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Do I need clean USB power when using DAC with its own power supply?


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9 hours ago, Archimago said:

Engineers who make DACs these days are also aware of potential noise so will address them in the designs whether common mode or otherwise. So unless we can demonstrate an issue with the DAC output using the stock power supply that came with the device, no need being concerned, right?

 

You are very naive in thinking that engineers successfully adress these issues. I don't know who you have been talking to, but there are plenty of manufacturers who will admit that DACs remain sensitive to noise and very few who claim to have successfully addressed this. 

 

Your logic demonstrates a fundamental misunderstanding of these issues. 

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1 hour ago, audiobomber said:

I read some, but it's just another anti-audiophile diatribe. Salvatore has been a troll for decades.

 

If I were looking for a measurement to correlate with PRaT, the first place I would look is transient performance. How closely does the DUT follow transient swings, i.e. attack sustain decay release? 

 

 

An anti-audiophile diatribe coming from an audiophile? Your non-sensical explanation that follows makes you sound more like a troll than anyone else. Transient response, attack sustain decay release are meaningless concepts in digital audio - these are just terms you  use to  express the impressions you get when a track is accurately reproduced and gives you a sense of PRaT.

 

In digital audio, things are very simple: either a recording is accurately reproduced by a DAC or it isn't. If it is, then everything else,  including PRaT, soundstage, ect.. follows. 

 

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16 hours ago, Archimago said:

Besides, when it comes to "setups", usually we're dealing with variations in speakers, rooms, maybe amps. Much less likely that small fluctuations in the USB DAC (noise or other distortion) are the main issues

 

Why is it so much easier for people to accept that a high quality turntable can significantly improve a system over a bad turntable, but not accept that the quality of a DAC could not have the same impact? 

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On 7/7/2021 at 9:20 AM, visigt said:

Can I simply block the "dirtu power"simply by blocking the power connection in the USB plug?

 

Whenever you have an electrical signal connecting  two equipment, noise can find a way from one to the other. The fact that the 5v wire is disconnected between your source and DAC does not effectively isolate the two (the data wires are also electrical signals...) . The best way to isolate the DAC from the source is to use an optical connection, but that introduces different problems.

 

If you want to follow the advice of those who believe that DAC engineers know how to deal with noise, then by all means don't bother with any of this and simply try to enjoy your system as is. 

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25 minutes ago, March Audio said:

Im afraid you are just generalising.  My anecdote.  I remember getting an ARcam Black Box (3 I think) and being hugely disappointed at just how little impact it had on sound quality over my existing (decidedly average) CD player.

 

I would present the issue in a slightly different way; that there is much assumption that issues are not solved, and regarding cause and effect.

 

 I go back to my previous comments. There is often much hand waving about nebulous descriptors which are then attributed to nebulous things such as "digital noise" without any real definitions, evidence or correlation.

 

If I show you a graph of jitter, showing very low levels, levels that have been demonstrated through controlled subjective listening tests to be inaudible, why would you continue to think that jitter is a problem?

 

I don't claim to know what is a problem or not, but I do know what I hear. I also do know that there are still "unknowns"! Why, because the engineers manufacturing DACs often admit it. They themselves don't understand all that is going on. They admit that solutions are partial and imperfect. But they (mostly) all agree on the issues...

 

I trust their own admissions more than the few amateurs who publish blogs to explain the contrary. 

 

Vis à vis your jitter graph/tests:

 

There is no guarantee that jitter on a test tone will correlate with jitter levels on an actual music track. 

 

Controlled subjective listening tests could yield inconclusive results because the impact of jitter/noise is identical in all DACs sampled during those tests. 

 

All these so called "objective" measures and tests are simply a fad made popular by a few amateurs. The fact that some DAC manufacturers have jumped on the bandwagon and started offering products that "measure well" is just "noise". 

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Here is one example:https://www.hifi-advice.com/blog/specials/an-interview-with-raphael-pasche-of-ch-precision/

 

HFA: Do you know of a reason why Music Servers also differ in sound?

 

Raphael: I think the collective answer from the entire industry is that we don’t really know. Nobody knows exactly. Think back to when CD was first introduced. Audiophiles agreed that it didn’t sound very good in the beginning, but look how far we came and it’s pretty decent now. I think we will see a similar process for servers and streamers. There are just a few more things that collectively we have to do. We just have to eliminate layer for layer, what is causing the problem, and this takes time. We provide the receiver, the Renderer, and people can do what they like on the source side. We do get a lot of feedback from our customers, which gives us clues.

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13 minutes ago, March Audio said:

 

You may well hear something, but why do you attribute it to a cause without any evidence?

 

With respect, your assumption that music is somehow different to a test tone when assessing jitter is incorrect.  Jitter is the variation in the dac word clock timing.  It is equally applicable to test tones as it is to music.  However with a steady test tone it allows the jitter levels and characteristics to be easily quantified where it cannot easily be done with variable music.

 

I dont know who or what you are referring to when you say "engineers/dac manufacturers admit it".

 

Can I suggest you read the BBC paper above.  Tests in that example were carried out by adding known quantities of jitter into the system.  Its not been tested in the way you imagine, but regardless, no 2 dacs have the same jitter characteristics.  Audibility thresholds have been well defined over many years of research.

 

 

If you look at a clock's specifications and take that as a measure of jitter then you are clearly missing out... 

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2 minutes ago, March Audio said:

I disagree with his comments and methods there. He really doesnt speak for 'the entire industry".   Customer feed back is extremely unreliable due to the the varied nature of their systems and inherently uncontrolled nature of there comparisons.  Talking generically about CDs 30 years ago is a specious argument.

 

Also him saying "There are just a few more things that collectively we have to do" implies that he does understand the problems.

 

Wishful thinking. 

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1 minute ago, March Audio said:

Its actually very simple.  You add known quantities of jitter into a system and see at what points listeners find it audible.  The levels are surprisingly high compared to what most DACs achieve these days.

 

That does not give us an indication as to how an accurate DAC would sound like. 

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7 minutes ago, March Audio said:

Again with respect, your argument appears to boil down to "I dont beleive you" regardless of what evidence or information is provided.

 

Please go and have a search round the internet and take a look at the information regarding jitter audibility and the research papers that are out there.

 

It then seems that even the "experts" don't agree... 

 

https://www.audio “science” review/forum/index.php?threads/is-jitter-audible.3235/

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5 hours ago, March Audio said:

Im not sure where that leaves us if people wont believe measurements and subjective listening tests.

 

No one said this was going to be easy!

 

Measurements are interesting but may not capture everything, and there are millions of reasons why subjective impressions (starting with our own) can be challenged.

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Here's another engineer (B.Putzeys) talking about the challenges of digital audio:

 

https://www.stereonet.com/forums/topic/317371-bruno-putzeys-darko-interview/

 

Here's a well respected DAC designer (among other things) who actually uses measurements to some extent (as most serious engineers do) - he's talked about how he uses them, but I cannot find that link. In his view, measurements were never meant to be used as a complete framework for evaluating equipment performance. 

 

I actually have not listened to the whole interview but trust the short summary provided in the link is accurate. 

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24 minutes ago, Archimago said:

Things are complicated. But let's keep it rational

 

By simply claiming noise and jitter are none issues because:

 

"If there is a noise issue that can be addressed, I cannot imagine that they would not fix it. (To be clear, the DACs these guys I've spoken to make are not cheap!)" 

 

Give us a break! Where's the science there??? 

 

Your blog is a series of rants against audiophiles, and that's fine, but let's not take everyone for complete idiots please. 

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I understand (from previous comments here) that Salvatore is a controversial figure, but I do find his articles interesting. Here is another one on "sound floor":

 

http://www.high-endaudio.com/rec.html#Noise

 

The concluding paragraphs are interesting, as he discusses his efforts to convert "hard-core audio sceptics". 

 

... when these objectivists finally admitted hearing the extra information (provided usually by tube electronics), they always went on to say that it was "much too subtle" to be concerned about, and usually further stated that they "couldn't understand how anyone could make such a 'big deal' about almost nothing". These events were rare and tiny "victories" for me, though still quite satisfying. This was because I always had the same last words ready for the objectivist: "It's the love and pursuit of these same audio 'subtleties' that defines an audiophile."

 

Perhaps some of us are more or less sensitive to particular aspects of sound reproduction, whatever the reason may be? (I'm not saying "audiophiles" have special hearing abilities). What is important to one person may be irrelevant to another.

 

Are these "subtleties" essential? When I'm listening to music on my phone with my 20$ Porta Pro headphones I cannot hear them, but I still enjoy what I'm listening to! But sometimes I tell myself: I can't wait to listen to this track on my speakers 🙂

 

We also have to acknowledge that our hearing is still an ongoing topic in scientific research. What makes it so sensitive (probably more so than audition tests may reveal)? Here's one interesting read:

https://news.mit.edu/2007/hearing-1010

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2 hours ago, firedog said:

And in spite of what many think  expectation biases are not conscious

 

Absolutely. I have found that there is a lot of reticence from some audiophiles to participate in blind tests as they are convinced they are "objective". My suspicion, however, is that some are simply worried about the outcome. They see it as a stressful situation where they may end up "losing" (what?).

 

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On 7/20/2021 at 6:39 PM, audiobomber said:

There are plenty of people on ASR who believe a $200 Topping is as good as a $2000 Mytek because of Amir's bullshit. I replaced the D50S with a Modi 3 that lists for half the price and got better sound. None of the measurements answer either of these two situations, so what good are they to me? The answer is... not much

 

While I agree with the conclusion, it is very possible that a 200$ DAC may sound just as good as a 2000$ DAC, or to be more precise, that neither will offer "high fidelity" (for different reasons). They may offer their own slightly different distorted version of a recording. 

 

People like AMR and Archimago have jumped in to this to offer "distressed" and "confused" audiophiles a way to discriminate between products based on a set of measurements.  We have talked about the limitations of their approach and challenged their premises. 

 

We could also blame "professional" reviewers who have proven incapable of offering useful advice and "clarity" in this big mess that is digital audio today. 

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To get back to the topic of USB, noise, and measurements... 

I would be curious to know:

 

- whether people who buy these new "budget" DACs purely based on specs and measurements end up keeping them very long ? Looking at ASR, it seems that forum members are in a permanent state of excitement about the newest models - while the previous models measured just as well or the differences were supposed to be inaudible!

 

- are these DACs really used with a direct connection to a noisy PC ? You find a lot of people raving about these DACs that end up spending a lot of time tweaking them, spend just as much money (or even more) on source equipment, external clocks, etc...

 

I have the impression, from reading various forums, that the ideas preached by the new audio gurus at ASR and other such sites are not in fact really put in practice by their followers.

 

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On the other hand, Jo Schmo looking to invest a little money into a home stereo system is probably not going to be purchasing a DAC these days, but will prefer the convenience of an "all in one" system with active speakers or an integrated amp with Bluetooth or wifi connectivity. If he were to read Archimago's blog or ASR's website he'd probably think the authors are just as insane as if he were to read the "novel way to massively improve the SQ of computer audio streaming" thread (and most others on AS) 😅

 

The so-called "non-audiophiles" who are interested in DACs and spend their days on ASR (for example) are probably no different than the "audiophiles" they criticize. 

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