• New Apple AirPort Express Bit Perfect But Still Limited

    by
    The Computer Audiophile
    Published on 06-18-2012 12:25 PM
    32 Comments Comments
    My new AirPort Express, white hockey puck version, arrived this morning. The first thing I did was connect it to my Berkeley Audio Design Alpha DAC and run several bit perfect tests at different sample rates and bit depths. The good news is the new AE is bit perfect at 16 bit / 44.1 kHz. The usual (bad) news is the new AE will play all other popular PCM sample rates but doesn't transmit the data bit perfectly. I hoped the new AE would at least transmit some 24 bit data but when I sent 24/44.1 music to my Alpha DAC it wasn't bit perfect. In the interest of due diligence I tested 24 bit / 44.1 through 192 kHz and none of the music was sent bit perfect. Only 16 bit / 44.1 was transmitted unaltered.








    One minor improvement that doesn't go far enough is the addition of an extra Ethernet port. This enables use of the AE as a wired router in addition to a wireless router. Unfortunately both Ethernet ports on the new AirPort Express only operate at 10/100 Mbit/s. Maybe Gigabit ports aren't needed as all audio is sent at 16/44.1, but using the new AE for other data needs will be a bit limited compared to almost all other routers including the AirPort Extreme.

    The USB port is also still limited to printers only (no audio output).

    I really like the default external power cord for the new AE. The previous Express units required the purchase of a separate power cable to use the device without plugging it directly into an outlet. I always hated plugging the entire AE into an outlet with a hanging digital cable. The look of a wall wart and the fact that the AE never fit tightly enough into the outlet were "first world" annoyances but annoyances nonetheless.



    Summary

    • 16 bit / 44.1 kHz music -> Bit Perfect
    • 16 bit / 48, 88.2, 96, 176.4, 192 kHz -> Not Bit Perfect but does play through the AE at 16/44.1.
    • 24 bit / 44.1, 48, 88.2, 96, 176.4, 192 kHz -> Not Bit Perfect but does play through the AE at 16/44.1.

























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    Comments 32 Comments
    1. realhifi's Avatar
      realhifi - 06-18-2012, 01:24 PM
      Inquiring minds want to know...how does it sound? Can it be a legitimate AirPlay device?
    1. wgscott's Avatar
      wgscott - 06-18-2012, 01:36 PM
      HOw does this perform as a repeater? The old ones were fairly sketch in that respect, at least in my hands.
    1. mayhem13's Avatar
      mayhem13 - 06-18-2012, 03:51 PM
      Quote Originally Posted by realhifi View Post
      Inquiring minds want to know...how does it sound? Can it be a legitimate AirPlay device?
      The older version was legit for Audio and IMO sounds great with redbook content. Since the new version tests bit perfect redbook, I see no reason to consider otherwise....but Chris has it in hand so best to defer to him.
    1. mayhem13's Avatar
      mayhem13 - 06-18-2012, 03:54 PM
      Quote Originally Posted by wgscott View Post
      HOw does this perform as a repeater? The old ones were fairly sketch in that respect, at least in my hands.
      With wifi as a repeater, the old version was also sketchy for me. I use an old Netgear N router as an access point instead. The nice folks at smallnetbuilder.com have a tutorial on repurposing wireless routers as access points.
    1. roscoeiii's Avatar
      roscoeiii - 06-18-2012, 05:01 PM
      Note that the Gen1 and Gen2 had quite different audio performance. The first generation had great jitter measurements. Not the case with Gen2
    1. HiFiGuy528's Avatar
      HiFiGuy528 - 06-18-2012, 06:06 PM
      What gen is this new one on? Anyone measured the jitter on this and the last version?
    1. Carson's Avatar
      Carson - 06-19-2012, 05:28 AM
      Thank you for the write up!

      I still don't understand the fundamental differences in streaming wireless with Airport Express and streaming wireless with Sonos or if I should be streaming without either of them. Do most of you guys use Airport to stream around the house?
    1. lentille's Avatar
      lentille - 06-19-2012, 06:57 AM
      HI Guys - I have also acquired one of the very new airport express units - my application is a bit different. I was streaming from my study to a squeezebox in the lounge - worked fine for 16/44 files. But 24/96 just would not cut it - the wireless signal was too weak and I kept seeing buffering messages on the squeezebox.

      So in goes the new airport express last weekend (in reality most wireless routers would work) - joined it to my network and I now use an ethernet cable out from the AE to my squeezebox (which in turn feeds a Centrance DACmini for DAC purposes).

      The AE works like a charm - my 24/96 files play without a hitch. The new AE is an elegant looking unit to boot.

      cheers
    1. dizziness's Avatar
      dizziness - 06-19-2012, 03:36 PM
      Interestingly, the DAC used is capable of 24/192. See: Rogue Amoeba - Under The Microscope » Blog Archive » Airport Express (Dual-Band) Disassembly. Asahi Kasei AKM4430.

      Too bad its not iOS based, then maybe someone could write a jailbreak firmware with 24/192 support. Has anyone tried this for the AppleTV2/3?
    1. realhifi's Avatar
      realhifi - 06-20-2012, 06:01 AM
      Quote Originally Posted by dizziness View Post
      Interestingly, the DAC used is capable of 24/192. See: Rogue Amoeba - Under The Microscope » Blog Archive » Airport Express (Dual-Band) Disassembly. Asahi Kasei AKM4430.

      Too bad its not iOS based, then maybe someone could write a jailbreak firmware with 24/192 support. Has anyone tried this for the AppleTV2/3?

      Interesting link to the teardown. Anyone know what else would be needed for this little box to spit out 24/192? Is it possible that this could be enabled to do this down the road?
    1. The Computer Audiophile's Avatar
      The Computer Audiophile - 06-20-2012, 08:21 AM
      I think the most difficult things will be sending higher resolution music to the AE rather than getting it to output up to 24/192. Apple has AirPlay locked pretty tight.
    1. Audio_ELF's Avatar
      Audio_ELF - 06-20-2012, 08:52 AM
      Chris...

      Are you sure AirPlay is limited to 16/44.1 & 48? I've seen suggestions that Marantz NA7004 works via AirPlay with 24/96 but those reports may be confusing its uPnP capabilities with AirPlay capabilities...
    1. The Computer Audiophile's Avatar
      The Computer Audiophile - 06-20-2012, 09:06 AM
      Hi Eloise - I'm saying the whole AirPlay ecosystem is pretty closed and limiting. Mainly getting iTunes to send audio higher than 44.1 will be the larger challenge rather than getting the hardware to output at a higher rate. If, and it's a big if, the Marantz supports higher than 44.1 via AirPlay the user won't be using iTunes at the moment. Sure there are many other playback apps, but for high resolution & wireless Apple products it's pretty limited.

      Do you know or remember how the Marantz NA7004 was tested with higher resolutions on AirPlay (if this is the case rather than UPnP)?
    1. deafjam's Avatar
      deafjam - 06-20-2012, 02:54 PM
      Thanks for the review. Could you please describe in more detail how you exactly connected between your computer and the AE, and the AE and your DAC?
    1. Akapod's Avatar
      Akapod - 06-20-2012, 03:09 PM
      @deafjam -- Computer to AE -- wifi. AE to DAC -- mini-toslink to toslink.
    1. extracampine's Avatar
      extracampine - 06-20-2012, 04:24 PM
      Whats it like for video - does the video & sound sync properly?
    1. Audio_ELF's Avatar
      Audio_ELF - 06-20-2012, 04:31 PM
      Quote Originally Posted by The Computer Audiophile View Post
      Hi Eloise - I'm saying the whole AirPlay ecosystem is pretty closed and limiting. Mainly getting iTunes to send audio higher than 44.1 will be the larger challenge rather than getting the hardware to output at a higher rate.
      Chris. Perhaps you have some insider knowledge: but I'm just curious what you base your assertion that it's iTunes which is the limiting factor rather than the hardware at the receiving end?

      I've certainly read of iTunes sending 24/96 to an iPad connected to a DAC via Camera Connection Kit (via WiFi though this maybe Home Sharing not AirPlay) so why the automatic belief it can't send high res to an AirPlay device.

      I'm not saying you are wrong: just there seams to be no official word (from Apple) and information from Marantz, Denon and others using AirPlay seems mixed/confused. And Google is of no help in this instance.

      Eloise

      PS. I can't find any more details of the NA7004 testing so that may be my faulty memory.
    1. dave_kiwi's Avatar
      dave_kiwi - 06-20-2012, 05:33 PM
      Ok, have posted this before, but here is a set of "tests" outlining testing done with "AirPlay".

      Am I Experienced?: Possibility for Airplay/AirTunes to Airport Express with Hi-Res Audio

      1. On Apple TV, up/down sampling is done on the Apple TV itself. (Not a big deal)

      2. iTunes ALWAYS down-sampling the audio file to 16/44.1k, no matter the remote end is an AE or Apple TV. In other words, iTune was hard-coded to down-sampling to 16/44.1k while using the AirTunes ................ (This sucks!!)

      3. The worst case for playing audio via AirPlay/AirTunes is: playing a Hi-Res file to an Apple TV!! Since the audio file is firstly down-sampled by iTunes and then up-sampled by Apple TV.
      So, the unanswered question is:

      How is 'Home Sharing' different than 'AirPlay' ????
    1. jhwalker's Avatar
      jhwalker - 06-20-2012, 05:44 PM
      Quote Originally Posted by dave_kiwi View Post
      Ok, have posted this before, but here is a set of "tests" outlining testing done with "AirPlay".

      Am I Experienced?: Possibility for Airplay/AirTunes to Airport Express with Hi-Res Audio



      So, the unanswered question is:

      How is 'Home Sharing' different than 'AirPlay' ????
      Home Sharing is simply file copying. So it literally copies the file from one device to another, no conversions.

      AirPlay is a feature that, according to the information I've read, converts to ALAC at 16/44 for streaming. To compound matters, the ATVs also are fixed at 16/48 (or is it 24/48?), so they resample all incoming 16/44 to xx/48 :/

      Like everyone else, I'd love to see AirPlay extended to 24/96 - I can live with out 32/384 for now
    1. dave_kiwi's Avatar
      dave_kiwi - 06-20-2012, 05:49 PM
      So, based on what you say re 'Home Sharing' with ATV2, playing music means that the re-sampling (down) would only be done once - on the ATV2, but 'AirPlay' would involve 2 re-sample steps: 1 x iTunes (16/44.1) and 1 x ATV2 (16/48).

      No wonder it's confusing :-)
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