USB audio cracked... finally!

[pkane2001]

 

46 minutes ago, PeterSt said:

 

Not bad thinking. But a filter set up like what's implied (resistors etc., opamps - that is, if you refer to that (I did not really look, sorry)), then I would not do that because of the variance in resistance (or capacity) because of heatup of the "filter" itself, which would be dependent on frequency etc. etc. etc. (even a kind of oscillation could be your share).

The result is that now the slope to trigger on is not consistent and that implies jitter and ...

... and maybe that is not important but ...

 

 

Or maybe just use a high-capacitance cable that will act as a low-pass filter?

[jabbr]

24 minutes ago, Jud said:

 

That sounds like a raised eyebrow. 

 

I think that I like minimum phase filtering less in my system, because it sounds to me like the imaging and localization aren't quite as good.  I could of course be imagining this, or if I'm not, the cause could certainly be something other than phase effects.

 

The "filter" here is not filtering audio information. The goal is purely to present the ideal waveform to the receiver circuitry. There is a paper I referenced way above which demonstrates how sub-nS changes in rise time of a digital signal change the switching at a receiver circuit. Perhaps think of it not that the signal itself is ringing but that a fast transition "bangs" on the receiver transistors too hard causing an oscillation. This has nothing to do with phase error in the signal itself which is determined by the fundamental. It is about shunting the excess energy in the waveform and allowing the switch to switch smoothly.

 

Does this correlate to SQ? Maybe, maybe not depending on the isolation between the USB receiver and the DSD/IS2/PCM bus.

[wushuliu]

So instead of expending a lot of money and time into USB cables, why not configure one's system so that you just need an adapter? Surely it's worth the effort to save $$$$. 

[Ralf11]

45 minutes ago, jabbr said:

 

The "filter" here is not filtering audio information. The goal is purely to present the ideal waveform to the receiver circuitry. There is a paper I referenced way above which demonstrates how sub-nS changes in rise time of a digital signal change the switching at a receiver circuit. Perhaps think of it not that the signal itself is ringing but that a fast transition "bangs" on the receiver transistors too hard causing an oscillation. This has nothing to do with phase error in the signal itself which is determined by the fundamental. It is about shunting the excess energy in the waveform and allowing the switch to switch smoothly.

 

Does this correlate to SQ? Maybe, maybe not depending on the isolation between the USB receiver and the DSD/IS2/PCM bus.

 

so, the proposed mechanism is that (some) bits are being changed from 0 to 1 or vice-versa?

 

if so, what sort of voltages are involved to do that?

[mmerrill99]

29 minutes ago, Ralf11 said:

 

so, the proposed mechanism is that (some) bits are being changed from 0 to 1 or vice-versa?

 

if so, what sort of voltages are involved to do that?

Oh dear!!!!!

It's about noise not bit flipping!!!!

[jabbr]

1 hour ago, Ralf11 said:

 

so, the proposed mechanism is that (some) bits are being changed from 0 to 1 or vice-versa?

 

if so, what sort of voltages are involved to do that?

 

Its not about bit flipping in the sense of bit errors, rather what happens when a bit transitions.

 

I referenced a technical note from Micron "TN-46-06: Termination for Point-to-Point Systems Introduction" its a PDF much earlier in the thread (with a link but google works just fine).

 

Start with Figure 11 and go all the way to Figure 20. 

 

This demonstrates the signal integrity in a digital system with the effect of rise time.

 

How the "squiggly lines" affect sound coming out of the DAC is another issue.

 

Voltages are roughly 3.3v

[Ralf11]

Thx.   The mechanism as to how an overshoot of dV persisting for time interval dT would affect the clock or stream of bits or (??) is what I am trying to figure out.  Digital circuitry is not my area either...

[mmerrill99]

1 hour ago, Ralf11 said:

Thx.   The mechanism as to how an overshoot of dV persisting for time interval dT would affect the clock or stream of bits or (??) is what I am trying to figure out.  Digital circuitry is not my area either...

Sorry, I thought you were just trying to be smart with bits-are-bits style arguments?

[mmerrill99]

Is there another possible culprit to this scenario - settling time - the ability of the USB receiver to settle to a steady state in between USB bit processing? If there is ringing from the fast risetime this would affect the settling time

 

It would explain why USB 3 hubs sound better than USB 2 hubs - they are designed to handle far faster speeds - PeterST's headroom quip makes sense.

 

But the faster silicon isn't just enough - it appears that it's not the full picture

[Superdad]

4 hours ago, mmerrill99 said:

Is there another possible culprit to this scenario - settling time - the ability of the USB receiver to settle to a steady state in between USB bit processing? If there is ringing from the fast risetime this would affect the settling time

 

It would explain why USB 3 hubs sound better than USB 2 hubs - they are designed to handle far faster speeds - PeterST's headroom quip makes sense.

 

But the faster silicon isn't just enough - it appears that it's not the full picture

 

Indeed, when designing the ISO REGEN, we knew we wanted to go with a more modern high-speed USB3.1 hub, and in single-variable comparisons (USB 2.0 vs. 3.1 hub) it was a remarkable improvement (Jud and Larry previously reported on their separate, blind, "G" versus "M" labeled prototypes--and they both quickly chose the USB 3.1 "G" version.)

 

In fact, the choice of hub (and the PS elements, impedance layout, etc.) made as large an improvement (different really) as the choice to use the Crystek 575.

[jabbr]

6 hours ago, Ralf11 said:

Thx.   The mechanism as to how an overshoot of dV persisting for time interval dT would affect the clock or stream of bits or (??) is what I am trying to figure out.  Digital circuitry is not my area either...

 

At this point it is known to work by handwaving ... 

[PeterSt]

12 hours ago, pkane2001 said:

 

 

It's analog signal carrying digital carrier for another analog signal

 

 

I'd say it is an analog signal carrying a digital carrier for a protocol which represents a digital signal which maybe represents an analog signal.

 

The latter is, for example, not present when a digital synthesizer is the source and which never saw an analogue mixer etc.

 

 

[PeterSt]

12 hours ago, mmerrill99 said:

- when risetime is fast it may be more difficult to ensure consistency in the timing - it's this inconsistent timing that leads to jitter & this is audible

 

Why would this be audible ?

 

I'm not saying it isn't. But I also don't claim it is.

It is a complex matter and it should start with defining the domain (jitter-where and such).

[mmerrill99]

12 minutes ago, PeterSt said:

 

Why would this be audible ?

 

I'm not saying it isn't. But I also don't claim it is.

It is a complex matter and it should start with defining the domain (jitter-where and such).

Well I think one approach is to determine, by experiment, what factors do audibly affect the sound & then to try to work out the mechanism that results in it being audible.

I'm not sure that approaching it the other way "how is it audible"is the most effective way?

In other words, an empirical rather than theoretical approach.

[PeterSt]

On 2017-7-18 at 6:36 PM, jabbr said:

Digital switching noise and precise sequence of digital transitions are a perfect example.

 

I propose that any waveform which is used to trigger on its slope(s) does not result in "switching noise" as such. And otherwise it should be defined what is the "switching" phenomenon.

 

Switching noise is a quite formal term for a digital switch and one can spend a year in taming such devices, were it about utilizing them with the least amount of "noise". I am talking about high(er) frequency switches, like 45MHz. 

Of course this is a very low frequency compared to what exists in other worlds, but the noise coming from those switches is baaaad (for audio).

Btw, they carry jitter - but now I am trying to be funny.

 

[Dev]

For a change....I was about to receive my Lush this Friday and was thrilled that all my pain was going to end this weekend but I just received a mail from UPS that its delayed due to "Severe weather conditions"....Looks like I will have to bear the pain a little more....someone rightfully said "No pain, no gain"  

 

On a serious note, I am very much looking forward to this cable and hope this cable to be my last usb cable purchase....

[PeterSt]

22 minutes ago, mmerrill99 said:

Well I think one approach is to determine, by experiment, what factors do audibly affect the sound & then to try to work out the mechanism that results in it being audible.

I'm not sure that approaching it the other way "how is it audible"is the most effective way?

In other words, an empirical rather than theoretical approach.

 

Well, the emperical approach seems to be the only feasible approach. And in the end this *is* what we are doing. But it takes ages (I am talking in terms of years, really - and those are only the years behind us).

 

I must note that such a path is the most dangerous because it depends on my ears (and the ears of only a handful of others in the same "field"). So what happens is, that I judge something as sounding better (which already takes me a week to be sure) to next reason out what actually happened at the technical level. And well, as we can nicely see by this topic, is how a world of "power" is not really capable to draw firm conclusions. What also has been shown is how member marce, who for sure is right in the EE field and possibly better than all of os (for sure more experienced than myself), also would not be able to get there on his own, because he already does not recognize the problem (or maybe by now he does). So it takes rarities as John Swenson and possibly me, to be motivated to work out "something" while we don't know what the something is. We do recognize a problem "somewhere" though.

 

I still recall from the day like yesterday one of the first posts from Gordon Rankin in here, which went something like this :

 

I don't know how it works; Isochronous USB should be stopping all jitter, but whatever I do the jitter is passed on.

 

Weeks later it appeared that the (then all new) USB DAC's showed the worse measurements of anything at the time.

Today we are close to 10 years further and I could reason out how a USB cable could be made, but only based on another USB cable which was made to spec as good as possible and still only after 10 or so attempts to find the direction of "tweak". When that was found it worked in one go.

But 10 years ??

And by my ears ? ... I'd be careful if I were you. 

 

 

[PeterSt]

21 minutes ago, Dev said:

but I just received a mail from UPS that its delayed due to "Severe weather conditions"

 

WTF ?

 

So yes, all shipments to the US look exactly like this.

All I know is that this plane should go from Koeln (Germany) directly to the US, but not all with the same plane I think. Anyway this is all about CA and one about FL.

 

Severe weather ? So this plane leaves, and is in 30 minutes in Paris or so. It should be the direction, but fell out of the sky underway.

Over here in Holland there was a Thunderstorm at 4:45 am (lasted an our or so). So who knows ... it nicely fits.

 

I wouldn't be surprised if you get your cables tomorrow (Friday) after all, as the delay seems to be 3 hours only. But then of course it is easy to let logistics fail.

 

Sorry ...

Peter

 

 

[Dev]

30 minutes ago, PeterSt said:

 

WTF ?

 

So yes, all shipments to the US look exactly like this.

All I know is that this plane should go from Koeln (Germany) directly to the US, but not all with the same plane I think. Anyway this is all about CA and one about FL.

 

Severe weather ? So this plane leaves, and is in 30 minutes in Paris or so. It should be the direction, but fell out of the sky underway.

Over here in Holland there was a Thunderstorm at 4:45 am (lasted an our or so). So who knows ... it nicely fits.

 

I wouldn't be surprised if you get your cables tomorrow (Friday) after all, as the delay seems to be 3 hours only. But then of course it is easy to let logistics fail.

 

Sorry ...

Peter

 

 

 

@PeterSt, nah...don't worry about it...its not a big deal after all

[BigAlMc]

At the risk of de-railing this fascinating technical chat about the ins, outs, dos and don'ts of USB transmission protocols  it's here!! 

 

 

[mmerrill99]

@PeterSt - Yes we have to use our ears to evaluate audibility which can be erroneous but IMO less so than being solely directed by measurements (what measurements when we don't know the mode of operation?) & that is what I was getting at with my post - a number of people demand the explanation of the mechanism of operation & measurements when  something like this is presented & the whole thread degenerates - glad this isn't happening here & we can get on with kicking around ideas about this

[BigAlMc]

@PeterSt Thanks for the friendly and very prompt service.

 

What are your recommendations / experience for burn in for these?

 

 

 

@austinpop - I'm going to let it burn in a bit before doing any serious listening or A-B-ing with the Curious cable.

 

Initial impressions. It's spongy!! 

 

Perhaps it's the spongyness that carries the USB in a non-2.0 manner 

[manisandher]

5 minutes ago, BigAlMc said:

What are your recommendations / experience for burn in for these?

 

Hey Alan, great that yours has come through.

 

Mine sounded pretty good from the off, but I think it's become a little more detailed-sounding over the week or so I've had it in the system.

 

5 minutes ago, BigAlMc said:

Perhaps it's the spongyness that carries the USB in a non-2.0 manner 

 

Yep, they do look 'spongy' - apparently, that particular sleeve is absolutely necessary. Fortunately, there's nothing spongy about their sound!

 

Look forward to hearing your thoughts...

 

Mani.

[PeterSt]

16 minutes ago, BigAlMc said:

Initial impressions. It's spongy!

 

Maybe it's air only in there and we forgot something. 

 

haha

[semente]

2 hours ago, PeterSt said:

 

Well, the emperical approach seems to be the only feasible approach. And in the end this *is* what we are doing. But it takes ages (I am talking in terms of years, really - and those are only the years behind us).

 

I must note that such a path is the most dangerous because it depends on my ears (and the ears of only a handful of others in the same "field"). So what happens is, that I judge something as sounding better (which already takes me a week to be sure) to next reason out what actually happened at the technical level. And well, as we can nicely see by this topic, is how a world of "power" is not really capable to draw firm conclusions. What also has been shown is how member marce, who for sure is right in the EE field and possibly better than all of os (for sure more experienced than myself), also would not be able to get there on his own, because he already does not recognize the problem (or maybe by now he does). So it takes rarities as John Swenson and possibly me, to be motivated to work out "something" while we don't know what the something is. We do recognize a problem "somewhere" though.

 

Why hasn't anyone come up with a more effective alternative for connecting a Computer to a DAC?

 

Do you think this kind of problem is inevitable and as such may as well be tackled in the USB connection?