Is the optical out put on my mac the best way to connect to a dac ?

toyota man

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Hi all Is the optical out put the best way to connect to a dac from my mac or the usb port I am thinking of getting an arcam dac on loan to see how my music from my pc will sound thanks for any help advice :cheers:
 

stevebrock

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I don't think it makes any difference, however depends what available connectivity on the DAC you have !

Personally I would go USB only as the physical connection is a bit more secure!
 

silikonas

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i have arcam r-dac connected to a macmini. i've tried both optical and usb numerous times and i think the usb gives me noticeably better quality than the optical - more detail, more clarity, just a better sound to my ears. and yes, the sound is uncomparably better than without the dac
 

busb

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Optical does one one big advantage over USB - noise isolation! My Sony Vaio, like most laptops, only has USB digital. If I connect it to my DAC with it plugged into the mains, I get very high levels of mush even when music is paused or the DAC's volume at its lowest. Fortuneately for me, I use an ATV's optical output to my DAC that uses Wi-Fi to stream by. Perhaps Apple use better PSUs than many Windows-based machines.

If I did choose to use my Sony, I'd have to buy a galvanic isolator or run it off its battery.
 

Neuphonix

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Not looking to start a 24bit Vs 16bit debate here, but I'm pretty sure that you can't send 24bit/192Hz files via the optic output. I seem to remember reading somewhere that 24/96Hz was the most it could handle.

Probably not a big deal but worth keeping in mind if you are planning on having hi-rez music files.

Could be wrong here though? I'm sure someone with more expertise than I can chip in.
 

andyjm

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OP,

Like most things, choosing a connection it depends on the circumstances. Optical has the benefit of isolating the PC from the DAC and can give noise benefits, although higher end DACs are now using isolation techniques for USB. On the downside, some optical implementations have poor jitter performance. Async USB has the advantage of removing any dependency of the DAC on timing from the PC and thus reducing jitter, but in many cases brings PC ground noise along with it.

I did a bit of reading about the Leema Elements DAC, prompted by another post. It seems to have the best of both worlds, async USB and galvanic isolation. There are still many ways you can stuff up the design of a DAC, but they are at least starting in the right place. It might be worth an audition.

If I were buying a DAC today, from a technical perspective on the type of internconnect, async USB and galvanic isolation would be at the top of my list
 

ID.

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In the case of DAC with asynchronous USB like the rDac the USB connection should be best. You can always try them both and see which you prefer.
 

chebby

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Neuphonix said:
Not looking to start a 24bit Vs 16bit debate here, but I'm pretty sure that you can't send 24bit/192Hz files via the optic output. I seem to remember reading somewhere that 24/96Hz was the most it could handle.

It seems worse than that on optical.

From Khetan Bharadia (WHF staff) on comments page of the rDac review....

"Just wanted to clarify the signals the Arcam rDAC will accept.

USB input: up to 24bit/96kHz

Optical input : up to 24bit/48kHz

Coax input : up to 24bit/192kHz

Wireless : 24bit/44.1 kHz"
 

andyjm

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chebby said:
Neuphonix said:
Not looking to start a 24bit Vs 16bit debate here, but I'm pretty sure that you can't send 24bit/192Hz files via the optic output. I seem to remember reading somewhere that 24/96Hz was the most it could handle.

It seems worse than that on optical.

From Khetan Bharadia (WHF staff) on comments page of the rDac review....

"Just wanted to clarify the signals the Arcam rDAC will accept.

USB input: up to 24bit/96kHz

Optical input : up to 24bit/48kHz

Coax input : up to 24bit/192kHz

Wireless : 24bit/44.1 kHz"

Optical capability is manufacturer specific - it depends what sort of job they made of the interface. While not really fair, putting this in perspective, undersea cables can achieve 100Gb/s over 6000Km (with repeaters).

In comparison, 24/48 is approximately 2.5Mb/s. Even if it is only going down 1M of poor quality plastic optical cable, its not really very impressive.

If I have got my maths right, Arcam have managed to build an interface running at 1/50,000th of the speed over 1/6000th of the distance (though like I said, not an entirely fair comparison).
 

andyjm

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chebby said:
andyjm said:
While not really fair, putting this in perspective, undersea cables can achieve 100Gb/s over 6000Km (with repeaters).

At least you don't get oil-tanker anchors dragging through your TosLink cables and severing them!.

Very true. Like I said, not really a fair comparison.

I did stuff up the maths. Getting old I guess. It should have been 1/50,000 of the speed over 1/6,000,000 of the distance.
 
andyjm said:
I did stuff up the maths. Getting old I guess. It should have been 1/50,000 of the speed over 1/6,000,000 of the distance.

Does that mean a transatlantic telephone call has a better frequency response than a hi-res download?!

I realise it doesn't, but your maths highlights the relative crudity of our audio gear. :)
 

steve_1979

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Both optical and USB cables sound identical in my experience (I've compared them in proper ABX tests). Just use whichever is the most convenient.

One advantage that optical cables have over USB cables is that they don't conduct electric. This means that two pieces of equipment that are connected by an optical cable are electrically isolated from one another which slightly reduces the chance of them both getting damaged if one of the fails.
 

Neuphonix

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chebby said:
Neuphonix said:
Not looking to start a 24bit Vs 16bit debate here, but I'm pretty sure that you can't send 24bit/192Hz files via the optic output. I seem to remember reading somewhere that 24/96Hz was the most it could handle.

It seems worse than that on optical.

From Khetan Bharadia (WHF staff) on comments page of the rDac review....

"Just wanted to clarify the signals the Arcam rDAC will accept.

USB input: up to 24bit/96kHz

Optical input : up to 24bit/48kHz

Coax input : up to 24bit/192kHz

Wireless : 24bit/44.1 kHz"

Sorry, what I meant was the maximum output capability via optic from the Mac was 24bit/96Hz. Pretty sure you can magange higher vis asynchronious USB? In the real world though gievn the number of these types of files being played it probably won't be an issue.

But of course you're right, the DAC input capability will obviously be a restriction as well.

So what happens if say you send a 24bit/96kHz signal to the DAC via optic. Presumably the DAC is smart enough to down sample the signal before sending it on?
 

6th.replicant

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USB is best for an rDAC, due to some clever thingy - aka "dCS asynchronous USB technology", whatever that is :? - which, in turn, is suited to OS X and iTunes because of their bit perfect-ness, I think... :shifty:
 

toyota man

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6th.replicant said:
USB is best for an rDAC, due to some clever thingy - aka "dCS asynchronous USB technology", whatever that is :? - which, in turn, is suited to OS X and iTunes because of their bit perfect-ness, I think... :shifty:
At last some one who speaks my language I think :rofl:
 

DavieCee

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With my MB Pro connected to a Beresford DAC, the USB sounds better than optical.

I am sure that it will be something to do with what people have said above but I am not fussed, just happy.

PS:- Optical cables aren't that expensive and you will probably have a USB cable lying around so try both and decide for yourself. :beer:
 

gurjitsidhu

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I have a rega dac and a MacBook Pro. What is the max quality my Mbp will output via optical/ using airport express optical and what about USB? Also I thought the rega dac can only recieve and manipulate a lower quality if from USB so I thought optical was better? I wanted to buy some 24-196 tracks but not if I can't output that resolution from the Mbp or preferably from my AE.

Many thanks!
 

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