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About opus101

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  1. Just from a quick eyeballing in Audacity - the channels are swapped and one of the two is phase inverted.
  2. opus101

    Corona Virus

    No, if its the same case I read about (article was in the SCMP) they were all seated on the bus for several hours. Enclosed space, no windows open, AC running.
  3. SBT testing of whether customers are happy? Are you serious here or just changing the focus to something not relevant to the discussion? Recall originally this was about my claim that there's evidence of happy customers. Your reply was 'I'd like to validate that' - by which you didn't mean that you didn't want just to rely on UT's claims they were happy but wanted to check for yourself?
  4. Are you curious as to the reasons those companies make DACs with copper connectivity or are you arguing to make a point like 'Those guys make DACs with those interfaces so cannot be so problematic' ? If the former, have you asked them? If the latter, consider how many manufacturers make products with single-ended analog inputs and outputs using RCAs.
  5. How would you validate it? Jud saying he's a happy punter should just be dismissed as 'no evidence' ? If not, then what?
  6. What is 'UT'? I'm with you on the points about jitter, despite having read the white paper I still cannot see how jitter is an issue unless DAC designers aren't implementing best practice in terms of PCB layout. Which is why I'd like examples of DACs in the marketplace where this has been screwed up. On the CM noise/isolation front, I would agree that fibre renders it a non-issue. Is anyone making a DAC which has fibre as its input?
  7. Just cherry picking one paragraph. ISTM that John Swenson isn't making any claims in his white paper about changing the sound because its very system-dependent. If he were to make claims, guys with your ideological persuasion would be even more down his throat than at present. ISTM this box is a fixer-upper and if the end user had a perfect DAC they'd experience no change at all. The reality is though DACs are all imperfect to some degree - to that degree there may be an improvement by adding the ER. There is the evidence of a considerable number of happy customers to consider - but with your ideological stance you prefer to dismiss that. As you want measurements start by telling John Swenson which measurements and why those measurements.
  8. Hi Alex - I take it that the scare quotes around the word 'educating' imply preaching rather than responding to a person's natural curiosity? In which case of course I agree.
  9. As I'm someone with a technical background I'd just like to point out here that while many techie guys are like that, not all are. For myself I find it enjoyable to engage in educating those without the technical chops when they're open to it (which isn't always the case).
  10. I'm not personally in any doubt about the common-mode noise issues, clearly they're very relevant. However the jitter arguments in the white paper seem to leave out a vital step - how does the groundplane noise make it into the DAC clock? Common ground impedance coupling is certainly a method that it can - so then if designers are indeed making that mistake, show some examples of it in real-world products. I note that Schiit is most likely (I dunno for sure, just from looking at their latest USB board) using transformers to couple the clock to the DAC - if this turns out to be true then at least they are on top of this problem.
  11. I'd not be concerned about things that might be relevant, I'd want a bit more certainty that it is relevant in practice. Groundplane noise isn't something new, I recall when I was working as a designer I came across it at the beginning of the 1990s, then it was called 'ground bounce'. There are pretty well-known ways to mitigate it so if this is a problem in practice (it might be that designers these days don't read Ott or the other gurus on EMC issues) then I feel education of designers would be the best long-term solution.
  12. So what is it that makes this mechanism - even if shown to be active in practice - relevant in the bigger picture? On your measurement result - fine, I don't have a different one because I have yet to see the relevance. Which is why I'm asking about that.
  13. What is it that makes the groundplane noise at the receiver relevant? Can't we just check at the output of the DAC (I'm assuming here we do have sensitive enough measurements for low-frequency noise)?
  14. You're aware that measurements made in normal mode probably won't show anything on the DAC's output are you? Isolation brings reductions in common-mode noise and there's no guarantee that'll get converted to normal mode at the DAC's output.
  15. Its not a request as such, just it would be good to see an example of how clocks get corrupted in DACs where the designers have made layout errors. It would help the industry to improve their designs. I am not expecting them to do this, its just a wish.
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