Baffled about computer power

opus111 said:

I have no such want. If you'd like to make progress in understanding SQ differences, you might wish to perform the experiment. If not, then don't.

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You seemed to have that "want" when you said this: "I'm just falsifying your claim here." If you want to falsify something you need data and specifics, not just a claim.

But our two situations are not symmetrical. You're putting forward measurements which you claim say something relevant about your kit. I explained why they do not. I put forward an experiment you could perform should you so desire. A proposal for an experiment is not a claim.

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You went way past a proposal. You are claiming industry standard tests are useless to quantify performance of transports. That is a tall claim and needs more than, "here is a test for you to run." I don't jump and run tests people propose if they can't meet the bar of making a good case for them and showing enough initiative on their own to gather data, and present them in a constructive manner.

This is nonsense. I agree I was vague about the number of tones so let me add detail. Try with a stimulus of 100 or more tones. Do you need any more detail to perform the experiment? If you still consider the experiment a 'vague metric' then explain what's missing.

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You need a lot more for me to go and fire up my test bench to do anything. Any audio tests blows a weekend for me. A weekend that I could use to enjoy music, movies or finish getting this boat ready to go on the water. What's wrong with you doing the test?

Firstly why do you need to do a comparison?

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Because that is the topic of discussion that you engaged in. People said traditional stand-alone transports are superior to PC based ones. So I presented similar measurements performed on both classes of products. You propose a measurement for which you have no data. So even if I measured a PC that way, we wouldn't have the same data on the high-end stand-alone product. I am not buying a $50K transport just to make a point.

You could begin by comparing the noise floor with a digital zero stimulus with that under a multitone stimulus. The digital zero would give you a baseline for determining the degree of noise modulation.

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I look forward to you sharing such data or reasons why you can't.

Secondly, just because something is 'industry standard' doesn't mean its any practical use. In this case I've explained why not, if you disagree then what have I said so far which isn't correct? Show me my faux pas please.

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It is your opinion that it is not of "practical use." To go against an entire industry you need to mount a very strong argument, backed by data and how we correlated that with listening test results. You haven't done anything other than saying I should go run some tests. The responsibility is yours to prove the usefulness of what you propose. It is not my job o help you with your argument by spending my time and resources testing it.

Now if you were polite and not confrontational, showed insight as to why this is a useful test, then I would have put it on my TODO list. Instead, you are doing the opposite so any interest I had in doing this test at the start are long gone.

Thirdly you're claiming something about 'personal tone' - chapter and verse please as this looks to be your own personal perceptual distortion to me. If you have evidence for the 'personal tone' then I'd like to see what it is.

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You have poor self-awareness to not see how badly it comes across when you say, " I'm just falsifying your claim here. " Falsifying claims? You took a casual interchange that was not heated and turned it into one. I bet if you provide a link to the forum that banned you, I can find similar lack of awareness to how your response comes across.

Finally, I'm being constructive here so don't understand why you request me to be constructive. What in what I have so far written isn't constructive - chapter and verse again please.

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I measure constructiveness two ways:

1. How much technical knowledge, and data is presented. You have done very little here.

2. How much negative emotion is thrown in there. And negative you have been.

In your next post, before you hit send, examine it on the basis of the above two criteria.

Amir, the original post is about Steve Nugent changing his Mac mini PS to a Linear one & finding a large improvement in SQ. He surmised that it was to some extent related to CM noise on the USB line. Opus111 concurred that it was such & furthermore that it was not easy to measure noise.
Your plots ignore any of this & show no measure of the contribution of noise to the evaluation of such "large improvement" in SQ.
Simply saying that your measurements are industry standard (ignoring noise) does not really hold any value in this discussion which I thought was about Steve's reported improvement.

I used this analogy before which Frantz didn't seem to understand but it's the story of the guy who dropped his car keys at his car & walks 50 yards away to search for them under the street light ( let me add this bit - it's the industry standard illumination )

amirm said:

No it is not "all" that one can say about audio quality. I am not writing a thesis on the topic . Simply adding some data points, taking us from mere words to something concrete. With respect to transports, where digital samples cannot change, measurements of jitter is a super strong component and that is what I shared. To prove the sensitivity of the test in showing such differences, this is my same laptop, driving an AVR using its HDMI input:

We see a substantially degraded (measured) performance. BTW, the two traces are the same measurement just changed in time! Once the AVR gave me the top results, next the lower. Such variations (triggered by activities internal to the machine) did not exist with S/PDIF.


(about the DCS...) From an objective point of view, those are superb results. They are somewhat incomplete however in that the stop short at maximum jitter of 3.5 Khz. I rather see the full spectrum as effect of masking diminishes with increased jitter frequency.

If you are asking me to make sense of why people have the preferences they do, we get into the same classic argument of not knowing if those observations, even if expressed by a million people, are accurate. We know the measurements however, are accurate. So in order to get some place rather than turn this into the classic back and forth, we should focus on the data. Once we establish that the measurements show state-of-the-art performance, then the area of disagreement becomes smaller.

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Thanks. Your picture shows that HDMI is not a good way of connecting a laptop to an AVR receiver - something WBF readers should already know from your previous posts about this subject. But since you have shown that all the "serious" equipment (or decent, as some people like to call them) can easily show SOTA measurements we should look if there is something measurable that correlates with preference. Just ignoring opinions because they do not seem accurate gives you peace of mind, but will not bring us explanations why some partnering of digital equipment gives us better sound quality in high-end systems.

BTW, did the Berkeley Alpha USB produce the best jitter results in music servers you have measured? I would hate reading a post from you stating that it was the second best after buying one to try.

jkeny said:

it was not easy to measure noise.

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Is there a reason the noise wouldn't show up on a scope or spectrum analyzer?

microstrip said:

BTW, did the Berkeley Alpha USB produce the best jitter results in music servers you have measured? I would hate reading a post from you stating that it was the second best after buying one to try.

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It is the best one I have test but my sample set is so small: just the two I mentioned. Audiophilleo and Berkeley. These are the brands we carry at work and hence the reason I can test them. I would have loved to get my hands on a dozen of them and test them all the same way. But can't see buying them just to run the tests .

amirm said:

It is the best one I have test but my sample set is so small: just the two I mentioned. Audiophilleo and Berkeley. These are the brands we carry at work and hence the reason I can test them. I would have loved to get my hands on a dozen of them and test them all the same way. But can't see buying them just to run the tests .

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I understand your point. I reformulate my question - your laptop connected to the Berkeley Alpha USB is the best music server you have experienced until now?

Julf said:

Is there a reason the noise wouldn't show up on a scope or spectrum analyzer?

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I think your question should be direct to Opus11, he was the one who stated this! Why didn't you ask him at the time he posted?

amirm said:

It is the best one I have test but my sample set is so small: just the two I mentioned. Audiophilleo and Berkeley. These are the brands we carry at work and hence the reason I can test them. I would have loved to get my hands on a dozen of them and test them all the same way. But can't see buying them just to run the tests .

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I don't understand, Amir, you have the Audiophilleo in your shop (& sell it I presume) yet you said you hadn't listened to it?? Do you sell it or use it in installations? Have you not listened to this?

Another datapoint posted on the original AudioAsylum thread http://db.audioasylum.com/mhtml/m.h...ALL&sortRank=None&sort=date&sortOrder=DESC&r=. This is a post from John Swenson, a well known designer:

I did my own XMOS fully isolated DAC, I can bypass the isolation or leave it in. With the isolation different cables make almost no difference, but power supply does make a difference. With the isolation bypassed the cables also make a difference.

I have not spent any time trying to track down the path of PS difference.

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microstrip said:

I understand your point. I reformulate my question - your laptop connected to the Berkeley Alpha USB is the best music server you have experienced until now?

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I have not done any music listening with my laptop. My laptop was what I used to drive the test instrument that I used to perform the AVR measurements. It is not my music server. My music server or I should say my subjective audio testing gear is a desktop. It was too heavy and complicated to move that machine to my hardware test lab and at any rate, I needed all the other programs that only exist on my laptop do that project.

Based on my measurements using the laptop, I would not however hesitate to place its combined performance at the top of the class using the Berkeley and async USB, combined with a high performance DAC.

By the way, combining this with the arguments in the other thread as far as "audiphile players," the J-test signal was played using ordinary code to play test clips in the instrumentation software. I even tested with Windows Media Player and as long as the pipeline was set to the same sample rate, and 24-bits so that dither would be below system noise level, same squeaky clean results were demonstrated. Again, this is my workhorse laptop with a dozen apps running on it including the heavy number cruncher one performing the real-time FFT on my laptop on behalf of the instrument which itself was hooked up using another USB port and was sending data back and forth furiously. So if these things are bad, then this represents the worst case situation! Clearly no stand-alone app was having to handle such workload.

amirm said:

....
By the way, combining this with the arguments in the other thread as far as "audiphile players," the J-test signal was played using ordinary code to play test clips in the instrumentation software. I even tested with Windows Media Player and as long as the pipeline was set to the same sample rate, and 24-bits so that dither would be below system noise level, same squeaky clean results were demonstrated. Again, this is my workhorse laptop with a dozen apps running on it including the heavy number cruncher one performing the real-time FFT on my laptop on behalf of the instrument which itself was hooked up using another USB port and was sending data back and forth furiously. So if these things are bad, then this represents the worst case situation! Clearly no stand-alone app was having to handle such workload.

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Of course, the other possibility, that you fail to acknowledge, is that this test is of no value in revealing differences. Car keys/Street lamp anecdote, remember?

jkeny said:

Of course, the other possibility, that you fail to acknowledge, is that this test is of no value in revealing differences. Car keys/Street lamp anecdote, remember?

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And what test would you suggest?

amirm said:

(...) Based on my measurements using the laptop, I would not however hesitate to place its combined performance at the top of the class using the Berkeley and async USB, combined with a high performance DAC.

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Thanks. Am I correct when I assume that almost all your comments about music server performance were exclusively based on this particular type of jitter test you have shown us? Sorry for taking so much of your boat time!

Hi

Reading the exchanges, many I find amusing, I may have to retract something I posted earlier in a different thread. Not verbatim, it was about a $500 music server "wiping" the floor with mega-expensive transports. This seems to have raised the ire of many... I may have been gotten too excited to see how a cheap PC played music in a way that is not discernible ,to me from expensive transports.
Yet in all this no one has come with one single measurement, I would allow just one in which case, a mega transport would surpass a PC feeding an asynchronous USB to their favorite dac. Just wanting to see one measurements in which a dedicated transport outshines any pc based system and what parameter would that be? Of course it cannot be price or looks or reputation.

FrantzM said:

Just wanting to see one measurements in which a dedicated transport outshines any pc based system and what parameter would that be? Of course it cannot be price or looks or reputation.

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Bragging factor?

FrantzM said:

Hi

Reading the exchanges, many I find amusing, I may have to retract something I posted earlier in a different thread. Not verbatim, it was about a $500 music server "wiping" the floor with mega-expensive transports. This seems to have raised the ire of many... I may have been gotten too excited to see how a cheap PC played music in a way that is not discernible ,to me from expensive transports.
Yet in all this no one has come with one single measurement, I would allow just one in which case, a mega transport would surpass a PC feeding an asynchronous USB to their favorite dac. Just wanting to see one measurements in which a dedicated transport outshines any pc based system and what parameter would that be? Of course it cannot be price or looks or reputation.

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Frantz,

Did you take any measurement to prove us that you only wrote that sentence because you got "too excited"? Only in this case this justification can be accepted.

BTW, to my knowledge no one was able to show a measurement that could correlate with the sound quality coming from very good transports - measurements could only exclude the very lousy ones.

microstrip said:

Thanks. Am I correct when I assume that almost all your comments about music server performance were exclusively based on this particular type of jitter test you have shown us? Sorry for taking so much of your boat time!

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I don't understand your question. If you are asking if I have also done listening tests, and spent far more with these systems than the measurement project, the answer is yes. I have lived with these systems for 2-3 years in this architecture (and more than a decade using Pro Audio cards). We have three music servers at work in different rooms/systems and have them connected using normal USB, the two async interfaces and multiple speaker/amp configs. I have spent hours doing AB comparisons. Those subjective results point to the async USB interface improving the performance of any external DAC/Processor that I connected them to, sans one. They also always outperformed non-async USB subjectively.

I have also documented my Berkeley vs Audiophilleo here: http://www.whatsbestforum.com/showthread.php?4160-Review-Berkeley-Audio-Alpha-USB

I don't push this data because as I say in that thread, everything I hear may be faulty. The effects of placebo are far stronger than the differences I hear. For that reason, I present the measurements because they are reliable and concrete in what they show.

We may also differ in priorities. To me the *content* of music is priority 1. Its fidelity, as shocking as it may be to many of you, is priority 2. I get far more enjoyment out of my new car stereo that lets me play my large music library from flash drive where I can listen to a ton of varied music as my mood mandates. In contrast, the CD is boring in that I wind up listening to the same CD over and over again as I drive long distances. Convenience for me is such a huge factor that once I adopted music servers, there was no going back. For that reason, you don't see me with a stash of high-end CD players to compare things to. I think they are obsoleted and dead, just not buried . They are the rotary phone of music systems. We absolutely know how to get superb performance out of a PC and the measurements show that in spades. As do the superb fidelity that I hear. At shows like high-end area of CES, 9 out of 10 digital systems I hear are based on music servers.

So don't look to me spending a ton of time worrying about what $$$ stand-alone players are like. It just isn't a priority for me either based on usage or what they think they can accomplish technically. All of this is of course opinion. The data was not .

jkeny said:

Of course, the other possibility, that you fail to acknowledge, is that this test is of no value in revealing differences.

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Oh, the test could not be more sensitive. It showed minute differences at below -120 db between async USB devices. It showed what happens when we go from one digital interface, S/PDIF to HDMI. In all of these cases, the measurements were *your* friend in that it shuts down the objectivist arguments that "digital is digital." Clearly there are aspects of system that impact digital reproduction and these measurements show them with superb discrimination. In that sense, you should be jumping with joy. I know I am . Indeed, the motivation for running all of those tests came from someone claiming on another forum that HDMI had gotten so good lately that there was no difference between it and S/PDIF. Well, the tests clearly showed that hypothesis to be wrong. So imagine my surprise to see you dismissing the test as having value.

If we agree then that the test is hugely useful in showing that digital is not just digital, we don't get to then throw it out because it doesn't serve some other esoteric agenda we have for it to show some other thing we imagine. For years, I had posited that there would be differences between digital domain interfaces and I have finally done the work to document them comprehensively in that article. You seem to have a hypothesis just the same, yet have not done anything to bring data to back it. So your hypothesis, unlike mine, is unproven.

Car keys/Street lamp anecdote, remember?

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No, you should remember why we have created digital audio tests. They are created by working backward from system architecture. We know for example that jitter ampliltude is proportional to frequency so we use a high frequency signal. We know how the PLL works so we test and measure low frequency jitter that is below its corner frequency. We know how serial digital interface works so we modulate the low order bit in S/PDIF. This is not your random analogy of me measuring the temperature of two cables and declaring them the same electrically because it is easy to do.

I am here as a resource to the forum and fellow audiophiles to bring more data to the table. But you guys are doing such a poor job of making your case, and providing details that I feel no motivation to go beyond tests that so clearly show what we want to see.