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Why can't audio be sent to an Airport Express's digital out at 24/96? and more ...

post #1 of 6
7/12/06 at 11:50pm
Thread Starter 
I have been researching the reason as to why 24/96 audio cannot be passed over the Airport Express to its digital output. Has anyone successfully sent 24/96 over an Airport Express to its digital output?

Can anyone answer this question?

Cheers,
-------------------------
Portable & Home rig mixed unintelligibly together:
iMod iPod (or G5 -> Airport Express (optical)-> Benchmark DAC-1) -> RS Emmeline 2 Raptor or RS SR71-> H600/Equinox or k701 (or UM2 w/SR71) - > ears.
Soon: G5 or MacBook? -> I2S modded Airport Express or USB w/IS2 RJ45 mod -> Turbomodded I2S modified Benchmark DAC-1 -> RS Emmeline 2 Raptor -> aforementioned headphone sans the UM2 -> ears.
Other stuff (ICs, etc.): P500 Powerplant, Shunyata Diamondback power cords, generic toslink optical cable, MIT T-2, Blue Jean Audio cables.
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post #2 of 6
7/13/06 at 3:23pm
Quote:
Originally Posted by elvisbot
I have been researching the reason as to why 24/96 audio cannot be passed over the Airport Express to its digital output. Has anyone successfully sent 24/96 over an Airport Express to its digital output?

Can anyone answer this question?
If you go wired USB from iTunes using a USB converter, it will pass 24/96, so iTunes is not the limiter. Only the wireless has this limit. I do not believe that 802.11g has this limit, but the AirPort Express hardware may have this limit.

Seems like the SB also has this limit. It is also 802.11g.
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post #3 of 6
7/13/06 at 4:16pm
Quote:
Originally Posted by elvisbot
I have been researching the reason as to why 24/96 audio cannot be passed over the Airport Express to its digital output. Has anyone successfully sent 24/96 over an Airport Express to its digital output?
You might find this article helpful.
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post #4 of 6
7/14/06 at 3:21pm
Quote:
Originally Posted by machead
You might find this article helpful.
There seems to be one error in this article:

"and is limited to music files that iTunes can read; ie, 16-bit data only"

iTunes can definitely read 24/96 and pass it via USB, so iTunes does not have this limitation.

Also erroneous:

"the fact that, as the AE doesn't have a local clock circuit, when the incoming data is interrupted, as it is when you change songs in iTunes, there is no longer a digital output to feed the DAC, which loses lock as a result"

Not true. The AE has a local clock as I have replaced it with a modded Superclock3. It loses lock for other reasons - primarily because when it gives up the network, the I2S signals into the PCM2705 stop and so the S/PDIF output stops.

Also the wrong conclusion:

"The AirPort Express stumbled when it came to its measured jitter performance—hardly surprising, considering it has to derive its 44.1kHz word clock from an asynchronous, probably encrypted datastream."

The local clock/PLL generates the S/PDIF signal and I believe there is some buffering.

The Jitter can be quite low if the circuit is modified and uses a Superclock3 or other suitable low-jitter oscillator.

Steve N.
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post #5 of 6
7/17/06 at 3:17am
Thread Starter 
Oy, I'm just going to dump the Airport idea and get one of those Ultraband USB hubs. That will make transfering the audio data much easier.

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post #6 of 6
7/17/06 at 8:55am
Other people at head-fi use the Airport Express and a DAC and haven't had problems with it?
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