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Digital Signal Transmission


TomJ

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3 hours ago, TomJ said:

But the problem then seems to be more about making the diagnosis. But how, without measurements? Seems to be a gamble.

 

No, not really, because we also have empirical data. The problem with that obviously is that e.g. I can only bring that across by words.

A doctor takes the anamnesis (apart from 18 century rough blood pressure measurement) and from what he learned he will have an educated guess. No need to measure something like an appendix (Blinddarm) issue to already know it's most probably that. The patient doesn't measure either. He only responds relatively to his normal life which is without pain.

 

... or pain in the ears ... or pain in the ears of his wife ...

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XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

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7 hours ago, Superdad said:

And all that stuff adds up and becomes audible.

 

Not going to go down the rabbit hole with anyone about why this above eludes standard FFT measurements at the analog output. That's a separate debate for which I will not take the bait.  

 

I was really hoping that you could explain why the most commonly used method for detecting jitter in the analog domain stops working for ethernet- or USB-connected DACs. What makes the simple, well-known, and well-documented FFT method fail in this case?

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1 hour ago, PeterSt said:

 

Tom, let's try to digest this (it has been said a couple of times by others, but please note it is crucial):

 

1. All switches or USB interfaces or USB cables or Ethernet cables, transfer the data 100% the same without any bit error. This counts for everything you read about changes in Sound Quality. And, if people stipulate that this is because of lost bits or changed bits etc., than they don't know what they are talking about (trust me on this).

 

2. Jitter is not about changed bits or lost bits. Thus, by no means jitters is caused by that. For now I won't go into details what jitter exactly is, except for that it is about a mechanism that reads upgoing voltages and/or downgoing voltages and that the moment in time that a voltage is seen as up- or downgoing, is not constant (see more below for further elaboration).

 

3. Despite the voltages are properly read (a 1 is read as a 1 when it should and a 0 ditto), the moment in time this is determined may change from audio word to audio word. Audio word : the level of the audio signal, which comprise the stream of such words. This is harder to explain for now (and for me to you), but let's say this is not important. The below is:

 

image.thumb.png.7dfff22843bb0715a4593f51590488f9.png

 

Let's envision that this is a clock signal. It exists in your DAC and it is used to "clock out" those audio words. A short cut of the story would be that at each upgoing / rising of the slope of this wave form, a new part of the analogue output signal is added. This is about this stream of audio words.

Let's say that the chips involved detect that the wave / voltage is definitely rising where you see the mouse pointer. But, first draw an imaginary horizontal line through this picture, and do this through the mouse arrow head;

You see three rising edges of the wave form, and you can now see that all three rising edges will not be detected at the same time, if you only draw that line and also draw a time scale under it. This is because the signal you see is noisy. The wave form "sculpture" is not as thick or thin at all places. ... Say that the left most edge is seen as rising "on average", the second one as too early (with the first one as the reference), and the 3rd one will be late (because it's line is thinner where the horizontal line crosses).

 

That is jitter and you could say "ohh, but I knew that !".

OK.

 

Now what you should take from this post is that this noise can be created by a countless number of sources. It can be that ugly switch, that misbehaving PC, that poorly shielded USB cable, that poorly terminated Ethernet cable and still countless more. Easier to see would be the power supply doing it, might that be a power supply somewhere that throws sh*t back into the mains, or might that be the PSU in the DAC being poor because it does not sufficiently reject that noise from elsewhere.

 

Jitter is the phenomenon which is audible, and the noise in that clock signal is the last instance which creates jitter.

If this last instance can be made 100% immune (and not 99% "because you won't hear that anyway"), THEN all else around it won't matter and it can be as noisy as it likes.

 

No isolation helps with this because of ...

 

"interference".

So Tom, that was your used word/phenomenon of which I asked you later whether you would know what you actually meant by it. I think I do (and it could be derived from your own (OP) text), because ...

it goes through air.

 

And now all stops. All we can now do is take care of those countless sources of noise. It includes you led light. It is everything.

The alternative would be to shield the clock (and even beyond toward the D/A conversion elements) such that it can not be interfered by such through-air "radiation" from elsewhere.

Galvanic isolation is only part of the solution (it may block noise in the copper lines and mind you, it may also block noise in the glass lines (the signal I showed you will just exist in glass the same, once it is only that noisy signal).

On a side note, think how re-creating a noisy signal, may create a cleaner signal (this is e.g. the "REGEN" devices of Uptone (Superdad)).

 

Since there are countless sources indeed and per source already countless solutions or counter attacks for it exist, DACs sound all quite different. And still each DAC *will* receive its bit perfect data. The USB solutions and even Ethernet solutions, all may sound different again. Not only because they may present a cleaner (regenerated) signal, but because they will just have a different radiation pattern. Ehm, for better or for worse, because definitely no manufacturer is taking that into account; this is totally out of our control, which is already caused by how devices are inter-linked.

 

So you see, it is not about a digital signal being bit perfect or not (because all is bit perfect in the first place).

 

Peter

 

Maybe you, Peter, can answer why Tom should worry about jitter over ethernet when his DAC shows absolutely no jitter-related widening or sidebands in the analog domain. What possible effect does this invisible jitter have on his audio output?

 

Why frighten audiophiles by telling them scary tales? Jitter really isn't that scary or sinister (or particularly audible except in large doses). It's just another source of distortion. It's not hard to detect and to measure. And apparently, not hard to stop if you check the few jitter measurements I posted earlier for a couple of $200 DACs. It's all great to keep postulating random radiation patterns, and ground noise, and fuzzy eye patterns causing processing "bounce". And yet here are a few recent DAC examples (add Tom's DAC to this list) that appear to be immune to any such noise on the input lines under normal operating conditions. 

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1 hour ago, TomJ said:

So something positive has to happen with the intona.

 

Tom, I don't know if it is still the case, but with the first versions of the Intona, Daniel showed the decrease of my mentioned 8KHz "distortion". Assumed that your RME won't get rid of that herself, it needs galvanic isolation to depress it to some degree. I know from that other means of galvanic isolation subject to a DAC that isolate i2s from the outside also helps the 8KHz distortion.

Mind you, this is only one element from quite some more. But at least Intona advertised with it (justified).

 

Edit

I'd like to add that the level of the 8KHz distortion is quite 100% related to grounding. Thus, do something slightly "wrong" with that (whatever wrong is, but for example the difference between earthed and not-earthed mains power) and the level is higher or lower.

USB is evil because its ground related to mains ground (this happens in the PC). This is why isolating USB does not even 100% help. Better ground schemes in the DAC helps best.

 

Lush^3-e      Lush^2      Blaxius^2.5      Ethernet^3     HDMI^2     XLR^2

XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

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So the goal is to prevent noise coming into the dac -right?

This should be the task of the isolator. But I have understood, that noise can "jump" from one side to the other in the intona -right? And maybe the USB cable #9.1 catch some noise from the environment.

But if the isolator would eliminate the noise, than I don't have to care about audiophile server or audiophile switches - right?

How about changing the isolator and cable (9.1 + 8.1) with an fiber usb extender like this: https://www.amazon.com/LINDY-42683-Optisch-Elektronik-Schwarz/dp/B00WJ8DNUK/ref=asc_df_B00WJ8DNUK but only shorter.

Then I only have to care about a clean power supply for the extender - right?

 

 

 

 

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52 minutes ago, TomJ said:

Then I only have to care about a clean power supply for the extender - right?

 

If all were that simple ...

First off, all which is glass (fiber) always sounds worse. This will be related (unproven) by the processing which is required to (in-DAC) convert back to copper. Throughout time a few in the group at Phasure (including myself) tried this (IIRC this was always about Adnaco).

 

56 minutes ago, TomJ said:

But I have understood, that noise can "jump" from one side to the other in the intona -right?

 

Although I myself could expect that such a thing would happen indeed, I could never prove that by means of measuring radiation (it is just not notably there). It is stuff at the complete other end that will radiate. Example : put in a USB cable in the PC and leave it open at the other end. *That* creates a transmitting antenna throughout the USB cable. And that is caught by anything willing to be a receiving antenna, like components in the DAC.

 

Your better option is to cascade two Intonas. At least this sounds notably better to me. I did that with my own isolator in-DAC, but this is hard to have consistently working. This is how that never because a commercial product and how I had to remove it too (for me it is useless to have better gear than the (potential) customers).

 

From my own isolator it is known that it blocks noise for IIRC 60% only ( @Superdad may still know the figure better than me).

So Yes, indeed it should be so that some of the noise "jumps" (this is hard for me to envision, but alas).

 

Tom, let's keep in mind that once you are as far that you tend to work on phenomena like blocking noise, the better approach really would be the ISO-Regen. That isolates and re-generates a clean signal at the same time. Regarding this, try to grasp that the bits can be captured 100% without error by such a device, and including isolation from the dirty (PC) side, close to the DAC the signal can be regenerated as clean as possible, preferably with a clean PSU indeed.

But ... welcome to the world of USB tweaks after all ?

Lush^3-e      Lush^2      Blaxius^2.5      Ethernet^3     HDMI^2     XLR^2

XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

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6 hours ago, PeterSt said:

 

Paul, maybe it is your time to constructively respond to this, might that be hidden in your genes somewhere.

Also, *I* personally have the OP in mind (you seem to have forgotten it):

 

 

Obviously we'd expect a negative response from you, would I propose that my software exists for a most explicit reason (explained by me to some degree in one of the first posts).

... there is nobody in this nice world that does not hear the differences between always bit perfect software settings.

... there is nobody in this nice world that returns one of our cables, while everybody is entitled to (instead people blindly buy new versions).

 

Even you did not return your Lush^2. Oh, okay, now I am too funny. But maybe you should.

 

With this latter in mind, I like to remind you - or just make clear to you, that nobody (maybe but me) is showing FFT's etc. etc. of HIS or HER situation. It's all manufacturer sh*t (if at all) or maybe these days AmirM biased nonsense (yes, sorry, that's what it is). So if Tom shows an FFT of his RME ADI-2 (which is a perfectly fine DAC for measurements for at least the D/A chips used) in his system, then nothing - just totally nothing tells me that in his situation with all possibly (!) improper grounding, the FFT would show as nice. So for this reason alone in his situation an other cable could make a difference, while in your situation (or Amir's) it does not make a difference at all.

 

May I, please, emphasize the fact that Tom clearly has a huge advantage of the Intona, which THUS makes the RME ... what ?

You tell.

And then to think (trust me) that I personally hear the processing of the Intona and that I for that reason can't bear it (in the end, after creating something better myself).

 

There is no better empirical test than thousands and thousands (yes, that is what it is) of people all being so happy that they a. keep on using and b. keep on upgrading, no questions asked.

Only those who never try, or those with such a closed mind that it is just impossible for them to hear-though, most probably won't even try. You are an - again-half - kind of exception.

 

So now *I* am scaring people eh ?

No Paul, I am practicing audio as a hobby and improve the quality of that, day by day. And I am not in it for the $. Not at all.


Peter, didn’t know you wanted Lush^2 back. Let me know where to send it. It’s been in a pile of other USB cables I’ve tested and didn’t find any improvements. 
 

As far as your empirical test — sorry, it doesn’t rise anywhere close to an objective result. Uncontrolled, sighted testing isn’t objective by any definition of the term, unless you’re specifically studying bias.

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58 minutes ago, PeterSt said:

 

If all were that simple ...

First off, all which is glass (fiber) always sounds worse. This will be related (unproven) by the processing which is required to (in-DAC) convert back to copper. Throughout time a few in the group at Phasure (including myself) tried this (IIRC this was always about Adnaco).

OK - So Toshlink always sound worser than USB.

Is this also the case for Ethernet to fiber and back in your opinion?

 

Quote

Tom, let's keep in mind that once you are as far that you tend to work on phenomena like blocking noise, the better approach really would be the ISO-Regen. That isolates and re-generates a clean signal at the same time. Regarding this, try to grasp that the bits can be captured 100% without error by such a device, and including isolation from the dirty (PC) side, close to the DAC the signal can be regenerated as clean as possible, preferably with a clean PSU indeed.

But ... welcome to the world of USB tweaks after all ?

 

So with ISO-Regen there is no need for audiophile switches and servers?

 

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27 minutes ago, TomJ said:

Is this also the case for Ethernet to fiber and back in your opinion?

 

I can't tell this because I don't use Ethernet interfaces, nor did I design with them. What's to be done at converting back to copper seems similar as USB to me, while the "decoding" of Ethernet is something I don't know the (current usage) impact of.

Ethernet is a different beast for noise signature because a. we use it all over, b. we also use it connected to the Internet, and c. to audio seemingly unrelated connections already change for SQ when the Ethernet cable is changed (say for a boutique one, but I have only experience with our own).

The debate around Ethernet switches is something I like to stay far from because although it is clear to me that the SQ changes with different switches, it is not clear to me whether that will be for the better or for the worse (I don't see the logic really).

 

34 minutes ago, TomJ said:

So with ISO-Regen there is no need for audiophile switches and servers?

 

If that would be the last element in the chain, then very far, theoretically, it would be correct. But it is not at all because my software still happily change the sound as always, without and with ISO-Regen. And thus the answer is (sadly) No - that need remains (but mind my (non-)opinion on switches).

If your mentioned "server" is the audio playing PC, then that is the most crucial of it all, these days. However, please notice that this is in the context of not-streaming from the Internet and only local playback (you mentioned this as making no difference for you).

 

If you first regard all the noise-"impact" as a number and state that a million, then something like a server contributing say 100.000 may be or will be inaudible for a difference. But if that 1 million is decreased to 200.000 first and the server remains (which is a logical process in the audio world) than the 100.000 the server contributes obviously implies half and the impact is no less than huge.

All what's left, next is going to have a larger impact again when diminished.

 

Maybe good to know:

If my proposed 1M of noise comprises of say 100 sources than noise is as noise is intended - it is random and for that matter quite harmless (you'd miss out on detail in the music, but in itself it is "bland"). Let's observe that 8KHz USB distortion again;

In the pictures you showed it will mostly be buried in that other (say 1M) noise. This is not so any more once most of the noise is tamed and put down to -160dBFS (see my discussion with Paul and my overlooked graph). Thus, where an FFT would be able to dig out distinct tones (like the 8KHz) it can't when all frequencies exhibit above the level of that 8KHz distortion.

But what if all other noise would have been taken out and the 8KHz remains ? It can easily be there at -140dBFS. Then it would be a relative severe distortion, although always people will exist who say that this has to be inaudible.

 

Moral: you may perceive no difference between local playback and streaming because that 1M noise is still present. That you miss out on the best sound is something else.

... As I said, hop in the car and come over because let's remember, I really can measure most of this easily and I won't rest until all is clean. And you have no idea how much audible this all together is (with say 100.000 left only).

On the other note, don't think I can measure the differences in USB cables, because apart from eye diagrams which tell nothing, I can't qualitative measure this. The change of a shield configuration will let you drop your jaw on the floor, and *still* I can not measure this. This all relates to the inherent low jitter such systems are these days (this is in the fs realm) and how this still determines the sound largely.

 

I hope this makes sense.

Lush^3-e      Lush^2      Blaxius^2.5      Ethernet^3     HDMI^2     XLR^2

XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

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14 hours ago, PeterSt said:

Not only because they may present a cleaner (regenerated) signal, but because they will just have a different radiation pattern. Ehm, for better or for worse, because definitely no manufacturer is taking that into account; this is totally out of our control, which is already caused by how devices are inter-linked.

 

Rob Watts talks about RF all the time for years now on Head-Fi forum. He describes it like a "fungus" that gets to all parts of a DAC. Increases IM distortion 

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58 minutes ago, PeterSt said:

In the pictures you showed it will mostly be buried in that other (say 1M) noise. This is not so any more once most of the noise is tamed and put down to -160dBFS (see my discussion with Paul and my overlooked graph). Thus, where an FFT would be able to dig out distinct tones (like the 8KHz) it can't when all frequencies exhibit above the level of that 8KHz distortion.

 

Not correct, Peter. FFT can dig well below the noise floor to expose 8KHz or other signals hiding below. The more FFT bins, the lower the noise per bin, while any other signal, such the 8KHz tone or some jitter side-bands, for example, remain relatively untouched. To dig well below the noise floor, all I need to do is apply a larger FFT setting on my analyzer.

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1 hour ago, asdf1000 said:

 

Rob Watts talks about RF all the time for years now on Head-Fi forum. He describes it like a "fungus" that gets to all parts of a DAC. Increases IM distortion 

 

Rob Watts also talks about the effect of noise-shapers being audible at -350dB. Sorry, if you believe that, I have a bridge I'd like to sell you.

 

 

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Just now, One and a half said:

Oh! You’ve never held a scope to a signal and the problem went away or was worse? This is lead loading, never experienced this ever.... ? then I take it your expertise is software and theorist electrical,  that’s ok.
 if you have a closet full of USB cables and can’t hear a difference with any of them, then your perception is different to the most of us here.

 

So nothing objective to share to substantiate your claim then, other than to call into question my hearing abilities and to attack my expertise (of which you know nothing)? You misunderstand the nature of objective evidence. It's not, and cannot be, based on any individual abilities or uncontrolled perceptions.

 

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45 minutes ago, pkane2001 said:

Not correct, Peter. FFT can dig well below the noise floor

 

So you didn't read accurately what I wrote.

Or I didn't write accurately what I intended, in your language.

Read again how I described noise. Or don't. I actually don't care.

Lush^3-e      Lush^2      Blaxius^2.5      Ethernet^3     HDMI^2     XLR^2

XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

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2 hours ago, PeterSt said:

If that would be the last element in the chain, then very far, theoretically, it would be correct. But it is not at all because my software still happily change the sound as always, without and with ISO-Regen. And thus the answer is (sadly) No - that need remains (but mind my (non-)opinion on switches).

If your mentioned "server" is the audio playing PC, then that is the most crucial of it all, these days. However, please notice that this is in the context of not-streaming from the Internet and only local playback (you mentioned this as making no difference for you).

 

As you can see in my topology the Logitech Squeezebox streamer is the audio playing device - its not a pc. No harddisk / ssd, wlan or other stuff like in pc. The streamer always gets his stream from the LMS Server over Ethernet with LAN isolator - from local files stored on the server or from a streaming provider.

The server transcode the stream (local files or streaming provider) into pcm before streaming to the clients (Logitech Squeezebox or KEF LS50). So if i say local playback it means streamed from my own server, not from the streaming provider like Tidal/Qobuz.

 

I am a bit confused (maybe this is strategy?).

If a device like ISO-Regen regenerate a clean USB signal for the DAC, why should one invest in other stuff like audiophile streaming client, ethernet cable, switches, servers with "low noise"? So a ISO-Regen destroy the business of all these companies? Ah, no - everything matters! But why, if the dac gets the cleanest signals he can get?

 

 

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23 minutes ago, One and a half said:

Conversation is now a parallel. No further dialog necessary, bye.

 

Not very satisfying. If you come to an objective thread to have a discussion, it would be better to present your point of view without personal attacks and mischaracterizations. If I ask for objective evidence, it's because this is the only space on AS where this is even allowed, but also because I'm very interested to see such evidence presented. Attacking me serves no useful purpose, proves nothing, and wins no arguments.

image.png.07863301da9c507c6f27515a0e65340b.png

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