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USB audio transmission isn’t bit true


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18 minutes ago, JohnSwenson said:

There actually IS a difference. Music uses isochronous transmission which has NO error correction. Most other forms of data use transmission protocols which DO have error correction, thus transmission errors get corrected so the end user never sees an error. With music there is no correction so transmission errors DO show up at the DAC.

 

Per my previous post transmission errors are very rare with shorter cables, but do happen a LOT with longer cables.

 

So while in some sense data is data, how music data gets sent over USB is very different.

 

John S.

 

What is the rate of these errors, in typical use case scenarios (i.e. computer to DAC, streamer to DAC, and shorter cables of 3 feet or less)?  The answer is "very rare" as you say but how is that quantified?

 

 

Hey MQA, if it is not all $voodoo$, show us the math!

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15 minutes ago, JohnSwenson said:

There actually IS a difference. Music uses isochronous transmission which has NO error correction. Most other forms of data use transmission protocols which DO have error correction, thus transmission errors get corrected so the end user never sees an error. With music there is no correction so transmission errors DO show up at the DAC.

 

Per my previous post transmission errors are very rare with shorter cables, but do happen a LOT with longer cables.

 

So while in some sense data is data, how music data gets sent over USB is very different.

 

John S.

Well I don't think that is surprising.  Use short enough USB, and quality USB cables (and I don't mean expensive audiophoolery cable), and it will work as it should.  I've seen where other people tested DACs with poor cable cobbled together overly long with DACs to see which can handle it with less trouble than others.  Keep cables short.  What an idea.  I've not found errors with 5 meter cables which is the suggested max.  That was at the slower speed.  

 

I've also used some of those active extenders and found they can reliably with no errors for hours send the signal up to 50 ft.  They make longer extenders, but I've not tested those for hours. 

 

 

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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1 hour ago, Superdad said:

 

Using a USB protocol analyzer.  John and I each have one from Teledyne Lecroy.

 

Of course this whole conversation of bit errors has little to do with transmitted USB signal integrity--and its effect on the PHY of a DAC's USB input (ground-plane noise/bounce and packet-data noise), which ultimately affects the DAC's master clock and is the real reason why  people hear differences with USB cables and regenerators.  :ph34r:

reminds me of the saying "the operation was a success but the patient died"

Regards,

Dave

 

Audio system

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2 hours ago, Superdad said:

 

Using a USB protocol analyzer.  John and I each have one from Teledyne Lecroy.

 

Of course this whole conversation of bit errors has little to do with transmitted USB signal integrity--and its effect on the PHY of a DAC's USB input (ground-plane noise/bounce and packet-data noise), which ultimately affects the DAC's master clock and is the real reason why  people hear differences with USB cables and regenerators.  :ph34r:

 

Is the physical layer (the "analog" foundation of any "digital" signal for folks who don't know) noise to which you refer here, measurable?  Is the effect that this noise has on the master DAC's clock correlated in measurements if not directly measured?  If so, what tool do you use for this job?

Hey MQA, if it is not all $voodoo$, show us the math!

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4 hours ago, Superdad said:

 

Using a USB protocol analyzer.  John and I each have one from Teledyne Lecroy.

 

Of course this whole conversation of bit errors has little to do with transmitted USB signal integrity--and its effect on the PHY of a DAC's USB input (ground-plane noise/bounce and packet-data noise), which ultimately affects the DAC's master clock and is the real reason why  people hear differences with USB cables and regenerators.  :ph34r:

 

What is mansr saying here then?

 

On 2/3/2018 at 8:34 AM, mansr said:

 A steady stream of errors results in buzzing or distorted sound. If the DAC simply ignores bad frames (i.e. doesn't pad or interpolate), too many errors in a short time can cause a buffer underrun which will be audible as a longer drop-out.

 

 

It sounds like errors can cause more than just clicks by mansr's statement?

I would be curious if one could inject noise somehow and see the error rate go up?

 

 

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26 minutes ago, beerandmusic said:

 

What is mansr saying here then?

 

 

It sounds like errors can cause more than just clicks by mansr's statement?

I would be curious if one could inject noise somehow and see the error rate go up?

 

 

 

Perhaps these threads may provide some enlightenment:

 

https://www.computeraudiophile.com/forums/topic/28494-a-most-horrid-usb-cable/

 

https://www.computeraudiophile.com/forums/topic/28590-86-metres-of-cheap-cable-what-could-possibly-go-wrong/
 

Sometimes it's like someone took a knife, baby
Edgy and dull and cut a six inch valley
Through the middle of my skull

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3 hours ago, crenca said:

Is the physical layer (the "analog" foundation of any "digital" signal for folks who don't know) noise to which you refer here, measurable?

 

Sure, and some of can be seen in an eye pattern--see very first post of this thread for example:

 

3 hours ago, crenca said:

Is the effect that this noise has on the master DAC's clock correlated in measurements if not directly measured?  If so, what tool do you use for this job?

 

John (Swenson) has measured differences in ground-plane noise right next to the DAC master clock input pin.  High-speed scope, spectrum analyzer, differential probes are the typical tools.

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1 hour ago, kumakuma said:

 

5 hours ago, Superdad said:

 

Using a USB protocol analyzer.  John and I each have one from Teledyne Lecroy.

 :ph34r:

 

Kuma, nothing in those links really applicable to my question, but i did find a link in one of the links you shared with some of archimago's findings, ...so thanks for the links.

 

Although not applicable to my question...Archimago states (and this was just about a bad usb cable, not purposely injecting noise into quad dsd:

 

The more data error, the less the amount of "normal sounding" music will be heard. Obviously if the data error occurs every few minutes, it might be difficult to detect, but if it happens frequently, it's not subtle.

 

I am still curious if you were to set up an environment which shows "typical" error rate playing quad dsd, if you could inject noise somehow and see if the error rate would increase.
 

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6 hours ago, Superdad said:

 

(ground-plane noise/bounce and packet-data noise), which ultimately affects the DAC's master clock and is the real reason why  people hear differences with USB cables and regenerators.  :ph34r:

 

Assuming noise could not increase error rate (which i am not convinced until someone actually tests and reports on injecting noise in a quad dsd signal), and noise could only affect DACs (not the error rate)...having a noisy computer doing heavy processing (e.g. quad dsd processing and if pc not optimized and have a noisy ps, etc..etc..), only 3' from your DAC does not sound like a good idea either....all the more reason to do fiber over ethernet....this also eliminate the need for a very expensive PS on your pc....and if you went enet directly into your dac without any usb intfc, you wouldn't need an expensive PS for your streamer either?  Just one LPS internal to your enet dac (e.g. altair comes with LPS and ultra low noise clock).

 

Sorry for crappy 5min diagram...but this is what i am thinking would be the most noise free environment.

 

No fancy usb cables, no fancy power supplies (perhaps one LPS included in an enet dac like altair includes an LPS).

 

Very simple design....if you have more money, but a better enet dac...less money buy something like TEAC NT505, ND8006, or even used NT503....the market should be flooded with enet dacs in coming years in all different price ranges.

 

No usb toys, no need for fancy ps for an expensive streamer...no isosynchronus transmission  errors,

image.thumb.png.c73941f572bab7884397751f14594198.png

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1 hour ago, beerandmusic said:

 

Assuming noise could not increase error rate (which i am not convinced until someone actually tests and reports on injecting noise in a quad dsd signal), and noise could only affect DACs (not the error rate)...having a noisy computer doing heavy processing (e.g. quad dsd processing and if pc not optimized and have a noisy ps, etc..etc..), only 3' from your DAC does not sound like a good idea either....all the more reason to do fiber over ethernet....this also eliminate the need for a very expensive PS on your pc....and if you went enet directly into your dac without any usb intfc, you wouldn't need an expensive PS for your streamer either?  Just one LPS internal to your enet dac (e.g. altair comes with LPS and ultra low noise clock).

 

Sorry for crappy 5min diagram...but this is what i am thinking would be the most noise free environment.

 

No fancy usb cables, no fancy power supplies (perhaps one LPS included in an enet dac like altair includes an LPS).

 

Very simple design....if you have more money, but a better enet dac...less money buy something like TEAC NT505, ND8006, or even used NT503....the market should be flooded with enet dacs in coming years in all different price ranges.

 

No usb toys, no need for fancy ps for an expensive streamer...no isosynchronus transmission  errors,

image.thumb.png.c73941f572bab7884397751f14594198.png

 

* music bits as perfect as can possibly be, all the way to the dac input.

* all processing is done away from listening room.

* the media converter is a VERY LOW power device and doesn't need any special power, but if make you feel better buy cheap $50 ifi power.

* Audio linux is $30 and has support for HQP or roon ... Volumio is $FREE if you want a web browser player, or you can use Jussi NAA image.

* Altair is ONLY DAC i know of under $2K that has (enet, LPS, and ultra low phase clocks)...hope to see a lot more of these devices to drive  down prices under $1K. (tell DAC mfrs to eliminate unnecessary USB circuitry to further reduce costs).

* The enet and dac in one unit so one trusted mfr and has been tested by mfr from input to output in one box, and you are providing as noiseless possible clean data with no transmission errors directly to it's input.

 

I bought CISCO 24 port GIGABIT switch with 4 SFP fiber connections used for $45, xceiver $11, cable $8, Fmc $25....solution is very cheap, very simple, and don't see how you can get it any quieter and no need for fancy PS or fancy USB cables.

 

 

 

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You'll intentionally not understand it of course.  Interference of noisy devices thru the air are not much of a problem.  Even a little distance helps tremendously, and that is assuming the noise is of a type picked up and harmful anyway.  If there is a noise issue the problems are magnitudes greater over wired connections. 

 

I've done this before, which you say doesn't apply to your exact situation.  Which is only an embarrassment to you which you won't understand.  I took a large PC supply out of its case, had the PC doing intensive power hungry video processing, and ran some RCA cables once around the supply.  You do get noise, noise you can hear.  I unwrap and move it 6 inches away, and you can measure some noise, but not hear it.  Move it two feet away and that noise is at such a low level it is swamped by thermal noise. 

 

Did the same thing with balanced XLR cable.  Nothing above the thermal noise floor even wrapped a few times right around the switching PC supply.  

 

With PS inside a metal case, and some distance you just aren't getting much irradiated noise that will effect something else several feet away.  Not from random OS actions and noise that isn't tuned to what anything else is doing.  Making a problem of something that is not one. Just because you can imagine it would be. 

 

Take a nice DAC, feed it from USB of 3 meters or less directly and you don't need anything else.  

 

It's funny the current digital fashion vs audiophile fashions of yesteryear.  Back then less was more and simplicity of high quality was sought after.  Like removing tone controls from preamps.  Now, more is more.  Instead of doing something of good quality everyone introduces fixes, and fixes for fixes and you get the idea the more widgets between A and B the better it will be. Rather bizarre.  

 

A good ethernet protocol would be fine too, but it is going to be the same story all over again.  You'll need a dozen boxes to condition things for that because  soon enough......somebody ........will hear.............. something.............

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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40 minutes ago, esldude said:

You'll intentionally not understand it of course.  Interference of noisy devices thru the air are not much of a problem.  Even a little distance helps tremendously, and that is assuming the noise is of a type picked up and harmful anyway.  If there is a noise issue the problems are magnitudes greater over wired connections. 

 

I've done this before, which you say doesn't apply to your exact situation.  Which is only an embarrassment to you which you won't understand.  I took a large PC supply out of its case, had the PC doing intensive power hungry video processing, and ran some RCA cables once around the supply.  You do get noise, noise you can hear.  I unwrap and move it 6 inches away, and you can measure some noise, but not hear it.  Move it two feet away and that noise is at such a low level it is swamped by thermal noise. 

 

Did the same thing with balanced XLR cable.  Nothing above the thermal noise floor even wrapped a few times right around the switching PC supply.  

 

With PS inside a metal case, and some distance you just aren't getting much irradiated noise that will effect something else several feet away.  Not from random OS actions and noise that isn't tuned to what anything else is doing.  Making a problem of something that is not one. Just because you can imagine it would be. 

 

Take a nice DAC, feed it from USB of 3 meters or less directly and you don't need anything else.  

 

It's funny the current digital fashion vs audiophile fashions of yesteryear.  Back then less was more and simplicity of high quality was sought after.  Like removing tone controls from preamps.  Now, more is more.  Instead of doing something of good quality everyone introduces fixes, and fixes for fixes and you get the idea the more widgets between A and B the better it will be. Rather bizarre.  

 

A good ethernet protocol would be fine too, but it is going to be the same story all over again.  You'll need a dozen boxes to condition things for that because  soon enough......somebody ........will hear.............. something.............

 

Just curious, do you use a fancy usb cable?

 

Either way, To be honest, I do believe you can have a "near perfect" usb solution provided dedicated, highly optimize, quality pc, and a standard usb cable...furthermore, I do not believe in any OMG MASSIVE Improvement enet solution over USB unless they had a crappy USB solution when they started.

 

I did have a crappy usb solution when i first started, and i jumped on enet within a month and noticed a good subtle difference, but easily notable.  I do believe usb toys work for noisy comptuers or older generation dacs, but it makes more sense to fix it before its broke imho.    I stuck with ENET but tried several usb solutions but always went back to enet.  Again most of this was even before advent of usb toys and fancy cables (or at least popularity of fancy usb cables)...i am talking 7-8 years ago...and after giving USB a chance several times, i have stuck with enet ever since (for my main system), i still use both USB and spdif for my office system.  I am not here to say that you can't have an optimal usb solution, because i believe you can....but on the other hand, i do not see any purpose in using an inferior transmission medium, and no reason to go back to it....you can build (as demonstrated) a very cheap enet solution, that no one can suggest will be weaker for any reason, or if they can, i would love their input. 

 

None of this was relative to why i started this thread though....I was just happy to learn the term Isochronous, and that the DAC does not get its data perfectly as many suggested....For me it was a stumbling block...regardless if it can or cannot affect SQ....I just kept hypothesizing different solutions and just couldn't accept that the dac always gets its data with 100% accuracy...and i was right.  I don't understand why people couldn't get that it was just a stumbling block for me and why people are so sensitive.  Regardless, i still think it can cause issues besides just clicks, and even MANSR and ARCHMAGO stated so as well (even if very unlikely with a PROPERLY tuned system).  To me,  it's irrelevant anymore, even if it couldnt' cause anyything more than clicks...I just don't need usb..it's unnecessary.

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3 hours ago, beerandmusic said:

 

 

Kuma, nothing in those links really applicable to my question, but i did find a link in one of the links you shared with some of archimago's findings, ...so thanks for the links.
 

 

You asked what mansr was saying and the first link answered your question, even providing recording of the distortion for you listening "pleasure".

Sometimes it's like someone took a knife, baby
Edgy and dull and cut a six inch valley
Through the middle of my skull

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21 minutes ago, kumakuma said:

 

You asked what mansr was saying and the first link answered your question, even providing recording of the distortion for you listening "pleasure".

Ok thanks...i went back and re-read...and i will even re-read again....

 

I downloaded one of the recordings and it was horrid...if high error rate can cause that, i do not want any error rate (grin)....

 

Most notably, he stated:

 

====

The first few seconds of the recording are fine. When errors start showing up, it's as an occasional skip which is clearly audible. The thing is, as soon as a single bit is wrong, an entire packet is discarded, and this causes a huge error in the recovered data stream.

====

 

So in conclusion, i do not want even a single bit wrong, right?

 

To me, if error rate can cause that which is not even listenable, there are many possibilities of what small error rates can do on different gear, even if just very subtle.

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25 minutes ago, beerandmusic said:

 

Just curious, do you use a fancy usb cable?

 

Either way, To be honest, I do believe you can have a "near perfect" usb solution provided dedicated quality pc, standard usb cable, and I do not believe in any OMG MASSIVE Improvement enet solution unless they had a crappy USB solution when they started.

 

I did have a crappy usb solution when i first started, and i jumped on enet within a month and noticed a good subtle difference, but easily notable.  I do believe usb toys work for noisy comptuers or older generation dacs, but it makes more sense to fix it before its broke imho.    I stuck with ENET but tried several usb solutions but always went back to enet.  Again most of this was even before advent of usb toys and fancy cables (or at least popularity of fancy usb cables)...i am talking 7-8 years ago...and after giving USB a chance several times, i have stuck with enet ever since (for my main system), i still use both USB and spdif for my office system.  I am not here to say that you can't have an optimal usb solution, because i believe you can....but on the other hand, i do not see any purpose in using an inferior transmission medium, and no reason to go back to it....you can build (as demonstrated) a very cheap enet solution, that no one can suggest will be weaker for any reason, or if they can, i would love their input. 

 

None of this was relative to why i started this thread though....I was just happy to learn the term Isochronous, and that the DAC does not get its data perfectly as many suggested....For me it was a stumbling block...regardless if it can or cannot affect SQ....I just kept hypothesizing different solutions and just couldn't accept that the dac always gets its data with 100% accuracy...and i was right.  I don't understand why people couldn't get that it was just a stumbling block for me and why people are so sensitive.  Regardless, i still think it can cause issues besides just clicks, and even MANSR and ARCHMAGO stated so as well (even if very unlikely with a PROPERLY tuned system).  To me,  it's irrelevant anymore, even if it couldnt' cause anyything more than clicks...I just don't need usb..it's unnecessary.

I don't use fancy USB cables.  Unless you consider a Belden fancy.  I've heard no problems using a netbook for basic music playback thru a USB to SPDIF converter.  I normally use a Lenovo laptop, or Macbook pro for music playback.  Or a low energy Lenovo desktop server.  

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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10 minutes ago, esldude said:

But note what mansr said.  If a single bit is wrong, an entire packet is discarded.  A huge error ensues.  If you aren't hearing the huge errors, then a bit has not been wrong. It isn't like analog where a little bit of low error causes a little bit of less good digital sound.  You get it, and its fine or OOPS, there was an error.  The errors are not a sound quality problem because they aren't happening for all practical purposes.  

that was in his test case....there are literally a million different possibilities with different hardware and different environments...the point is that error rate can and will affect SQ...but again, I believe can be avoided with a "properly optimized system".  I think USB can be fine, but that it is subject to SQ issues....even when using a non-optimized multi function pc, i had hard time telling if i liked usb better than enet or visa versa...so with a well tuned usb system, i see no practical issues.

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4 minutes ago, esldude said:

I don't use fancy USB cables.  Unless you consider a Belden fancy.  I've heard no problems using a netbook for basic music playback thru a USB to SPDIF converter.  I normally use a Lenovo laptop, or Macbook pro for music playback.  Or a low energy Lenovo desktop server.  

Ok, cool...i don't get some people that suggest USB is perfect yet they buy a fancy cable...

I use spdif predominantly for my second system...but that is also used with the computer i am typing on (smile).  sounds fine to me...

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1 hour ago, esldude said:

But note what mansr said.  If a single bit is wrong, an entire packet is discarded.  A huge error ensues.  If you aren't hearing the huge errors, then a bit has not been wrong. It isn't like analog where a little bit of low error causes a little bit of less good digital sound.  You get it, and its fine or OOPS, there was an error.  The errors are not a sound quality problem because they aren't happening for all practical purposes.  

 

Another thing comes to mind, why things may not be "obvious" noise as in clicks or "horrendous" like mansrs test case, is because the dacs are designed to interpolate....it may not get the right data, so it interpolates (and may or may not be correct interpolation), leading to subtle differences rather than obvious differences....again, just speculating....(I am sure someone will pop in and tell me i don't know what the helllll i am talking about, and i Probably don't)....but again, the point is that even a single misplaced bit can wreak havoc....sure the dac does its best to correct...but again, imho, better to get it right the first time.

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@beerandmusic

 

If you want try by yourself the effects of one errored bit or more take an audio track and then modify one or more bits in a single or more sample. Then play the modified version and compare.

When an audio packet (max 1024 bytes) is detected faulty it is not discarded just played as it is.

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