Digital Signal Transmission

[pkane2001]

2 hours ago, sandyk said:

Then why don't you list some of the  "myths"  in order of importance that you believe are false. 

 

Here's one you might like: something to do with audible differences between two bit-identical files, one transferred by a USB stick, the other by a noisy internet download.

 

5 hours ago, TomJ said:

As I see that my questions also opens in this forum cans of worms with never ending discussions please ignore this.

 

Despite the name, this is not the forum to have such discussions. What USB isolator and DAC are you using?

[pkane2001]

4 hours ago, PeterSt said:

@TomJ, Although you wouldn't say it, @pkane2001 is your friend in this thread. He may also be the only one. Haha. But at least he measures (I do too), finds (marginal) differences, and next ignores that because he can't explain it.

Did I say this about right, Paul ?

 

Not quite, Peter. I can explain the differences, when they are present, easily. I ignore them because they are both, way below any known audibility of such effects, and because no matter how much I've tried, I can't hear the difference they cause (like your Lush cable). But, that's just me. That's why I wrote the software that I did. I did these for myself, mostly, but now others can do these tests for themselves.

[pkane2001]

2 hours ago, sandyk said:

Even the use of pop rivets in the construction of a PC's metal case can cause some audible degradation,  including reduced stereo separation and a degraded sound stage, as well as a grainy background or what appears to be a veil over the sound. 

 

Of course! Got anything objective to back up this bold and exciting claim? I'm ready to weld if you do 🤪

[pkane2001]

1 minute ago, sandyk said:

This came as a result from Gary's suggestion.

 https://audiophilestyle.com/forums/topic/60381-hdd-to-case-bonding-uptick-in-sq/?tab=comments#comment-1102477

 

 Of course, if you don't believe that markedly reducing the measured A.C voltage drop between the 0 volts of the case of an internal SSD and 0 volts (Earth) of the internal PSU matters . . . . . .

 

So you’re talking about improving a ground connection, and not just about rivets sounding better? Ok, I’ll put my welder away, then ;)

[pkane2001]

1 minute ago, fas42 said:

 

My feeling is that the panels of the case, if metal, are not well electrically connected - if relying on pop rivets to do this, it most likely will fail; from paint, etc. If self tapping screws, which properly bit into the metal, were used, I suspect the variance would go away.

That I can believe. I’ve seen a number of cases with poor ground connection with screws on top of a painted or an anodized surface that are likely not to make good contact.

[pkane2001]

3 minutes ago, sandyk said:

 Not that your DeltaWave S/W will be likely to show the obvious audible improvement though, because your beloved checksums remained the same after the same CDs were re-ripped  !😊

Sorry, Alex, checksums are your hobby. Never bothered with them.

[pkane2001]

38 minutes ago, PeterSt said:

 

Paul, you are so funny. But I am sure that you think that the "quality" of a PC does not matter. Am I right ?

I mean, if this is clear(ed) then we can understand your fun better.

 

PS: I am half-serious. But you'll know what I mean. So your answer is of some importance (which is also half-serious, but 0.5 + 0,5 makes 1).

The quality of the case rivets doesn’t matter if it’s properly grounded, Peter.

[pkane2001]

10 hours ago, PeterSt said:

 

Tom, USB *is* evil. Trust me. It can be turned into an interface with lower jitter than SPDIF, but this is so difficult that it took 6 or 7 years after asynchronous USB was "invented" for audio to get there by one or two DAC manufacturers.

 

And a hint for you (it could silence you somewhat 🤫): USB implies a relatively very high 8KHz signal, which is right in the audio band. It is pure distortion. Here too, it is the most hard to tame, but it can be done to at least something which should be inaudible, but which will still always be measurable.

In itself this signal implies (data-) jitter, because it is an oscillation beating with the DAC's audio clock.

 

Peter,  I think you're making very general statements that are a bit out of date and not supported by facts. The 8KHz signal caused by Isochronous protocol's microframes has been mostly defeated or down to a very low level, usually below -120dBFS. Even in many inexpensive DACs over the past few years. Any "beating" or interaction with the DAC clock would be at a level below that. Here's an example. Do you see anything of concern here at 8KHz or anywhere else? This is a tiny portable DAC powered by USB, under $200:

 

 

Another $200 DAC, see any 8KHz here?

 

On the other hand, here's a Schiit Modi 3+ with a custom USB input (Unison) - a $99 DAC. A tiny blip of 8KHz signal visible, at about -140dBFS:

 

Now compare this to the same Schiit Modi 3+ DAC over SPDIF, tell me which one is better:

[pkane2001]

6 hours ago, TomJ said:

Hi Peter,

I always find it funny how you are immediately dismissed as ignorant in these audiophile forums when you ask questions that do not fit into the worldview.
I am not an electrical engineer and I will not become one.
I have spoken of it myself that I am amazed at the amount of effort that is sometimes put into it and I do not understand it because it does not reveal itself to me with my knowledge.
I keep getting answers that bad jitter is to blame and that jitter is also the cause of the deterioration of the sound over the network - which is absolute nonsense, since all systems use TCP / IP.
For your information: I have a streamer that is operated with an LPS (I am aware that the USB power is otherwise useless). The streamer streams via USB to an Intona isolator, which is passive and has no other power supply, such as the Uptone Regen and therefore does not worsen the power situation.
Between the isolator and the RME ADI 2 DAC is a NEO Oyaide d + Class S cable, on which the + 5V contacts are masked on both sides.

Which DACs are you talking about that have overcome the USB problem? 

 

RME ADI 2 DAC is pretty much immune to the usual noise from USB line, so ignore any potential issues with PC case rivets or 8KHz noise :)

 

[pkane2001]

16 minutes ago, TomJ said:

Maybe USB is not so popular because you can't fumble around here enough and you can't make such a big secret about the great sound optimizations.

 

 Where there's a will, there's always a way 😄   

 

[pkane2001]

12 minutes ago, PeterSt said:

 

Maybe it is too difficult to understand my poor English. I never said that today this is still a problem. I only said it has been hard to overcome. And sure, once one gets it done, all can do it, as long as the data is shared.

 

Your measurements show nothing as the noise level is too high (hence the FFT not deep enough etc.). Next up is your (obviously) expected "but you can't hear that". I think I was ahead of you with that one.

 

Tell me again where I was wrong of off somewhat.

N.b.: You could ask me to show the 8KHz at just over -160dB - but it is useless because that too would be from I think 2015, and techniques  undoubtedly improved again.

 

 

Ah, OK. So it won't imply jitter.

No wait, that jitter would be at inaudible levels.

 

Wait... -160dBFS isn't deep enough for you? What is?

[pkane2001]

26 minutes ago, Superdad said:

Show me where @PeterSt was arguing in favor of S/PDIF over USB.  Peter has been designing serious DACs for at least a couple of decades—and has been pushing the envelope on USB input for his DAC. And he has some very sensitive measurement gear.

In fact, his DAC is one of only two on the market (the other being the Auralic Vega G2) with USB galvanic isolation at the input—BEFORE the USB PHY/MAC processor.

 

I think it is funny how some folks buy into the notion that the ex-Microsoft guy who bought an AP analyzer and floods the net with graphs somehow is somehow smarter than all the high-end engineers and chip guys who have been deep in this for decades. I could compile a list of renowned engineers (including Mike Moffat, Damian Martin, Ted Smith, John Curl, Michael Pflaumer, and Keith Johnson) who Amir has basically dubbed “hacks.”

 

I don't think Amir is smarter than anyone. But, his measurements are there for everyone to examine, interpret, and try to disprove or confirm, unlike some of the manufacturers that promise these for years after making claims and releasing a product ;) That's what objective evidence is, Alex.

 

[pkane2001]

5 minutes ago, PeterSt said:

Always in good spirit Paul. So now I said that -160dB isn't good enough ?

Where ?

 

Here you go:

Quote

Your measurements show nothing as the noise level is too high (hence the FFT not deep enough etc.). 

 

Since the measurements I posted go down to -160dBFS, and you say the noise level is too high, I assume you are looking for something lower? By the way, that's just the FFT noise floor, I can go deeper with larger FFT, but why would I want to?

[pkane2001]

5 minutes ago, sandyk said:

 Bovine excreta  !

Just as your usual assumption that it is below the audibility threshold is  if it's over -120dB

 Your typical stance appears to be  " IF I can't measure it, then you can't hear it" 

 Yet you were unable to measure the things that Frank confirmed hearing, as another poster  from the Objective side also did, then attempted to distance himself from it. In that case it was with a couple of comparisons that sounded different despite identical Binary content, where I then removed a few mS from the beginning of one track so that they no longer had identical SHA256 checksums, yet still sounded different to both posters.

 You should find those posts somewhere in the Objective area unless the OP later edited them out to to suit his desired conclusions .

Alex, civilized behavior would be much appreciated.
 

And what’s your obsession with checksums? As far as I can tell they have nothing to do with this conversation, and yet you keep bringing them in.

[pkane2001]

4 minutes ago, sandyk said:

 Then stop bringing my name back into it, and ridiculing my reports about improving the earthing of many typical PCs as discussed by one and a half in his thread.

 

Hate to tell you, but you weren’t the Alex I was addressing.

[pkane2001]

Just now, One and a half said:

Since you are not electrically minded, think of the noise that is on top of the USB signal as a virus. Currently the tools we have to measure that virus is a 18th century telescope. We know it’s there, can hear the effects, make a good guess of what it is, but cannot measure.

Thats why there is very little data since it is difficult to measure in the first place. When I mean difficult the instruments are well beyond most professionals starting at EUR150k +++ and that won’t get anywhere close.

What’s so difficult about measuring noise in an analog signal? It’s really not rocket science. I’ve not heard of such expensive equipment being required for the task. What exactly does this super-instrument measure?

[pkane2001]

3 minutes ago, sandyk said:

 Your reply is every bit addressed to all participants in this thread, and once again is being used to ram down our throats content from ASR that most members are not interested in, or if they are, can choose to view their content directly.

 

Did you first seek permission from ASR Admin to repost their content in this forum ? 

What’s your problem, Alex? You don’t agree with what I say, I know that. But being rude and trying to insult me is just childish behavior.

[pkane2001]

9 minutes ago, One and a half said:

Ok, any high impedance probe on a scope has far too low an impedance to measure this conducted noise. It is necessary to have several gigs of impedance, so the scope will have no influence. 18th century telescope is what we have now.

It easier to measure noise at frequencies above 30 MHz, since the receiver is decoupled from the source. Soon as there are conducted emissions through a wire, the story radically changes.

Then it should be trivial to show  an example that demonstrates the need for such high impedance probes. Something that demonstrates that with standard probes or the cheaper analyzer probes there’s some significant noise that’s being missed. Can you please share this? 

[pkane2001]

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?

[pkane2001]

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:

 

 

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. 

[pkane2001]

6 hours ago, fas42 said:

 

Ah, good ol' measurements - if you are suffering pain, and I can't measure anything, then it must be in your head - the scientific community can't exist if this fundamental truth is not accepted, 🤪.

 

The pain of poor sounding playback will just go away if you keep studying graphs and charts of brilliant measurements, taken of your gear on the testbench ... take twice daily, or as needed. 🙂

 

A doctor subscribing to Frank's approach to diagnosing may not be my first choice :)

 

Me: Doctor, I've been having this cough....

Dr Frank: Let's remove your appendix, it's most often a problem in people of your age

Me: shouldn't we at least run some tests, get some lab results, an X-ray or two?

Dr Frank: No need, tests are for those other doctors that read textbooks and look at charts

Me, a week later: Doctor, my appendix was removed and yet I'm still coughing

Dr Frank: Ah, that's because you have two kidneys and they are unbalanced. We'll need to remove one.

Me, two weeks later: Doctor, I'm still recovering from the two surgeries, but my cough has not gone away

Dr Frank: It must be your heart, let's do a bypass

Me, a month later: Doctor, I'm feeling awful, I can barely move, have chest pain, and bleeding from all my incisions... but I'm still coughing

Dr Frank: I suspect it's your foot. We'll need to amputate

Me: I'd like to get a second opinion from one of those "other" doctors, if you don't mind

 

 

[pkane2001]

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.

[pkane2001]

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.

[pkane2001]

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.

 

 

[pkane2001]

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.