Is the Optical Cable Dying? (cnet.com)

Geoffrey Morrison from CNET explains how the optical cable is "dying a very slow death": The official term for optical audio cable is "Toslink," short for Toshiba Link. Developed in the early '80s to connect their CD players to their receivers, it was a red laser optical version of the Sony/Phillips "Digital Interconnect Format" aka S/PDIF standard. You've seen standard S/PDIF connections a bunch too; they're often called "coax digital." Optical had certain benefits over copper cables, but they were also more fragile, and for a long time, more expensive. Though glass cables were available, for even more money, most optical cables were made from cheap plastic. This limited their range to in-room use, primarily. Through the '90s and 2000's, the optical cable was near-ubiquitous: The easiest way to get Dolby Digital and DTS from your cable/satellite box, TiVo, or DVD player to your receiver. Even in the early days of HDMI, right next to it would be the lowly optical cable, ready in case someone's receiver didn't accept HDMI. But now more and more gear are dropping optical. It's gone completely on the latest Roku and Apple TV 4K, for example. It's also disappeared from many smaller TVs, though it lingers on in larger ones, a potentially redundant backup to HDMI with ARC. The reason for this? Soundbars...

Comments

Reason

[ledow]

"The reason for this? Soundbars..."

Nope.

The reason for this is - I don't want a separate connector for audio unless it's in conjunction with another connector (i.e. I either want one cable only, or one cable + additional audio to go to external devices). The external device itself could happily use the HDMI audio, and offer passthrough / splitting of the signal.

The problem is that the "other" connector almost certainly has to be able to supply video, audio, data and - sorry - power. Fibre cannot supply power. Ever.

And then most people would rather give it a whole HDMI with everything, rather than run a separate cable just for audio. To be honest, splitters are in the throwaway price range now, even with HDCP support etc.

The problem is that manufacturer's think "fibre just for audio" is a useful thing to have alongside "copper that does absolutely everything" when both are commodity pricing. Hell, just give me 10 HDMI slots and if I really want to run a soundbar, I'll run one with HDMI and/or put a convertor on it.

The other thing that matters - nobody really cares about the fibre "perfect sound" rubbish except audiophiles. But that's like saying "nobody cares about the flight simulator being pixel perfect except for qualified 747 pilots". You can't cater to that niche, as the business case isn't there to do so in a commercial product. But 99.9% of people are quite happy with MP3s, copper cables (especially digital copper cables), and the various MPEG/H264 etc. compressions.

I've been in IT for 20 years. I've honestly NEVER used an optical connection for sound. I deploy AV stuff all the time. I've even done bits of theatre stuff. The only optical connections I've ever used a networking fibres. And they are so cheap they don't even figure, what costs is the cutting and polishing, which wouldn't be present on a pre-made patch cable. So I also call rubbish on the "fibre is expensive, or can't reach across the room" line too.

But if I've never used SPDIF, I'm pretty sure most other people haven't either. And given that even RCA connectors are going the way of the dodo (and SCART in Europe), I can't say that SPDIF is going to last any longer.

Now, if you had a hybird, cable/fibre. Maybe that would serve. If it could do everything HDMI did. But HDMI even does Ethernet if you buy the right kit. So I can't fathom how you'd cut into their business.

All we really need is a merger of USB3 and HDMI and we have one connector for ABSOLUTELY everything. Including a decent amount of power. But fibre isn't necessary for that and would lose enormously if it was attempted.

Re: the soundbar reason is bs..

[thegarbz]

Erm the coax connector is digital, in fact the exact same digital data as optical.

Coax noise affecting the digital signal? Not Gonna happen.

Sorry but you're quite wrong about this. The signal may be exactly the same but the parent was talking about isolation and interference. Groundloops induce noise on signals, especially if the source is something like a PC. Having the cable connected vs disconnected is clearly measurable on the DAC / Receiver. In once case I even had a cheap receiver that woud lose lock on another signal if certain sources were connected via coax.

This *shouldn't* be a problem as any receiver worth its salt should be isolating the coax inputs via a pulse transformer, but outside of high-end DACs that practice was rare. Most receivers took grounds from the coax and connected them directly to the digital grounds of their DACs.

Why does it matter for a digital signal? Well in most cases the receiver would recover the clock via a PLL locked to the the incoming signal, so any deviation from perfect on the incoming signal at best could produce a measurable penalty on the analogue output, if the grounding wasn't setup perfectly it could introduce noise from the source, and at worst it could cause locking problems.

The same applies to electromagnetic interference which is why the professional AES3 implementation is typically done via buffered outputs, balanced signalling (XLR connectors), and transformer isolated, even though it is still carrying the same S/PDIF signal.

Re: the soundbar reason is bs..

[azcoyote]

You are correct that a digital signal is naturally protected against noise to some extent inasmuch as the noise should not be mistaken for signal.

However, noise can still interrupt a digital signal if it is significant enough. Noise is a problem in my setup because I have my PC in my basement and my monitor, speakers, and peripherals on the second floor. I push the length limits of USB 3 and HDMI using active repeaters, and they still have problems both because of the long parallel runs and because they come too close to the washing machine power line. When the washer is running, even with the repeaters, there's significant mouse lag. Without the HDMI repeater, the video signal is choppy. I haven't done audio over HDMI in this setup, but I imagine it would be a problem too.

So I use Toslink optical. Yes it's far from perfect because it compresses the signal, but most of my PC's audio is compressed in a lossy way at some point. Also I had to install a hacked driver to enable 5.1 in the first place.

I agree that Toslink optical seems to be on its way out because it was pretty hard to find the right equipment at an affordable price. It's sad because I would really like the technology to be updated and improved to carry 5.1 lossless. But the fact is that most people do not care about audio quality but only about convenience (hence the popularity of even low-quality Bluetooth devices).

As for me, I really wish that I could afford the optical USB cables I've seen on Amazon to try to reduce the mouse interference. Otherwise, I may have to open up the wall in the washroom and better shield the cables from the power line.