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Comment by someguydave | Hacker News Reader

I use optical audio in a mac mini as a home theater TV driver. No thanks.

These days optical audio is dying when it comes to home theater systems, primarily due to its lack of codec support. You can't passthrough DTS-HD over optical, you can over HDMI.

I used to use optical audio but it was superseded by HDMI for home theater and USB for hifi.

edit: I'd be curious to see what people are using optical for today (I'm under the impression audio pros mainly use USB interfaces as well)

I bought a soundbar for my TV a couple months ago. Recent Samsung model. Has optical. I beleive the only other option was 3.5mm jack.

Interesting. I bought a pretty cheap soundbar this year (from Yamaha) and I think it had optical as an option (along with 3.5mm and Bluetooth) but the main interface was HDMI-ARC.

And it works great over ARC! The TV remote's volume buttons get passed through automatically, and it turns itself off and on along with the TV. I don't even know where the soundbar's own remote is anymore.

Shockingly, I need optical for a $300 set of gaming headphones I purchased within the last year (Astro A50). Maybe it’s the only way they can do pass through, dunno.

Never would have guessed that for headphones! I guess they have some kind of a dock?

Wireless (non-Bluetooth) Sennheiser headphones also take optical input (as well as 3.5mm). Since they're only doing stereo, and require a digital-to-analog conversion on the headphone side, makes sense to avoid an additional analog-to-digital on the transmitter side.

It’s (likely) because they don’t want to add a secondary hdmi output for audio like a lot of other high end gear uses.

Headphones are stereo (okay, there are some exceptions), and optical S/PDIF can do stereo PCM, so there's no quality downside. But for home theater audio, you can't do any lossless multi-channel formats over optical S/PDIF, so the vast majority of enthusiasts will use HDMI.

I'm not a pro audio guy, but I think if you want to work with any external audio device and want that connection to be noise-free, your safest bet is still optical.

I have an external DAC/amp, and I had been using optical until I recently upgraded my workstation. Now I am using USB, because the new motherboard doesn't have optical; I assumed USB would be fine, so the lack of optical wasn't something I considered with the purchase.

Unfortunately there's an awful amount of hiss with USB on this DAC. I'm not knowledgeable enough to pinpoint what's causing it, but standard remedies I've found (eliminate ground loop, try ferrite cores, get a usb filter) have not made a difference. It could be the USB interface on the DAC side, I have no idea.

While I don't _need_ an external DAC, I like using one for a few reasons: mine has a low output impedance which is good for some headphones, a convenient switch to toggle between headphone and speaker output, and a big volume knob with really smooth action. I like it. The alternative is to use the motherboard's ports; this motherboard does jack sensing such that the rear line out gets disabled if something is plugged into the front, so switching between headphones and speakers involves plugging/unplugging the headphones all the time. I also don't like adjusting volume through a tray applet.

Since it’s USB, it has to be the DAC generating the hiss. No amount of electrical interference can do anything to the digital audio going Ofer USB.

I thought so too, but regardless, with this same device there is no hiss when connected via optical. So if I had the option, I'd be using optical vs. USB today, which was what the GP asked.

Logically, it seems like if you had a USB-optical dongle you would have no further trouble. I don't know if there is such a thing, but I do know that in that situation all the 'it's digital, so it should be perfect' talk becomes somewhat true.

You'd be converting from USB to optical, at which point you'd break the ground connection which would be where your hiss is coming from (assuming it's still noiseless when still being used with optical). Then, your concern would be jitter and whether the added conversion is adding lots of jitter to the equation. Your DAC might (or might not) be good at rejecting jitter noise. I've got a Lavry DA10 that's exceptionally good at rejecting jitter (in crystal mode), but that's mastering grade and maybe overkill for you.

It wouldn't add literal noise, but it's also possible for the USB connection to be more jittery than a different computer making the optical connection. That's partly hardware and partly software design (controlling how the data stream is buffered, and associated things that might slightly modulate the audio data clocking). So a change in computer feeding the DAC could also substantially affect the 'sound' of the DAC, as well as the noise issue you observed.

I agree, that should work. I haven't seen USB-optical devices that weren't straight media converters though. Everything that converts USB to spdif is advertised as a DAC, so I'd have two DACs.

This isn't a huge issue for me, it's just an example of where I'd prefer to use optical. If it ends up bothering me such that I need to fix something, I'll 'fix' the motherboard.

But it sounds like its the same DAC, which was hiss free with optical. So it's not the DAC "generating" the hiss. Rather electrical "interference" making it over to the analog side from the digital side.

So it's the DACs fault, but maybe it's fair to say that it's harder to make a good DAC when USB is how the data is being delivered. I'm sure a high end USB DAC doesn't have this issue, but I'm pretty impressed with my cheap offbrand optical DAC that was $11. I'm guessing I would not be so impressed with the $11 USB version.

A higher quality USB DAC either has to do quite a bit of signal clean-up, and may use its own power supply rather than trying to clean up the USB power from the computer.

Optical has the benefit of always being electrically isolated.

The electrical interference can't do anything to to the digital audio, but interference on the USB cable can potentially be picked up by the analog amplifier circuitry in the DAC. I had a particular combination of headphone, DAC and amplifier years ago that I could hear electrical noise on when no music was playing.

Absolutely. I work as a sound engineer and have used lots of things of this type, and it's particularly easy to understand how a USB connection to the computer would wreck the sound of a cheap (sub-$1000, not professional) DAC.

Optical digital means perfect isolation from the ground plane of the computer. It's that simple. The DAC can do whatever it needs to manage its own noise levels, but you're pretty much guaranteed a huge difference from entirely decoupling the DAC from the computer's ground plane. That electrical interference can do a surprisingly enormous amount of damage to the analog circuitry of the cheap DAC, which itself is probably not very resilient at rejecting any sort of electrical interference.

> Unfortunately there's an awful amount of hiss with USB on this DAC.

If you used optical before, it can be reasonable to use USB->optical. A lot of USB audio interfaces already have this. I'm not making use of it, but the USB interface I have on my Mini has an optical out.

Pro audio for recording has been shifting to USB over the past few years. They were heavily on Firewire or PCI card formats before, but USB has finally gotten fast enough to do the throughput, and of course it's much cheaper and more standard.

USB has had the throughput to handle multichannel audio for decades; USB still has issues regarding device priority when it comes to the nature of its interaction with the OS.

And thus throughput is not enough. In pro audio, we can't afford dropouts or lost data, even when the CPU is under heavy load.

I've got a pre-ARC TV, so use optical for my home theatre. Am hell-bent against smart TVs, so my next display will probably be either a digital signage display or a projector still without ARC.

I want to smash a Sony engineer with a hammer because my goddamned $5000 smart TV keeps insisting on switching from tv audio to external audio to tv audio to external audio to tv audio to external audio.

It doesn't matter that I have my audio preference set to "prefer external audio" because the effing thing decides to switch back and forth between 2 and 30 times on startup, and maybe 80% of the time it settles (properly) on the receiver, and 20% of the time it tries to use the TV speakers, which are off, and of that 20% of the time, at least half of the time I HAVE to power everything down and start all over again. The other half of the time I can go through the menu with the slow-ass on-screen menu, and manually toggle back to receiver.

I just want an effing option that says "never in hell try to use the fucking TV speakers, for the love of god".

My (very low-end) Samsumg soundbar only has optical and 3.5mm in. I think a lot of cheap equipment still uses optical.

Sonos, which might be one of the most hyped average user audio things in the last years, only offers optical inputs for their soundbars. Imho it's a pretty huge limitation on Sonos side, but maybe they did it because HDMI ARC is still flaky in many setups and they prefer ease of use. Or simply because of cost savings.

Still pretty popular in the 2-channel audio world... audiophiles, in other words.

I'm probably in a tiny niche but I use it so that I can have optical out to my speakers and analogue out to an extension cord with a plug next to my keyboard that I plug my headphones into. This means I can swap between audio devices without touching cables or plugging things in to go headphones -> speakers depending on whether I want to annoy my wife with my music or not.

I have the same setup actually! But my speakers only take analog in so I use a cheap USB sound card.

The easy answer is: same thing I was using it for 10 and 20 years ago. Audio equipment doesn't age nearly as quickly as personal computers. I'm not going to replace my entertainment system just because there's a new Mac.

Also, I've had compatibility problems with HDMI between my old Mac Mini and my receiver. I don't know how to troubleshoot those sorts of issues. I do know that optical audio always works perfectly with every device I've ever used it with, though.

says the person who keeps buying products without optical audio ports.

Somehow HDMI audio is still less convenient for me.

I send HDMI to my TV which sends optical to my sound system, and it still works pretty well. Earlier this year I bought a nice sound system with a receiver for the reasons you mentioned, but it added extra lag to my video games, so I returned it. My current sound system also supports ARC but it causes most of the same problems. Decoding those fancy codecs creates lag on every system I've tried, so sticking to LPCM over optical seems to be the only way to enjoy games still.

Isn't that little headphone port a combo optical/electrical port that you can plug either headphones or mini-toslink-whatever into ?

Isn't that what it was before ? I swear I had previous mac minis with a combo port like that ... why would they not continue that ?

Yes that is precisely the thing that used to be in all macs that they discontinued

Now that I think about it, axing the optical audio ports was probably a deliberate move by Apple to nudge home TV users of mac minis into using Apple TVs, where they have way more control over the interface and content.

edit: apparently Apple TV doesn't have optical audio either.

The AppleTV doesn't have optical audio either.

Ok well I guess that's even dumber than I thought. I hope apple takes that $2 per device savings in optical audio parts laughing to the bank.

Don't judge, maybe the next version of the mac mini will be waterproof!

lol

I doubt it -- the number of users who use a Mac Mini as an entertainment center is probably so small Apple barely thinks about them. More likely is that HDMI has superseded the optical audio port for most users, so they save money by removing a port few use these days.

It's still a little weird. I think a lot of people would have a separate A/V receiver and speakers; maybe this is changing as old equipment gets replaced, but I suspect there are still far more homes with optical-capable A/V receivers than HDMI-capable ones.

This is just a standard annoying thing with Apple though. Their designs are very 'forward looking' in that they don't consider what potential customers already have so much as they do what their own future peripherals are going to need.

At this point HDMI is not a particularly new thing; my Marantz receiver from ~2007 had HDMI connections on it. Audio-only digital connections aren't necessarily going the way of the dodo yet, but they're becoming progressively more niche. So are home theater PCs, of course.

Anecdotally: I do have a Mac mini with my receiver, which I replaced this year. But the new receiver not only has USB input, it has wifi and built-in clients for Spotify, Tidal, Pandora, TuneIn, Roon, whatever protocol Windows uses for media sharing whose name I'm utterly blanking on right now, and a dozen or so other services, with Apple Airplay 2 theoretically coming in an update.

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