Amir at ASR claims Uptone won't sell the ISO regen to him...

[mmerrill99]

 

27 minutes ago, Jud said:

 

Hmm nothing.

 

My statement was preceded by and predicated on "In that case," meaning in the case where we were not successful in obtaining measurements.  So first, it is looking toward a future possibility, not assessing current facts.

 

The designer, a highly qualified and experienced engineer, has a theory of operation of the circuit.  (I.e., this is not a "shot in the dark.") Two blind tests selected the version of the circuit that ought to've worked better to accomplish the design intent.  At this point the question is whether or not measurements will become available to confirm the circuit works as designed.

 

 If we aren't able to get the measurements (not a trivial thing), then what do we think?  Maybe it works, though we haven't been able to confirm how?  Or we ignore the "chops" of the designer and the blind test results and say we won't concede even the possibility it may?

I agree, Jud

 

What seems to be missing in this whole discussion, on both sides, is that doing relevant measurements, capable of revealing audible differences of the type reported for the ISO Regen requires focusing on the likely theory of operation & deriving a set of measurements that will best uncover whether this theory shows in the measurements.

 

To my way of thinking, Amir's approach lacks the necessary dedication & focus to achieve meaningful measurements. His measurements are cursory & generic in nature & people have to judge their validity. IMO, they would certainly not qualify as in any way definitive in answering the question of the audible effectiveness of this device.

 

It's interesting to note that those who seem to be so invested in measurements don't seem to be able to bring themselves to admit this aspect of measurements - they seem to talk about them as some sort of absolute & incontrovertible factor

[mmerrill99]

1 hour ago, mansr said:

No, I haven't done rigorous testing. However, I'm not the one selling it, so that burden isn't on me. I also have no reason to suspect them of secretly adding reverb rather than doing what they say they're doing.

But you are making claims & we all know, in the world of the objectionist :), claims need proof, right?

How do you know you are not also changing some timing/phase issues & this is what you are hearing? 

[mmerrill99]

2 minutes ago, mansr said:

Sure, there are "fakes" that don't actually meet the spec. That's a problem. The point is that by using the official logo, you are stating that the device/cable conforms to the spec. Whether or not that is true is a different matter.

And the spec is a guarantee that there are no bit errors (or very, very negligible bit errors - nothing is absolute)

 

Bit errors are not & never were in question in these USB audio device improvements

 

Time to stop confounding the issues!

[mmerrill99]

Are you saying that USB audio has bit errors?

[mmerrill99]

8 minutes ago, Jud said:

One comparison to the optical isolators you are familiar with is that although they provide isolation, they can have relatively high levels of self-noise and may therefore not be the best choice to use in DAC circuitry.

All isolators introduce jitter, some more than others. Optical isolators also do not work at high speed USB 2, which is what most USB audio now utilises

[mmerrill99]

19 minutes ago, pkane2001 said:

 

Great. So, the effect of ISO REGEN is then to do what... reduce jitter compared to an optical isolator?

You don't seem to understand that your $25 optical isolator cannot isolate at this 480Mbps speed so your claim "it will break up current leaks and ground loops just as effectively" & asking what the ISO Regen does is silly - the ISO Regen does actually " break up current leaks and ground loops" at the USB speeds now used in audio, unlike your optical isolator

[mmerrill99]

23 minutes ago, pkane2001 said:

 

Please explain how an optical isolator will not stop ground loops or leakage currents.. By the way, current audio standards require well under 100Mbps bandwidth.

If a channel can't pass the USB signal, your question is nonsensical - your optical isolator can block everything including the 480Mbps signal so dead silence is guaranteed

 

No matter how much you protest, current USB audio uses 480Mbps as it's de facto standard

[mmerrill99]

2 minutes ago, pkane2001 said:

 

The only reason ground loops and leakage currents are a problem in a conventional circuit is that they are traveling along pathways that were not designed to filter them out. In an optical isolator, it is trivial to filter out all noise and leave the data signal since they both come through the same input.

 

Regardless of USB speed, the actual audio data rate is a lot less than 480Mbs. Isochronous transfer protocol allows the endpoint to decide what portion of the overall bandwidth will be used for the transfer. None of the commonly used audio protocols/formats approach anything close to 480Mbs.

Ah, it seems you are confused about the USB protocol - the speed to be used for the whole transmission is negotiated at the handshaking stage. Most USB audio devices will negotiate to high speed usage. The overall data transfer rate is dynamically controlled by the asynchronous protocol based on buffer fill rates. The amount of data in each microfarme is varied to slow down or speed to the data throughput BUT a microframe is sent every 125uS & this is what has to be accommodated in the 480Mbps.

 

Don't confuse the 480Mbps bandwidth with the actual data throughput 

[mmerrill99]

20 minutes ago, pkane2001 said:

 

Not confused at all, but this is irrelevant to the topic. There are plenty of optical isolators that work at 480Mbs. What's your point?

Hold on there, you started all this with this claim " A friend used to make optical USB isolators and sell them for $25 about 10 years ago. I suspect that this will break up current leaks and ground loops just as effectively. So, what else does ISO REGEN do that a $25 piece of kit doesn't? Reduce jitter, perhaps? "

 

Which I pointed out was a baseless claim. If it isn't baseless then post the technology he used & we will see if it handled 480Mbs.

 

Now you are trying to broaden your claim with confused statements 

 

Apart from the corning USB high speed optical isolator (that jabbr pointed out & which isn't reliable), name another optical isolator which works on 480Mbps USB.

 

Either show all these optical USB isolators which trivially work at 480Mbps or ..................... 

[mmerrill99]

5 minutes ago, pkane2001 said:

Sorry, but you jumped into the middle of a conversation. All I was saying with this is that optical isolation is nothing new, it has been done a long time ago. You're right, the $25 optical USB isolator from 10 years ago was 12Mbs, I just checked. But it wasn't designed for audio. There are optical isolators that can handle rates much greater than 480Mbs,  but again, that's not what the discussion was about.  I suggest you go back and read it from the beginning.

Nope, I don't need to go back, I was following the posts in this thread & you specifically made the claim about your friend's USB isolator in answer to Speed Recer's post:

3 hours ago, Speed Racer said:

You are looking at too narrow of a picture. If all you consider is the digital signal itself, there would be zero reason to to buy any type of decrapifier. You have to consider the effect ground loops, AC leakage, etc., have on the receiver USB PHY. In other words, you need to consider all aspects of what the ISO Regen does and how it might affect the music to judge its effectiveness. Not just jitter....

[mmerrill99]

8 minutes ago, plissken said:

Jeez. The point is you weren't blind comparing a DAC with and without. You were comparing items that most likely have very measureable differences in output and one of those out putting something so far out of spec that the DAC was expecting it then got sideways. 

It's amazing the level of unfounded speculation in this one paragraph - is this called blue sky thinking or is it BS thinking

 

8 minutes ago, plissken said:

I mean I'm pretty sure I could feed a DAC something out of spec that it isn't expecting / designed for, say 120V, and wouldn't even need any speakers connected to tell the difference. 

And running with this BS to build strawman arguments

 

[mmerrill99]

20 minutes ago, jabbr said:

 

Are you kidding? You aren't even doing the test I proposed aside from ? 40 dBc -- that's terrible. I certainly hope its the ADC otherwise the DAC is really bad.

 

Do you see the specs of the Crystek clock? That's a $20 part. You have no way to get close to measuring it.

 

 

If this is a phase noise plot, then the increase as offset goes down is what is seen. In this case you can't determine whether the plot is primarily of the ADC clock or the DAC clock and so there's no way to determine whether some device like the Regen is having any effect.

 

In any case if you apply this phase error curve to a single tone you will see the significant distortion I am discussing assuming your simulation or actual measurements were of sufficient resolution.

 

Ah, who cares about the details of how to do a decent measurement - any measurement (no matter how bad) is better than none,  right? I'm sure we see Amir's mindset being channeled here

[mmerrill99]

2 minutes ago, jabbr said:

 

Ah ok  I misinterpreted what you were doing ...

 

Yes lower close-in phase error will get a more narrow peak. This is math. I know this is a new concept that doesn't appear to be widely described but I am very confident of the underlying math. 

 

 

The point is he has absolutely no idea what portion of the close in phase noise is accounted for by the ADC jitter or the DAC jitter so if he then proceeded to measure a ISO Regen in front of the DAC & got exactly the same plot he might well declare that the ISO Regen has no effect.

 

This is called measurement Amir-style

[mmerrill99]

5 minutes ago, Jud said:

 

Yes, that's just what happened with my DAC - black smoke with one hub, white smoke with the other, so of course I knew which one to choose as Regent, er, Regen.

One was elected Papal Regent by decree of the Archbishops - an infallible blind test, I would say

[mmerrill99]

 

35 minutes ago, jabbr said:

I'm trying to give people who publish wideband FFTs with spectrum analyzers the benefit of the doubt in not knowing exactly what measurements should be done. Does the Regen decrease clock jitter at the DAC? Who knows. Would it be audible? Who knows? For all I know it could all be leakage current/grounds loops or even something else.

Yes close in phase noise, common mode noise, leakage currents (all possible aspects that are improved with the ISO Regen) will not be amenable to analysis by an AP SYS2722 analyser - it takes some effort & experience to decide what is an appropriate measurement & what is needed to achieve this measurement - man with AP does not qualify.

[mmerrill99]

17 minutes ago, jabbr said:

 

Ok so let's consider whether these numbers are audible (except that the values will rise as the offset lessens...)

 

Consider: http://www.phy.mtu.edu/~suits/notefreqs.html these are bass admittedly but look how close the notes are together in Hz ... so could the 1Hz offset phase error have a significant effect? A "blur" function of the FFT of a song using Matlab might be close ...

Yes, this might be a more profitable parallel line of investigation - find some way of simulating  close in phase issues in songs (not single test tones) & test for audibility Vs level & characteristics.

 

Have any audibility tests of this nature been conducted before?

 

Is it worth thinking about this in terms of image processing i.e. motion blur in video?

[mmerrill99]

45 minutes ago, jabbr said:

Is this important? I think so ... let's try to predict where the sound might be different. Offhand, I'd say that frequency "blurring" of say 1 Hz would have a more significant effect on the bass than the treble. As per the list in the link that I posted above, you see that bass notes are separated by just a few Hz, so I 

predict that this would be more of an issue. But you tell me? How do these sound differently? Do they? If so, we could start to measure how small a difference in linewidth is audible. I don't know;) 

I too would like to see any differences that exist at this close in level.

 

As to audibility, this is a complex question. Essentially we are looking at frequency modulation but a number of things have to be realised - we are dealing with music, not pure tones. The significance of this is that the shape of sound envelope is a significant factor in what we audibly perceive, not just a single tone. The sound envelope (or spectral envelope) is made up of the various stages of the sound - attack, decay, sustain, release. Such a sound envelope can persist for a number of seconds.

 

Let's say that within this couple of seconds timeframe, phase noise has affected the recreation of this envelope ( the amplitude of some of the individual peaks are not correct) - does this audibly effect what we hear?

 

Zwicker & Fastl's book "Psychoacoustics - facts & models"  have looked into frequency modulations but like most auditory research, using tones rather than the more complex test signal such as music. Some of their findings with pure tones is that slow frequency modulation gives rise to the perception of roughness to the sound & frequency modulation in general gives rise to the perception of pitch changes.

 

So, the psychoacoustic ramifications of such close in phase noise is not simple. I believe it would be wrong to say that it more strongly affects low frequencies but who knows?  

[mmerrill99]

1 hour ago, semente said:

And even though I wouldn't mind giving it a listen I would like to see some measurements.

The problem is that the necessary measurements have apparently not yet been conceived...

 

1 hour ago, semente said:

Sorry for the foundation-level question but what is the eye-pattern analysing/representing?

I wonder does this represent the majority? People who want measurements but really are not capable of deciding what the measurements mean?

 

What would be the benefit of such measurements if they are not something you can evaluate?

 

So lets say a set of measurements are made & posted. one side says they 'prove' the effectiveness of the device & the other side says it doesn't & that they want more definitive 'proof'. Where are you then at?

 

I'll tell you where you are at - exactly the same point as you are now at in this thread.

All this talk about measurements is just smoke & mirrors & people should examine their motivations & the scenario above to check their motivations in all of this, fiasco.

 

I mean "I wouldn't mind giving it a listen" - well then give it a listen For god's sake - these preconditions are just BS

[mmerrill99]

6 minutes ago, semente said:

 

IF I am able to "understand" a measurement then I have no need for other people's interpretation.

I don't have any sinister pleasure in looking at measurements UNLESS I can read them.

Well, you didn't seem to understand what the eye pattern measurement signified or what it even was - so what measurements do you want to see (which you understand the meaning of) before you will "have a listen"?

[mmerrill99]

3 minutes ago, mansr said:

I just like playing with oscilloscopes.

Could you lend it to Semente - he's looking for a plaything!

[mmerrill99]

3 minutes ago, semente said:

 

I had seen the eye pattern before, in one of the previous topics about the Regen if I remember correctly, possibly originating from Pinkfishmedia.

I am curious about how the Regen can improve data transfer and consequently D/A performance.

Listening won't be of much use.

You stated you wished to see measurements before you would "have a listen" - I asked you what specific measurements you wished to see which you will understand. Care to answer that?

[mmerrill99]

4 minutes ago, semente said:

 

Does it vibrate?

No but I'm sure you'll get some pleasure from looking at two sinewave peaks

[mmerrill99]

7 minutes ago, Fitzcaraldo215 said:

Zero, and you?  I am not a plumber or a carpenter either, but I think I understand what they need to have in their toolkit.

A glass hammer & a bucket of steam?

[mmerrill99]

4 minutes ago, kumakuma said:

 

Zero as well but, unlike the two of you armchair quarterbacks, I'm not the one lecturing others on how to do their jobs or run their business. 

Or that they want 'measurements' but don't really understand what this means or what to do with the 'measurements' when they get them - more arguments, I predict 

[mmerrill99]

7 minutes ago, Daudio said:

Listening won't be of much use

7 minutes ago, Daudio said:

 

I also add you to my IGNORED MEMBERS list for severe cluelessness. No need to waste further time reading nonsense.

Yes, it's really bedazzling how deep down the rabbit hole some people can go - I'm sure what's up is down & what's down is up now in their world?