 DD signal.

The bigger concerns are for the reliability of the device and the range/power of the IR remote.

kinger8938 · 1 Dec 2019 at 18:05

Must admit, everything above has gone mostly over my head

Are we saying, they should be ok, but may not be too reliable in terms of the unit itself?

lucid · 1 Dec 2019 at 19:11

Yep. The TL; DR version is...
'Q: will it change the sound? A: No, or not so you'd notice'
'Q: Will this work out of the box and keep on working? A: 50/50 chance'
'Q: Is the remote powerful and does it have good range? A: Flat no, or extremely unlikely'

The natural follow-on question then is whether there's something better.

Looking at the products on Ebay and Amazon, I would say not unless you're willing to spend over £60 on a CYP brand switcher.

kinger8938 · 1 Dec 2019 at 19:34

lucid said:
Yep. The TL; DR version is...
'Q: will it change the sound? A: No, or not so you'd notice'
'Q: Will this work out of the box and keep on working? A: 50/50 chance'
'Q: Is the remote powerful and does it have good range? A: Flat no, or extremely unlikely'

The natural follow-on question then is whether there's something better.

Looking at the products on Ebay and Amazon, I would say not unless you're willing to spend over £60 on a CYP brand switcher.

I think I'll give one a try and see. Then theres the optical cables themselves? Is it the same story? For a non-audiophile like myself, will they all be much the same?

lucid · 1 Dec 2019 at 20:27

Optical cables; at this level they all do the same job.

I can't believe how some manufacturers make gold-plated optical cables. That's completely redundant. lol

The signal is pulses light. Gold-plating makes bugger-all difference to a signal that isn't electrical. In fact, it's debatable whether the few micros of gold flash that counts as gold plating in most electrical AV cables has any real benefit either, but that's another story.

There's some optical cables as thin as pencil lead on the rain forest site. They start at a couple of quid delivered. They'll do just as well as the fat cables at a tenner of more.