Apple AirPort Express and Digital Jitter..

I'm doing something which I can't really afford, but doing it anyway ... I'm upgrading my Stereo ... I like music, and  believe it should be played at the highest affordable quality.

So after getting a new Stereo Amp (Creek Evolution 50A), I got a new Phono Amp. and then started looking for a DAC ... and after reading I do not know how many posts I decided to get an S.M.S.L M8 (from Amazon fro €249.99), not too expensive and according to what I can read very good.

So I got it hooked it up to my amp, connected my Notebook (Macbook Air 11" / 2011) using USB ... sounded nice, then my Macbook Pro Retina with digital (fiber) in some way better than USB, slightly more air and openness. Then decided to use my old Apple Airport Express (MB321LL/A - 802.11n version 1) using it's digital output (I don't like the build in DAC - it's a bit too dark for me), and this is where I started having doubts about my buy.

There was drop out, all the time. Right I changed, to direct WIFI; same, I change to a newer model (the square one which I also have), same jitter, ever 1-2 seconds a drop out.

I asked on head-fi.org and someone after a few days suggested that I should try to reduce the jitter on the Airport Express ... and after a a couple of hours I found this thread/post on the Apple Support forums, suggesting that it's firmware problem, and that the solution is to downgrade to firmware 7.6.1.

See that could be a problem, as finding it as a download is not that easy, but I was in luck it's possible to do it directly from the AirPort Utility (click on the version while holding down 'option'), and select 7.6.1 ... wait ... reboot ... and it works.

With the square Airport Express (802.11n version 2) it's not possible to downgrade to 7.6.1 (I only see 7.6.2), there is a bit more information here:

  • http://www.leighsmith.com/node/2317

  • http://www.laszlopusztai.net/2013/02/11/downgrading-airport-extreme-to-7-6-1/


But I have not been able to figure out what version the square is ... if someone know please let me know.

So, jitter is a problem for all firmware's after 7.6.1 ...

 

Comments

Pierre said…
I have more or less the same issue, excepet that I have the apple express airport version 2 that was shipped with 7.6.2 and I cannot roll back to 7.6.1 from the airport utility directly.
BUT the utility offers the option of loading a firmware from a file. Ive looked everywhere on the web without success. You are the only person I found that I can send a message to.
If you could find a way of exporting the firmware to a file and send it to me, you would be helping me a lot lot.

Many many thanks in advance for an answer!
Casper said…
I am sorry but I no longer use my AirPort. I had a look at ~/Library/Application Support/Apple/AirPort/Firmware has nothing more than version.xml ... And I don't see a way to get Airport Utility to export the firmware from the device.

On the other hand I am not sure that the square one (version 2) actually would work with an older version than the version it was shipped with.
Casper said…
Look here: https://forums.macrumors.com/threads/airport-express-7-6-1-firmware.1857963/#post-20871386, The 7.6.1 is not available for Airport Express version 2.
Pierre said…
Thansk a lot for taking the time to answer;
If you can check just one last thing : in the version.xml files, there are in fact the links for the utility to download the firmwares.
IF you can search for "7.6.1" in the file (it can be opened with any text editor). There should be several (maybe 4,5) inputs like this :

location
http://apsu.apple.com/data/114/041-3395.20120130.Ka1Br/7.6.1.basebinary
productID
114
sizeInBytes
6364116
sourceVersion
76100.4
version
7.6.1


if you could send me the links obtained (ideally the one for productID115, it is my airport express, be maybe some number between 107 and 117) it would maybe do it

Thanks again

Pierre
Casper said…
It does, this could be from an Airport Extreme:


location
http://apsu.apple.com/data/117/041-3396.20120130.OpvuO/7.6.1.basebinary
productID
117
sizeInBytes
6549800
sourceVersion
76100.4
version
7.6.1


There you have the download link, enjoy.
Pierre said…
Yes it seems you may be right.
The 117 is an airport extreme, and my express refuses to take its firmware.

I think I will have to replace it with another solution (any 3rd party airport receiver that has digital audio output, maybe I'll try and setup a raspberry pi, probably the cheapest solution)
If it is only a matter of software, it is however a shame that apple did not bring any soution to this problem that was brought up many times over the years...

Nevertheless, thanks again for your help, it was very nice of you

Pierre

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