USB Cables: The High End

[kana813]

After reading this thread and some USB cable reviews, I can buy into the idea that a well designed and constructed USB cable might improve SQ by helping to control the EM and RF interference generated by all computers.

 

Since everyone is aware that these PC noise issues exist, I'm surprised that more USB DAC makers don't

use opto-couplers like the Stereophile Product of the Year, Ayre QB-9.

 

If a USB DAC or USB converter had opto-couplers and a well designed internal linear psu, the USB cable

shouldn't be an issue.

 

If I had to spend $500. or more on a cable to get my USB DAC or USB converter to sound better, I think I'd starting looking for a different unit.

 

[Part-Time Audiophile]

I spoke with the guys over at Ayre and they, perhaps regretfully, suggested that the USB did matter. Even on their DAC. Not sure what that means for the opto-couplers thing ....

 

[cfmsp]

"If I had to spend $500. or more on a cable to get my USB DAC or USB converter to sound better, I think I'd starting looking for a different unit."

 

Couldn't have said it better myself. Indeed, I said pretty much the same thing very recently in a different thread. If the problem requires a $500 USB cable to 'fix', I"d look for the source of the problem and try to fix that rather than spend money on a cable.

 

I don't buy into the idea that a $500 USB cable is needed for, let's say, maximum resolution, nor for proper reproduction of input signal at the output, with respect to meeting the requirements for 'digital' transmission. For Async, even less should be needed to successfully deliver the signal intact, IMO.

 

I can believe that better cables prevent artifacts from damaging the signal along the way - which by the way, is likely the reason that shorter USB cables sound better, i.e., they have less chance to pick up noise - but if the issue is such that a $500 - $2800 USB cable are required for better sound, I remain unconvinced that there aren't less expensive ways to solve the problem(s).

 

But then again, I use a very inexpensive ($15) Firewire cable, as apparently do most people with a Firewire DAC.

 

YMMV,

clay

 

 

[kana813]

Clay-

 

I saw your comments over on:

 

http://www.audioasylum.com/cgi/vt.mpl?f=pcaudio&m=65794

 

and the shorter is better comments by Mr.Rankin.

 

I wish Mr.Rankin could comment on the "basic tests," he does

on USB cables to evaluate their performance.

 

I agree with your suggestion to look for the "source of the problem," rather than spending money on a bandaid fix.

 

Aloha,

 

Dan

 

 

 

[Part-Time Audiophile]

BTW, is anyone actually doing A/B testing with this class of cabling?

 

[Part-Time Audiophile]

"If I had to spend $500. or more on a cable to get my USB DAC or USB converter to sound better, I think I'd starting looking for a different unit."

 

Not sure where this tangent is going, or how it got so off course or why (other than as as an excuse to extend a rant), but I don't think anyone said that USB DACs require expensive cables to "fix" them? What does that even mean, "fix them"? Are you implying that USB DACs are all broken, as a class? Or that non-USB DACs, b/c they don't need expensive cables are therefore superior? If the latter, please elaborate. If not, then what are you talking about?

 

"I don't buy into the idea that a $500 USB cable is needed for, let's say, maximum resolution, nor for proper reproduction of input signal at the output, with respect to meeting the requirements for 'digital' transmission. For Async, even less should be needed to successfully deliver the signal intact, IMO."

 

Look, at the risk of belaboring the obvious, cables aren't "fixes", and precious few are seriously looking at cabling as effective tone control. Those of you that are, stop it. More strongly, no cable is going to transform your DAC into a DCS stack, no way, no how. Your USB DAC, whether it's $100 or $2500 (or more), will sound exactly like what it sounds like, regardless of what cable you hook up to it.

 

The question on offer was: what if you could make your great DAC sound better? If this is possible (still an open question), then you have to ask yourself -- what does "better" mean and how much "better" is enough to justify the cost?

 

FWIW, I take it as read that there is no unit out there, regardless of cost, that cannot be made to sound better that it is when it ships from the manufacturer. Perhaps you disagree. If so, fine, you can stop reading and responding and be happy with your Belden and Belkin cabling -- you're done! If not, then as I've suggested before, any improvements that I believe that are actually on offer, especially wrt cabling, are all going to be rather small, especially when weighed against the overall sound of the system.

 

But is $500 too much to spend, if that 1% improvement is something that is audible and desirable to you? Coming at this another way, what makes you think that your calculus on this question has any relevance to mine?

 

As for an extended discussion of why "digital transmissions" aren't actually digital, but instead, electrical and therefore analog, feel free to dig around as this has been covered at extreme length elsewhere (on this very site, for example, by Gordon Rankin, Steve Nugent and many many other people far smarter than me). Whether you believe them or not is another point entirely, but as a layman, I'm not sure I have a right to an opinion on the matter. YMMV.

 

[Part-Time Audiophile]

I agree with your suggestion to look for the "source of the problem," rather than spending money on a bandaid fix.

 

As I suggested above, this is the $64k question. I think it'd be better said this way, however:

 

"Would the money you're willing to spend on a 1% improvement be better spent instead on a potential 10-15% improvement?"

 

Just a thought.

 

But again, choice in cabling isn't a "problem" that needs to be "fixed" nor does it imply that one exists. It's a valid area of improvement, especially if one is doing so with the open-eyed expectation that the overall improvements to be gained may and probably will not be large. Or in most cases, even audible.

 

[kana813]

"BTW, is anyone actually doing A/B testing with this class of cabling?"

 

How can you A/B USB cables on a USB DAC or converter that only has

one USB input?

 

"Would the money you're willing to spend on a 1% improvement be better spent instead on a potential 10-15% improvement?"

 

Yes, if you want to improve a "great DAC," IMO, a $500. cable isn't the way to go. If you want better sound, go inside the boxes and improve things like the TX/RX components, psu, clock or analog output stage. Since you have a modified DAC, hopefully you know this.

 

 

[CG]

Actually, I'll disagree some here.

 

The problem that USB cables may be addressing may in fact not be the DAC at all, per se. More likely, it's a *system* issue.

 

In almost every audio system, there are more undefined grounding and common mode paths than you can shake a Firewire cable at. All of these can and likely will affect the sound output from the speakers or headphones. This is not voodoo or some exotic audio situation - it's plain old analog system design considerations. Unfortunately, not much of this is talked about in the audio world, never mind that anything might be done about it.

 

Whenever I read about some guy fixing his system by adding some kind of "ground" wire to get rid of RF, I just chuckle. Yes - what he did may well have improved his situation a lot. But it wasn't because he added some miracle EMI drain to the system. Ground is an arbitrary reference point and nothing else. That wire that's used as a ground connection changes impedance with frequency in a radical way simply as a function of its effective length. "Ground" for RF is anything but.

 

So aside from the usual role of transmitting the desired data signal from the computer to the DAC, a USB or Firewire cable also adds a common mode connection between the computer and the DAC as well. It's not a bug - it's an undocumented feature. If you are concerned about what effect the power wire in a Firewire cable has, then you should equally be concerned about the ground connection. By definition it is as dirty as that power connection. What do you think those bypass capacitors in the computer power supply actually do?

 

I could go on for pages on this subject, but will spare all of you, as well as my fingers. Anybody with more interest in the subject should look here for starters: http://www.hottconsultants.com/ A college freshman EE course about nodal analysis would help, too.

 

And no, I'm not saying that $10K USB cables are a magic solution either. But they are not necessarily snake oil remedies either. If you believe that ground connections make a difference, you fundamentally should also accept that USB cables can make a difference, too. Even if you don't like the price and object on that basis.

 

Your DAC may suck. Your computer may suck. Your power may suck. Maybe not. But when you put them all together, they are not the same components as when they are used in isolation.

 

Usual disclaimer: I am not in the audio business. I never was. Nobody in my extended family ever was, at least as far as I know. That is unless you consider working as a cashier while in high school for a department store that sold small appliances as well as ladies underwear, sports equipment, cameras, and the usual array of stuff like that. Same for my dogs. I *have* bought audio equipment, however.

 

[cfmsp]

 

No time for a lengthy reply here, but CG has the just posted the jist of my response, IE, it's all a system.

 

One way to think of this is - we are all independently implementing (i.e. engineering, whether we know it or not) solutions that previously were single-box CD players. Every component in our 'solution' has an electrical/physical connection and therefore interaction with one another. Make sense?

 

In a single box solution the cables, I"m fairly confident, did NOT cost $500, let alone $2800. ;0

 

A simple analogy - people sometimes unwittingly use cables (connecting, e.g., separate preamps & amps) as expensive tone controls due to impedance issues. This type of thing could be occurring in the computer to DAC interface with a heretofore not well understood problem. What Dan and I are saying effectively is - if your amp and preamp don't interact well together, using an expensive cable to fix an impedance mismatch is not attacking the source of the problem.

 

Feel free to spend money on cables as you wish, but that's not how I would do it.

 

cheers

clay

 

PS, no one poster gets to prescribe how the conversation in a thread flows, even if they were the opening poster.

 

PPS, one man's 'rant' is another's call for sanity.

 

 

 

[Elprior]

What a fine CA Judge Dredd you have become

 

All of you be advised !

Either you go the firewire way, or be... judged.

 

Elp

 

[CG]

My take is that consumers have limited control over what goes on between equipment they select. Unless they build the gear themselves or choose to modify gear they purchase, there isn't all that much they can do to optimize their system electrically - acoustically is a different story.

 

So, if you find that hanging your USB cable from paper cups makes an improvement, why not? Or if using a separate power conditioner dedicated entirely to your computer improves the bass to your taste, why not? As long as basic human rights and criminal laws aren't violated, it's between you, your banker, and those you live with.

 

The big alternative, aside from the soldering iron, is to keep swapping out equipment until you get something you like. Certainly enough people do that.

 

[cfmsp]

 

nice,

 

I'm not much of a reggae musician (wikipedia is your friend), so can't say necessarily that Judge Dredd fits me.

 

General Ludd? perhaps!

 

 

;0

clay

 

 

 

[CG]

Umm, today Wiki wasn't your friend.

 

Judge Dredd is a science fiction character. English in origin. Portrayed on the screen by Stallone.

 

http://en.wikipedia.org/wiki/Judge_Dredd

 

 

[cfmsp]

 

"Umm, today Wiki wasn't your friend."

 

CG, I see your point, and raise you one!

 

I was using wikipedia as a source for plausible deniability for the connotations ELP was suggesting by invoking the reference to Judge Dredd (which you point out and which I had never hear of). Thus my reference to Judge Dredd as a reggae musician (and the pointer to Wikipedia to validate such).

 

always glad to read your posts, CG.

 

 

 

[Elprior]

@CG : u're right.

@Clay : lol, for previous and latest posts.

 

Elp

 

[audioAl]

Get ready for backwards compatible, download and upload at the same time, USB 3.0 cables next year. Two mainboard companies already sell motherboards for these new cables. Big advancement! audioAl reporting!

 

[CG]

Now I'm going to cause problems. Again.

 

Like most of you, I have a computer driven digital audio source.

 

The computer is a Mac Mini.

 

The DAC is USB fed. I won't get into which DAC it is (so don't ask!), but I will say that it is very highly rated by people on CA and elsewhere, and it sells for far more than the computer does.

 

The two are normally connected with a moderately expensive 0.5 meter cable. Don't ask which cable; I will only say that it didn't arrive in a blister pack.

 

I thought I'd try an experiment around the USB connection. So I "obtained" an eval board for a fancy USB isolator IC. (Don't ask about this either, because that's not the point and I won't tell you...) This particular eval board is set up so that both the VBUS and the Ground lines from the computer are entirely isolated from those connections to the DAC. In fact, they are as isolated as they can be while still being on the same equipment rack.

 

Just to make it even more interesting (and easy), I powered the downstream side that connects to the DAC with some alkaline batteries.

 

This was inserted right in between the computer and the upscale USB cable that feeds the DAC. A de-ferrited Kimber USB cable connected the computer to this eval board.

 

The result? Pretty noticeable difference. To me, all good. How good? I have no idea how to quantify that, but it was pretty good. At least to me. Was this from breaking the VBUS connection? From breaking the Ground connection? From using a battery supply? All of the above? Some of the above? None of the above (I may have imagined it...)? I'm not sure. I'm not entirely sure I even care.

 

BUT, never mind all that... Here's the point.

 

I bypassed the alkaline batteries with an electrolytic capacitor. It was an OS-CON something or other. It sounded different than with no bypass. So, I thought I'd neaten up the kludge some. The OS-CON's leads were about a 1/4 inch too short, so I dug around and found a similar Panasonic traditional electrolytic cap and installed it in the OS-CON's place. It sounded a little different. Not much, but a little.

 

Keep in mind that this battery supply only powered the secondary side of this isolator chip. The power for the chip runs through a regulator to do so. It also powers a small portion of the digital section of the DC that is normally powered from VBUS. I'd guess that this goes through a regulator and filtering in the DAC as well.

 

How many levels of isolation is that? The bypass cap *still* made a modest difference.

 

So, yeah; I think that something like a cable can make a difference. If that bypass cap could, a cable could, too. The cable actually passes the USB signal, as well as a lot of other signals, too.

 

[cfmsp]

 

CG, thanks for upsetting the applecart, quite interesting.

 

 

"So, yeah; I think that something like a cable can make a difference."

 

You've mentioned this a couple of times now, so I thought I'd (re-)clarify my point of view. I've never believed that USB cables can't make a difference, if I did, I'd be a direct contradiction to the guy who 'invented' USB DACs (you know the one).

 

What I said is - I'd investigate the sources (which I assume to be other than the cable) of the issues before spending $500 or more on a USB cable, as I personally would rather make investments in components other than cables.

 

Mind you, I"m not against cable investments - I'm awaiting a pair of balanced ASI Livelines to connect my ULN-2 directly to my J2, as an example - but only after other issues have been resolved, and in computer audio - as you've pointed out - there are LOTS of factors that could influence the sound.

 

clay

 

 

 

 

[CG]

Well yeah, but as a consumer what else can you do aside from optimize the cable situation and things like that? Buy a new computer? I'd think a new Mac Mini would be as practically good as one could purchase off the shelf. Buy a new DAC? Again, just what are the options there? Then when you put them all together, you get a different situation entirely.

 

Not too many people want to become specialized engineers in their hobby time, nor do they want to make the investment. So, their options are limited. This is the nature of a hobby like this that would seem to be widespread because so many people listen to music through their iPods, radios, and computer speakers, but it is not. Being an audiophile is not quite like being an aficionado of Stanley Steamers and working to maintain your collection, but it is closer to that than scrap-booking is.

 

[cfmsp]

"Well yeah, but as a consumer what else can you do aside from optimize the cable situation and things like that? Buy a new computer? I'd think a new Mac Mini would be as practically good as one could purchase off the shelf. Buy a new DAC?"

 

well, yes, when one starts making investments in the $500 range (not to mention $2849) then these (DAC, computer, etc.) become viable options. I'm no fan of converters, but we also have converters in the $500 range that offer alternatives to mere cables (while introducing an additional cable into the equation, so perhaps a net loss).

 

We also have optimizing AC as a worthwhile endeavour, etc.

 

Call me simplistic and pedantic, I just have a hard time believing that an expensive USB cable is required for optimum sound. Perhaps it's because I don't hear/read of similar requirements related to Firewire interfaces? Actually you could bet on that.

 

As always, CG, thanks for your response.

 

Judge Ludd (or should I say Judge Ned)

 

PS, just saw this on another thread, you might recognize it.

"That seems like a lot of work when a new DAC would probably do better..."

 

replace 'work' with 'money', and this could make a portion of my argument.

 

 

 

 

 

[Lars]

Expensive USB cables are not required, but can and often do sound different from each other. Some even sound so good that they have to be purchased.

 

[CG]

"Perhaps it's because I don't hear/read of similar requirements related to Firewire interfaces?"

 

Perhaps that's because there are no existing Firewire products marketed this way.

 

I think the thing that clouds this discussion, as it always seems to, is that people look at cables (or whatever) and say to themselves something like, "$200? &%#@ that! I could build one of those for $7.41, and it would be as good." And, perhaps they could. More likely, they'd invest tens if not hundreds of hours and the equivalent raw parts to get there. If that's what you want to do with your time, that's fine. BUT, that's a separate argument over the efficacy of a cable solution.

 

I myself always wonder why software costs so much. The BOM for software is close to zero. The labor should be inconsequential, since these same people would be fooling around on their computers anyway - for no pay - if they weren't putting software together...

 

[Part-Time Audiophile]

"Expensive USB cables are not required"

 

This is where I think the argument goes off the rails, so it's worth repeating. Cables are required -- obviously -- but expensive ones are not. By no means. And no one, AFAIK, is saying otherwise.

 

Expensive, or more properly, *alternative* cables (whatever their price might be) are merely an option.

 

As such, getting worked up about the DAC b/c it uses an interface that might possibly perhaps who knows benefit from those cables is beside the point. The point isn't the DAC's input. The point is that the quality of that input mechanism might be variable.

 

I think it's interesting to note that, regardless of the input, every DAC has analog outputs, yet no one gets worked up over the fact that those outputs might be impacted by the design of the wire that connects to them.

 

As they (used to) say (even though this might horribly date me): garbage in, garbage out.

 

[cfmsp]

 

 

"As such, getting worked up about the DAC b/c it uses an interface that might possibly perhaps who knows benefit from those cables is beside the point. The point isn't the DAC's input. The point is that the quality of that input mechanism might be variable. "

 

Let's presume for argument's sake that jitter is the largest known detrimental factor (relative to those things arriving at the input of a DAC) that influences the sonic quality in computer audio playback. Personally I'd spend the bulk of my money reducing the sensitivity to jitter within the DAC (via, e.g., high quality local clocks fed asynchronously) as opposed to trying to filter/eliminate jitter with a (more expensive) cable.

 

That's the most practical example (I can offer) of what my point has been all along.

 

YMMV. I'm cool with that, are you?

 

clay