USB audio cracked... finally!

[PeterSt]

3 minutes ago, mmerrill99 said:

It may explain why some cables sound clinical & involving?

 

Yes, both at the same time. Great eh ?

 

Anyway, I'm here now. I have not much time, but will try to provide some insight here or there.

 

Peter

[PeterSt]

5 minutes ago, mmerrill99 said:

it the phisolator is only using the Silanna isolator with no urn reclocking after it, then it is introducing jitter into the USB signal - that is a fact.

 

@mmerrill99,

 

Finally finding some time to post in this topic, I like to grant you to be correct in almost everything you stipulated or stated. And mind you, my "correct" is only my perception as a person too. So let it be clear that I too don't have the multi 100K equipment needed to 100% verify what all could be reasoned (and then confirmed by listening) - I wish I had.

On another note, the things I could measure and promised myself to measure, I did not even do because of the result. So at this time I can only be excited about how eye diagrams actually look like, but with the explicit notice that already connecting the equipment will "destroy".

 

The others being explicitly part in the discussions about what could theoretically be done and attacked - same story. It looks like we all learn fast but more importantly, that it does not look like copying from others without actual knowledge. So it is really funny and great to read back about by own contemplations and how actually a fine USB Audio cable could be constructed from reading through this topic. Well, sort of, because the set parameters (and as we can reason - a lot of them exist !) are unknown. That is, for now they are a little secret. I hope this is allowed.

But as we will see further down the line (next posts as far as time permits) there is no voodoo going on and nothing is coincidental. What is quite crucial though is that I happened to start out with the Clairixa which the very best as I could complied to the USB2 specs. So with that as a firm base for specs which coincidentally also implied the best sound (confirmed by all of its owners) I could start changing the now well known parameters.

 

 

[PeterSt]

3 minutes ago, mmerrill99 said:

Sorry, that should have read "clinical & uninvolving" - bloody predicitive text.

 

 I know. And I was going to get back at this anyway. Here :

 

16 minutes ago, mmerrill99 said:

it the phisolator is only using the Silanna isolator with no urn reclocking after it, then it is introducing jitter into the USB signal - that is a fact.

 

Things are not as they seem. By far not.

With the notice that all isolation introduces jitter :

 

....  How much jitter was actually there in the first place ? Now notice that we did not see any plots / eye diagrams of that and what's known from Uptone does not show the comparison (there is no complaint anywhere, and just my observation). However, it can be measured. Ehm, for my own set up. So ?

 

The jitter of an isolation device is a quite complex matter, as it is not shown nor proven by any means (that I even have seen) how jitter emerges in that one particular situation. So think about this ... jitter ... why ?

All is about delay in the first place. But delay is no jitter.

When more than one path is involved like USB has two of them for the data alone) then we talk about (possible)  skew. But skew is no jitter again. However :

 

Once there is skew in order, this is very highly challenging for jitter. Why ? well, because the one bit of current needed for the one signal, is detrimental to the current needed to the other signal. And NOW all bets are off.

 

Lastly, but this is very personal, the jitter specs of that chip must have been observed by someone who by now must have OCD because of jitter, because he thinks that the jitter itself causes the chip to fail. Alex said "Ask PeterSt" and I say "ask Alex". Or IOW, those (chips) guys don't know what they are doing anyway in this particular situation, so all is up to ourselves to make it work. And so we did. And this includes attacking jitter or the effects of it or otherwise it just does not work (for hdds it does all right, but not for isochronous audio data).

 

OK, a far too long post about all what is not related at all. But a bit of background.

The post could be an introduction of something which *is* important : I see the Lush compared with jitter bugs and regenarators and that kind of things - no. It is just a cable. No active devices in there. Also no resistors. A cable. But nothing like a USB cable. But USB is transferred over it. 

 

[PeterSt]

15 minutes ago, mmerrill99 said:

USB signal integrity seems to matter - this has all been stated already on this thread but the exact mechanism by which this audibly affects the DAC's output isn't nailed down yet

 

This is very crucial as it is beyond our control. Well, together with the perception that indeed the error detection and communication caused by it is influencing SQ (current draw at the receiver side, possibly explicitly thinking about the uneven current draw)  it is crucial.

 

It is beyond our control because we seem unable to influence this. We might be able to check it for a particular situation, but I don't think a commercial product can me made out of it. This story is infinitely longer, and because in my view it is unrelated to what the Lush does, what remains is my statement that I did not work on that at all.

Important side note : while I think I know all about it. And I refer to that stupid chip again (man, when I write about this chip, I think in terms of lawsuits).

[PeterSt]

2 minutes ago, Panelhead said:

As you keep digging into the whole USB system from computer, cable, and G3 dac is there still room for further advances?

 

Yes. But it will be harder and harder to unequivocally confirm by my self (say before real production and  shipping) that the change is an advance. The G3 upgrade really took me a year of being unsure because of a so different sound. It worked out in the end, but needing a year to be sure is a bit, well, hard.

 

To stay on topic, not so with the Lush and I actually just talked about it;

I aimed for something explicitly with a most good idea ... bought many pieces of test cable and braid / sleeved etc. before I knew I was going to right direction and once the direction was set I already created the first "commercial" about it for the Phasure forum. That sure I was, albeit I postponed that post 2 weeks after all.

The point is : once something suddenly turns out in real music, you know the difference. This is not about "are these highs for the better or are they shrill in that other album" (which takes me days). So no, this is really about music as such and how all suddenly plays together. I didn't even know it could exist ...

(end of commercial, but is really is about that - I would not even claim the cable sounds "better" or such ... it WORKS (better))

[PeterSt]

3 minutes ago, mmerrill99 said:

I don't believe that "it is beyond our control" We can control it up to a certain point but ultimately not render the USB port completely immune to the signal integrity of the incoming USB signal

 

OK, we talk past each other a little;

With not under control, I mean that I know what is going on (you too, because you recognized it is about timing) and this timing is different for anyone.

 

Notice that I - but mainly another technically involved bloke on this side of the pond - is working on this and focused on the timing indeed (this involves MoBo and USB Interface adjustments). They work out for sure, but only for me with my analyzer; If I'd try to do it for you it won't work out. Your climate is better or you just have that airconditioner.

Anyway, in that realm I talked. Of course there is more, but my subject (f we recognize it exists) is sufficient to be out of control.

[PeterSt]

Yes, correct. But please absorb what I wrote about it. Okay, you already did, but my context is that datasheet where indeed it is stated. It is also not the lowest (it is bad). But now you tell me the jitter coming from my super duper Stealth PC with Linear supply and the Xeon cores acg (Anthony) mentioned.

 

See ?

 

There is another subject involved I don't like to talk about because it is too much off topic. But if needed later I will refer to this line of text.

[PeterSt]

3 minutes ago, semente said:

What does "clinical" or "involving" mean?

 

OK, nice side step and my perception only :

 

Clinical is an old fashioned term my father used. Maybe many still use it, but in by book it has been scratched. This is because :

All should be sounding clinical as it unveils everything (translate the word and you get where I want to go with it).

 

But clinical is equivalent to cold.

And cold is the opposite of involving. Well, sort of. When things sound too cold, you won't be able to get involved with it. It is too far from you and what your brain likes.

 

Clinical sound can only emerge form high accuracy and then in the sense of "no ringing". With high ringing all buzzes and sounds gray. It smears. How can "analysis" happen when all is smeared.

 

But this is one of the great aspects of the Lush. It seems it is able to smear (just saying) but pertain the detail. This needs more elaboration (but is not easy).

[PeterSt]

3 minutes ago, semente said:

So what have you achieved by not complying with the USB spec: a more accurate audio signal transfer or "better" sound?

 

Well observed. See previous post.

The latter.

 

It is also the very first time that I worked with a subjective parameter. Really.

[PeterSt]

47 minutes ago, pkane2001 said:

And why does USB jitter matter to the timing of audio samples that are controlled by the onboard clock at the DAC?

 

Albeit I said in a previous post that this may not matter at all really, it will theoretically because of uneven current draw.

 

Generally people (like John Swenson) explain this in the sens of noise on the ground plane etc. - and while this is so, it is better to think in the realm of when current is drawn (needed) then something else also needing the current, suffers. So no matter the "speed in supply" we try to provide and no matter the current draw can not even be measured with normal equipment, the property of current is that its supply is limited.

Be the first and you're good. Be the second without recovery and you're in pain (you just get less in the time span of the first). And the effect ? jitter in the D/A process (the voltage waves are not equally high/steep).

[PeterSt]

Just now, semente said:

A bit like a (good) CRT vs. a flat display?

 

Not really comparable I think because the one is analogue and the other digital.

 

Compare Oled with LCD etc. or Amoled of your phone.

But too far off to work it out.

 

FACT is that I created the Lush with pure analogue properties.

Aha ...

(well, not really aha, as all digital is also analogue but we will see later, hopefully)

[PeterSt]

Before I sit down for the (non Oled) TV for some F1 watching, this is what I wrote in another topic yesterday ... food for thought perhaps (and call me crazy if you like) :

 

What thus Lush cable does (and I described it on my own forum a couple of weeks back) is "connecting" individual wave cycles. I know, this is too far out to ever come up with, but this *is* what I attempted. You can say it smears as hell, but in a "too narrow pipe" fashion. So there is no ringing in order and no digital filter or analogue filter could do it (as they all ring). Maybe it is best to call it "shaping" (of the tops of wave cycles). And now this cable suddenly sounds analogue as LP. I am serious.

 

Before someone asks me how I'd think this may ever happen in a USB cable which only passes on digital data, even in packeted form ... no answer. But my approach has been in a fashion as if it was an analogue cable (like an interlink) *because* I could hear the very same properties for the conductor material as we can perceive from loudspeaker cable. The stupid thing is, I was already hearing that myself, and then someone came for audition and he described the very same without knowing a thing about any USB cable (test, which was active at the time). And *then* I started working with it.

 

Till later.

 

 

 

[PeterSt]

15 minutes ago, Superdad said:

Not quite sure if you are referring entirely to me above Peter, but to be clear:

 

16 minutes ago, Superdad said:

Having worked with (and "fought" with) the Silanna chip and its engineers for over

 

I referred to that engineer(s) and you + John fighting (them) independently from me.

My message in that post kind of was : while in the end they "admit" (or something in that realm) that reclocking is necessary, I solved it in a different way. In the end this is - or should be about jitter again.

And the under tone : they were IMO so far off with everything, that I don't believe much of anything at all. In the end you guys implicitly followed the idea of reclocking helps (nothing new for you of course with again an undertone that you helped them with it) but I retained (to be ignorant) that it can do without. And so it can.

Btw, my reference to the eye diagram was the perception in the back of my mind that something was not 100% with it; I only now recall that it was a kind of other way around : you showed the eye diagram from the comparison of no-REGEN with ISO-REGEN, which was a bit strange for me because I'd expect REGEN vs ISO-REGEN. But no issue anywhere instead of my false argument for not seeing results regarding jitter; we did and apologies.

 

Side note : the Phisolator can be bypassed in 5 seconds, and so far everybody likes it better with it.

 

The relevance to the Lush topic is that - as you know - I didn't even like to proceed with our "Resolator" and announced a better idea. The Lush is not that idea but it came from from that idea. Without that idea (or without you guys) I wouldn't have been motivated for another cable (yet).

 

Now, a few months later, I could show you a nice never posted post. So Alex, you can now have that post as I predicted everything you ran into by now. And I did not spoil your vacation with it. 

Later, somewhere.

 

Thank you Alex.

Peter

 

 

[PeterSt]

52 minutes ago, Jud said:

@PeterSt believes this must have to do with current draw.  John Swenson, as Peter mentioned, believes it has to do with injecting noise onto the DAC’s ground plane because the USB receiver chip must work harder.

 

Hi Jud,

 

Notice that noise as such is essentially the same as the current draw (spikes) as I refer to. But possibly the current draw story is better to understand.

Noise could be called invariance in voltage level. With the assumption that all noise has a source, the current draw spikes is such a source.

 

My explanation about the "capacity" of current, is almost the same (but not 100%) as the ground plane being subject to "noise". So we can say that any current draw changes the potential of the ground plane somewhat.

And without spending too many word on it : this is now super crucial in the galvanically isolated environment, including EMI etc. because of it.

And this is indeed how USB cables become suddenly more important (hey, in the end all has been touched in this topic - now combine it into something workable ).

 

Regards,

Peter

[PeterSt]

Just now, Jud said:

OT: BTW, @PeterSt, Verstappen or someone else?

 

Haha. Hamilton. Verstappen was 4th.

But someone from Holland (Bauke Mollema) just won an etappe in the Tour the France. Also rare.

[PeterSt]

21 hours ago, jabbr said:

 

It is perplexing that despite purported improvements in USB isolation there are still ?dramatic? differences in the "sound" of USB cables? I'd think that the goal of USB isolation/reclocking/regeneration is to eliminate the vagarities of cable impedance etc.

 

Hi Jonathan,

 

No, why or how ? What would be true though is that an isolation device may act as a buffer (as an active device) between the start of the cable (say at the PC port) and the USB receiver and that cable reflections may be consistent over DAC implementations (read : must always be the same DAC). So if you think like this, another such a device at the PC end could make the reflections consistent over isolation devices (beginning and end of the cable provided by the same manufacturer). All it now further takes is a cable also provided by that manufacturer and the interface between the isolators is under control. Assumed that the manufacturer can measure reflections of course and that he is able to control your DAC for received amount of data.

 

Give it a few years and ... such an interface won't even exist any more because it can only fail more and more.

Let's be happy we have sound at all !

And really, there is so much wrong with audio that we seem to be able to improve the rest of our lives. Even if you're 20 only.

[PeterSt]

14 minutes ago, Jud said:

But is Hamilton your favorite driver?

 

By now Hamilton is nobody's favorite driver, as he doesn't join the party on the circuit which all drivers join, while he has his own party, this time on Crete. By now he's acting like a childish playboy. At least that's how "we" see it.

[PeterSt]

2 minutes ago, Doak said:

I am using a DIY USB connector from ISO Regen to DAC that I like more than the supplied USBPC because I find it more LUSH (hope that isn't a registered trademark).

 

Hi - You can bet it is.

https://uk.lush.com

[PeterSt]

If someone else is not faster :

 

On 2017-7-15 at 6:19 AM, acg said:

The Lush is around 200 euro depending on length.  At this stage I am unaware of anyone out of the Phasure group that has one but I intend to take mine down to the Gold Coast next time and have a play with it in a couple of excellent but completely different systems to mine.  One of them is the guy that makes the Curious Cables (he has a fantastic system) so it will be very interesting to hear The Lush in that system against that cable.

 

In a later post Anthony was even more explicit about this.  So, planned ...

Not sure this is the best idea though (for that person).

 

 

 

[PeterSt]

2 minutes ago, austinpop said:

 

In general, I do find I can hear cable differences, but they tend to - for me - be subtle, not transformative.

 

Yes, I can 100% imagine this. But this really is another thing. Btw for the Clairixa counts the same.

Anthony should really ask the Curious guy how he actually comes to decisions about making a USB cable. I know mine and mine really use "properties" so to speak. But others ? ... what I learned is that it is so difficult to get what you what you want (by components) that possibly people travel the easiest path with a nice sleeve.

But of course I can't really know.

 

Thanks,

Peter

[PeterSt]

7 hours ago, Ralf11 said:

I mean does Thunderbolt as implemented via USB-C solve (or reduce) the problems in USB 2 as an interface?

 

FWIW, I don't think so. It is the protocol doing the damage (that's a bit tough but alas) and that won't change a thing.

Btw there won't be much difference with using a PCIe interface with USB outputs. And on that part, we (over at Phasure) tried many things regarding this, up to everybody using a Silverstone USB3 card, just because it sounded special. But other elements caught up with it and I don't think many use it any more.

The thing here is, once you can hear a bit more fro your system, everything matters regarding USB. Buy 10 different PCIe cards and they will all sound different and you will keep one as your best one. Until the Operating System changes - then you have to start all over.

Buy a JCat Femto etc. card - that too sounds different.

 

In the end those "tweaks" don't work, because they work by random aids. Your system suffers from something, and the aid will change the sound. Will it be for the better ? actually you will know when you e.g. buy another DAC and suddenly it does not work for the better any more.

From the point of view of the manufacturer it can be looked at differently with the same conclusions : if something works for really everyone, then the application is really good in absolute sense. And the fun is that when working in a quite close group, this is easy to detect (but also carries great responsibility). What I mean is, once an application has been worked out and it works for a 100, then when a first comes along where it does not work, then

a. I need dare to say that something has to be wrong at the customer's end;

b. The customers needs to have an open mind and help searching for the culprit.

 

A bit of a blabla story but this is really how it can work and how everyone can help each other and make progress.

Back to the quote above, what can be predicted is that the speed of e.g. USB3.2 helps to overcome problems in general (the speed is by far not needed for audio but spades of headroom is always a good thing). This is (in my view) how USB3 always sounded better than USB2 (at the PC's end) and how a USB3 hub in the ISO REGEN sounds better than a USB2 hub in the same environment. We shouldn't make this a subject in this topic, but a lot with audio (if not all) is about headroom we don't anticipate because we can so-called calculate it isn't necessary.

[PeterSt]

4 hours ago, pkane2001 said:

I'm willing to experiment, and test out theories. What Peter suggests is not that hard to test: low-pass filtering of USB data transmission and possibly separating power supplies between the input and the output parts of the USB receiver is doable.

 

Hey hey ...

 

I think it was you who responded with a "Cool!" from a conclusion you made yourself; it was a bit hard for me to reply to that because of the way you put it there (as I recall it). But now I can do better. 

 

Low-pass filtering is not going to work out because you will eliminate the data itself. So say that USB transmits 480mbs then you can see this as equivalent to 480MHz in order for the bits (which is analogue square wave) to pass through the cable. And, as someone else nicely presented : plus a bit more or else the square wave is a sine.

So low pass filter that to e.g. 500KHz and no data arrives in the receiver.

 

IIRC you responded to my "tunnel" presentation, which implied "shaping" as such. Call it clipping and technically (electrically) you are where I like to to be. Mind you, this is not at all the same as "band limiting" which is what got to your mind, if I understand correctly.

But no harm done, because the cable already exists.

 

In order to not make this 100% ballony, think oscillator output. This can be square or sine, and both will work for almost all applications. Now sit back and try to reason what will work better for your application.

My promise : now there is suddenly so much involved that a group of fine engineers will get mad from all the ideas each one may bring to the table.

 

[PeterSt]

3 minutes ago, semente said:

Have you ever thought about designing a dedicated PCIe USB card?

 

Ricardo, yes. But the result will always be vague in advance.

Secret : in 7 months of time I will have a new interface with very fresh ideas. And that one can be predicted. It is a study project for our Paul (who managed to study embedded engineering without me pushing him) and if I'm right such a project would be for graduated and beyond. He's in his 2nd year soon.

[PeterSt]

4 hours ago, mmerrill99 said:

Can you detail your thinking on this?

Do you mean the software side or the hardware side?

 

Hi mmerrill,

 

I don't think I can add much to what is already known;

 

It is about the 8KHz which is right in the middle of the audible spectrum and thus can never be filtered out. This in itself creates the plethora of solutions to counter attack that noise (which really sticks out its neck when normal system noise drops under  ~-140dB.

 

It is about the communication itself which has its own life. So the packets and how much data they contain and thus also how much current is drawn per time unit; this always changes and changes.

 

It is about (similar as above) the unconnected clock speeds at both ends with which all needs to deal with (this is possibly less known).

 

It is in the end about the somewhat unnecessary difficult protocol in itself. I mean, no audio sending data device requires it and no audio receiving device requires it. Someone just thought that USB was a good idea.

Of course it was at first because it eliminated the soundcard as such (5 million people may not even understand the importance of this), but the sound had also to be good.

And so we actually still fight a bit with that.

 

[PeterSt]

4 hours ago, mmerrill99 said:

Not sure this holds up - in USB 3 receiver chips there seem to be two separate engines - a USB 2 engine & USB 3 engine - they each handle their own protocol independently of the other. USB 2 only operates at 480MHz, no faster

 

Your more general point that the chip itself is built to be capable of handling the faster speed USB 3 (5Gbps?) may have some significance though even when it's only handling USB 2.0  480Mbps speed throughput?

 

Faster settling time of on-chip components could well be significant here?

 

All matching what was on my mind when responding.

It goes a bit beyond this when you think of things like the heat-up which is now insignificant (and thus also does not change properties once playing) and what about jitter specs which again also matter.

Regarding the latter : ... *if* jitter matters indeed (and very indirectly it will but this is far sought).

Notice that with jitter I again refer to the propagation times (which are just 10 times faster), and the skew on the two data lines which now also has a lesser distance (and this results in jitter on the net data line).

 

Anyway, you can see how over-sizing almost always helps with audio, and also how these things are nog easy to guess for consumers.