Apple says computer has digital audio out, but really??

[newrigel]

It all boils down to your op amps and/or pre amps, and conversion and your clock source precision. If you want to use an iMac or mac mini to be used as a media server then the optical is a great way to get audio to your distribution amp... (even then I'd probably go HDMI) today but for pro audio production, you'd want to go with a dedicated solution.

[FMiguelez]

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So would it be accurate to say that one of the reasons the Apple built-in audio card is Prosumer (as opposed to professional) is because of its lack of a good clock source precision?
So this bad clock causes a lot of jitter? Is that its main problem?

What else? Once everything is 0's and 1's, I can't think of another bad reason besides a less-than-ideal clock...

And I had no idea this optical cable carried LIGHT signals and no voltage or electric signals... how cool is that

Ok. You guys have helped me clear out a lot of misconceptions I had regarding this subject.

Thank you for bearing with my 101 elementary-cabling questions

[cuttime]

So in theory, if I kept all the gain at nominal levels, my mixes would sound the same with a digital or analog connection, correct? As in whatever comes out of the iMac won't sound louder if connected via analog or louder if connected via digital, yes?
At the end, any audio coming out of the little slave computers will be recorded digitally anyway (by freezing or bouncing in the slave and transferring to the master computer, or simply, by recording into the master computer via VE Pro/ethernet).

Yes, in theory, but I've had very poor results with the built-in analog audio. I think it is designed for cheap headphones or consumer grade television. I think a lot of it has to do with the impedance of the jack (of which I have no idea), and the mismatching thereof. Could explain the crappy sound. Worst of all, if I use too much amplification, I hear processor noise in the signal path.

[Armageddon]

In a nutshell, all Intel Macs have a built-in combo analog/96 kHz digital audio out. An easy way to test this: play a 24-bit/96 kHz sound file. Anything older than an Intel Mac would require an external A/D/D/A converter or a sound card in order to actually hear the file playing. It was added on the Intel machines mainly to facilitate home theater-type digital sound, so that's about the level of quality you're going to be dealing with, though having the option is nice in a pinch. Let's put it this way, Apogee probably didn't notice a dip in sales when it was first introduced. I myself tend to forget Intel Macs can do it altogether, unless I accidentally open a 24-bit/48+ kHz sound file without hooking up my interface and still hear audio playing.

This setup would be useful if you were using just VIs and wanted to compose or even mix without added hardware, or if you were on a laptop on a plane, etc. For serious engineering, though, you'd probably want a better converter and something with built-in pres and a decent word clock. Even just getting a Tascam mixer with a FireWire or a USB 2.0 option would be a step up.

As for the how, the stereo analog output (and input) is being transmitted via the ring and tip on your miniplug jack, same as always. If your jack has the S/PDIF optical tip, it reads as a digital plug, as opposed to an analog one. That's the beauty of a combo jack. I have an old G3 iBook whose miniplug audio out also served as a DVI output, and if you plugged in a special DVI miniplug-to-RCA cord, it was outputting stereo audio as well as video. The only difference between a regular stereo miniplug audio plug and the DVI version was a slightly longer tip.

[n2mpujack]

And the MacPro desktop has Toslink connectors for audio I/O. I know we were talking about laptops but just thought I'd throw this in for the sake of completeness.

[mhschmieder]

Actually, I've read quite a few reports that the audio built into the Macs is superior to most external stuff, but gets bypassed by most pro people simply because they need more than two channels. But I'm talking MacPro, not the audio outputs on the prosumer/consumer Macs.

I'm curious about this myself, because I am considering using my new MyTek two-channel AD (and eventually DA) converter to interface directly to the MacPro hardware for overdubs, after initial tracking, for best quality and lowest latency.

But like FMiguelz, a lot of it is abstract to me since I have been living in prosumer G4 iMac land for almost a decade now...

Anyway, some very good and useful responses here, even for those of us who do know a fair amount about the connectivity options and cable conversion options. Pictures are worth a lot, and there are some very good ones here to reference...

[Armageddon]

Actually, I've read quite a few reports that the audio built into the Macs is superior to most external stuff, but gets bypassed by most pro people simply because they need more than two channels. But I'm talking MacPro, not the audio outputs on the prosumer/consumer Macs.

I had no idea that the MacPro's were set up that way, but it makes sense, since they're practically designed for pro audio and video. Unfortunately, the plug on the laptops, Mac Minis and iMacs are of the stereo miniplug variety, and pull triple duty as an optical out, an analog headphone jack and a stereo analog computer speaker output. I can't vouch for the quality for the optical out, which, again, I'm sure is at least home theater quality, but for that kind of setup, if you're doing live audio input and not just working with VIs, you'll definitely want a dedicated audio interface with decent preamps, or at least a decent preamp with A/D conversion that you can hook up to your laptop's optical jack.

[James Steele]

This is interesting to me, because I just recently got a used Mac Pro 1,1, and in theory I should be able to connect a TOS LINK digital cable from the back of my Mac to the TOS LlNK connector on my Presonus Central Station and boom... there ya go. In fact, if I ever just want to experiment with mixes and stuff, I suppose I could "rest" my MOTU interfaces and just go straight to the Central Station.

I know Brad was saying they had pretty decent D/A converters in the Central Station... probably not better than my HD192, but decent. On top of it the meters in the Central Station would be accurate when connected to it via digital. I should probably pick up a cable tomorrow at Fry's just for giggles.

[coolcolin]

James, don´t get your hopes up too much, the latency using this optical connection makes overdubs pretty much impossible. I have been using the opto out on my MBP and Mini for 2 years but only for mixing. It sounds pretty OK.

ColinP.

[Armageddon]

This is interesting to me, because I just recently got a used Mac Pro 1,1, and in theory I should be able to connect a TOS LINK digital cable from the back of my Mac to the TOS LlNK connector on my Presonus Central Station and boom... there ya go. In fact, if I ever just want to experiment with mixes and stuff, I suppose I could "rest" my MOTU interfaces and just go straight to the Central Station.

Well, it's about damn time! I know people are still using dual-core G5s for music, but they may be forced to switch over before long, since most third party manufacturers are dropping support for all non-Intel Macs like crazy. I jumped the train from Tiger not that long ago for that very reason (most upgrades are now Leopard-specific or higher; they won't even open in Tiger). Plus ... it's a Mac Pro, man!

Your situation is a conundrum, however, since I'm assuming you have a card (eSATA?) for the HD rig and TOSlink is only good up to 96 kHz. Not that anybody sane mixes in 192 kHz without ProTools, yet, but neither your HD rig (especially with an eSATA card) or the built-in TOSlink should be giving you much latency, if any. Is it possible to just use your built-in TOSlink for tracking and basic mixing, then switch over to the HD 192 for final mixdown and mastering?

Again, it seems to me that the biggest advantage to having onboard digital audio would be to the laptop set, where traveling with an audio interface -- or, worse, trying to set up this rig on a plane or on the road -- would be a bit cumbersome. Oh, and to the people only working with VIs, who don't require A/D conversion or preamps going in, and can always lug their laptops to a studio with compatible audio interfaces if they need a top-notch output. I have a pretty compact interface, but there's been quite a few times where I question why I'd need it when I do about ninety-nine percent straight VI composing. Just thank your lucky stars we're not back in 2000, where all Macs came equipped with bottom of the line 16-bit/44.1 kHz Sound Blaster-style A/D/D/A cards that sounded like excrement.