USB audio cracked... finally!

[semente]

5 minutes ago, PeterSt said:

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).

 

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

[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.

 

 

 

[mmerrill99]

24 minutes ago, semente said:

 

What does "clinical" or "involving" mean?

 

It should have read "clinical & UNINVOLVING"

 

27 minutes ago, semente said:

In my experience, as you remove playback-generated "grime" from the signal the sound becomes "smoother"/"softer" and you can hear more of the recorded detail.

But I don't know how this can be applied to a USB interface/connection.

Yes, I agree - that's why I said that some cables (the Clairaxa) may sound clinical & uninvolving because it is revealing the jitter in the system.

[pkane2001]

1 hour ago, PeterSt said:

 

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).

 

Sure, Peter. That could actually be an explanation. The fix, then, is a better power isolation, or even separate power supplies to the two sides of the DAC USB receiver.

[pkane2001]

1 hour ago, PeterSt said:

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.

 

 

 

Cool! So it sounds like the cable is bandwidth limited, filtering out higher frequencies and smoothing out edges of the square wave. This should be fairly easy to test with a low pass filter in-line with some 'standard' USB cable data lines.

[Superdad]

4 hours ago, PeterSt said:

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...

 

Hi Peter:

(Before I comment, everyone here should know that there is much mutual respect between Peter and myself--well, really between Peter and John Swenson as myself I am nothing, not an engineer. )

 

Actually Peter, I did post before-and-after eye-patterns in the first post of the ISO REGEN Listenening Impressions thread, and to the extent that one can interpret jitter from those (width of verticals near crossing), we at least showed the SI improvement versus straight out of the laptop.  And our USPCB A>B Adapter was not even used to connect the ISO REGEN to the analyzer.

 

Quote

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 ?

 

Not only is the considerable jitter (and noise) of the Silanna chip measurable, its impact can be heard quite clearly.  For anyone wanting to hear this--and it is in fact highly instructive about the sonic impact of high jitter in the USB stream--I suggest you buy one of the few devices out there which use just the Silanna chip and do not reclock with a hub chip.  The CoolGear and origInal ALLDAQ units are examples.  They sound terrible in almost every way, and they make instrument placement very vague.

And now, after working with Silanna since late 2015 (when I approached them and said we wanted to pair a hub chip with it--something they had not yet considered), their own application sheets and designs call for use with a hub chip.

 

Quote

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).

 

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

I never said that the Silanna chip's jitter (quite the same as for most typical digital isolator chips of the non-USB variety as used in many DACs after the USB PHY/processor--400-600ps) was the cause of functional problems.  Just that "reclocking" (a misnomer here) is necessary.  Such is a key part of the SQ of the ISO REGEN anyway--though the reasons why the phase-noise "fingerprints" of upstream devices survive into the DAC are not yet entirely understood.  It goes beyond just good SI, and this is something that John will be studying more when he finishes building his version of the TimePod phase-noise analysis probe.

 

[Of course our decision to use the Crystek 575 in the new product came long before incorporation of the galvanic isolator.  We built identical "uber-REGEN" boards that differed only in their clock. One had the $1.20 Crystek 3391 as always used in the original USB REGEN, the other the $9.60 CCHD-575--which BTW comes out in production from Crystek with FAR better phase-noise than the old published plots from the data sheet still on their web site, the plots that came with 3 random samples we received 16 months ago had 10Hz offset figures of -108, -110, and -112--completely amazing for a production clock at this price.

It took less than 30 seconds of comparison to know we had to use the better clock. Not subtle!]

 

Having worked with (and "fought" with) the Silanna chip and its engineers for over a year, we understand quite well where the functional issues come from, both in terms of interfacing with other parts (hub chip in our case) and with regards to grounding and charge build up.  Peter knows what I mean here: he hinted at and documented (in his forum) some of his own struggles with the Silanna. (In the end we have worked out some arrangements with Silanna which I have been asked not to discuss publicly.)

Suffice it to say, with effort, the thing can be made to be 100% error free with isochronos audio.

 

Sorry for going quite off-topic from Peter's new cable.  But I know all the participants of this thread are interested in the above topics anyway.

 

Peter, I'll be sending you a PM to purchase your new cable.  I am nothing if not curious--and of course always looking to improve my music system!  

 

Best,

--Alex C.

 

[Jud]

1 hour ago, pkane2001 said:

 

Sure, Peter. That could actually be an explanation. The fix, then, is a better power isolation, or even separate power supplies to the two sides of the DAC USB receiver.

 

Hi Paul.

 

@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.  In either case, these effects would then in turn affect the DAC’s clock and/or the zero crossing point of the signal (determined by comparing signal to ground, the latter notionally being zero, but if there is noise on ground, it isn’t actually zero; you can read ESS white papers where much is made of noise reduction on the ground side).  I read a post from Gordon Rankin in another forum a couple of years ago that I interpreted as supporting the ground noise theory, but I don’t know enough to be sure I was interpreting correctly.

 

I don’t know of confirming measurements for either hypothesis at this point.  Because we’re talking about an effect happening in the DAC clock as it’s working, I think the measurements would have to be in the analog domain; or, as John Swenson once mentioned to me, you could essentially build the world’s most precise ADC.

[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

[Jud]

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

[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.

[Jud]

7 minutes ago, PeterSt said:

 

Haha. Hamilton. Verstappen was 4th.

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

 

Right, I watch all the races (and qualifying).  But is Hamilton your favorite driver?

[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.

[Doak]

1 hour ago, Superdad said:

 

Hi Peter:

(Before I comment, everyone here should know that there is much mutual respect between Peter and myself--well, really between Peter and John Swenson as myself I am nothing, not an engineer. )

 

Peter, I'll be sending you a PM to purchase your new cable.  I am nothing if not curious--and of course always looking to improve my music system!  

 

Best,

--Alex C.

 

Would love to read your comments on using the Lush USB cable with ISO Regen, Alex. 

Also curious about its use into compared to out of the unit. 

BTW: 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).  

Doak 

[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

[elcorso]

6 minutes ago, PeterSt said:

 

Hi - You can bet it is.

https://uk.lush.com

 

Peter,

 

You gave me a good idea!

Can it be used when you're in the shower listening to music with your Lush?

 

Roch

[jabbr]

1 hour ago, PeterSt said:

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.

 

As you know the reason to impedance match the cable as well as to properly terminate the receiver is to prevent reflections. Indeed that's how you know your impedance is matched!

 

Regarding skew, indeed different than phase noise but generally lumped in with "jitter". There are also different types of skew. eg speed of bit/clock transition vs different time of signal arrival.

 

Very interesting... if you look at the clock  optimized version of the DSC1 you note that 1) clock distribution chip (potato semi has low pin-pin skew) as well as 2) equal trace lengths to the shift registers.

 

Balancing tends to reduce ground plane switching noise. Also careful bypass cap networks are essential -- any one bypass cap will have impedance peaks.

 

Also dealing with these issues in FPGA or chip is black magic and so ther are undoubtedly many receiver circuit dependencies.

 

But yes there are a class of situations where introduction of skew on purpose leads to less noise!

 

I think these are relevant and hopefully readable: 

1) http://web.stanford.edu/class/archive/ee/ee371/ee371.1066/lectures/lect_07.2up.pdf

2)  http://pages.hmc.edu/harris/class/e158/04/lect19.pdf

 

See the discussion of pros & cons of removing "hard edges"

[austinpop]

So - 7 pages of discussion of why this or that can or should sound better. 

 

But in terms of listening impressions and comparisons with USPCB and other cables?

 

Other than the OP, I've seen exactly one actual review. Very helpful, thanks @hols. 

 

Anyone else? 

[manisandher]

9 minutes ago, austinpop said:

But in terms of listening impressions and comparisons with USPCB and other cables?

 

You may have to wait a short while before non-Phasure users start reporting their impressions of the Lush. I only first listened to my own Lush 4 days ago. It was apparent within the first few minutes that it was unlike any other USB cable or 'tweak' I'd tried. I sincerely hope others will feel the same when they try it (I'm kind of confident they will!).

 

Mani.

[Jud]

26 minutes ago, austinpop said:

So - 7 pages of discussion of why this or that can or should sound better. 

 

You’ll thank us later.

 

But yes.

[austinpop]

Got it - be patient!

 

I have to be honest - I was unaware of the Phasure, um, universe, until @hols mentioned the Lush cable on another thread.

 

Would I be laughed off the thread if I asked if anyone could compare it to the Curious 0.2m link?

[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).