What happens to an audio signal from media player to dac

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"No differences" is the problem here, and how that can be known.

You want bit perfect, well then, that's simple: you compare every bit.. And you obviously can't to that visually with Audacity, and you surely already lost the battle if you need to match volumes. You'd need som other tooling for that that looks for the phase difference between the two files, and when found compares the two (it's a litte bit more complicated than that) sample for sample. If there is no phase difference, then checksumming is indeed the way to go.
 
As for jitter, I do not have a good way to measure SPIDF or USB jitter, but in many ways I don't care. What I do care about is if it makes a difference to the analog output of the DAC. That is the signal that matters, because that is the signal I listen to.

Bless you. This very simple and obvious notion seems to be beyond the grasp of many audiophiles.
 
now wait a minute... you're basically saying that all those people in the search for the perfect USB cable should just find real hobbies or, God forbid, simply start enjoying the music? you're basically questioning the validity of thousands of lyrical cable reviews out there, you do realize that, don't you? shame on you, that is one cruel perspective :(
 
but what's wrong with the excitement of waiting for the doorbell to ring, hoping it's the postman bringing the new USB cable? or with the joy of unpacking the nice package with trembling hands, to discover a nice, colorful, silky-smooth sleeve? or with the impatience of writing a review for it at CA? or... with the the fact that it brings oh-so-much-more closeness to the music yet at the same time leaving just the tiniest room for improvement, so that the noble quest for a better one can continue?
I truly think all those hours in the lab looking at scopes made you forget the simple joys of life :( when did we lose our humanity?
 
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but what's wrong with the excitement of waiting for the doorbell to ring, hoping it's the postman bringing the new USB cable? or with the joy of unpacking the nice package with trembling hands, to discover a nice, colorful, silky-smooth sleeve? or with the impatience of writing a review for it at CA? or...

Nothing, really. If that's the talisman which helps your brain enjoy the music more (or just entertain you), then there's nothing wrong with that. Now once you (or the guy selling the talisman to you) try to relate this to physical reality, expect that evidence-based sourpusses will probably say mean things unless there's some actual evidence. But that changes the enjoyment and entertainment not one whit.
 
now wait a minute... you're basically saying that all those people in the search for the perfect USB cable should just find real hobbies or, God forbid, simply start enjoying the music? you're basically questioning the validity of thousands of lyrical cable reviews out there, you do realize that, don't you? shame on you, that is one cruel perspective :(

You're jumping to a major delusion there - in assuming the SQ differences attributed to cables are down to jitter. IME they're not - CM noise is the culprit. Async USB is immune to jitter as the clock's in the DAC, the guys (for example Charles Hansen of Ayre) do still report SQ differences with that :D
 
You're jumping to a major delusion there - in assuming the SQ differences attributed to cables are down to jitter. IME they're not - CM noise is the culprit.

I guess some of us might be sourpusses enough to ask for some kind of proof of the validity of your theory...

Async USB is immune to jitter as the clock's in the DAC, the guys (for example Charles Hansen of Ayre) do still report SQ differences with that :D

Ah, yes, so the people selling the stuff report differences. Right.... :)
 
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You have experienced some effects and possibly made some observations by making measurements.
exactly what I wanted to say. I'd guess that common mode noise is not differentiated from jitter by listening alone, so maybe abraxalito has some measurements. also, aren't there any more effective solutions for CM noise than cables (low capacitance?)? and if a good cable is the only solution, is there any esoteric technology involved that justifies the prices?
 
Yes there are ferrites for CM noise on cables. Or CM chokes for balanced cables like USB - Steve Nugent (Empirical Audio) is even selling some CM chokes of his own design for a tidy sum :) Personally I would recommend spending as much on ferrites as on the cable - no more than single digit $.
 
but then again, doesn't this mean that all those waxing lyrical about cable differences are describing noise flavors?

Intermodulation distortion caused between the audio and the HF noise yes. That would be my hypothesis. The solution that arises from this hypothesis is to provide better CM filtering on cables.

Here's a theory for you Julf as you're seemingly interested in those: The audio industry at large doesn't like the SQ differences to be down to something tangible like CM noise, they'd prefer to keep selling stuff that fixes up non-existent jitter problems. Like picosecond clocks for example. What do you reckon?

aren't there readily-available USB cables with ferrites already fitted? I think I have one that came with some gadget at home.

Yes but probably only to meet EMC regs, not to give low IMD.
 
Intermodulation distortion caused between the audio and the HF noise yes. That would be my hypothesis. The solution that arises from this hypothesis is to provide better CM filtering on cables.

The USB data cables are differential / balanced, so high common mode rejection should be easy to achieve. Ground/power is more problematic - but if you don't use the USB power, but have an independently powered DAC, galvanically isolating the connection is trivial.

This of course doesn't apply to optical - no common mode issues there.

Here's a theory for you Julf as you're seemingly interested in those: The audio industry at large doesn't like the SQ differences to be down to something tangible like CM noise, they'd prefer to keep selling stuff that fixes up non-existent jitter problems. Like picosecond clocks for example. What do you reckon?

I agree that you probably have a point about the high end of the audio industry not being too keen on the answer being too easy, but I don't think that applies to the whole audio industry.
 
Intermodulation distortion caused between the audio and the HF noise yes. That would be my hypothesis. The solution that arises from this hypothesis is to provide better CM filtering on cables.
worth trying as long as it's in the one figure range.

Here's a theory for you Julf as you're seemingly interested in those: The audio industry at large doesn't like the SQ differences to be down to something tangible like CM noise, they'd prefer to keep selling stuff that fixes up non-existent jitter problems. Like picosecond clocks for example. What do you reckon?
picoseconds you say? how about the $10k femtosecond MSB clock?

Yes but probably only to meet EMC regs, not to give low IMD.
worth giving it a try though.

(nice sig BTW. but JMK is defunct as of now which makes for an interesting problem :D )
 
The USB data cables are differential / balanced, so high common mode rejection should be easy to achieve. Ground/power is more problematic - but if you don't use the USB power, but have an independently powered DAC, galvanically isolating the connection is trivial.

Haven't seen a trivial (i.e off-the-shelf) way to isolate UAC2 yet but I had heard that ADI was working on a solution. You know of a trivial solution?

I agree that you probably have a point about the high end of the audio industry not being too keen on the answer being too easy, but I don't think that applies to the whole audio industry.

Fair point - consider my post edited to qualify the word 'audio' with 'high end'.
 
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