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

[March Audio]

2 hours 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? 

Prat is just a made up term, it has no meaning.  

 

Just ask people to explain it and see how far you get.  If you take the actual meaning of the words then it makes little sense.

 

If someone is concerned about pace, rhythm and timing, don't ever play an LP record with its inherent speed fluctuations which are massive compared to digital audio.

[March Audio]

16 minutes ago, hopkins said:

 

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? 

Because the difference between low/high quality dacs is comparitvely small while between turntables its much larger.

[March Audio]

17 hours ago, Archimago said:

 

Tell me, what is this "digital noise" you speak of and what do you think "jitter" does when music is playing? Do you not think the "high frequency blur" will show up in testing?

 

Since some of these characteristics like the "blur", constricted sound stage are audible in your experience, can you hypothesize as to a test design that would differentiate DACs?

 

I think this is what bothers me.  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.

[March Audio]

1 minute ago, fas42 said:

 

Lack of PRaT is very much a subjective sense of the music - it's comparable to an orchestra playing with no conviction, in a practice session, causing the conductor to start yelling at the musicians, wanting to kick their backsides - he knows the PRaT is bad; and has to shake them up, to lift the mood.

I had to answer this even though I'm trying not to feed Frank.

 

How can you possibly compare a conductors function to that of a playback system?

 

All the things the conductor controls in an orchestra are fixed permanently in the recording.

 

Pace rhythm and timing are exceptionally tightly controlled in a digital system.

 

 

[March Audio]

4 minutes ago, hopkins said:

 

When you read listening impressions on digital audio system configurations you would not think so! 

Aaahhhh.....but that's the inherent problem of uncontrolled subjective listening tests.

[March Audio]

4 minutes ago, fas42 said:

 

it is indeed that the musicians are "dragging their feet" - since I have heard the very same track full of life and vigor on other occasions, the fault must therefore lie with some aspect of the playback SQ.

No Frank, the difference is in your head.  That's not meant to be rude BTW.  You just really need to recognise that your (mine) perception is not a constant.

 

If you did you might stop chasing your tail with all your pointless tweaks.

[March Audio]

38 minutes ago, hopkins said:

 

Perhaps. But now think back about CD players. We had no trouble accepting the fact that a high quality CD player sounded better than a cheap one. We had explanations for this, (jitter being one of them). Now all of a sudden when it comes to computer based audio , we solve one issue (accuracy in extracting the data - provided a file is bit-perfect) but we trust that all other issues have been solved (jitter, noise)? Why? Probably because most DACs don't actually solve these issues, and because we don't fully understand them (and rely on a few amateurs running test tones and showing us nice graphs to demonstrate that DAC designers are all competent - most of these designers admitting themselves that they don't understand all that is going on!). . 

 

Unfortunately computer audio has solved some issues but has also created entirely new ones. 

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?  Why would you think the designer doesnt understand the issue?  I appreciate that you just used jitter as an example, but it is one area that has been very well researched for many decades.  Here is a BBC paper from nearly 50 years ago on the subject.

Digital sound signals: Subjective effect of timing jitter - BBC R&D

[March Audio]

14 minutes ago, hopkins said:

 

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 all agree on the issues... 

 

Concerning your other points:

 

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. 

 

 

 

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.

 

[March Audio]

8 minutes ago, hopkins said:

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.

I disagree with his comments and methods there. I can assure you 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 their 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.

[March Audio]

Just now, hopkins said:

 

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

I agree. Who is doing that?

 

You absolutely must measure the dac output. You then correlate  subjectively with what people hear.

[March Audio]

1 minute ago, hopkins said:

 

Wishful thinking. 

A conclusion based on what evidence?

[March Audio]

1 minute ago, hopkins said:

 

Good luck doing that with an actual track...

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.

[March Audio]

Just now, hopkins said:

 

This is wishful thinking on your part. 

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.

[March Audio]

2 minutes ago, Rexp said:

You still don't get it, there are no measurements that correlate with the listening experience. You science guys have failed to develop the appropriate tech. 

Sorry its you thats not understanding.  There are subjective listening tests that correlate jitter levels with audibility.  That isnt measurement, that subjective listening.  Its a correlation of cause and effect.

[March Audio]

44 minutes ago, hopkins said:

 

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

No, but that wasnt the point.  It was about one of the problems you cited as being an audible issue, specifically jitter.

[March Audio]

40 minutes ago, hopkins said:

 

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

 

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

I don't see what the disagreement is, it is just stating that the audibility of jitter is dependant upon its nature (frequency etc).  All very well known and understood.

[March Audio]

13 minutes ago, opus101 said:

 

Audibility of jitter is also dependent on DAC architecture (noise-shaping etc.) but I don't see that stated in many places.

 

Even if it is, the source in itself is irrelevant to the audibility. It's the nature and level of jitter that counts

 

All of this is very well researched and documented.

[March Audio]

39 minutes ago, opus101 said:

 

You have some doubt that architecture matters to jitter audibility?

No, I was differentiating between audibility and the fundamental cause for the jitter.  The fundamental cause is not relevant to audibility, the nature and level of the jitter is.  You were conflating the two.

[March Audio]

9 minutes ago, The Computer Audiophile said:

Seems like this discussion should be split into two. One in the subjective main part of the forum and the other in the Objective-Fi section. 

Possibly, but note that in this specific example of jitter the evaluation of audibility is very much based upon subjective listening tests.

 

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

[March Audio]

Just now, The Computer Audiophile said:

Some people just can't help themselves. I can count on one hadn't the number of threads @March Audio has entered that haven't turned into a pissing match. 

Sorry Chris but that implication is offensive.  Stop blaming me for the reaction of others.  Everything I have said in this thread is backed up with scientific evidence.  If others want to believe in fairies fine, but lets not make me out to be the bad guy.

[March Audio]

3 minutes ago, The Computer Audiophile said:

Who is "us" and why do you care so much?

All of us.  

 

If some want to only hear or allow one side of the story then thats a sorry state of affairs.

[March Audio]

Just now, The Computer Audiophile said:

You're a perpetual line stepper. You know the rules of the forum, yet constantly step on the line. 

 

It doesn't matter if everything you said was true, people come here to enjoy this hobby and you continually challenge people just trying to have fun. That's why we have the objective sub-forum. Your crusade to save people from themselves and right every wrong in audio is what's offensive and not a good look for you or your company. 

No crusade Chris, just commenting on the subjects that come up.

 

If this is only about "having fun" why are you on a crusade with MQA?

 

By your comments here, it seems that MQA should just be allowed to slide by because the fact that it does nothing useful is unimportant.

 

Some people are convinced that it improves sound and you are "spoiling their fun" by pointing out otherwise.

 

Thats just hypocrisy.

[March Audio]

3 minutes ago, The Computer Audiophile said:

Have at it in the objective forum. You know this. Don't pretend it's censorship.

So a parallel thread for every subject because some here are incapable of reasoned debate and get offended every time some information contrary to their view is presented.

 

If thats what you insist upon.