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

[jabbr]

1 hour ago, mansr said:

Nice straw man. I've never suggested that everybody must understand and personally validate the design of everything they use. It is quite sufficient that somebody does this. The problem with many audiophile widgets is that nobody has done anything to validate their operation. In some cases, the manufacturer even actively prevents others from testing it. Would you buy a car from a manufacturer who refused to let it undergo standard testing? What of a car manufacturer who was found to be rigging tests in its favour? Do they get a free pass, or are they hauled in front of court?

 

Ah... a car manufacturer might not let you or I perform tests on a car that we intended to publish hence the concept of the independent testing entity as imperfect as that is. We don't have standards (yet) for what tests are appropriate. Do you have any suggestions?

[mansr]

3 minutes ago, Jud said:

I believe both Bill and Dennis use digital room correction/equalization.  There is substantial academic literature regarding human insensitivity to the overall system frequency response this is designed to optimize.  Nearly all these systems use minimum or intermediate phase filters.  Is the favorable response to these systems due to overall frequency response optimization, or to a slight euphonic "reverb effect" in the audible range from the post-ringing of these filters?  I'm unaware of academic/scientific studies proving one or the other.  Why Bill and Dennis, you cock-eyed subjectivists!

I don't know about Bill and Dennis, but I use DSP mainly to tame a few low-frequency resonance peaks and for subwoofer integration. The difference is readily measured and easily audible with some music (anything hitting those peaks gets a boomy and uneven bass). I doubt it makes much audible difference above a few kHz, but the effect is again measurable and it can't hurt to have a more correct response.

[Jud]

12 minutes ago, mansr said:

it can't hurt to have a more correct response.

 

Are you quite certain, through scientific testing you or someone else has conducted, that it is a more correct response via-a-vis any possible reverb effect in the mid and upper portion of the frequency band?

[jabbr]

7 minutes ago, Don Hills said:

 

For 1): ... So to my layman's mind, the other way of looking at this is that the clock is constantly speeding up and slowing down by random amounts. These speed variations are more pronounced over longer time periods. An analogy might be driving a car, and randomly stepping on the accelerator or brake. The longer you step, the greater the speed deviation. This neatly leads to your 2), where the analogue signal output of the DAC also varies in "speed" (frequency) as the clock speed varies. As you say, this is measurable.

 

Yeah ok that distills a lot of math and physics down -- the clock speeding up and slowing down isn't "white noise" random, rather "pink" or 1/f random, that is to say the speeding up and slowing down is greater for lower frequencies (at the same base clock frequency).

 

7 minutes ago, Don Hills said:

 

Things get interesting when you try to determine what amount of variation is likely to be audible. There have been tests performed with different types of phase noise, and the worst audible case is still orders of magnitude beyond the performance of any competent DAC.

 

People have focussed on the baseline phase noise which is indeed low for "competant DACs". If you look at the close in phase noise it is drastically higher -- how many DACs report their 0.1Hz phase error? What dB would you expect the limit of audibility to be? hint: I bet vast majority of DACs would exceed a reasonable number you might propose.

 

7 minutes ago, Don Hills said:

 

For example, most people seem to be quite comfortable with the "jitter" (wow and flutter) performance of turntables, although they are audibly bad. This is easily shown. Play a 1 KHz tone from a test LP. It sounds ok at first, then you start to notice small anomalies. It doesn't quite sound as solid and substantial  as it should. Then change to the same tone from a test CD or other digital source. The difference is not subtle. But the effect disappears when you compare music on the turntable and digital source, even though the same effects are present in the musc as were audible in the test tone.

 

This is slightly different: If you were to plot phase error against offset frequency, a turntable and clock oscillator would have different curves -- and what I think we are hearing when there is "wow and flutter" is a particular resonance due to the physics of the turntable. Where they are the same is that both will generally have increasing phase error with close-in offsets! Some clocks can have resonances etc, I am describing the general appearance of general phase error plots of clock oscillators (as demonstrated by Crystek and others)

 

In any case yes, the degree to which this is audible, or limits of audibility are not yet known (at least by me)

[mansr]

Just now, Jud said:

Are you quite certain, through scientific testing you or someone else has conducted, that it is a more correct response via-a-vis any possible reverb effect in the mid and upper portion of the frequency band?

I'm quite certain that removing, say, a 5 dB hump at 100 Hz is better than not doing this.

[plissken]

52 minutes ago, jabbr said:

 

There are two sides to this coin:

 

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.

 

We know what to measure for because we know the problem the regen is stated to solve. 

[Jud]

5 minutes ago, mansr said:

I'm quite certain that removing, say, a 5 dB hump at 100 Hz is better than not doing this.

 

Better than not doing it if you factor in potentially adding euphonic reverb in the mid and upper frequencies?

 

You said the difference in bass was "clearly audible" to you.  Did you test this blind so as to remove any expectation bias, or even better, research the academic literature to confirm scientifically the favorable effects you thought were clearly audible?

[mansr]

1 minute ago, Jud said:

Better than not doing it if you factor in potentially adding euphonic reverb in the mid and upper frequencies?

 

You said the difference in bass was "clearly audible" to you.  Did you test this blind so as to remove any expectation bias, or even better, research the academic literature to confirm scientifically the favorable effects you thought were clearly audible?

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.

[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.

[Jud]

17 minutes 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.

 

I am not selling the ISO Regen.  I did, however, participate in a blind test of two candidate designs, where I very quickly selected the one most like the current production model because of what I felt were clearly audible differences.  The other blind test participant did the same.

 

Of course with regard to minimum phase and intermediate phase filters, there's no "secretly added" reverb.  Rather there is the potential for reverb if post-ringing has that audible effect, something various people have said is so, but that hasn't at least to my knowledge been established in the scientific literature one way or the other.

[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.

[mansr]

24 minutes ago, Jud said:

Of course with regard to minimum phase and intermediate phase filters, there's no "secretly added" reverb.  Rather there is the potential for reverb if post-ringing has that audible effect, something various people have said is so, but that hasn't at least to my knowledge been established in the scientific literature one way or the other.

Filter ringing occurs at inaudible frequencies. Reverb is something else entirely.

[R1200CL]

Since this thread is about a guy called Amir.     Why is he not part of the discussion ?

[Jud]

17 minutes ago, mansr said:

Filter ringing occurs at inaudible frequencies. Reverb is something else entirely.

 

I've read several people quite familiar with digital filtering (as I recognize you are yourself), including Miska, Peter, and whoever did the filter design work for Ayre and Charles Hansen, say that ringing, though ultrasonic, smears the audible signal over a greater period of elapsed time, creating an audible effect similar to reverb.

 

Another effect of intermediate and minimum phase filters is dispersion, spreading out the signal in time in accordance with frequency.  This occurs at audible frequencies.  The people responsible for the design of the ESS DAC chip have written that this can provide an increased sense of depth.  However, I haven't seen perception of this depth effect confirmed in the scientific literature either.

[jabbr]

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.

 

Here is a technical discussion from 1984, the HP 3561a: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1984-12.pdf , in which these exact issues are discussed. Notably:

 

frequency range: 125 microHz (that's right!) to 100 kHz

frequency resolution within this range: 640 microHz

 

So the equipment needed to do these sorts of measurements has been available well since the 1970s but this for 30 years. Additional specs and details are in the above link.

 

This simple and relatively specific measurement that I am proposing has not been widely discussed, or perhaps not yet discussed, so I will write this up as an article.

[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.

[Booster MPS]

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.

 

Fun fact:  You can sell any thing/product without having to prove anything about it.  If you disagree with the functionality of it, keep your dollars in your pocket and keep moving on.

[PeterSt]

2 hours ago, jabbr said:

how many DACs report their 0.1Hz phase error?

 

Zero.

 

How many DACs report their phase error at any other distance ?

Also zero.

 

And otherwise ... link ?

[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? 

[mansr]

28 minutes ago, Jud said:

I've read several people quite familiar with digital filtering (as I recognize you are yourself), including Miska, Peter, and whoever did the filter design work for Ayre and Charles Hansen, say that ringing, though ultrasonic, smears the audible signal over a greater period of elapsed time, creating an audible effect similar to reverb.

Those people all sell their own various magic potions intended to remedy this supposed problem. I won't go so far as to call them liars, but they have more than a little motive to exaggerate the severity of the issue. It is trivially true that band-limiting a signal involves some amount of "smearing" in time if the input has high-frequency content that gets removed. Low-pass filtering and smearing are synonymous, insofar smearing can be considered a technical term at all.

 

[PeterSt]

1 hour ago, pkane2001 said:

Right. That's why it's important to publish not just the measurements, but how these were done.

 

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.

 

 

[mansr]

3 minutes ago, PeterSt said:

No-one in the world sells USB cables with specs

Anything carrying the official USB logo is required to conform to the standard specification.

[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

 

[cpvniii]

Only on an audio site can one read about the Lord, Donald Trump and man made climate change while discussing the Regen and related components. Gentlemen, no matter your stance, this is a microcosm of our society. Sharply divided by anger, fear and ignorance. Carry on.

[jabbr]

17 minutes ago, PeterSt said:

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.

If your DAC had better isolation, the cable wouldn't make a difference