Airport Express Set-up

Posted by: Blobdang on 04 March 2009

Its been a while since I was here, Hi!

OK there's probably been numerous posts on this but..maybe just to bring things update:-

I'm using itunes from my macbook more and more for convenience over my tried and trusted CD5. Mainly WAV & Apple Lossless streamed to Airport Express, from there to my NAC102.

How can I improve sound quality?

Previous threads talk about putting a DAC between the AE and 102? - if so which DAC? Any other suggestions?

All ears...
Posted on: 04 March 2009 by Harry H. Wombat
Blobdang hi--

Have a look in the Distributed Audio room on this forum where this post will no doubt be moved. Members have various DACs or you could of course delay any purchase until the NAIM DAC arrives.

There is a lot of talk there about one DAC in particular, the L@@@@y which many people find suits them very well. Although there are many DACs out there at all price points there are few if any places to audition them.
Posted on: 04 March 2009 by Harty601
The difference between the analogue and digital outputs of the AE are pretty massive. I used to run an AE into the DAC on my supernait and now run an apple TV into it. I have to say, uncompressed files played off my mac sound very impressive, it's not up to the standard of my CDX2 but bang for buck is very impressive.

Rich
Posted on: 04 March 2009 by 'haroldbudd'
Use a " Glass Fiber " optical cable between AE and DAC. There are at least 3 of us on the forum having great results with the VDH "optocoupler " (one using it with an AE) but there are other companies making them such as the Wirewolrd Supernova 3 and some cheaper ones on eBay. A noticable improvement over regular plastic fiber.

cheers
Posted on: 04 March 2009 by Harry H. Wombat
But which DAC would everyone recommend for a DAC first-timer. The L is quite expensive, even more so now.
Posted on: 04 March 2009 by 'haroldbudd'
The Beresford is a steal considering the price, I bought one for fun since it was so cheap and was impressed . It takes a couple of days to start singing but one would have to spend around $500 to better it. It's a great "intro" Dac and I think many others who use one on with Naim kit will agree. Above it there are many options though.....
Posted on: 04 March 2009 by Exiled Highlander
I swapped my Beresford (latest version) for a Cambridge DAC Magic - great improvement for very little outlay IMO. Oh, and it looks 100X better, again IMO of course! Smile

Cheers

Jim
Posted on: 04 March 2009 by Mr.Tibbs
Here's the rub - the Airport Express is inherently quite 'jittery' and so needs a DAC that can reject the jitter if great sound is to be achieved. The Benchmark DAC-1 is reputed to be superb in this respect, but still (as I've recently found out) not even it can completely work around the problem. Basically, instead of streaming via the AE I plugged a macbook straight into the DAC-1 and was startled at how much better the music was. Don't get me wrong, the AE is not bad at all (with a suitable DAC), but it is not in MAC/DAC territory.

Mr Tibbs
Posted on: 04 March 2009 by Mr.Tibbs
quote:
Originally posted by avole:
Yes, the reports are that if you use the inbuilt AE dac, it is quite jittery. However, if you use an external DAC, which uses the optical out of the AE, such is not the case.


No - the point I'm making is that the digital optical output of the AE has poor jitter performance. Stereophile measured the digital output of the AE and found it to 'bit perfect' but blighted by jitter. Any external DAC (no matter how good) will have problems dealing with high levels of jitter - to an extent readily heard IME.

Mr Tibbs
Posted on: 04 March 2009 by spacey
mr tibbs, the reviews not clear in that respect. i read it as avole says, its bit perfect and the jitter is only in the BB dac section. it sounds exactly the same either wired or wirelessly in my system. my HP media laptop has optical out, i tried it from that and streamed via AE, both at the same time playing the same files. flicking between inputs and without looking at the map, i could'nt hear any differences.
Posted on: 04 March 2009 by Eric Barry
I'm with avole and r-tee in my parsing of the Stereophile review.

In any event, they reviewed the G AE, not the N that's been out a couple of years so who's to know if performance is the same, never mind that Apple could easily have changed the relevant parts without telling anyone.

So, can anyone measure jitter at the AE optical output? Inquiring minds &c.
Posted on: 04 March 2009 by Mr.Tibbs
The AE DAC is not causing the jitter. The report clearly states that "Its (measured jitter) is hardly surprising considering the AE has to derive its 44.1 word clock from an asynchronous data stream". Clearly this inherent jitter (prior to the DAC) will therefore be present at the optical output.

I'd say the latest AE fares no better in this respect. The DAC has been changed, but the method of deriving the word clock remains the same - and that's where the problem lies. Sorry guys, but a mac direct to my DAC-1 smokes the same mac streaming via the AE. End of.

Mr Tibbs
Posted on: 05 March 2009 by spacey
http://www.stereophile.com/accessoryreviews/505apple/index.html

make of it what you wish..... to me its sound identical to direct wired via PC. i have got both working at the same time playing the same tunes - they sound the same. there has been many many discussions about mac'v'pcs i have setup two threads recently, with the same outcome - they sound the same - if setup properly
Posted on: 05 March 2009 by spacey
Fig.7 Apple AirPort Express, high-resolution jitter spectrum of analog output signal (11.025kHz at –6dBFS sampled at 44.1kHz with LSB toggled at 229Hz). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Grayed-out trace is spectrum of Musical Fidelity X-DACV3's analog output taken under identical circumstances with it driven by the AirPort Express's S/PDIF digital output via 6' Monster TosLink.

However, this performance becomes moot when the AE's digital output is used. The grayed-out trace in fig.7 shows a similar spectral analysis of the Musical Fidelity X-DACV3's analog output while it was driven by the AirPort Express via the Monster TosLink cable. The noise floor has dropped by 4–5dB, the word-clock jitter to a respectably low 258ps, which is actually better than the case with the standalone D/A processor driven directly by my PC's S/PDIF output (provided by an RME PCI card).

Considering that the AirPort Express's analog output is basically a freebie function added to a computer Wi-Fi hub, jitter aside, its measured performance is quite good. The beauty of this unassuming component, however, is its S/PDIF data output, which allows the AirPort Express to assume a respectable role in a true high-end audio system.

quoted from the link above
Posted on: 05 March 2009 by Blobdang
Er, thanks guys.

So 'jitters' aside, coming back to my original question can I safely say that using a DAC between the AE's optical output and 102 will improve things noticeably?... and for an investment of say between £100-£200 a Beresford/ Cambridge Audio DACMagic or Musical Fidelity VDAC would suit?
Posted on: 05 March 2009 by Jay
I would start with the cheapest option, the Beresford, and then go from there. That's what I did and am still using the Beresford a year on.

Jay
Posted on: 05 March 2009 by spacey
i would also recommend the use of a glass optical cable. i use the VDH optocoupler II, many people have compared this with a high quality coax and couldnt tell the difference. i think chord do one too. remember it needs to be 3.5mm minijack optical to toshlink. what the budget for dac? theres been a few D10 floating around for 350ish on fleebay
Posted on: 05 March 2009 by Mike Smiff
Is the VDH optocoupler indeed glass optical? I have read the VDH web page and it dose not mention the optical cable being glass or plastic,it just states "medical grade".
Posted on: 05 March 2009 by 'haroldbudd'
Yes, I believe the 6moons review of it ( do a search) as well as others go into detail about it. There are other much cheaper glass ones on fleebay but, have no idea of the quality as the manufacturer is obscure.
Posted on: 05 March 2009 by Mike Smiff
Ah yes,it seems so after reading the 6moons review,

I have been mulling over the VDH/Chord mini tos/toslink.

Thanks,Mike.
Posted on: 05 March 2009 by Mr.Tibbs
quote:
Originally posted by r-tee:
Fig.7 Apple AirPort Express, high-resolution jitter spectrum of analog output signal (11.025kHz at –6dBFS sampled at 44.1kHz with LSB toggled at 229Hz). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz. Grayed-out trace is spectrum of Musical Fidelity X-DACV3's analog output taken under identical circumstances with it driven by the AirPort Express's S/PDIF digital output via 6' Monster TosLink.

However, this performance becomes moot when the AE's digital output is used. The grayed-out trace in fig.7 shows a similar spectral analysis of the Musical Fidelity X-DACV3's analog output while it was driven by the AirPort Express via the Monster TosLink cable. The noise floor has dropped by 4–5dB, the word-clock jitter to a respectably low 258ps, which is actually better than the case with the standalone D/A processor driven directly by my PC's S/PDIF output (provided by an RME PCI card).

Considering that the AirPort Express's analog output is basically a freebie function added to a computer Wi-Fi hub, jitter aside, its measured performance is quite good. The beauty of this unassuming component, however, is its S/PDIF data output, which allows the AirPort Express to assume a respectable role in a true high-end audio system.

quoted from the link above


Ironically, the above actually confirms what I've been saying: That the AE has poor jitter performance at the optical output! Trying to cure the problem later (at the outboard DAC) is never going to be 100% successful. Let me put this another way, if you were buying a CD transport to use with your DAC, would you just choose the cheapest one available and expect it to sound every bit as good as a TOTR transport?

quote:
make of it what you wish..... to me its sound identical to direct wired via PC. i have got both working at the same time playing the same tunes - they sound the same. there has been many many discussions about mac'v'pcs i have setup two threads recently, with the same outcome - they sound the same - if setup properly


Except that I get different results using the same mac (and therefore the exact same setup), when connected direct rather than streaming via an AE. I cannot blame this particular AE either, because I've got another one that sounds exactly the same -- considerably less good than the mac direct. IMO you really need to beg/steal/borrow a Macbook and try it direct before writing off what I'm saying. Who knows, perhaps the optical output of your PC is little better than the AE - that would explain why you hear no difference in your situation.

Anyway, I'll let you AE fans get on with it - I need to go see what spare cash I can find to buy a Mac Pro ;-)

Mr Tibbs
Posted on: 05 March 2009 by Mr.Tibbs
quote:
Doesn't that rather go against what you're saying?


Not at all. All they are claiming is that they can get a better result compared to a PCI sound card. Actually that (comparing it to a computer sound card) is also quite enlightening, because it means they are not really expecting miracles from the cheap and cheerful AE - unlike you guys it would seem!

Seriously, I wish the AE>DAC really was the equal of a Mac/DAC -- it would save me a wadge of upgrade cash.

Mr Tibbs
Posted on: 05 March 2009 by 'haroldbudd'
I don't have an AE so I am Mac/DAC and correct me if I am wrong but does not the AE pass on at only 16/44.1 ? It is recommended by Apple audio engineers and others such as the guys at Benchmark to set audio-midi at 24 bits and sample rate as high as your Dac goes, even if you are only playing 16/44 files, so wouldn't the AE hinder that? Or is it just the built in D/A in the AE that can only do 16/44 while the optical out can pass the full rate? just curious.

cheers
Posted on: 06 March 2009 by Mr.Tibbs
quote:
Originally posted by avole:
Mr Tibbs,

As I thought. The point is that the image is the same, and it's the DAC that's introducing the jitter. Remember that the AE sends a bit perfect file to the DAC, and, since it's difficult to encode jitter, any that appears will come from the DAC. The same goes for a PC/Mac connection, too.



Sorry, but I don't agree with that at all.

If what you are saying is correct then I should hear absolutely no difference between music streamed via an AE > DAC-1 or the same music played direct from the same Macbook > DAC-1, yet the difference is obvious. It's the sort of difference you might expect if you were to upgrade from a good mid-range CDP to a TOTR CDP.

Assuming the bit stream is identical in both cases, then the only other possibility for a difference in sound is that one source has more jitter than the other. I've read nothing in the Stereophile test or on this thread that comes close to providing an alternative explanation.

The proof is in the pudding - do yourselves a favour, try a Macbook direct to your DAC and then you'll realise the AE has its limitations as an audiophile-grade digital source.

Mr Tibbs
Posted on: 06 March 2009 by Mr.Tibbs
quote:
As I said, you can't encode jitter. If there is a difference, it's not that. It's far more likely to be what the itunes does before sending files to the AE - itunes does impose restrictions as the article states.


No matter what iTunes does before sending the files (it converts them to lossless if not already lossless, BTW) the output of the AE has been shown to be bit-perfect (same a the native Mac). Therefore, the data is identical so blameless.

quote:
Would love to compare with a mac, but that'll have to wait until the next job comes along...


Please do - then come back and tell us what you hear. I promise not to say 'told you so' :-)

Regards

Mr Tibbs
Posted on: 06 March 2009 by Mr.Tibbs
quote:

Ergo it's not introducing jitter, then, and the sound will be entirely dependent on the D


<bangs head against wall> NO, the data is identical in as much as it is 'bit perfect' IE the correct amount of 0s and 1s in the correct order. BUT, the amount of jitter present on the 'bit perfect' data is an entirely independent and separate issue! The AE and macbook push out the exact same bitstream. If we apply your logic (no difference in jitter) then the result would sound exactly the same, using the same DAC.

They don't sound the same, therefore it HAS to be down to jitter.

I'll let you have the last word!

Mr Tibbs

PS yes, mac's are very impressive and useful to have for all sorts of reasons - not just audio.