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What a long, strange trip it's been -- (Robert Hunter)

Discussion in 'Mike Moffat (Baldr)' started by baldr, Oct 13, 2015.
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  1. Abtr
    Galvanic isolation basically and *generally* means electrical isolation (either inductive or capacitive). It's not an audiophile term per se: https://en.wikipedia.org/wiki/Galvanic_isolation
  2. Ableza
    Yea like I said, you being new to these threads should take the time to search and read the comments here and on Jason Stoddard's thread about this topic. And please don't become one of those "Google Knowledge" experts who thinks becaue something is on Wikipedia that makes it absolutely true.
    sam6550a, MWSVette and quimbo like this.
  3. Abtr
    Well, enlighten me please. Are you suggesting that electrical noise from the source is not an issue with USB audio?
  4. AudioBear
    These days trying do be honest and educate about the technology can be a loosing battle. At a certain point if you want to keep selling a product that lacks all the buzzwords, you have to add the buzzwords. Schiit still eschews DSD, MQA and all that but it seems like in this case they were willing to galvanically isolate because that was part of their USB fix. This in no way mitigates the fact you stated. Galvanic isolation, for reasons Baldr explained at great length many posts ago, is clearly not the problem with USB. I also think Mike will concede that with Eitr or Gen 5 USB, USB is now acceptable if not his preference,
    MWSVette and Ableza like this.
  5. Ableza
    Not at all. I'm suggesting that "galvanic isolation" is a meaningless buzzword, a misuse of the term. There is nothing "galvanic" about transformer isolation. There is quite a bit that is electro-magnetic about it though. "Galvanic" is a type of corrosion that occurs between two dissimilar metals, often accelerated by the presence of high saline content. It is also a process used to zinc-coat steel.
  6. earnmyturns
    It is, but "galvanic isolation" (whatever that marketing term means) is not the solution by itself. The frequency band that need to be allowed through from source to destination to convey the electrically-encoded digital USB signal can also carry electrical noise that can interfere with the internal operations of the DAC. So, Eitr/Gen 5 use both transformer-based isolation and digital signal regeneration with accurate S/PDIF clocks to try to block as best as possible (at that low price point) a wide range of potentially DAC-affecting electrical noise. The experience of many, including me, is that Eitr/Gen 5 do a fantastic job of bringing USB from mediocre sources (eg. a RPi) close to much more expensive sources, Nevertheless, also in my experience still nothing works as well as AES from an Auralic Aries femto into my Yggy.
    Last edited: Feb 10, 2018
    Baldr, liamo, Abtr and 1 other person like this.
  7. Abtr
    Sorry, you're obviously wrong here.. Galvanic: "relating to, or producing a direct current of electricity" (https://www.merriam-webster.com/dictionary/galvanic). Galvanic isolation: "a principle of isolating functional sections of electrical systems to prevent current flow" (https://en.wikipedia.org/wiki/Galvanic_isolation). I agree galvanic AC isolation is frequency dependent..
    Last edited: Feb 10, 2018
  8. Ableza
    Whatever, knock yourself out!
  9. MWSVette
    Time to break out the popcorn....
    FrivolsListener and Ableza like this.
  10. Ableza
  11. AudioBear
    This may be one of those situations where both of you are right. Ableza is historically correct about the original use of galvanic and galvanic action. In recent years, however, the term has been co-opted to mean isolation of signals in electrical and even optical circuits. There is absolutely nothing galvanic about optical isolation but there you have it, it's a commonly used term.

    It is of interest to go back and read the headers on the wikipedia entry ( https://en.wikipedia.org/wiki/Galvanic_isolation )

    "Electrical isolation" redirects here. It is not to be confused with electrical insulation.
    This article needs additional citations for verification. Please help improve this articleby adding citations to reliable sources. Unsourced material may be challenged and removed. (April 2014) (Learn how and when to remove this template message)

    Afterthought edit: The New Oxford Dictionary defines galvanic as:

    galvanic | ɡalˈvanik | adjective 1 relating to or involving electric currents produced by chemical action. 2 sudden and dramatic: hurry with awkward galvanic strides.

    it occurred to the chemist in me that galvanic action is based on a difference in potential, generally resulting in a DC current which, as Ableza suggested, can cause corrosion. Strictly speaking, galvanic isolation can be used for DC isolation but of course noise and RFI are not DC. I guess there is no law against a bunch of electrical engineers deciding to adopt a chemistry concept and morph its meaning into a term that is useful for them. I would have used electro-isolation but hey, galvanic is a better buzz word. At the end of the day this is how languages evolve. And buzzwords are how marketing makes a living.
    Last edited: Feb 10, 2018
    Abtr likes this.
  12. Abtr
    I honestly don't see how this refutes my previous statements about the need for so called galvanic isolation to isolate a DAC from its *electrically* noisy (USB) source. In fact Schiit appear to agree that this principle is important by launching their new Gen 5 USB and Eitr.

    Note that it can be said that e.g. an optical connection provides perfect galvanic isolation because there is no electrical current (direct or alternating) involved, although there are other (jitter related) problems with optical interfaces..
  13. Ableza
    You have completely misunderstood me if you think that's what I am saying. My point, and Mike Moffat's in the post I quoted, is the term "galvanic" is meaningless in this situation. That it is misapplied. it was made up by someone to mean electromagnetic isolation. I am not implying that the issues solved by isolation are not important. On the contrary, it is why Schiit's Gen 5 USB solution is so superb. But calling it "galvanic" is like me calling stroopwafel a vegetable.
  14. AudioBear
    Setting aside the problems with optical interfaces, I totally agree that this is today a correct use of the word galvanic. When everybody is using a term, whether they understand it fully or not, it becomes part of the language whether some of us like it or not. Personally I don't like it when meanings are changed, but that's not the point, when it comes to linguistic drift, the majority rules. Think of all the slang terms like "cool" or "chill out" that bear no resemblance to the original meanings of the words.

    In Schiit's case, and I shouldn't put words in their mouths, I think they are simply saying, go ahead and electrically isolate a USB circuit. It will still suck because there are other problems clocks and timing, jitter, etc that are not solved by isolation. Eitr and Gen 5 USB were designed to deal with more issues than galvanic isolation. USB can still sound bad even if isolated. Hence the complaints about the use of the buzzword.
    MWSVette likes this.
  15. earnmyturns
    What you said above shows exactly why the term "galvanic isolation" is a bad choice for what we are discussing. A circuit intended to block DC leakage is irrelevant to what matters here, which is the leakage of time varying electrical noise from digital source to DAC. The signal we want to preserve, the electrical encoding of the bitstream, is also time varying, so passing it through correctly while blocking noise in the same frequency band is not a matter of simply blocking (DC) current. Any circuit that blocks all (time varying) current flow blocks all signal (basic electromagnetism)! That's why Mike Moffat and several of us with a traditional EE background (well, mine is partial as I fled EE for math and CS early on) object to the misuse of the term "galvanic isolation" when discussing time-varying signal and noise.
    Last edited: Feb 10, 2018
    DougD and MWSVette like this.
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