Did We Overhype USB Audio And Overlook Possible Pitfalls?

[徐中銳]

Recalling that Ken sent me the English Q&A exchange to read, of his October 2015 Polish-Interview, extracting this :

Why is the quality of music reproduction 'from files' still unsatisfactory?

Very simple!! You start having PC for file playback!! PC is the highest noise generator you can imagine and what it can cause for very sensitive Audio signal!!! Play-Back file music is wonderful thing but you have to know what you are up against!!!! Still very long way to go I would say but very nice challenge!!!

 

Published Polish :

« Dlaczego jakość odtwarzania muzyki z plików '' wciąż niezadowalająca?

Ależ to bardzo proste. Punktem wyjścia jest przecież komputer PC, który służy jako źródło do odtwarzania plików. Komputer PC jest najstraszliwszym generatorem zakłóceń, jaki tylko można sobie wyobrazić, a fakt ten może powodować wielkie problemy dla bardzo wrażliwych sygnałów audio. Odtwarzanie plików muzycznych to jest wspaniała rzecz, ale trzeba zdawać sobie sprawę, z czym to się wiąże i wobec jakich wyzwań się staje. To jest wciąż jeszcze bardzo długa i daleka droga, ale chciałbym powiedzieć, że to jest bardzo ambitne wyzwanie. »

[r_w]

Has anyone noticed though that USB can sound utterly fantastic (eg, Aurender N100 > Auralic VEGA)?

 

So what if it needs a bit of help a la REGEN, etc... all systems need a bit of help (good mains, vibration management, optical LAN isolation, etc, etc)

 

USB sounds fantastic, when it's in an optimised environment!

... it really does.

 

:-)

[firedog]

Of course USB was over-hyped - everything in audiophilia is.

 

But it has become ubiquitous because it is: easy, available on any computer, and allows playback (with proper software) of all sample rates and formats.

 

I have what I consider a good USB solution - but I'm using 2 USB add-ons. That in itself sort of doesn't make sense.

 

In theory, I'd like an ethernet or network based solution - it avoids many of the noise and other issues of USB. But those solutions have their own issues, and the even the very best present day solutions (Merging) still have some limitations that would make it difficult for me to adopt.

 

Let's face it: everyone's system is different. There are lots of good solutions around: SPDIF, AES, Ethernet, toslink, and USB. Each one has some specific implementations that seem to have been "perfected". At least for some people.

 

Chris, you love your present solution with the Berkeley converter - so why worry?

 

Maybe someday there will be a USB solution that doesn't require "extra boxes", and the "problem" will be solved.

[Paul R]

So how does superspeed eliminate the need for a driver? Is there some secret new protocol that only runs over superspeed that all OS manufactures have included in their offerings? I certainly have not found any such thing, but I certainly could have missed it.

 

John S.

 

I am not sure what you are talking about John. I just said that USB 2.0 audio is already perfectly compatible with USB 3.1 ports. In fact, it is compatible with anything that is compatible with the basic device profile. (Aren't you on one of the teams for USB.org?)

 

Both MacOS and Linux already have drivers that support high speed - users rarely if ever have to install special drivers for DACs. I think there are standardized Windows drivers now too, so perhaps the Windows world is going that way as well.

 

I think I said the opposite of what you think I said. However, I will point out that newer 3.1 hardware does seem to work better, the same as networks work better when the switches have higher backplane bandwidth. That isn't a proposition I would vigorously defend, just an observation.

[Paul R]

I disagree. There is a connection available on all 2016 notebooks that is better at isolation and much more widely employed to transport audio to playback devices than USB.

 

We are, of course, talking wifi and technologies such as airplay, chromecast or roon.

 

If we want to improve quality of ubiquitously available audio playback, we should focus on getting good endpoint implementations of these technologies.

 

I'm with you on this one Peter - though I still say the current railing against USB is kinda overblown in itself.

 

But I think there are two subjects being discussed here - getting from a computer to a DAC and then inside the DAC itself.

 

Getting from a computer to a DAC, be that from a machine one meter away or a machine halfway around the world, TCP/IP protocols over some form of network is, I think, one of the better answers.

 

Inside a DAC? A TCP/IP interface to i2s seems nice. But actually, the i2s half of that is already in most DACs anyway, so what's the beef?

 

Building a good DAC and building a good source, as well as designing the transport between them are all different subjects -no?

 

By the way, using USB to transport the data to a DAC, the same as ethernet or wireless, may be a good idea, especially with very high speed interfaces. That is, *not* using USB Audio, but using data transfer modes.

 

-Paul

[jabbr]

Optical or wireless transmission have the inherent advantage of electrical isolation. I wonder if as much time and as many resources were placed into developing either of these, whether they would be ahead of where USB is now?

 

If there were a recognized market, an optical to I2S board would be available. Using an FPGA/ARM processor it would be programmed to take the Ethernet input from the SFP, convert and output I2S/DSD, in pretty much the same way that the Amanero USB board uses an XMOS processor to convert between USB and I2S/DSD.

Done correctly it would be better.

 

The more recognition optical Ethernet gets, the more likely someone will make the effort to commercialize this.

[richard kimber]

I've never understood why there has been so much support for USB. I use ethernet. My music is on HD, a DLNA server send the files to a client when requested by an app on my tablet. The client outputs the digital data to my DAC. Works well, at least with 24/192 (I'll be able to try DSD when John Westlake produces the new FDAC).

 

- Richard.

[realhifi]

 

"Did We Overhype USB Audio And Overlook Possible Pitfalls?"

Who is "we"? See both Naim Audio and Linn HiFi for alternatives to USB based digital audio playback. Both companies have been using (and improving) these alternatives for years.

[sbgk]

Thought a large part of the regen success is due to the signal not exercising the dac chips so much, so is the problem not usb but the noisy signal passed to usb . If more care was placed in feeding usb a clean signal then there wouldn't be so much of an issue.

[The Computer Audiophile]

Correct, but he was mentioning CRC, this is a 'Check', not a correction.

Yes, but he mention there was no "additional" correction. Thus, implying (after first stating) there is correction to begin with.

[eganz]

Has anyone noticed though that USB can sound utterly fantastic (eg, Aurender N100 > Auralic VEGA)?

 

So what if it needs a bit of help a la REGEN, etc... all systems need a bit of help (good mains, vibration management, optical LAN isolation, etc, etc)

 

USB sounds fantastic, when it's in an optimised environment!

... it really does.

 

:-)

 

I agree that USB can sound fabulous.

I also recently purchased an Aurender N100H and Auralic VEGA (used).

I'm getting fantastic sound from this combination.

 

In fact, this Aurender concentrates on just the USB output.

 

I looked into optical isolation for the ethernet, but instead installed a tiny and simple Wi-Fi bridge which provides isolation (due to wiring challenges).

And yes, I have regenerated power, vibration isolation etc., although I have not yet tried the regen.

 

I agree that we should consider/promote other interfaces going forward (such as I2S), but we should also celebrate the success that we have achieved in playing our modern high-resolution PCM and DSD files.

 

Eric

[d_elm]

Asynchronous USB solves the problem of the clock as it now is provided by the DAC instead of the data stream. However data integrity is not supported as the connection is unidirectional and there is no possibility for the DAC to tell the sender to retransmit if there is a CRC error on a packet. This is why some USB cables provide better SQ than others as the error rate is lower or zero. I wonder about a simple hardware but more complicated software interface using two asynchronous USB connections, each running unidirectional but now with two channels both ends are free to send to the other at any time, ie bad packet send again. TCP implemented this and transmission windows.

[goldsdad]

[...] This is why some USB cables provide better SQ than others as the error rate is lower or zero.

 

Please provide the measured error rates for specific cables.

[JBNY]

I'll repeat, USB audio has no error correction (as told to me by the Godfather of USB audio, Gordon Rankin).

 

 

Async USB Audio has error detection in the from of a CRC attached to the packet. But there is no error correction, meaning the ability to retransmit the packet like in Ethernet etc. So if there is an error in a malformed or corrupt packet, it is simply discarded from the buffer. I don't need Gordon to tell me that I have read the RFC myself and worked in the IT industry for years. What people never seem to tell you is that packet errors are unbelievably rare in transmitting packet data. USB can be troublesome because of the noise from PC itself but that almost never translates to errors in packet transmission. What happens most times is the manufacture of the DAC has problems dealing with noise that can come via the USB bus and makes it's way into their DAC. It's how they deal with that noise is what makes the USB implementation work better for some DAC over others.

 

 

 

 

Has anyone noticed though that USB can sound utterly fantastic (eg, Aurender N100 > Auralic VEGA)?

 

 

So what if it needs a bit of help a la REGEN, etc... all systems need a bit of help (good mains, vibration management, optical LAN isolation, etc, etc)

 

 

USB sounds fantastic, when it's in an optimised environment!

 

 

... it really does.

 

 

:-)

 

 

USB can indeed sound great. As you wrote, some neeed more help than others, not evey DAC manufacture is a the same. As someone else mmentioned when I went to a Unbuntu based system almost all my USB issues went away, and no drivers needed on Ubuntu.

[d_elm]

Please provide the measured error rates for specific cables.

 

I have no quantitative data but to force a bad situation try a USB 1.1 cable and listen for the difference.

[mansr]

I have no quantitative data but to force a bad situation try a USB 1.1 cable and listen for the difference.

 

You mean forcibly run USB2.0 over a USB1.1 cable? Then you're using an out-of-spec cable, and of course there may be errors.

[The Computer Audiophile]

Async USB Audio has error detection in the from of a CRC attached to the packet. But there is no error correction, meaning the ability to retransmit the packet like in Ethernet etc. So if there is an error in a malformed or corrupt packet, it is simply discarded from the buffer.

I believe that's what I've been saying as well.

 

 

 

I don't need Gordon to tell me that I have read the RFC myself and worked in the IT industry for years.

Working in the IT industry can mean anything from a janitor at IBM to the President of Salesforce. Neither position is likely to know much about the specific USB audio standard. Thus, I'm not sure where you are going with your statement. Plus, I hate to act as if I know this stuff too well, which is why I recommended asking Gordon or John who may know more about implementing USB audio at a high level that anyone on the planet.

 

One more thing, did you take my comments, directed at someone else, personally for some reason?

 

 

 

 

What people never seem to tell you is that packet errors are unbelievably rare in transmitting packet data. USB can be troublesome because of the noise from PC itself but that almost never translates to errors in packet transmission. What happens most times is the manufacture of the DAC has problems dealing with noise that can come via the USB bus and makes it's way into their DAC. It's how they deal with that noise is what makes the USB implementation work better for some DAC over others.

 

Good, we agree on this as well. I only raised the error correction issue because a previous comment implied that USB audio has error correction.

[徐中銳]

why some USB cables provide better SQ than others [?]

 

They should update this—but it's what they said : ​

Marantz' White Paper Guide to PC-Audio pdf :

In this document we will mainly focus on the last option on the list' date=' the [b']USB-B connectivity[/b] as this is the recommended way for music lovers to enjoy their music in the best quality possible. The player acts as a DAC– Digital to Analogue Converter (in fact it replaces the soundcard of your PC / MAC) and directly converts the digital music signal to analogue domain to hand it over to the amplifier.

 

But first let’s dig a bit more into the different ways of accessing music to get a better understanding and clarify some terminology...

 

 

TIPS AND TRICKS TO GET THE BEST FROM YOUR USB-DAC

 

1. Select a good USB cable (sound will be strongly influenced by the USB cable; interference & noise).
   
2. USB-Cable: Not longer than 5m, and the quality of shielding will also have some influence on the sound quality. Test several cables to optimise performance. Try adding a Ferrite Core as used on some network cables.
   
3. We strongly recommend you to add a Ferrite Core on your network cable to minimize noise interferences.
   
4. For the PC / Mac an SSD hard disc is preferable – SSD stands for Solid State Disk and has, in comparison to standard hard disc, no rotating elements inside. Another step to reduced interference. Sound will be even smoother and more detailed.
   
5. Use your PC or Mac only for Music listening. Kill all unnecessary running apps. There is no need for a high performance super-fast PC. Standard processor is just fine.
   
6. If you use Spotify streaming service, make sure you set the data rate to 320kps – highest resolution.
   
7. DSD playback. The NA-11S1 supports DSD2.8Mhz (64) and DSD5.6Mhz (128). In case of DSD2.8 playback “DSD2.8224MHz” will be shown. For DSD5.6 it is “DSD>2.8224MHz”, this >means bigger than 2.8.
   

[gmgraves]

For whatever it's worth, I recall having a long talk at the Newport Beach Show (at least that's where I think it was) with Keith Johnson (of Spectral and Reference Recording fame). A very nice and very knowledgeable man.

 

And I asked him about which digital interface he preferred. He would not state a preference. He firmly believed that the quality of the interface was secondary to the quality of implementation of that interface in the respective device.

 

While I'm certainly not qualified to judge, his explanation had a ring of truth to me.

 

Joel

 

A lot of industry "personalities" are reluctant to endorse or condemn any current technology or protocol for fear of being misquoted or quoted out of context. Can't say as I blame them.

[JBNY]

Working in the IT industry can mean anything from a janitor at IBM to the President of Salesforce. Neither position is likely to know much about the specific USB audio standard. Thus, I'm not sure where you are going with your statement. Plus, I hate to act as if I know this stuff too well, which is why I recommended asking Gordon or John who may know more about implementing USB audio at a high level that anyone on the planet.

 

 

One more thing, did you take my comments, directed at someone else, personally for some reason?

 

 

I meant no offence at all, sorry if my post was misconstrued. I realize you were responding to someone and really was just putting that out for general knowledge. But it probably could have been worded better, sorry about that. For me, being in the IT industry was running networks, server farms and coding applications. Anyway, just trying to get along that USB is pretty robust, more so that pretty much anything we have ever had in the audio world before. And done right can sound pretty spectacular.

[crenca]

 

Good, we agree on this as well. I only raised the error correction issue because a previous comment implied that USB audio has error correction.

 

So, yes USB is not a packet based delivery as normally defined (as for example Ethernet {part of the TCP/IP stack}) but it is known that actual transmission errors (barring a particularly bad implementation) are statistically not significant, what IS the basis of criticism for USB in audio exactly? I have to come back to implementation effecting other things and the quality of parts/design in said implementations effecting the DACs sound in ways not generally clearly defined. What am I missing?

[Richard Dale]

So, yes USB is not a packet based delivery as normally defined (as for example Ethernet {part of the TCP/IP stack}) but it is known that actual transmission errors (barring a particularly bad implementation) are statistically not significant, what IS the basis of criticism for USB in audio exactly? I have to come back to implementation effecting other things and the quality of parts/design in said implementations effecting the DACs sound in ways not generally clearly defined. What am I missing?

 

USB uses packets

[JBNY]

So, yes USB is not a packet based delivery as normally defined (as for example Ethernet {part of the TCP/IP stack}) but it is known that actual transmission errors (barring a particularly bad implementation) are statistically not significant, what IS the basis of criticism for USB in audio exactly? I have to come back to implementation effecting other things and the quality of parts/design in said implementations effecting the DACs sound in ways not generally clearly defined. What am I missing?

 

 

Async USB is absolutely packet based delivery, there is just no retransmit option like Ethernet. But I agree, transmit or recieve errors are very rare, like one packet error over days and day of packet delivery. I don't think you are missing anything.

[crenca]

USB uses packets

 

In the context of this conversation most folks are thinking of a system like TCP/IP that will re-transmit packets if corrupted, the idea being that USB is effecting sound quality because it does not...

[tallica1]

I can almost guarantee ALL who complain about a USB connection DAC should be changing out their current hardware which is the most likely cause of your dissatisfaction with your sound