Gordon Rankin Says I'm Wrong About USB Cable Sound!

[Snowmonkey]

Whether Mr Rankin is right or wrong, this illustrates a fundamental flaw which frequently arises in the objectivists' logic. They assume that they have a logical model which completely explains a phenomenon and reject any observations which do not quantitatively agree with their model, then someone comes along with a different, but equally valid model and their argument goes out the window.

[beanbag]

Thank you. I think that is all we need to know.

 

Umm, so were you going to address any of the points I made?

[Paul R]

it's what i use!

 

It is my basic "go to" cable, and what I buy as gifts for friends still using those $0.03 printer cables that come with 29 printers... Makes an amazing difference.

[Paul R]

If this would be the case, you would get very noticeable crackle and pop while playing back audio. Especially with DoP. The errors cannot be clever enough to hide only in the LSB bits (and DSD doesn't have such)...

 

Curiously, I have not had a single error on files located on USB HDD's... (and for example M2Tech hiFace uses bulk mode transfers, and I believe that's the case with Mytek and exaSound too, same mode is used for HDDs)

 

12% is, in objective terms, not a large number. I do see occasional errors on USB transmissions. And of course, in streaming audio, the DAC does have to deal with that, much like bulk mode transfers.

 

By the way, I bet if you instruments the USB driver, you would see errors.

 

Paul

[Jud]

Well, it wasn't that long ago that many 'experts' (Gordon included?) were saying that USB cables could not sound different if used in async USB mode. Those of us who tested this knew it was incorrect - USB cables continued to sound different. Having tried a bunch of USB cables myself, I took the plunge (only fairly recently) and bought an expensive 'Tellurium Black Diamond' USB cable. And yes, it sounded totally different to any of the others I had (generally smoother sounding).

 

For about the same outlay as the Tellurium Black Diamond, I had my Phasure NOS1 DAC upgraded to 'a' status. The NOS1a is totally immune to effects of the USB cable and/or PC. I can verify this - the Tellurium Black Diamond now sounds identical to a $1 stock USB printer cable.

 

All the 'experts' (Rankin, Swenson, Smith, etc) are right. But only one has come up with a solution.

 

Mani.

 

Hi Mani. Actually, Peter's description of his solution seems (from my quick reading) to be tailor-made for what John Swenson has described as the problem. (beanbag, it would be nice if you would stop "quote mining" John Swenson, i.e., taking one out-of-context quote and using it to support a position he does not hold, that USB cables cannot sound different.) And Gordon Rankin's description of the problem may not be so very far from what John has said either, if we had a chance to get the two of them chatting together about it.

[Habanero Monk]

If you didn't know, there are audiophile Ethernet cables and there's a similar debate over whether they can possibly have any impact on SQ. A reviewer I trust has said that they most certainly do. I intend to give one a try as my next upgrade.

 

I have a JPlay dual-server configuration where the two computers are presently connected via a generic Ethernet cable. That cable is (literally) central to my setup, so I'll be listening for a significant difference. If I don't hear one, the fancy Ethernet cable goes back.

 

 

After some testing with a $350 AQ Vodka and a BJC CAT6 and BJC CAT5e I am dubious of anyone scoring 90% out of 20 flips of the coin with a cable that passes spec. If it doesn't pass spec then it's not Ethernet.

 

The issue is once Ethernet has passed data error free, it's data that is error free.

 

For starters your computer is playing this out of RAM. JRivers default pre-buffer is 6 seconds. What this means is that you can start playing a song, pause it, pull the Ethernet cable, and hit play again, pause, play. All with the cable just hanging there.

 

Ethernet is a data device, not an audio device.

 

Take a $350 cable, take a $13 cable (assume both pass certification). Create two folders on your computer and use the $350 cable and download a track from HD Tracks. Take the $13 cable and download the same track.

 

Use Foobar's AB/X function. I'm willing to bet $$ you couldn't follow the bouncing yellow ball 18 out of 20.

[Jud]

find a cable manufacturer that will guarantee...that his cable can pass, ideally, a 2.6 GHz, or at least a 0.5 GHz perfect square wave

George, I think something may have been lost in the translation here, or was imprecise in Gordon's statement of the problem. I have no argument with the general point that the cable must be able to pass signal variations much faster than the audio frequencies or even digital sample rates we are familiar with. But there is no physical device in the universe that can pass a "perfect square wave," since that requires instantaneous (faster-than-light) variation of the signal. That is also why a "square wave" in actuality has no frequency, at least as we think of frequency in audio, video, or electromagnetism, since no matter how high the frequency of a sine wave, it won't have instantaneous rise and fall time. Thus there is really no such thing as a "2.6GHz" or "0.5GHz" square wave. So general point = fine, specific description = I have a nitpick or two.

[Habanero Monk]

In that case you should probably obtain a reputable, but non "hi fi" branded CAT7 cable to compare to the Audioquest. Then you will know if it is the CAT7 in comparision to CAT5 or 6, which is making any difference.

 

Keep in mind I don't think the cable can be called officially CAT7 unless it is using the GG45 connector.

[beanbag]

(beanbag, it would be nice if you would stop "quote mining" John Swenson, i.e., taking one out-of-context quote and using it to support a position he does not hold, that USB cables cannot sound different.)

 

Umm, excuse me, I did not use his quote to support a claim that USB cables do not sound different. I used it to support the claim that USB cables can not sound different due to data loss reasons.

[Jud]

Umm, excuse me, I did not use his quote to support a claim that USB cables do not sound different. I used it to support the claim that USB cables can not sound different due to data loss reasons.

 

...which, depending on how you construe the term "data loss," is still not a fair representation of his position.

[JohnSwenson]

Hi George,

USB isochronous mode (async is one of the variations of isochronous mode) does NOT have error correction or re-transmission, it does have error detection, but you can't fix the data with that, just know it happened.

 

Isochronous means constant time, it was designed for streaming applications where it was presumed that there was no time for re-transmissions, thus there was no provision for it in the standard.

 

Note that disk drives etc do NOT use isochronous mode, they use a different mode which DOES allow for re-transmission etc

 

Most modern USB implementations in DACs use high speed mode which runs at 480 mega-bits per second. A cable which is only good to 0.5GHz is almost useless with that, it would only allow a sine wave at 480MHz, the variations in timing which define the data would be almost completely gone, you need much higher bandwidth to be able to get any useful data out of it at all.

 

I agree with Gordon, there are major impedance issues all over the place in USB implementation (BTW it's no better in FW), there are quite a few motherboards that don't come close to proper impedance matching from chip to connector, a LOT of DACs that don't get it right from connector to chip and of course cables that don't get it right. This gives rise to a major mish mash of reflections on the bus. That is what those input receivers have to try and deal with and why they have to work so hard at it.

 

The remarks from Gordon seemed to say that he thinks there are massive amounts of actual data errors happening all the time, I disagree with this, I certainly don't see this with the DACs that I build.

 

The issue of the async back channel is an interesting one. THIS is where I do see things getting very interesting. There are computer/software combinations that do have a hard time dealing with the speed change packets sent from the DAC to the host, if these happen often enough it can cause the infamous "clicks and pops" that sometime seem to plague some computer/DAC combinations. Sometimes changing cables CAN help these packets get properly dealt with.

 

John S.

[bluesman]

Well according to this organisation, there are plenty of USB cables that meet the 90 ohm specification.

USB.org - USB-IF Compliance Program

 

Seems like you just need to find a cable that has passed the compliance testing.

 

I haven't a clue whether it matters at all to SQ, but the spec is not that precise (i.e. there is no "90Ω spec"). The impedance spec is the range between 76.5Ω and 103.5 Ω. It's on page 8 of the USB document.

[wgscott]

Whether Mr Rankin is right or wrong, this illustrates a fundamental flaw which frequently arises in the objectivists' logic. They assume that they have a logical model which completely explains a phenomenon and reject any observations which do not quantitatively agree with their model, then someone comes along with a different, but equally valid model and their argument goes out the window.

 

Do you have an example in mind?

[Snowmonkey]

Do you have an example in mind?

Well the topic of this thread for starters. We seem to have segued neatly from "USB cables can't possibly make any difference" to "why variations in impedance in USB cables make such a difference".

[new_media]

I don't think any "objectivist" ever claimed that a USB cable that was wildly out of spec to the point of causing data transmission errors couldn't possibly make a difference, but I would expect the effect to be more like drop outs or pops rather than collapsing of the sound stage or decreased attack or some such.

[wgscott]

Well the topic of this thread for starters. We seem to have segued neatly from "USB cables can't possibly make any difference" to "why variations in impedance in USB cables make such a difference".

 

The only thing I have ever said was that it "shouldn't" make a difference, and that differences, if they do exist, should be quantifiable (measurable) and presumably are the result of manufacturing defects that could be addressed or avoided.

[wgscott]

Let's take another look at what you wrote:

 

They assume that they have a logical model which completely explains a phenomenon and reject any observations which do not quantitatively agree with their model

 

Again, do you have a specific example in mind?

 

...then someone comes along with a different, but equally valid model and their argument goes out the window.

 

If it is equally valid (presumably meaning it explains and predicts the same phenomena), then the "model" is likely to be the same thing, not different.

[gmgraves]

Now that you're more open to the idea, if you're so inclined, you could listen to some USB cables.

 

No thanks. I'll take your word for it. Like I said earlier, I have heard differences between USB cables before, but they were so small, and so ambiguous that I put it down to expectational bias. Now that Gordon has convinced me that it was not my imagination, I see that the magnitude of these differences is, to me, anyway, trivial. This level of differences might be important to some listeners, but its not important to me. I've been down the "neurotic audiophile" route, and have come out the other side. I do not have any intention of having that monkey on my back again. If I were to list for you the number of turntables, arms, cartridges and speakers I've owned in my lifetime, you would be aghast! All that money spent chasing an elusive goal that can never be attained. These days, I just review components and recordings and listen to the music.

[Miska]

By the way, I bet if you instruments the USB driver, you would see errors.

 

It should be handled by the hardware without need for software interaction...

[thesurfingalien]

Mea Culpa, I guess. I just had a nice discussion with Gordon Rankin of Wavelength. Gordon is the man who designed the Ayre QB-9 and the AudioQuest DragonFly DAC, as well as the WaveStream® IsoSynchronous USB protocol. He said a number of things that really took me aback. The first thing he said was that yes, USB cables do sound different. They shouldn't but they do. He says the reason is because most manufacturers are unable or unwilling to make their cables with the correct 90 Ohm impedance and be able to pass up to a 2.6 GHz perfect square wave. He says that unless those two parameters are met, the USB feedback mechanism doesn't work because reflections get the signal confused on the computer end. Without it, there's no way for the computer to know that it's sending the data at the proper rate and bits get dropped. Since USB receivers have no error correction (this was news to me) a dropped bit gets interpolated at the DAC, and distortion increases. He says that this situation is not helped by the fact that Windows, including Win 8, generate 12% more hard errors in a digital audio bitstream than does Apple's OSX! He also says to play your computer audio directly from memory for lowest error rate on either platform, and if possible, keep your music on a Firewire, eSATA or Thunderbolt drive rather than USB.

So, If you want your computer sourced digital audio system to sound it's best, find a cable manufacturer that will guarantee his cable's impedance at 90 Ohms* and that his cable can pass, ideally, a 2.6 GHz, or at least a 0.5 GHz perfect square wave (seems like a pretty high frequency to me), and that your music server runs OSX rather than Windows.

 

*Gordon also told me that virtually NONE of the cable manufacturers out there have any way of measuring the impedance of their cables and many believe that a lower than 90 Ohms is preferable because it allows them to sell longer runs. He says that because any deviation from 90 Ohms (higher or lower) is damaging to the data stream, lowering the impedance of the cable doesn't work. Also, an apps engineer at Belden just told me that most cable companies buy their actual wire from suppliers who will customize things like sheath color and dielectric material, and it's possible that many suppliers supply essentially the same cable to multiple audio cable makers.

 

Hi George,

 

I hate to question Mr. Rankin's words, but I wonder why it is that I can use various cheap USB-cables that came with various USB-equipment to connect my Windows 7 laptop to a USB(2)-harddisk and send terabytes of data over a period of 3+ hours, and not have a single error occurring? I have checked this with a USB protocol-analyzer, which reports all re-sends of data-packages...

 

Correct me if I am wrong (or anyone else who has better information, for that matter), but I believe that, despite the protocol for transmission being different, the method of transfer is exactly the same.

 

Kind regards,

Peter

 

In addition... Do most DACs not drop faulty packages? Basically playing 1 ms of silence? If that happens on a regular basis, it should be clearly audible...

[gmgraves]

If you didn't know, there are audiophile Ethernet cables and there's a similar debate over whether they can possibly have any impact on SQ. A reviewer I trust has said that they most certainly do. I intend to give one a try as my next upgrade.

 

I have a JPlay dual-server configuration where the two computers are presently connected via a generic Ethernet cable. That cable is (literally) central to my setup, so I'll be listening for a significant difference. If I don't hear one, the fancy Ethernet cable goes back.

 

I'll go you one better. Understanding the mechanism better, now, I'd be willing to bet money that the high-resolution files that get downloaded from HDTracks and equivalent sites sound different from the same files actually stored on the supplier's servers. That thought ought to get the neurotic juices flowing!

[gmgraves]

Well according to this organisation, there are plenty of USB cables that meet the 90 ohm specification.

USB.org - USB-IF Compliance Program

 

Seems like you just need to find a cable that has passed the compliance testing.

 

 

Seems reasonable.

[Snowmonkey]

The only thing I have ever said was that it "shouldn't" make a difference, and that differences, if they do exist, should be quantifiable (measurable) and presumably are the result of manufacturing defects that could be addressed or avoided.

I wasn't thinking of you specifically when I referred to "objectivists". More those who state that something can't happen, rather than shouldn't happen.

[gmgraves]

Well, it wasn't that long ago that many 'experts' (Gordon included?) were saying that USB cables could not sound different if used in async USB mode. Those of us who tested this knew it was incorrect - USB cables continued to sound different. Having tried a bunch of USB cables myself, I took the plunge (only fairly recently) and bought an expensive 'Tellurium Black Diamond' USB cable. And yes, it sounded totally different to any of the others I had (generally smoother sounding).

 

For about the same outlay as the Tellurium Black Diamond, I had my Phasure NOS1 DAC upgraded to 'a' status. The NOS1a is totally immune to effects of the USB cable and/or PC. I can verify this - the Tellurium Black Diamond now sounds identical to a $1 stock USB printer cable.

 

All the 'experts' (Rankin, Swenson, Smith, etc) are right. But only one has come up with a solution.

 

Mani.

 

 

Ayre says that their latest iteration of the QB-9 is likewise immune from the vagaries of different USB cables.

[gmgraves]

George, I think something may have been lost in the translation here, or was imprecise in Gordon's statement of the problem. I have no argument with the general point that the cable must be able to pass signal variations much faster than the audio frequencies or even digital sample rates we are familiar with. But there is no physical device in the universe that can pass a "perfect square wave," since that requires instantaneous (faster-than-light) variation of the signal. That is also why a "square wave" in actuality has no frequency, at least as we think of frequency in audio, video, or electromagnetism, since no matter how high the frequency of a sine wave, it won't have instantaneous rise and fall time. Thus there is really no such thing as a "2.6GHz" or "0.5GHz" square wave. So general point = fine, specific description = I have a nitpick or two.

 

 

I've been thinking about that, Jud. The more I think on what he said, in the context of the conversation, I may have misinterpreted his meaning. On reflection, I believe that what he meant was that a USB cable needed that high of a bandwidth to be able to pass a perfect square wave at the frequency of the USB signal. A lower bandwidth might cause either integration or differentiation of the wave shape, which could cause an increase in errors or jitter perhaps. I think the 0.5 GHz was meant as an absolute minimum, and the 2.6 GHz was what he considered ideal (and I suspect higher than 2.6 GHz would be all right too). That's the only way to me that those numbers would make any sense. What do you think?