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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...
"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.
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.
Is optical audio dying? I have to ask, was it ever alive?
I have an extension to that: Should it have ever been alive?
The standard which had limited distance, limited performance (20bit max vs 24bit standard for AES3 using S/PDIF), implemented with cheap plastic cables, using cheap LED based transmitters, and even cheaper receivers all to carry a signal that also is used to clock the digital parts of downstream equipment meaning the quality of the signal was important, rather than just the ability to send a 1 and 0.
It should have never existed. The AES3 standard was far superior. The cost to implement was equal (buffered driver + BNC vs dedicated powered transmitter / receiver electronics), and if it was isolation you wanted a cheap pulse transformer should have been the choice.
It was conceived at a time of an ideal future where our entire lives would be dominated by light for everything. I often wonder how we got to 1000baseTX networking at a time where people were saying we'll never get beyond 10mbps without fibre.
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.
Incipiamus, fratres, servire Domino Deo, quia hucusque vix vel parum in nullo profecimus.
and it works great.
At work we have a very nice looking executive conference room that was mostly configured before I worked here. If you look at that picture the audio equipment is behind the wall with the pictures on it. The main screen is behind the photographer, and so is the PC that runs the main screen. The tech who did part of the original setup ran an 1/8" to RCA cable from the TV's output all the way to the audio amplifier behind that other wall, past florescent lights and everything else in the ceiling. To say the least there was a buzz in the system that I could sometimes get rid of by wiggling cables, putting a little shielding here or there and praying for the best. I didn't like that solution.
Now, I can work fiber optics, I learned that from my years at NASA. I had never really worked with TOS before beyond using some cheap plastic light-guide short distances on stereo equipment on occasion and with my Turtle Beach headset on my work Mac, main system sound went to the dongle via TOS and the USB portion did voice - an awesome setup on what would have been an awesome headset had they not used the most brittle plastic they could find to mold it. I started calling fiber suppliers looking for the connectors so I could make my own cable - they didn't call back. It took a little research to find out that TOS doesn't work on standard OC3 cable, or any other fiber I have run in the past, part of the reason my suppliers didn't carry it. I also found mixed information about the range of TOS saying it topped out around 15 feet or so, and some giving it a lot more.
I figured out it's a lot like Ethernet - some who learned Ethernet 25 years ago is going to keep in mind there's a limit to accumulative cable length throughout the whole network, the longer you make one cable the shorter the rest have to be, that it's a collision based system where only two systems can talk at a time, etc... Things that used to be true and are still true on really, really old equipment, some of which may still be in use, but using more up to day components there's a new reality. You can now buy TOS in high quality glass fiber, and it will go further. You still have limitations because the width of the fiber has to be "wide" to accommodate signal - at least I assume it does, I don't know if it's single-mode or multi, but I'm assuming it carries a wave form instead of a simple on/off since the requirements seem to stand. I eyeballed the room - I didn't really measure it, and I shopped. I found a 65 ft cable from a company I had never heard of and I have to tell you it works great. No more static, the sound quality is great. The only complaint is they can no longer use the TV remote to change volume, but the volume keys on the keyboard work. Since they only use the Direct TV in that room during really big soccer matches I don't see an issue.
I don't think I could have stretched HDMI that far. I could have converted it to SDI and changed it back to do it, but that would require an active box on both sides since nothing in play supports SDI natively. SDI is great for professional equipment, but the budgets I get to do thing usually don't allow for true professional grade equipment - not to mention pro grade equipment is usually a little behind consumer grade equipment when it comes to screen sizes and other little features that advertising people lock onto and "must have". I think I'm finally past having to explain to desktop users why they're better off with a wired keyboard and an Ethernet cable instead of wireless and WiFi, the power of news and buzz words is incredibly strong to marketing people and even though pure logic can win a lot of arguments, when the person who controls the money wants the biggest things with the right buzz words you sometimes have to get it, and SDI isn't a modern buzzword, even if modern SDI can support 4K.
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