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

[pkane2001]

1 hour ago, Keith_W said:

Alex, I have faith that you and John Swenson know what you are doing. If you feel that Amir's methodology is flawed and would result in flawed measurements, why not post your own?

 

Fully agree.

 

Alex @Superdad, you have to believe in measurements if you are doing engineering work. If you don't, then I have no interest in your product. Publish your own measurements so that you can prove Amir wrong. I understand you're busy and have had little sleep. But please do it soon, because I am curious about your device and would like to purchase it if measurements bear out what is claimed by John Swenson: reduction in jitter at the DAC. 

[pkane2001]

8 hours ago, Superdad said:

As to the degree to which various DACs and their USB input are affected by variations in SI--and why that can have an effect on the DAC's overall ground plane and master clock--John has written extensively about that, and other (both DAC and external device) manufacturers have worked on the issue to improve their products. Just because the lay person does not grasp or acknowledge certain deeper engineering issues doe not mean they don't matter or exist.  

 

Alex, all your eye pattern plots prove is that the USB signal is improved from some poor USB port on some PC. That tells me nothing of the effect this device will have on SQ, since I don't know how or why this would translate into better SQ. Please explain this to me in "lay person" terms, or even in technical terms.

 

John Swenson stated that this device works the following way:

Quote

My current thinking on USB interface is that there are at LEAST three things that can degrade the sound coming from a DAC. All of these work by increasing the jitter on the clock feeding the DAC chip(s). This can happen in two different ways: increasing the jitter of the local clock itself, or modifying how the DAC chip receives the clock, which effectively increases the jitter INSIDE the DAC chip.

(highlight is mine)

 

As I understand this, these effects should be easily measurable at the output of the DAC. I don't buy the argument that this is impossible to measure due to variations in DACs. A measurement without and with the ISO REGEN should show an improvement in jitter. You can pick the worst possible DAC, or the best possible DAC, I don't care -- pick one that best demonstrates your device. Just show that the device does what is advertised.

[pkane2001]

12 minutes ago, sdolezalek said:

you clearly hear a difference that the "measurement" addicts seem to suggest cannot exist

 

What baffles me to no end is how so many folks get convinced that measurement couldn't possibly be useful in predicting audio performance. I'm sure that some snake oil peddlers would like you to believe that. But objective, repeatable measurement is key to testing the performance of any electronic device. This is overwhelmingly the practice of all competent electronics engineers and designers.... except, it seems, in hi-end audio.

 

If the device 'cannot be measured' or 'the measurements don't demonstrate what it does' then how do you know that it does anything positive to the signal? To me, this is a warning sign that the manufacturer or the designer don't know what they are doing or trying to hide something. Especially if they tell me that I wouldn't understand even if they tried to explain it. Try me: I'm not that dense.

 

Being able to pick the device out in a blind test is a good start, but that only proves there is a difference. Whether the difference is for the better or worse will often depend on the preferences of the listener.

 

My approach is to research a device before I buy it. I want to understand what it does, how it does it, and whether there is some objective proof (in the form of measurements) that the device achieves these goals. Obviously, I also would like to hear that others found that the device works, producing the advertised effect. Does this make me a "measurement addict"? So be it.

[pkane2001]

52 minutes ago, jabbr said:

1) Measurements are only good if the correct measurements are done. Any scientist worth their NaCl knows that someone doing a measurement with an agenda will produce skewed results. Even the choice about which measurements to perform or even which equipment to use can affect an agenda and skew results.

 

Right. That's why it's important to publish not just the measurements, but how these were done. This allows for independent (or even biased) others to try to reproduce them or show how they were wrong. But, as the first step, I would like to see even a skewed result from the manufacturer. I need at least some confirmation that measurements are being done and that they have a  chance of showing what is being claimed. This is particularly true when a claim is made that the device does something new, and as of yet, unproven.

[pkane2001]

10 hours ago, sdolezalek said:

I think the real questions are understanding what to measure, and what to hear in a blind test.  

 

Cleaning up digital signal through isolation or regeneration results in an improved quality of digital signal. That's fine. That seems to be confirmed with the posted eye pattern plot.

 

How this translates into an improved analog signal, how to measure this effect and how to determine the degree and quality of audible improvement is the question. Assuming no bits are flipped in transmission, the only effect an improved, regenerated digital signal can have on the analog output is to affect timing errors. I.e., reduce or increase jitter.  

 

That's why I keep asking to see jitter measurements, as that's the only thing this device can truly change at the output of my DAC that might matter to SQ. Since John Swenson says that he doesn't have the instrumentation to measure the effect on jitter (yet), then any audible improvement claimed for the device, at least for now, must remain a conjecture, an educated guess.

[pkane2001]

15 minutes ago, jabbr said:

I have discussed the method to measure the effects of "jitter" specifically phase noise on the analog output of a DAC. My proposal is to feed a pure tone of, for example, 1kHz, digitally encoded, into a DAC, and perform a high resolution spectral analysis. It has been questioned as to whether existing equipment would have sufficient resolution in order to do this, and that equipment designed for the audio range would need to be developed.

 

@jabbr, that makes sense to me. This is actually something I've attempted previously with my low-end ADC. No go, since the distortions of the ADC were too high, covering up any effects of the low level jitter on the signal. I used a 24-bit/96Khz Behringer ADC for this, REW for signal generation and FFT analysis, and MacBook optical SPDIF input for digital signal capture.

[pkane2001]

2 minutes ago, PeterSt said:

 

Are you serious ?

I sell USB cables. Btw the best in the world. What measurements would you require ?

 

Of course you are going to tell us that you use $1 cables because the $10 don't come with measurements to prove that they are better than the $1. And Oh, the $1000 also don't come with measurements.

 

Hey, you know what ? I just made a new USB cable. It is even better than its predecessor. No, typo, it sounds better, it *is* not better.

Who says it sounds better ? me. Maybe you too after trial with money back guarantee.

 

Who tells what is and what is not better ? me again.

So what *is* better ? better is in this case : better on USB spec. So you'd want measurements of that, right ?

 

Dream on.

No-one in the world sells USB cables with specs. Oh, commercial hoopla, but that is something else.

 

 

 

Just because something is done the wrong way and the masses accept this does not mean I have to follow suite.

 

I don't just talk about this stuff. I've made my own USB cables, created separated power and data cable, also  injected LPS 5v power USB cables, tried different shielding and no shielding, etc., and yes, I even tried to measure them by measuring jitter at the DAC 

 

Guess what? I'm still using the $15 cable, not the $1, as that one was causing drop-outs at quad DSD. No difference in sound quality once the cable is not losing bits, I'm afraid. Needless to say, I won't be selling any of my cables to unsuspecting masses.

 

Send me one of your cables, and I'll tell you if it makes a difference

 

[pkane2001]

Just now, 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....

 

OK, I considered them... And yet, all these effects get corrected on the digital side before entering the DAC with ISO REGEN.

 

How does anything a digital decrapifier do in the digital domain translate into an improvement in analog signal? 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?

[pkane2001]

9 minutes ago, mmerrill99 said:

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

 

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

[pkane2001]

39 minutes ago, mmerrill99 said:

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

 

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.

[pkane2001]

15 minutes ago, mmerrill99 said:

If a channel can't pass the USB signal, your question is nonsensical - an 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

 

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.

[pkane2001]

1 hour ago, Jud said:

 

Hi Paul -

 

I would guess it's not impossible to do the degree of noise reduction in the DAC itself as is done with the ISO Regen - one could essentially have an ISO Regen inside the DAC, or in other ways reduce aspects of self-noise and ground and leakage currents.  (Though recall one reason BADA said it kept its USB/SPDIF converter separate from the DAC was for noise reduction purposes - perhaps avoiding radiated EMI [I don't know, just blathering here]?)  But I think you'd agree the concept of keeping noise out of the DAC clock is solid.  And my impression at least from what I've read is that John seems to have had a pretty good handle on component selection and circuit and board design to accomplish that intended goal.  

 

We're then left with the topic of whether any reduction in noise accomplished by the ISO Regen will be audibly evident in the analog product.  The blind testing is for me a fairly strong indication *some* change is making it through to the analog side.  I can always be flat wrong, but the amount of readily identifiable difference between the two units with no expectation bias operating, plus the identical results from the other tester, does leave an impression even from these anecdotal results.

 

Of course we then run into the issue of figuring out whether the change (crediting for the moment the notion that I'm correct about the existence of a change) and the mechanism causing it are as John intended.  For that we may have to wait awhile.

 

 

Hi Jud,

 

I agree with most of what you are saying. Keeping the noise out of the DAC clock is a good thing. This effect should be measurable with existing tools. Hence, my 'quest' to see a jitter plot with and without ISO REGEN.

[pkane2001]

1 minute ago, mmerrill99 said:

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 

 

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?

[pkane2001]

44 minutes ago, mmerrill99 said:

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 ..................... 

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.

[pkane2001]

Gee

Just now, Speed Racer said:

Show me a USB 2.0 High Speed compatible optical isolator......

 

Took me all of 5 seconds to find. Check out those USB 3.0 units, too!

http://www.sitech-bitdriver.com/products/usb.htm

[pkane2001]

10 minutes ago, Speed Racer said:

No, not extenders. A device designed as an inline isolator. I'd used an Ethernet extender before I would use an optical extender.

 

The product you came up with retails for $1499.00.

 

So a fiberoptic extender is not an optical isolator? I'll look for a cheaper one for you the next time I have some time. 

[pkane2001]

8 minutes ago, plissken said:

 

I'm at a loss how:

 

1. You can guess at a problem that you can't quantify so you can see what's going on but...

 

2. Still develop a solution 'in the blind' for it (whatever 'it' is)

 

And once you have developed such a solution, how do you know that it achieves the desired goal? More to the point, how do I know this, if you can't provide objective data?

[pkane2001]

18 minutes ago, Ralf11 said:

The cause of "any audible improvement... at least for now, must remain a conjecture, an educated guess."

 

But a blind test can reveal whether it sounds better without knowing why (or maybe not caring).  

 

A difference found in a double-blind test does not prove an actual improvement. It proves that there is a difference between A and B samples, but which one is better is based on the listener and their preferences and therefore is not objective.  

 

Consider the online survey where the majority of 150 listeners preferred a flawed MP3 lossy compression over the non-lossy original in a blind test using their own equipment. Over 55% of folks with high-end, expensive equipment preferred the sound of the less accurate recording and only 29% preferred the lossless version. Does that mean that MP3 is better?

[pkane2001]

2 minutes ago, jabbr said:

The upper plot clearly has a wider linewidth (width of peak). Let's measure this as the width in Hz at the 50% height of the peak.

 

I like it! Measuring FWHM of an audio tone. I believe I've seen this done before in the late 90's. Don't recall who tried it, but I'll try to locate it. So is it your thinking that the width of the peak is related to jitter? 

 

[pkane2001]

4 hours ago, jabbr said:

50% height is standard. With a Gaussian peak it the point of maximum slope. That means that slight errors in placing the exact vertical level will have the least effect in the measured horizontal.

This measure is called full width at half maximum (FWHM) and is a very convenient way to measure the width of a gaussian-like function that is independent of the peak value. For a gaussian, this measure is proportional to the standard deviation. There are some other functions that might be more applicable for this particular measurement, for example some with much longer tails.

[pkane2001]

7 hours ago, esldude said:

Ah, that term I recognize from astronomy.  You might use it to characterize 'seeing' conditions based up how jittery the atmosphere is making images. 

 

Ah yes.  Very curious to hear how many audiophiles are also amateur astronomers. Both have been my hobbies for a very long time

[pkane2001]

25 minutes ago, The Computer Audiophile said:

 

Such a topic also calls for a shout-out to @astrotoy

 

"Larry received his Bachelors degree in astronomy from Harvard and masters and Ph.D in astronomy from the University of California, Berkeley. His area of research was in theoretical astrophysics modeling the atmospheres of stars."

Nice! Love the "modeling the atmospheres of stars" part. That sounds like a really fun topic for research.

[pkane2001]

5 minutes ago, rb2013 said:

Some theories go so far (Penrose/Hameroff Orch-Od) it's actually quantum mechanical based.

 

And only listening will be able to determine the ISO Regen's value.

 

There's perhaps just a tiny difference in the amount of complexity between an ISO Regen and a human brain, so I still hold out hope that ISO Regen might one day be measured