Async-USB 24/768 NOS1 up and running!

[manisandher]

Initials thoughts on SQ to come, but just wanted to give you all a heads up first.

Later...

Mani.

[Gerard]

Initials thoughts on SQ to come, but just wanted to give you all a heads up first.

Later...

Mani.

Great!!   

Have Fun!!

 

[Nick]

Mani hi,

I have this vision of you being rooted in front of your system since you made you post at 1:20 this afternoon 

Any thoughts, good ?

Best Nick.

[manisandher]

Firstly, sorry it's taken me a while to continue with this thread.

... I have this vision of you being rooted in front of your system since you made you post at 1:20 this afternoon 

Quite honestly, I was a little disappointed with the asyn-USB NOS1, which kind of made me refrain from posting my initial thoughts. Oh don't get me wrong, when I first got it all working, it sounded very good. But it didn't give me that 'wow' feeling like I had the first time I listened to the original NOS1.

And I'm really glad I waited. I've spent most of the day (and yesterday? - I can't remember) exchanging emails with Peter to figure out a couple of problems. But what transpired was the discovery of a major, major problem - my computer was not allowing XXHE to take full control of the OS and 'do its thing'. I thought it was, but with Peter's help discovered that it wasn't. Anyway, after a whole day of trying things, I decided to try loading XXHE onto my other dedicated music PC. This time everything worked out fine. The 'Minimise OS' in the new version of XXHE worked fine.

I've moved the PC that works into my main room and am listening to the NOS1 right now. And what can I say? I think the best way of describing the sound of the new async-USB NOS1 to the original is that this one is so much more musical. It still has all the detail, but you just forget listening to this because you get so pulled into the music.

I could sit here and write about how amazing Vaya Con Dios sounds right now... blah, blah, blah... but I won't. Actually, I'm finding it hard to write anything constructive. The sound I'm getting from the async-USB NOS1 is utterly, utterly amazing. What else can I say?

There are a couple of points that I think are worth mentioning though.

Firstly, I'm not sure how much of this amazing performance is down to the new NOS1 interface or actually the 'Minimise OS' function in XXHE. All I can say is that before I managed to get this function to work, the NOS1 sounded good, but not particularly much better than the original.

The second point is that I'm 'only' using 8x Arc Prediction. Peter needs to do a little more work on the USB driver to allow for 16x AP (i.e. 705.6/786KHz). I'm not sure if this will provide much more of an improvement - I can't imagine how - but we'll see.

On a final note, I just want to thank Peter for all the time he's taken to help me get things sorted over the weekend. I've never experienced this level of collaboration/help from any supplier/manufacturer of, well, anything before. I feel totally privileged to be member of the 'Phasure club'.

I'll post more thoughts/experiences when I've got anything new to say. For now, listening has become a totally new experience... again!

Mani.

[PeterSt]

[this will be a fairly long post, but I guess I'm at rest now somewhat ]

Hectic as things are already, and with in between jobs a died main server (took me 5 full days to recover it), I forgot about a tiny winy little thing : XXHighEnd.

Yea, this is a totally stupid thing;
I am listening myself through a rather "tweaked" XXHighEnd from right after 0.9z-5-2 was put up (2.5 monts back), but it was merely about manual control to keep things right than that I could really use XXHighEnd to do it. This was also when I said it would take a LOT of programming to get it all done. Ok, I had been working on that ever since (again in between jobs of course), and along the way I got sort of distracted by that other improvement I found, really working on the first NOS1-USB to go out. That by itself kept us busy for an unplanned month. Still a good decision, I say afterwards.

As we know, again in between, I set myself to finding decent playback means for the Mac (succeeded), and while over two weeks back I sat down to finish the driver on the 768 part that server died.

Next thing I knew is that we started to send out a few first DACs while they were physically ready anyway, and at being late already I finished the driver in 384 fashion which was already prepared for a longer time. So, all set !

Well, no, because when Mani had unpacked a first NOS1-USB, I only then managed to think of XXHighEnd not being finished yet. For what ? well, for that sheer fact it just needs that better OS environment I already talked about in another topic. So, it worked allright at my place for long, but this really is different from having a fool proof production version. Normally only a commercial issue (too many bugs maybe), but this time a dangerous one (unbootable PCs maybe).

In the end I got it done with only 1.5 days of NOS1's being under mains control and steaming up - doing nothing further - at Mani's place. Here I want to thank Mani for his patience and offering his "no problem Peter !", but while I'm at it anyway, I must *also* gracefully thank a few other people, eager to wait for the box to arrive, that box arriving when they themselves had to leave before that. Yes, I am referring to Norwegian people, who all seem to work offshore.
And yes, I could also extend the story to such people sending me an email about the good time to send the NOS1 for their upgrade, that email not being read by me because that server being down, and *when* I read it, the man in question just left the day before for his little-long boat trip. NOS1 at home, wife at home - wife does not want to pack and send it. Yes, I would be mad.

Maybe I tell these totally seemingly unrelated stories, because indeed I care. At least I would hate it when something like this happened to me.

Allright. So I think it was last Friday when I could send an XXHighEnd version (denoted 0.9z-6-0) to Mani of which I thought it was reliable enough to do its job.
What I/we did not know, is that it didn't do a thing of what it was supposed to, and let's say that a stack of coincidental circumstances prevented showing its real state and merits.
In the end it was only yesterday late afternoon that it could be determined that one stupid little program just didn't do a thing, while it was supposed to do all. At this moment I still don't know why, and all we can tell is that on one PC it just doesn't run, while -so appeared- on the other it nicely works.

At this moment it must be so that now first this XXHighEnd part is finished into a reliable state, and only next I can proceed on those 768 drivers. It really shouldn't be a problem, as nowhere I judged or measured anything with the 768 drivers myself. I have them running allright, but only for technical testing and never for listening so far. But you can bet I'm eager myself, because it only can get better again.

Firstly, I'm not sure how much of this amazing performance is down to the new NOS1 interface or actually the 'Minimise OS' function in XXHE. All I can say is that before I managed to get this function to work, the NOS1 sounded good, but not particularly much better than the original.

If the latter would have been the end of it, I would have been satisfied myself. At least that is how it started out with the USB thing, because it's realy tough to get it going well. So, when it happened for the first time that everything started to sound normal, I was happy as a child. Remember, it would be able to replace a nice - though awkward interface. This is worth something.

I think if you listen longer to that normal XXHighEnd situation (all tweaked as far as it went in 0.9z-5-2), you would have "seen" that there is more. You can just feel it. At least that was my response to it back then (3 months back ?). There seemed to be more potential still, but it merely tells you "hey, my environment ain't right man !". I started to hear my amps (and they indeed were wrong), and I started to hear "XX needs more control over it" while it couldn't.
Yes, this will sound like much blahblah, but it really is true.
Also, I hope that it is allowed to refer to my own words very similar to these from Mani :

Actually, I'm finding it hard to write anything constructive.

I had the same problem, and said it needs new phenomena to decribe music experience. All we know of, does not work anymore. Today I still have this problem myself. But what it does, and this was the current subject, is that it tells you where to be when something doesn't sound right - or urges for more. It is really strange, and so far it always led me to where to be (well, looking at how the solutions concerned worked out indeed).

And so, this main part is about the OS which needs to be tweaked far more than before. Something like : before (original NOS1) the DAC could mask quite some, but today (NOS1-USB) there is nothing masked.
On this matter I must notice that during the past month all has been undertaken to improve on the gain stage. I talked about that allright, but this was *before* this last month. So, I saw some lights, and really thought I had to finish that before a first USB would go out, or otherwise it had to be shipped in again, later. Now, that too brought improvements which are hard to describe, but anyway I never talked about them (who cares since all will be new anyway, and I'm exaggerating always of course).

Where was I ? ah, that OS. Yes, I can imagine that without NOS1 too, it will be the biggest improvement ever. But also a maybe dangerous one. At this moment I can't tell whether now for everybody the Q1 etc. won't do a thing anymore, but if it doesn't it means that you will be hearing your DAC way better. Whether that will be a good thing ? I sure hope so. But let's see, because it now won't take ages anymore before it's put up. May still need two weeks or so - we'll see.
Anyway, I'm sure it will be before people start to send out their original NOS1's for upgrading it, so they will be able to judge too. I honestly never did and as a matter of fact I had removed my own "nice old interface" physically removed from my own NOS1 last week. So now I really can't anymore.

Allright. So far for now. Mani, great thanks for all of your efforts, and I'm so glad we could find the culprit just before I went off for another death last night. Very important to me, because

I'll post more thoughts/experiences when I've got anything new to say.

... I know you won't be there this week. So, still something to work out for this one stubborn PC, of which of course there will be more out there. But I will work it out.

Peter

[pedal]

Mani,

It seems being first in the line is a curse, not a blessing, he-he. My condolences.

Thankfully I have my v.1 NOS1 running perfectly at 384, so no hurry in upgrading before the initial problems are solved by Peter.

[manisandher]

Well if what I experienced into the early hours of the morning was a curse, then sign me up for eternal damnation.

The sound was like nothing I'd ever experienced from ANY replay system ever. Once you've gotten yours upgraded, and running 0.9z-6, you'll understand.

Unfortunately, I can't find the words to do justice to what I've been hearing. It's just utterly, utterly sweet, musical and soooo believable. A BIG step up from the v1 NOS1 and 0.9z-5-2.

Mani

[manisandher]

Oh and I forgot to mention that it took me 15 mins to get everything working perfectly on my second PC. Totally straight forward.

Mani.

[Nick]

Well if what I experienced into the early hours of the morning was a curse, then sign me up for eternal damnation.

The sound was like nothing I'd ever experienced from ANY replay system ever. Once you've gotten yours upgraded, and running 0.9z-6, you'll understand.

Unfortunately, I can't find the words to do justice to what I've been hearing. It's just utterly, utterly sweet, musical and soooo believable. A BIG step up from the v1 NOS1 and 0.9z-5-2.

Mani

Mani,

I guess the learning you and Peter have been through must have been frustrating but may help others.

Great to read about the15 mins installation on your another machine, your post reads like the spell is cast even before the DAC is run in, fantastic news.

Nick.

[christoffe01]

Oh and I forgot to mention that it took me 15 mins to get everything working perfectly on my second PC. Totally straight forward.

Mani.

Hi Mani,

- the USB port at your PC connected to the NOS1 should be very well selected. See "Device manager/USB controller", there are different values shown (10% / 20%).
- the USB cable has an influence to the SQ to. A normal USB cable is counterproductive to our target for an outstanding SQ. (see USB cables from manuf. Audioquest or Aqvox) On your system you will / must hear the difference.

Joachim

[PeterSt]

- the USB cable has an influence to the SQ to. A normal USB cable is counterproductive to our target for an outstanding SQ. (see USB cables from manuf. Audioquest or Aqvox) On your system you will / must hear the difference.

I don't think so ...

[christoffe01]

- the USB cable has an influence to the SQ to. A normal USB cable is counterproductive to our target for an outstanding SQ. (see USB cables from manuf. Audioquest or Aqvox) On your system you will / must hear the difference.

I don't think so ...

Hi Peter,

there was a test in a HiFi magazine (einsnull - 4/2011) and they hear  differences. In our systems you will hear a "fly walking on the window".

Please test, such a 1m cable costs around €150,00.

Joachim

[PeterSt]

Joachim,

We are not talking about a random (async) USB thing. You were addressing Mani and his NOS1-USB. Maybe you recall that it comes from my hand ... haha

If anyone wants to spend 150 (in any currency) on a USB cable, please do so. But I think you can reserve some space on eBay already before it arrived.


About selecting a port with the best free bandwidth ... only true by theory; when there's another device consuming, say, 30%, *that* one will die out. Phasure USB will have the highest priority on the bus.
Btw, don't ask me what will happen with "System 20%", and whether that will be allocated too, in order to next kill something of the system.

Regards,
Peter

[christoffe01]

If anyone wants to spend 150 (in any currency) on a USB cable, please do so. But I think you can reserve some space on eBay already before it arrived.

Regards,
Peter

Hi Peter,

there was a test with USB cables, between a Supermarket USB cable and a Kimber USB for € 70,00,  in the "hifi & records" (equivalent to the HiFi plus in the UK) already in issue 4/2009.

Their commentary:
The sound of the cheap cable was grey, thin, harsh sibilants, less fluid, wrong timing etc. (connection between an iMac and a dCS DAC)


My comment:
When there are "losses" within the USB cable between the PC and the NOS1, you will not hear the full potential of the NOS1.
We are spending thousands of Euros for a NOS1 DAC and are giving away .............. .
In our systems we hear the difference of EVERY cable. EVERY!!!!!

My proposal:
You buy a decent USB cable (manuf. Aqvox) for appr. € 150,00, perform a 2-5 hours hearing session, and with a negative result I will buy the USB cable together with the NOS1 upgrade!

Done?

Best

Joachim

[christoffe01]

Joachim,


If anyone wants to spend 150 (in any currency) on a USB cable, please do so. But I think you can reserve some space on eBay already before it arrived.

Regards,
Peter

Hi Peter,

please see

http://www.6moons.com/audioreviews/entreq/usb.html

best Joachim

[Flecko]

The length and quality of the usb cable is important if the device draws power over the cable. That is easily hearable. If the device has it's own power supply the impact of the calbe becomes much smaler. I tested this with my DI, which has it's own supply. Between a 60cm Monster USB cable and two 4.5m Noname USB extensions + 60cm Monster cable I could not hear any difference. The test was "quick and dirty" but I have no bad feeling because of the use of the extensions. It is for sure dependent on the device you use but if it is done the right way, it should hardly matter.
Especially Aqvox is a firm that likes to collect money for nothing. Look at their usb driver. They sell you the "Aqvox USB Driver" for 100€ which is 1:1 a driver developed by ploytec, which costs 50€. this driver is also included in a lot of studio usb equipment which costs including the driver about 100€. The same with "their" new amp-xt, which looks like a copy a BMC amp-1. They print Aqvox on the label and collect 1000€ more. I would not buy anything from them.

[PeterSt]

Oh boy ...

Losses ? LOSSES ? what losses ? this is data (no audio).

Furthermore this can only be about noise. I tell you : no noise is there.

Don't believe all you read (without knowing the ins and outs really).

Peter

[christoffe01]

Oh boy ...

Losses ? LOSSES ? what losses ? this is data (no audio).


Peter

Peter,

I wrote

quotation mark - losses - quotation mark

whatever it might be.

best

Joachim

[Nick]

When I was using a synchronous usb interface (a much modded m audio transit) I tried a lot of usb cables and they did make a difference. The best setup by far was a diy unshielded woven cable with 3 hot wires and 2 earth all 0.5mm silver. The cable was just under a meter with only signal, no power. It beat all comers and made a noticeable difference to sound quality.

That was synchronous usb however, Peter is using asynchronous and depending on the transfer protocol across the usb this could really just be the same as data transfer from the pc into the NOS interface. If this is so then the time critically only exists when the data is clocked in to the ADCs so no real problems with the usb cables. This is all just guess work only Peter really knows 

Anyway I would be happy to try my best diy silver cable against the one Peter recommends when my asynchronous NOS1 comes back. I buy into what Peter is saying though and I don't think I am going to hear any difference. Will let you know, it might save a little money 

Best,

Nick.

[manisandher]

Especially Aqvox is a firm that likes to collect money for nothing. Look at their usb driver. They sell you the "Aqvox USB Driver" for 100€ which is 1:1 a driver developed by ploytec, which costs 50€. this driver is also included in a lot of studio usb equipment which costs including the driver about 100€. The same with "their" new amp-xt, which looks like a copy a BMC amp-1. They print Aqvox on the label and collect 1000€ more. I would not buy anything from them.

Adrian, you are aware that B.M.C and Aqvox are closely related, right? (Although we all know that husband and wife teams are a nightmare ) Also, if you look at their respective phono stages, the AQVOX (which I actually have) is substantially cheaper, though I'm sure not as good quailty.

The B.M.C. amps look really interesting, on paper at least, and seem pretty well-priced too. I've read the reviews on the B.M.C. website, but does anyone have any first-hand experience?

Mani

[PeterSt]

What some of you, maybe, do not get, is that there is USB in general, and USB with high attention from someone like me;

If you leave USB without attention it is super-sh*t and your cables *will* help - but don't solve the cause. In the end this is not related to async USB or not, although async USB will indeed not incur for "data loss" (with or without quotes).

So, it is about noise, and exactly the reason why even async USB DACs are subject to XXHighEnd influence (never mind for now how *that* works).

All 'n all you you seem to think that USB is some very transparent and untouchable thing, but it really is not. Well, not in my hands.

Peter

[Per]

Some days ago I stumbled over this excellent interview in UltraAudio on Music Server design

http://www.ultraaudio.com/index.php?option=com_content&view=article&id=135:matan-arazi-on-music-servers&catid=31:general&Itemid=46

Here is an extract from the interview talking about noise:

Jeff Fritz: How important is noise -- electrical, mechanical, etc. -- in a music server? Is EMI or RFI an issue?

Matan Arazi: Extremely important. Once we’ve established that a music server is bit-accurate (and virtually all good ones are), and after we’ve reduced jitter to the minimum possible, we have to start looking at the analog aspects of the digital connection to the DAC. Let me explain this for a second: Even though the connection between the music server and the DAC is a digital one, that digital signal still passes through a cable, which is an analog medium. Transmitting a pure digital signal through any analog medium requires infinite bandwidth, which can be achieved only theoretically. Thus, the digital signals are modulated (the exact modulation type depends on the type of connection and cable) so they can be transmitted through a cable, and the modulation/demodulation process can add undesired effects to the signal. In most computer-based scenarios this isn’t a problem, but with a DAC it matters, because DACs bridge the digital and analog domains and are highly susceptible to analog noise. Furthermore, since the computer is an environment full of electromagnetic noise, some of this noise can be transmitted by the cable and work its way into the DAC. Based on our experiments, I believe that differences in the analog parameters of the connection between the music server and the DAC account for the majority of the differences in how different music servers sound, even when using the same DAC. It is this radiated noise (along with differences in grounding) which is also the reason why some people notice differences in the sound when different USB cables are used, or why music servers with solid-state disk drives generally sound better than those with mechanical hard drives. As before, less vibration and less noise mean better quality. (text in bold by me)

Further on XXHighEnd is mentioned favorable  

In addition, using dedicated playback applications, such as the excellent Amarra or XXHighEnd programs, is beneficial because these programs are carefully designed to optimize audio quality by minimizing various parameters inside the computer that can interfere with the playback or increase noise or jitter.

In my humble opinion this interview about Arazi's all out assault on a state of the art Audeeva Conbrio music server is a very interesting read for us computer audiophiles - with a lot of insight into what goes into different aspects of construction. Just thought I would share it.

Per

[Flecko]

Adrian, you are aware that B.M.C and Aqvox are closely related, right? (Although we all know that husband and wife teams are a nightmare Tongue) Also, if you look at their respective phono stages, the AQVOX (which I actually have) is substantially cheaper, though I'm sure not as good quailty.

No I wasn't! This explains the similarity in the amp design. I got mad at them after I found out the USB driver rip off. And since they seem to take technology made by others and selling it for a higher price I put them from my list. There is good stuff in their program. But it looks at least possible, that you will get the same things from another distributor for less money.

The B.M.C. amps look really interesting, on paper at least, and seem pretty well-priced too. I've read the reviews on the B.M.C. website, but does anyone have any first-hand experience?

They do. But I think there could be a flaw. They use the current of the outputstage of the DAC. And this is normaly not designed to deliver current. I guess the input impedance will be low due to that concept (I can not find a datasheet) and this could limit the number of DACs with which this amp will sound good.

[christoffe01]

USB

please see:

http://www.AudioAsylum.com/forums/pcaudio/messages/9/90402.html

also highly possible: HF distortions, signal reflexions due to impedance mismatches

----------------------------------

another interesting link

http://www.sabritec.com/technotes/PDF/High_Speed_Digital_Tutorial.pdf

[manisandher]

Some days ago I stumbled over this excellent interview in UltraAudio on Music Server design

http://www.ultraaudio.com/index.php?option=com_content&view=article&id=135:matan-arazi-on-music-servers&catid=31:general&Itemid=46

Haha, here is what Matan goes on to say:

"Since the FireWire and USB interfaces are actually PCI devices inside the computer, I would bypass them if possible, as Peter does in his Phasure DAC and its PCI Express umbilical."

Peter, apparently you've gone the wrong way going from PCI to async-USB.

I think Matan's favourite DAC is the Pacific Microsonics Model Two. Being able to compare the two, I know he'd be blown away by the async-USB NOS1.

Mani.

[Flecko]

@Christoffe
Thanks for the links. Especially the second one is interesting. A nice summary of signal transmission (also it seems my estimation of the slewrate was right ). But the point is, that if you transfer data, not audio, via usb there is an error correction. That will compensate for such effects. otherwise you would not be able to copy a picture or a program onto an usb stick for example. It depends on the USB interface and how it cummunicates with the pc. I am no expert on this, Peter can you explain it? How does this digital audio would look like and how is it handeld compared to the data? In which cases we have a digital audio signal (no error correction) and when we have data, if we listen to music from pc?

[Per]

Some days ago I stumbled over this excellent interview in UltraAudio on Music Server design

http://www.ultraaudio.com/index.php?option=com_content&view=article&id=135:matan-arazi-on-music-servers&catid=31:general&Itemid=46

Haha, here is what Matan goes on to say:

"Since the FireWire and USB interfaces are actually PCI devices inside the computer, I would bypass them if possible, as Peter does in his Phasure DAC and its PCI Express umbilical."

Peter, apparently you've gone the wrong way going from PCI to async-USB.

I think Matan's favourite DAC is the Pacific Microsonics Model Two. Being able to compare the two, I know he'd be blown away by the async-USB NOS1.

Mani.

I saw that too, Mani. To me it just shows how much Peter is ahead of the so called cutting edge with his new usb nos1 dac design.

Per

[christoffe01]

USB

here we can find nearly all informations about .......... .

http://www.usb.org/developers
http://www.usb.org/developers/usbfaq/
http://www.usb.org/about/faq/

[PeterSt]

But the point is, that if you transfer data, not audio, via usb there is an error correction. That will compensate for such effects. otherwise you would not be able to copy a picture or a program onto an usb stick for example. It depends on the USB interface and how it cummunicates with the pc. I am no expert on this, Peter can you explain it? How does this digital audio would look like and how is it handeld compared to the data? In which cases we have a digital audio signal (no error correction) and when we have data, if we listen to music from pc?

Of course error correction is important - *if* there are errors. But IMO this is seeking for things which normally don't occur anyway. Similar to normal CD reading (by a CD Player) which may read errorneously and because the lack of time to re-reread (inifitely like EAC) it will spit out the errors (outside inherent error correction). So, do we care ? yes if the results are ticks etc. (and this sure happens !), no (again IMO) when we might think it will degrade sound in general. I say this is non-sense because it would imply that the level (volume) is slightly changed (meaning the least siginificant bits are being read wrongly or twisted or make up something), which is not a logical thing at all. When errors are passed on, all will be wrong, and when it is about the most siginificant bit there will be a tick when the current (momentary) level is low, or when the level is high there will be a tick when -again- the most siginificant bit is read wrongly. All in between exists too, plus it is hard to imagine that when one audio word is wrong that this will be audible (merely think about a few 100 in a row).

Normal isochronous USB is the same. No error correction, but what's the real problem.

Which leads us to an asynchronous connection which indeed is about error corrected normal data. The conclusion must be no different : what can it help. Oh, it can help the other way around : too many errors will consume the bandwidth progressively, and *now* you have ticks and glitches and gaps (the data can not be delivered in time, no matter the buffer used with async).

So, done. Remember, my view.

But my view is also that this is all about jitter. Ok, I won't be the only one. *Now* things change, and they change from so many angles that the number of characters allowed in one post will be too few to complete it.

Jitter is about timing errors which is the most easy to be looked at as wow from a turn table. Even the frequency can be as low as one rev from an LP, or lower. But also rather infinitely higher.

The audio data -now looked at in the "audio stream" realm- is supposed to pass through the convertes (D/A but also A/D) in a 100% constant fashion. We don't need to look at 0's and 1's to understand that the letting loose of the samples (like 44100 per second) must be let loose in a most even fashion, or otherwise we'd have strange things on the frequencies happening. Just keep on thinking wow from the turn table ...

The "frequency" (!) in which the samples are let loose are determined by some clock. Let's not make it difficult, and let's imagine the clock to be right next to the D/A chips.
The clock is (or can be) a crystal, and although it will have its own resonation (frequency) it is driven by current. Or voltage if you want, but Ohm's law will tell you that it is about both always, at least when one can change.

Although it won't be the 100% truth (or at least not in all cases) it is now the most easy to think that the voltage level can change by influences on the current. So, hammer on the current in the same circuitry somewhere, and the voltage (and/or current) that drives our must-be-stable clock, will have impact on the stability of that clock. Yes, we talk about picoseconds or less these days, as the impact of time difference on a certain frequency. Let the clock run fraster and the frequency we want to hear gets higher. If that would be all, it is no problem, except for that our music track may last 5 seonds less than officially intended. But it is about the stability and and roughly said the clock outputting a different frequency of her pulses within that picosecond dimension.
Now high frequencies (like 10KHz) will be disturbed.

Because many things happen inside of an audio chain (I extend this way outside the DAC on purpose), all kind of "self frequencies" hammer on that supply for the clock. It could be the 50/60Hz mains supply, it can be a voltage regulator (of any random high speed), there can be 100 of those regulators in one device, it can be that other clock in there (like a base 48KHz vs. a base 44.1KHz), it can be a receiver chip - it can be way many;

All these frequencies, also depending on their individual level, interact. They interact to a multitude of additional (!) new frequencies. Now it will not be hard to imagine that these may come together (in one peak) once per 10 seconds, 1 minute, 3 minutes or even days. Now we are talking about the real wow, and it really exists. It is mighty audible as well, at the moment you heard the same without. For example, a nylon string guitar can sound so straight. But with jitter, you wouldn't know what is wrong, because it just sounds good, and you wouldn't know how the artist manipulated the strings. Btw, a Jazz guitar the same.

Since there's all the talk about "computer noise" sneaking into our DACs, I should be mentioning noise as that other reason having impact on jitter. There is not much difference with the before layout, because noise is again about hammering frequenies on to our signal. In the end there *is* no difference, and I say that even white noise does not exist. Maybe at the molecule level, but we will never get to see *that*, because there's always other sh*t around first.

When this "noise" gets into our clock supply, there is not much difference on the impact, although there may be a difference on the current fluctuation. So, the before outlay merely suggested that the current was not stable and thus something like a clock needing current is not able to run stable (think of a car which continuously holds back and forth again), while with noise coming from outside the voltage peaks will not be stable (think of a lamp dimming and back on the frequency of the mains). Now it is a matter of stuff relying on voltage peaks (and all digital is !), and *now* we have the problem of slopes (of voltage waves) arriving earlier and later, just because noise (illegal peaks) ride on them. And hey, here is mr jitter again ! (this time *behind* the clock, the square wave coming from it having its slopes changed).

Now, on to our subject (wasn't that USB ?), all we need to know is that it is the worst. It creates 8KHz spikes because that is the frequency of USB and how it transmits the packets of data. If you look at it, it's only 20dB or so (I forgot) above the normal noise floor. But since I claim that noise rides ON the signal, I say it sounds like sh*t. And it really does. And for those who again recall why I was reluctant to go any USB route ... now you know.

This noise not only rides on the signal, it influences all angles I talked about above. So, not only the analogue signal because you'll see it back as a modulated signal on top of that audio signal, but long before that it influenced jitter by all means thinkable. This is also why USB DACs don't measure good on jitter at all (maybe by now this changed, I don't follow everything and all).

By now you will also be able to imagine how any computer noise will sneak into any interface means, USB foremost, because that packet sending current surge starts in the PC. But the other way around as well : anything that happens in the PC will influence that signal itself. So now we have the 8KHz with a superimposed other pile of frequencies and from there the mess is unpredictable, but it *is* a mess.

And by now you'll also start to understand how software like XXHighEnd can exlicitly influence all this ...
And this is not by changing any bits.

Peter

[Flecko]

Thanks for your explanaition Peter.
Some things poped up my mind while reading this.

1. About errorneously read out of cd's:

So, do we care ? yes if the results are ticks etc. (and this sure happens !), no (again IMO) when we might think it will degrade sound in general. I say this is non-sense because it would imply that the level (volume) is slightly changed (meaning the least siginificant bits are being read wrongly or twisted or make up something), which is not a logical thing at all. When errors are passed on, all will be wrong, and when it is about the most siginificant bit there will be a tick when the current (momentary) level is low, or when the level is high there will be a tick when -again- the most siginificant bit is read wrongly. All in between exists too, plus it is hard to imagine that when one audio word is wrong that this will be audible (merely think about a few 100 in a row).

I once made a test with hexcompare. I compared three different settings in EAC. The settings were:
1. Setteing the hook at Accurate Stream and Drive buffers data.
2. Setting the hook just at buffers data
3. Setting the hook at reads CRC error information, Accurate Stream and Drive buffers data.

For the first two settigns I got exactly the same data with hex compare. They off course sounded the same.
The third setting produced a different kind of data. All the numbers shown in hexcompare were changed. It also sounded different.
I decided that method 1 and 2 should be prefered because they gave the same results. But wouldn't this mean that you can alter audio data in a  way you do not hear clicks and pops but a slight alteration of the sound?

2.: About noise

When this "noise" gets into our clock supply, there is not much difference on the impact, although there may be a difference on the current fluctuation. So, the before outlay merely suggested that the current was not stable and thus something like a clock needing current is not able to run stable (think of a car which continuously holds back and forth again), while with noise coming from outside the voltage peaks will not be stable (think of a lamp dimming and back on the frequency of the mains). Now it is a matter of stuff relying on voltage peaks (and all digital is !), and *now* we have the problem of slopes (of voltage waves) arriving earlier and later, just because noise (illegal peaks) ride on them. And hey, here is mr jitter again ! (this time *behind* the clock, the square wave coming from it having its slopes changed).

There is on the one hand the strive for high speed and low latency but if it is all about noise and jitter, wouldn't it be very important to have the pc hardware as simple as possible? Like one of those intel atom pc's or maybe an uATX mainboard would be preferable to use for an audio pc. You would stop the creation of noise from it's beginning because there are less parts that can create noise. This would be what cics did with the Fit-PC2. Did you ever tryed such a simplified setup?

[Bigear]

Anyway I would be happy to try my best diy silver cable against the one Peter recommends when my asynchronous NOS1 comes back. I buy into what Peter is saying though and I don't think I am going to hear any difference. Will let you know, it might save a little money 

Hi Nick,

did you test this already?

thanks,

Bigear

[Nick]

Hi Bigear,

Yes I have the home made lead between PC and NOS USB at the moment. To my mind there is an improvement in sound, though not as large as experienced with other USB interfaces i'v used.

In the scheme of things it's a minor tweak i would say, the NOS USB sound with a standard cable is already amazing.

Best Nick.

[Bigear]

Thanks Nick,

hopefully I will get the new USB version soon so I can experience it myself!

- Quint