Measured evidence that bit perfect playback software alters the analog output of DAC's?

[esldude]

MM- I'm sorry Dennis, but what you think can be done, and what can be done are not the same. One can do just about *anything* in software, including mucking about with the drivers. Not even particularly difficult to do if one knows what one is doing. Rather different for S/PDIF and USB, but the idea is the same. And yes, there are limits to how much you can do and still have the system operate without error.

 

It doesn't take much change at all - think in terms of jitter to get an idea of the scale. And there are other, better things you can modify to make changes too.

 

For example, we used to program music on AM radios by mucking around with processor, memory, and IO activity in computers. (Bigger computers than you are used to today of douse, like PDP 11/45s...) That was a game we played decades ago.

 

Most machines are better shielded now, but it is quite possible to do the same thing. If you mess about with HDMI it is *very* easy to do, though you had best put a test loop on the cable instead of a video monitor. Modifying system activity, and different types of system activity, is a quite plausible way to change the sound and still retain a bit perfect data stream.

 

Actually, I am a little surprised you even have a question about that- but then I guess unless you have been neck deep in data transmissions it may not be quite as blindingly obvious. And while it is easy, it is easy only when you already know what to do. I might have assumed there.

 

I don't have any special knowledge about what the player guys are doing, but all the "big" players are here on CA. I was not being facetious or ornery when I suggested you ask them.

 

-Paul

 

Come on Paul, you just put it out there without thinking it through.

 

One can do all sorts of things in software in various systems yes. In this context, in this discussion, using an SPDIF stream from USB you can't do what you were claiming. You monkey about with the SPDIF all you want, but it will get re-clocked in this scenario. You monkey with it enough and it will not stay connected without drop out. Are you still going to insist on such a thing?

[sbgk]

Nice to find everyone being so civil in the debate today. I do so wish that some of you--especially Dennis--lived closer to me in California. Honestly, in less than an hour I could demonstrate so clearly the ways in which a half dozen or more of these crazy things make a material difference in the presentation and "reality" of the music. I would not in the least be able to measure or point you at exactly what to measure, but I have no doubt that all skeptics would walk away scratching their heads at what they hear with their own ears. Even Ethernet cables between two computers with one sharing its hard drive for music transport. John Swenson spent the weekend at my place early this month and that was one comparison that floored him because it makes no sense!

 

Good evening to all,

AJC

 

P.S. SandyK: I still sense you pushing the idea that a better power supply (for the computer in this case) will reduce the differences heard between other variables. I continue to find that the opposite is true--as it has always been with just about everything in audio: The better you make things, the more readily differences between other elements will be heard.

 

Yes, it's nice to see the debate moving forwards rather than going round in circles.

 

Different tcp/ip settings also make a difference eg disabling Nagles algorithm etc

 

more here SpeedGuide.net - TCP Optimizer

[sandyk]

P.S. SandyK: I still sense you pushing the idea that a better power supply (for the computer in this case) will reduce the differences heard between other variables. I continue to find that the opposite is true--as it has always been with just about everything in audio: The better you make things, the more readily differences between other elements will be heard.

 

Alex C.

I only just noticed the above.

I am in 100 % agreement with your last sentence. That never ceases to amaze me.

However, while a Linear PSU will improve things overall, I don't believe that you can make the highest possible improvements without separate high quality power supplies to the various areas . This has also been the experience in John Kenny's Irish forum where they tried Linear PSUs but found the most marked improvements came from separate battery (!) supplies to different key areas other than the motherboard. I am not a fan of battery supplies in a PC, but I do agree with ultra clean power to areas other than just the motherboard and via normal internal PSU cabling .

I will forward you a PM which isn't by any means disagreeing with your current approach, just suggesting there is more than one way to skin a cat..

Alex K.

[Paul R]

Nope. I would not argue with anyone who insists that a USB audio stream is the same as a S/PDIF data stream. However, I will try to suggest some areas you might want to invest some study time into - if you have a software background that gives you at least a basic foundation. (I don't know if you do or not, thus the qualification.)

 

Are you aware what a S/PDIF driver does when it senses data starvation? Or when it senses more data that it can transmit at the current data rate? Or how it will pad frames? Or how you can transmit non PCM data as PCM? All this is really basic stuff, even though it varies slightly from OS to OS and driver to driver. There is a lot more.

 

Isochronous USB transfers are similar in concept, but far from the same in execution. To begin with, they are packetized... and secondly, unlike other forms of USB transmissions, they typically do not consider the integrity of the data to be critical. (That would be up to the application... even if that application happens to be "firmware" in a device.)

 

Async USB - in general terms - just puts the timing of an isochronous transmission in control of the DAC. The devil is in the details though, and don't believe that generalization will give you a working understanding of Isocronous Asynch USB transmissions. Asynch USB was a brilliant idea and works amazingly well. As I pointed out though, there are other things software can do that can affect the sound - even with an Isochronous Async transmission.

 

Again, I suggest rather than acting like you can pass judgement on something you are evidently not very well informed on, you should ask the folks on the system here who build software players what they think. If you ask nicely, they might be inclined to guide you to a better understanding and perhaps provide more details to satisfy your curiosity.

 

-Paul

 

 

Come on Paul, you just put it out there without thinking it through.

 

One can do all sorts of things in software in various systems yes. In this context, in this discussion, using an SPDIF stream from USB you can't do what you were claiming. You monkey about with the SPDIF all you want, but it will get re-clocked in this scenario. You monkey with it enough and it will not stay connected without drop out. Are you still going to insist on such a thing?

[Jud]

And then there is the dastardly, mean, skeptical perspective. They know it does nothing, but as long as the charade continues they make happy customers which makes for happy software writers. No measurements desired in that scenario. And look at how long that has worked in wire. Occasional pseudo-science measures, white papers with lots of hot air and little substance, some talk of materials or winding geometry. Going strong to this day with no signs of letting up. Every year more expensive cables are out there than the year before. And while this isn't the DAC thread, wow, I know it isn't exactly news, but I have read in the past week of a $50K DAC, Stereophile has a review of a similarly expensive one in this issue (the whole thing USB, upsampler and transport is more than $100k), and another at $120k is being discussed here at CA now. Plus the first one in my list is available with extra abilities on custom order that can push that to $250k, yes a quarter million for one DAC. So regardless of whether it works or not, plenty of room for software to go yet.

 

Well, before we go there regarding player software (and I surely agree there is overpriced stuff living on reputation in the world of audio - whether there's a greater or lesser incidence here than with other sorts of pricey products I can't claim to know), let's consider two things:

 

- A fair amount of the "goodness" in Miska and PeterSt's players in particular is in filtering (and in Miska's case, dithering), and Damien's player has the very well thought of iZotope SRC software bundled with it. As I said previously, while the capability to transmit a bit perfect signal is a necessary starting point for this software, it is not nearly the only thing they do, and for most users not the most important.

 

- Let's not ignore Anthony's (acg) comments in other threads (and I think in this one?) that by use of the various means of controlling the OS and computer hardware in PeterSt's player he is able to minimize voltage fluctuations on the computer's power rails, and that he subjectively finds the best sound in this situation. Certainly there are several steps between minimizing voltage fluctuations in the PC and changing the analog output of the system, but it seems like an avenue that might benefit from further inquiry before we start speculating that (aside from filtering, which is a big aside) these players are doing nothing.

[Audio_ELF]

- Let's not ignore Anthony's (acg) comments in other threads (and I think in this one?) that by use of the various means of controlling the OS and computer hardware in PeterSt's player he is able to minimize voltage fluctuations on the computer's power rails, and that he subjectively finds the best sound in this situation. Certainly there are several steps between minimizing voltage fluctuations in the PC and changing the analog output of the system, but it seems like an avenue that might benefit from further inquiry before we start speculating that (aside from filtering, which is a big aside) these players are doing nothing.

I think this is where the gulf is though ... it may be shown that you can minimise voltage fluctuations, but (as far as I know) all we have to say these fluctuations affect the analogue output of the DAC (the only way they can cause a sound difference IMO) if by people saying they hear a difference.

 

Before expending effort on reducing such fluctuations, surely you should be as certain as possible that the fluctuations affect the analogue output ... and to do that Dennis argues that sighted listening is not enough.

 

Eloise

[Paul R]

Measuring analog output is not as simple as measuring digital output- the more sensitive you set your test equipment, the more differences there are. (Speaking in terms of trying to say the output is identical from two different samples.)

 

This is always true. Even temperature differences can affect the output at some level. The argument is, and always has been, are those changes above or below the level of human audibility.

 

It turns out the answer to that is most often "maybe." It isn't as sit and dried as we all would like to think.

 

-Paul

 

 

I think this is where the gulf is though ... it may be shown that you can minimise voltage fluctuations, but (as far as I know) all we have to say these fluctuations affect the analogue output of the DAC (the only way they can cause a sound difference IMO) if by people saying they hear a difference.

 

Before expending effort on reducing such fluctuations, surely you should be as certain as possible that the fluctuations affect the analogue output ... and to do that Dennis argues that sighted listening is not enough.

 

Eloise

[Audio_ELF]

P.S. SandyK: I still sense you pushing the idea that a better power supply (for the computer in this case) will reduce the differences heard between other variables. I continue to find that the opposite is true--as it has always been with just about everything in audio: The better you make things, the more readily differences between other elements will be heard.

I'm not sure I follow you logic here Alex ...

 

Surely if we are saying that software causes differences in sound quality due to variations in draw on the PSU, then if you improve the PSU to reduce those variations then by logic then you get closer to eliminating those differences.

 

Eloise

[4est]

Surely? I feel that is a conflation. Both the power supply and the computer create noise. A better PS suppresses the former, and may help absorb the latter, but it is two different items as I understand it. I do not see the The PS as the primary cause, but the fluctuations within the computer (HD, CPU, video ect).

I'm not sure I follow you logic here Alex ...

 

Surely if we are saying that software causes differences in sound quality due to variations in draw on the PSU, then if you improve the PSU to reduce those variations then by logic then you get closer to eliminating those differences.

 

Eloise

[mayhem13]

Although not entirely off topic, all we're doing now is the same audiophile roundup......speculating as to what may be the cause of subjective claims of differences in bit perfect files.

 

In Jud's example, the environment has changed, not the bit stream. In this case, one could make a case for the possibility of a reduced noise floor and less jitter within a more stable electrical environment. One could also easily make a case that both changes are so low, they are in fact in audible.......and round and round we go. If Gordan's expertise in the field is recognized, then I think we have to at least reexamine adding jitter into the realm of possibilities as well.

 

Again, something relieve at would be a simply statement from one of the software developers......'yes, I have measured and audible difference with and without our program and No, I cannot share these measurements because.............' Some argue there's nothing positive for the developers to do as such but I don't agree with that logic from a sound business perspective. Trust is everything. I've trusted my ears and they reveal no appreciable difference BUT I remain open to evidence my ears are either damaged or just flat out wrong. Nothing close minded about that IMO.

[sandyk]

I'm not sure I follow you logic here Alex ...

 

Surely if we are saying that software causes differences in sound quality due to variations in draw on the PSU, then if you improve the PSU to reduce those variations then by logic then you get closer to eliminating those differences.

 

Eloise

 

Eloise

My understanding was that Alex C wasn't talking about software with this one. He was more discussing differences he hears due to storage on different media,which may present very different power supply loads.

 

Alex

[Jud]

I think this is where the gulf is though ... it may be shown that you can minimise voltage fluctuations, but (as far as I know) all we have to say these fluctuations affect the analogue output of the DAC (the only way they can cause a sound difference IMO) if by people saying they hear a difference.

 

Before expending effort on reducing such fluctuations, surely you should be as certain as possible that the fluctuations affect the analogue output ... and to do that Dennis argues that sighted listening is not enough.

 

Eloise

 

I believe I hear good things happening, and you'll recall the other thread about the great similarity between Superdad's and my subjective impressions of several months' worth of Audirvana+ public and beta builds, so there's some level of possible confirmation there. But I haven't seen measurements, and even after measurements there are audibility questions, so definitely not any level of scientific certainty at this point.

 

It was measured evidence Dennis asked for in his original post, and I don't know of any such for the final analog product, only for a step in the process (voltage fluctuations). I'd love to see actual measurements as well. But Dennis mentioned in his recent comment the possibility that the player developers are engaging in an intentional charade, and to me it's premature for folks on the forum to say with any certainty either that something good is happening or that it's all a fraud, based on the state of things at this point.

[sbgk]

at the lowest level of player development I found that assembly instructions had there own affect on SQ eg a sub instruction produced sibilance vs an add or dec instruction, why this should be is down to the microcode behind that instruction that's embedded in the cpu. For this reason I think that software players are self limiting in SQ and the best solution is for software to load ram that's close to the dac and then use hardware controlled dma transfer. Maybe one day we'll see such a device. Kernel streaming has options that allows for a modified form of this and win8.1 had some words about hardware offloading, but that seems more aimed at notepad devices.

 

So there's your improvement options for a software player - don't use a software player.

[rennq]

I'll make it multiple choice:

 

A. It would reduce time I could spend posting here for your enjoyment.

 

B. Most (though not all) EE's have the opinions and ideas I do about this stuff. So what is to gain?

 

C. Would you feel better if I had different opinions than yours, but were better credentialed?

 

D. The two years and the money it would take to get an EE would be possibly better spent by just taking that sum of money to buy a really nice USB cable and listen to it for two years until they improve USB some more.

 

Predictable Dennis response.

 

A. Inflated sense of importance.

 

B. Believes he already knows everything.

 

C. Common Dennis tactic here. Deflect the real issue, which is you and your abusive, demanding, condescending, incessant, trolling behavior and try and make it appear as though someone is attacking your "opinions" or interests in measurements. This tactic works on a few who aren't quite smart enough to see through it. Eloise, surfingalien, Boris75 have certainly fallen for it. It's been explained many times that no one is attacking opinions or interests in measurements.

 

D. Always include the snide, belittling audiophile remark to get that pat on the back from the sheepish supporters. "Hey esldude, that's a good one, hah hah, durrrr."

[rennq]

But Dennis mentioned in his recent comment the possibility that the player developers are engaging in an intentional charade, and to me it's premature for folks on the forum to say with any certainty either that something good is happening or that it's all a fraud, based on the state of things at this point.

 

Wouldn't you agree that this is extremely bad behavior on his part (as well as libelous)? It's just a matter of time before he gets himself into a bit of trouble, I think.

[esldude]

at the lowest level of player development I found that assembly instructions had there own affect on SQ eg a sub instruction produced sibilance vs an add or dec instruction, why this should be is down to the microcode behind that instruction that's embedded in the cpu. For this reason I think that software players are self limiting in SQ and the best solution is for software to load ram that's close to the dac and then use hardware controlled dma transfer. Maybe one day we'll see such a device. Kernel streaming has options that allows for a modified form of this and win8.1 had some words about hardware offloading, but that seems more aimed at notepad devices.

 

So there's your improvement options for a software player - don't use a software player.

 

Do those instructions measurably effect the output?

[esldude]

Wouldn't you agree that this is extremely bad behavior on his part (as well as libelous)? It's just a matter of time before he gets himself into a bit of trouble, I think.

 

Jud can give his answer but I didn't claim this is fraud. It was a list of possible reasons measurements are not supplied.

[Jud]

Jud can give his answer but I didn't claim this is fraud.

 

Indeed, and I wouldn't want anyone to think that was what I was saying (that you were claiming fraud - just as you say, I thought you were simply listing possibilities).

 

Back on topic from here, hopefully.

[Paul R]

Do those instructions measurably effect the output?

 

What exactly are you measuring?

 

In terms of processor resources or in micro timing, yes, they do.

 

-Paul

[rennq]

Back on topic from here, hopefully.

 

Agreed.

[esldude]

Well, before we go there regarding player software (and I surely agree there is overpriced stuff living on reputation in the world of audio - whether there's a greater or lesser incidence here than with other sorts of pricey products I can't claim to know), let's consider two things:

 

- A fair amount of the "goodness" in Miska and PeterSt's players in particular is in filtering (and in Miska's case, dithering), and Damien's player has the very well thought of iZotope SRC software bundled with it. As I said previously, while the capability to transmit a bit perfect signal is a necessary starting point for this software, it is not nearly the only thing they do, and for most users not the most important.

 

- Let's not ignore Anthony's (acg) comments in other threads (and I think in this one?) that by use of the various means of controlling the OS and computer hardware in PeterSt's player he is able to minimize voltage fluctuations on the computer's power rails, and that he subjectively finds the best sound in this situation. Certainly there are several steps between minimizing voltage fluctuations in the PC and changing the analog output of the system, but it seems like an avenue that might benefit from further inquiry before we start speculating that (aside from filtering, which is a big aside) these players are doing nothing.

 

Yes all the software you mention does more than bit perfect. Those effects change measured results. Some have questioned the audibility in some areas, but that something changes in the output is clear.

 

With others we are back to some people say that they can hear it as the primary evidence.

[esldude]

What exactly are you measuring?

 

In terms of processor resources or in micro timing, yes, they do.

 

-Paul

 

Gee Paul, read the thread title. Measuring the analog output. As an audio device I care not at all about any changes if the analog signal going to my speakers is unchanged.

[Paul R]

Gee Dennis - how are you defining an analog output as being identical? What level of difference will make it non-acceptable? What kind of difference? What difference do you expect or predict will be visible? I have already said that the processor output can affect the analog signal out of the DAC, and many people have pointed out that electrical noise can pass into a DAC and affect the output signal.

 

You know as well as I do that an analog signal varies from second to second, and you also know that changes, such as jitter, are measurable in an analog signal only with great difficulty. Declaring an analog signal identical is a matter of degree only. In gross, of course the analog signal from any DAC, given it is fed the exact same input, will be identical in gross but possibly very different indeed in fine.

 

Be real- you are setting one tiny little expectation and trying to define all your assumptions from there. People have already told you yes, there are measurable differences. People have pointed out how software can cause those differences. And you have been pointed to people who can, if they are willing, help you understand what changes relate to what output.

 

Is your target here to understand or simply to make a point?

 

As for the thread title - the analog output of DAC's what exactly. I was assuming the apostrophe was merely a typo.

-Paul

 

 

Gee Paul, read the thread title. Measuring the analog output. As an audio device I care not at all about any changes if the analog signal going to my speakers is unchanged.

[Jud]

Yes all the software you mention does more than bit perfect. Those effects change measured results. Some have questioned the audibility in some areas, but that something changes in the output is clear.

 

With others we are back to some people say that they can hear it as the primary evidence.

 

Right. I was suggesting that in the long slog toward real knowledge, exploring the effects of minimizing voltage fluctuations in the PC might eventually prove a fruitful place to look for the kind of evidence that can be measured.

 

(Anticipating responses along the lines of what might constitute evidence but not be subject to measurement by lab apparatus - agreement to some arbitrary level of specificity by two or more independent listeners on a description of sound quality differences between two players, or two versions of a player, for example.)

[Superdad]

I'm not sure I follow you logic here Alex ...

Surely if we are saying that software causes differences in sound quality due to variations in draw on the PSU, then if you improve the PSU to reduce those variations then by logic then you get closer to eliminating those differences.

Eloise

 

Guess I should speak for myself here (but thanks 4est and sandyk): I have never postulated than s/w SQ differences were based on variations in draw on the PS. My note to SandyK was simply that I have always found that improvements in one area (PS in this case), make it easier to hear changes of most all other variables (s/w, resistors, transistors, capacitors, cables, album masterings, etc.). With only a few exceptions over 40 years, I have yet to have a system improvement make a prior audible variable less audible.

 

There certainly are exceptions, both past and in the future that I can think of. They most always have to do with circuit topology and/or improving immunity to certain variables. Indeed the USB interface has and will continue to an area subject to improvement. John Swenson is exploring some new techniques of USB isolation (and he has already done an S/DIF input that surpasses most others--watch for the Bottlehead DAC with that one). And of course there is already considerable variation in USB input immunity between various existing products (both DACs and USB>S/PDIF converters). I have heard only a very few others, so I can't comment on whether I think those products are more immune because they are opaque, or if they are actually more immune and still transparent.

 

I hope the above makes sense. I don't think any of what I said is terribly controversial.

 

Alex C.

 

Another P.S. for SandyK: Because you asked, and because I am nothing if not open-minded, I will make new rips of a couple of favorite CDs with our new PS running my mini. I will compare them (by ear) to the same tracks ripped with same method on same computer when it had the SMPS in it.