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Old 18th March 2014, 11:28 PM   #11
TNT is offline TNT  Sweden
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Originally Posted by Julf View Post
...and that is rather theoretical....
Rather? Please explain how, theoretically, a NAS could affect word clock jitter in the D/A?

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Old 18th March 2014, 11:32 PM   #12
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Originally Posted by mBox View Post
NAS [Ethernet] --> Raspberry [USB] --> BRIK DAC [AUX] --> AMP

http://webbuilder3.asiannet.com/ftp/...0Converter.pdf
6moons audio reviews: Brik Audio DAC and integrated amplifier

I'm using kernel streaming on the Raspberry. The stream's supposedly untouched.
That the stream has bit integrity is paramount. If it isn't I would not call the errors necessarily "jitter". The important in this case is that it is altered i.e. not good.

I can assure you that how the kernel in a NAS is configured has no impact on jitter. Loss of data, alteration of data OK, but not jitter as in bit/word clock timing error at the DA chip. No.

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Old 19th March 2014, 06:01 AM   #13
Julf is offline Julf  Europe
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Rather? Please explain how, theoretically, a NAS could affect word clock jitter in the D/A?
I was leaving some space for the "everything matters" crowd.

The NAS itself can't really affect it in any way, but the network traffic causes varying load on the RPi. We can go through theoretical scenarios of how that would have an effect on clock jitter, but for practical purposes it does not matter.
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Old 19th March 2014, 12:02 PM   #14
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Since MPD is buffering the audio before sending it to the DAC how could playback on my DAC actually be affected by network traffic with final destination RPi?
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Old 19th March 2014, 12:06 PM   #15
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That the stream has bit integrity is paramount//
My stream is probably bit-perfect there's no re-sampling before sending the bits to the DAC.

cat /proc/asound/card0/pcm0p/sub0/hw_params in linux returns bit-perfect playback
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Old 19th March 2014, 12:27 PM   #16
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Since MPD is buffering the audio before sending it to the DAC how could playback on my DAC actually be affected by network traffic with final destination RPi?
You wouldn't believe some of the more far-fetched theories I have come across. But then again, there are those who claim to hear a difference between different C compilers used to compile the player software. Personally I would describe them using a word for small kitchen appliance for cooking soups and stews that is also the name a village in North Yorkshire. Interestingly the two parts of the word are also slang words for psychoactive drugs...
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Old 20th March 2014, 10:28 AM   #17
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Ok Ok, so the "nature" of the incoming data to the DAC could have, via power feeding etc., effect on the properties of the Rasberry spdif generation.

Galvanic isolation is good. Toslink very nice if clock re-generation is performed downstream of the opto link.

Toslink/spdif -> PLL -> DAC ... no.
Toslink/spdif -> PLL -> memory buffer -> *new* clock -> DAC ... yes.


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Old 20th March 2014, 10:38 AM   #18
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Galvanic isolation is good. Toslink very nice if clock re-generation is performed downstream of the opto link.
I agree. Only problem is synchronisation of source and DAC - at some point your buffer will overflow or underflow if you don't do any sort of flow control (this is the big benefit of async USB).
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Old 20th March 2014, 11:09 AM   #19
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And the drawback of have to rely on that asynchronous mechanisms in-built clock. Because thats the clock you are listening to. And around it goes
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Old 20th March 2014, 11:30 AM   #20
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And the drawback of have to rely on that asynchronous mechanisms in-built clock. Because thats the clock you are listening to. And around it goes
Sure - but async does allow you to have totally separate clock domains if you want to. S/PDIF, EBU, toslink etc. don't, unless you arrange a separate clock feed, slaving the source to the DAC clock.
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