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Apple Airport Express to DAC

Hi,

I have an evolution 100A and 50CD. When I run digital audio through an apple express via toslink to the 50CD DAC, it sound great, but there is "skipping". I searched online and couldn't find an immediate cause of this.

I am running Apple Airport Express to a Creek EVO 50CD DAC via minijack to toslink optical cable.  There is intermittent "skipping" that I cannot figure out. If I run minijack to RCA on the amplifier (EVO 100A), there is no skipping.  I asked creek support and this was the conversation:

creek: It sounds like there’s an issue in using that type of cable. This is not a true way of using an optical signal. I would suggest using the jack to phono rca lead as this will use the DAC in your Creek unit rather than the built-in DAC of the Apple product.

me: I'm confused. Running optical signal to my creek DAC is wrong? You suggest running minijack to RCA on the EVO 100A amplifier? How does the EVO 50CD get the digital signal from the EVO 100A?

creek: An optical signal can only be transmitted down an optical cable that’s terminated with TOSLINK blocks at both ends.There are no digital signals past between the Evolution 50CD and Evolution 100A. The signal is only analogue; not digital between these devises. I would suggest running an RCA phono cable from the pre-amp output of your Evolution 100A and plugging that signal into the jack socket of the Airport Express.

me: but the minijack out on the airport express is a combo analog/optical output. (picture of back of airport express from apple website showing analog/optical port).

creek: /crickets

Can anyone explain what I'm doing wrong?  Thanks for your help.

Cable: FosPower (3 Feet) 24K Gold Plated Toslink to Mini Toslink Digital Optical S/PDIF Audio Cable with Metal Connectors & Strain-Relief PVC Jacket.

Airport Express: whatever the latest version was with firmware updated.

128x128pandrus
leemaze
330 posts
 
HI @robr45 actually it seems to not be the case.  

The Arcam dac, Cambridge dac, Marantz dac, Creek dac all have trouble holding the lock from the Airport Express.  Some people think it is an issue with SABRE DAC chips.  CambridgeAudio was able to make some sort of update to the DacMagic that fixed the problem.

found on another forum, Cambridge apparently said:
"Basically, the Airport does not output a smooth SPDIF clocking. Every now and then, the Airport will sporadically adjust its output clock to track the desired sampling rate.
These adjustments are very sudden and are the cause of the noises and/or drop-outs describe". 

And from the designer of the M-DAC:
" First first Gen worked without Drop outs when set to High Bandwidth... With Gen 3 they changed the Chip set and its even worst then the first for Jitter performance - with large discrete jumps in clock offsets - these jumps throw off (unlock) any dac with decent jitter attenuation (Tight Lock Bandwidths) - ironically Dac's with poor jitter attenuation cope with the Jumps, but off course they have poor jitter attenuation..."

What I don't understand is why a reclocker, like the iPurifier, would lose the lock as well.

But I know many people have also had success with this set up, so I'm wondering what specific model DACs they've used.

@pandrus did you try updating the firmware on your integrated or reaching out to Creek?
robr45's avatar
robr45
319 posts
 
Might I suggest replacing the airport express with something that can properly output a digital singal then? Seeking a dac that can cope with a poor implementation of spdif doesn't seem to make sense. A gen 2/3 Apple TV has no such issue and can be had for less than $50.  
pandrus's avatar
pandrus OP
14 posts
 
@leemaze I did speak with creek - see original post - their customer support seemed entirely clueless.

@robr45 I do have an old apple tv lying around - I'll try it out.
pandrus's avatar
pandrus OP
14 posts
 
Also @audioengr posted this in another thread...


audioengr2,934 posts03-14-2013 10:14pmIt will work however it has the highest jitter of any digital source. This can be fixed with an in-line reclocker like the Synchro-Mesh. This will make it equal or better than the best transport.

Steve N.
Empirical Audio
leemaze
330 posts
 
Good idea @robr45 !

@pandrus any luck with the apple tv?

Regarding @audioengr comment - I don't think it's the jitter.  It must be something else, because i tried a reclocker between my airport express and the Fiio D03 DAC - the iFi SPDIF iPurifier - and that couldn't hold the lock either.  But when i took the iPurifier out of the chain the DAC holds the signal fine.

Very strange....
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