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

[jabbr]

33 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.

This isn't an easy question to answer because of the peculiarities of USB audio transmission. Corning makes a fiberoptic USB extender but the 5v signal needs to travel alongside. Why @PeterSt's three levels of isolation don't "work" ... entirely ... is a bit perplexing and the answer may get complicated, and I think might involve re-engineering the USB interface itself (the boards at the DAC end). At this point we could readily test out USB vs fiberoptic Ethernet (on the same interface) and this would help determine how much is "galvanic" isolation vs "other factors". For me, being able to measure changes in such factors at the level of the DAC clock, as well as analogue output, is essential to ending what will undoubtedly be a permathread until then. In the meantime, for example fiberoptic Ethernet, is "full galvanic" and we will undoubtedly see proliferation in this area -- at least if Merging/Ravenna et al have their way

 

But in terms of isolating I2S or DSD lines, for example, the GMR isolators have a greater bandwidth than optical in terms of what are commonly available.

[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.

[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 

[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?

[Daudio]

2 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?

 

Dance, monkey, dance... 

 

[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 ..................... 

[Speed Racer]

I did a Google search and could not find a USB 2.0 optical isolator that supported High Speed (480Mbs) mode.

 

The fact that pkane2001 does not understand that USB 2.0 audio uses High Speed mode and the optical isolator he refers to does not makes me wonder why he is even posting.....

[jabbr]

http://www.adnaco.com/products/s3a/

 

[Speed Racer]

4 minutes ago, jabbr said:

http://www.adnaco.com/products/s3a/

 

 

That requires a Adnaco-H1A PCIe card in a PC. It is not a simple inline USB optical isolator.

[jabbr]

9 minutes ago, Speed Racer said:

It is not a simple inline USB optical isolator.

Nothing here is simple  

[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.

[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....

[Speed Racer]

9 minutes ago, pkane2001 said:

There are optical isolators that can handle rates much greater than 480Mbs,...

 

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

[esldude]

10 hours ago, jabbr said:

 

 

Ok so there are two different measurements that we've been discussing and I need to clarify what is what:

 

1) Measure "jitter" or more properly phase error in the DAC clock: This is done with phase error measurement equipment. There are several ways to measure phase error using both analog and digital techniques, so-called "vector network analyzers", the venerable HP 3048A and newer equipment such as the John Miles TimePod as well as offerings from Keysight nee Agilent nee HP.

 

Phase error is provided as a plot : http://www.crystek.com/crystal/spec-sheets/clock/CCHD-575.pdf -- in this case the Agilent E5052A was used to take the measurements. See how the phase error rises as the offset frequency goes down? Thats called "close in" phase noise. Yes this phase error goes down to an offset frequency of zero. But phase error is always measured with respect to the clock frequency e.g. 11 Mhz, 22 Mhz. "Jitter" is 11 Mhz +/- offset where offset varies from 0 to ...

 

2) Measure the effects of jitter at the analogue output of the DAC: I've been discussing "line width" and widening of the peak in a number of recent posts. If you take a pure tone -- and for the sake of our discussion here, a 1KHz sine wave tone generated at 24 bits 352 kHz, or DSD256 or DSD512 (for the sake of our discussion) and take this digital stream and send it to the DAC, in an ideal situation the DAC will emit a pure 1kHz sine wave.

 

Phase noise, specifically close-in phase noise will cause a distortion in the output of the pure sine wave. What does this look like? It causes the "peak" in the spectrum to widen. That's called "linewidth". It goes up with increasing phase error. If we take the DAC output and run it through a spectrum analyzer such as the Audio Precision that "Amir" uses (quotes because i've never met him and he's not here  then what would be a thin line at the 1kHz frequency will spread out. This is caused by applying the phase error curve as above, to the pure tone.

 

Hopefully this makes more sense, and (2) is proposed as a way for folks who have a spectrum analyzer to measure the effects of clock jitter on the analogue output

 

3) I'm not being coy here: if the linewidth of a pure tone does not measurably widen with a high quality measurement e.g. not single Hz increments but let's say 0.1 Hz or better increments, then jitter at the DAC clock is not having an appreciable effect on the analogue output. I don't know that 0.1 Hz increments are the specific resolution needed but you know, basically if the 0.1 Hz phase error is not significant your clock is doing a great job

 

I think this is very misguided without some reason to believe such close in differences are problem. 

 

Lots of ways to think about this.  A one degree C difference in temperature changes the speed of sound enough that it alters the relationship between direct and reflected sound to a level many times greater than a small perturbation of clock jitter at .1 hz.  Or even 1 hz.  This is just barking up the wrong tree. 

 

You don't know what you are trying to achieve.  Is it 100 dbc/hz at 10 hz offset, is it 100 dbc/tenth hz at a .1 hz offset?  And why other than better must be better?

[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

[Speed Racer]

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.

[esldude]

9 hours ago, jabbr said:

 

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).

 

 

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.

 

 

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)

Here is the type plot you are discussing of a couple pedestrian pieces of gear.  64k FFT of a 12 khz tone with 48 khz sampling.  Firstly because the FFT is not 1 hz you adjust by reducing the number by 1.3 db for 1 hz equivalence.  This is also a voltage measurement so for power relative to the carrier you divide these numbers in half.  The dotted line at 10.3 hz offset would give just short of 45 dbc/hz.   The inserted result at 1.5 hz is just short of 40 dbc/hz.  Now the measuring ADC is not an AP unit.  Specs are it has about half the jitter of the DAC.  Suggestions are your measuring device be 10 db better which this one isn't.  So some of that is the ADC. 

 

Does the Regen make a significant audible difference that somehow results in the same measurement on such a device or slightly worse?  So the improvements are all at something less than 1.5 hz and very audible?  Seems like a real reach to me.

 

[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. 

[jabbr]

23 minutes ago, esldude said:

I think this is very misguided without some reason to believe such close in differences are problem. 

 

Lots of ways to think about this.  A one degree C difference in temperature changes the speed of sound enough that it alters the relationship between direct and reflected sound to a level many times greater than a small perturbation of clock jitter at .1 hz.  Or even 1 hz.  This is just barking up the wrong tree. 

 

You don't know what you are trying to achieve.  Is it 100 dbc/hz at 10 hz offset, is it 100 dbc/tenth hz at a .1 hz offset?  And why other than better must be better?

 

It is really very simple: you need to measure a quantity before determine the extent that it is audible. What I am saying follows directly from the mathematical curve which is measured. Feel free to load the curve (e.g. the Crystek) into a simulator and show yourself what happens.

 

But that is beside the point which I am making -- the point here does not have to do primarily with audibility. It is primarily to determine whether the device has a measurable effect. If it has an effect which is measurable then we can discuss whether the effect is audible.

 

Since you feel this is misguided, do you have a specific proposition in which you would otherwise make measurements to determine whether a specific device has an effect on the "jitter" on the DAC's clock ... oh and don't try to use a sound card with an ADC because you will need to first ensure that the clock of the ADC is better than the clock of the DAC -- those are basics.

[jabbr]

20 minutes ago, esldude said:

Here is the type plot you are discussing of a couple pedestrian pieces of gear.  64k FFT of a 12 khz tone with 48 khz sampling.  Firstly because the FFT is not 1 hz you adjust by reducing the number by 1.3 db for 1 hz equivalence.  This is also a voltage measurement so for power relative to the carrier you divide these numbers in half.  The dotted line at 10.3 hz offset would give just short of 45 dbc/hz.   The inserted result at 1.5 hz is just short of 40 dbc/hz.  Now the measuring ADC is not an AP unit.  Specs are it has about half the jitter of the DAC.  Suggestions are your measuring device be 10 db better which this one isn't.  So some of that is the ADC. 

 

Does the Regen make a significant audible difference that somehow results in the same measurement on such a device or slightly worse?  So the improvements are all at something less than 1.5 hz and very audible?  Seems like a real reach to me.

 

 

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.

 

[plissken]

6 hours ago, Jud said:

 

Crossover slopes weren't being tested.  Circuit components were. Would you like to know which of two pieces of equipment performing the same function but  built with different parts sounded better (or if there was no difference)?

 

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. 

 

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. 

 

Also did you ever consider that you have $655 worth of gadgets driving a $349 DAC and that taking that $1000 you could have absolutely dumped the entire, problematic USB system, for a TEAC NT 503, Cambridge Audio, or the like and went Ethernet were even the designer of the Uptone product line very much doubts that with an in spec cable Ethernet audio devices could be affected? 

[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

 

[mansr]

5 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. 

I was fooling around with an old Cambridge Audio AVR recently. As it turned out, feeding it an unexpected, but in-spec, S/PDIF signal made it emit smoke.

[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

[esldude]

24 minutes ago, jabbr said:

 

Are you kidding? First, what is your x-axis and what is your y-axis? 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. The test I proposed, assuming you are doing the second test would have a single peak at 12 kHz with a measurable width. I've suggested that you do 0.1 Hz increments but good spectrum analyzers from the 1980s do 640 microHz increments ... 

 

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

This is what I described.  And no the Crystek graph has no single peak it actually starts at 10 hz from the carrier.  I lined my graph up so the edge is lined up with the peak.  So you are seeing the upper sideband.  I am not measuring a 100 mhz clock.  I am measuring the 12 khz tone of a DAC.  No I don't have 1 microhertz resolution.  If I did, the 1 hz wide level would measure somewhere close to the same. 

 

The x-axis is clearly there.  0 to -180 db voltage.  The y axis is in hertz.  In this case spanning 12 khz to 12.5 khz.

 

Now part of the reason I posted this is to show you are comparing apples and oranges in one sense.  Yet if you wished to do comparisons this way it would be valid as far as it goes.  Same idea different frequencies.  Lower jitter will net better results on such a graph.  Not all types of jitter mind you which is another problem with the assumption close in jitter is of large importance.