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USB cable supposedly improving DAC sound quality? How can I take other posts seriously after that?  

post #1 of 256
Thread Starter 

I was just browsing around the forum, reading various threads and I ran across a post where someone mentioned the huge upgrade in sound that an upgraded USB cable brought their DAC. Then another person chimed in talking about how great the USB upgrade was. They were talking about increased sound stage, "musicality", "tonality", and all the usual stuff I hear mentioned with regards to sound quality. The only problem is, it's physically impossible for an upgraded USB cable to provide those things. USB is digital. The data going from the computer to the DAC is 1s and 0s. It either gets there or it doesn't. I.e. music either plays or it doesn't. It's not analog, so the cable simply can't affect the sound that way as there is no actual sound traveling through the cable, just data that gets decoded by the DAC. It's just like saying a $100 HDMI cable makes the picture on your HDTV really "sparkle" and really "brings the colors out". It's just physically impossible.

Now it's possible that a well shielded USB cable could improve sound quality over a cheapo cable by reducing outside interference, but they weren't talking about lowered hiss or interference sound. And this wasn't the first thread I've heard people talking about better sound from a USB cable on this forum either.

What bothered me was the realization that if Head-fi'ers are making posts like that, and even agreeing with one another on such patently false information (thus creating a consensus which can further sway others' opinions), how can I take anything that is posted here about the sound quality of amps, DACs, upgraded cables, or even headphones seriously? How likely is it that so and so amp doesn't actually increase sound stage or "musicality", but is purely placebo. Or a DAC or headphones. I've seen a confirmed case (usb cables), so that makes me wonder about every other opinion on sound quality that I read here.

How much of this stuff is just in Head-fi'ers heads as a placebo affect? How much do we want the $300 upgraded Cardas headphone cables to be better so we hear it that way and post about it, thus priming others to feel the same way when they buy there's because now they heard it's better so they look for a change that isn't there -- and hear it. I feel like the natural group-think that online forums have contributes even further to this, echoing around each individuals placebo affect so that they not only get it from themselves but get it fed back to them in the form of a group consensus (which is a powerful force on the brains decision making processes and on the way we experience things).

I'm interested in everyone's opinions on this. I don't have much personal experience with different equipment, so it's hard to evaluate others' evaluations because I don't have a good frame of reference. But reading things like that a USB cable noticeably improved sound that a DAC was putting out makes me take everything else with a HUGE grain of salt.

Now on the flip side, I just bought a pair of Sennheiser HD600s (my first pro quality headphones) partially based on feedback I read here and they sound absolutely phenomenal -- worlds better than any headphones I've ever heard in my life. And they are highly reviewed here, so obviously there is good info here. I just wonder how much other info found on this forum is purely placebo.

post #2 of 256

Make sure to take your salt shaker everywhere you go on this forum.  Even with regard to headphones, amps, and sources (and not "tweaks"), there is a lot of BS.  Heck, these days a lot of people will recommend or comment on equipment they have never even heard, let alone owned, simply based on what they have read from others!  Just as bad are those who are blatant fanboys, not to mention the fair share of shills.  Hang around here for just a few weeks, and you will very quickly be able to tell from which angle everyone is coming from.  There is a lot of worthwhile information and experience on this board, so don't lose hope :) 

 

In regard to the usb cable-esque stuff, including power cable enthusiasts...  suffice it to say that in the end, it's best to just ignore the cable people - doubly so for the digital cable people

post #3 of 256

I don't use USB to S/PDIF transports or USB DACs, but the only thing I can think of that might possibly make a difference would be the wires in the cable handling the power.  I do hear differences to my gear with different makes of both AC and DC power cords, so at least in my opinion the same thing could be happening with USB cables.  I'm certainly not claiming this is the case, just a hypothesis.  The other possibility is placebo, of course.


Edited by IPodPJ - 3/26/11 at 2:20am
post #4 of 256

I prefer a well-built cable over a cheap one. If I spend a lot of money on my gear I don't feel comfortable plugging ultra-thin bargain cables but I don't believe they noticeably improve the sound. The only thing I do believe in is upgrading your power supply. It's the same with computers. A stable PSU with a stable volt rail makes your system run smoother and without hiccups. In my experience and opinion, same thing for an amplifier and DAC. 

 

There are a lot of threads on this same subject. Check out the "amplifier A/B comparison" thread for some interesting insights. $100 Fiio E9 vs. $1000 Beta22 for example. 

post #5 of 256

Note that SPDIF cables do affect the sound, because of jitter. In SPDIF, not only is the clock is recovered from the signal, it uses biphase mark code, which makes the jitter also signal dependent. There was a paper explaining this very well, but I can't find it at the moment.

 

This will have to do, but it's a bit too technical:

http://www.tnt-audio.com/clinica/diginterf1_e.html

 

Because of this, cable bandwidth, noise, reflections from the connectors, even kinks in the fibre (when using toslink) will all affect the sound. If any of this applies to USB as well, I don't know, it will depend on the protocol.

 

A true asynchronous connection, on the other hand, can never have this problem, as the clocks are independent. It can, however, occasionally lose a sample.

post #6 of 256

I hate optical cables, mostly due to their fragility. The only one in my setup is from the PS3, and only because they didn't include digital coax.

 

I prefer to stay out of the more questionable angles entirely.

 

 

...but I have to admit that I'm running Monster speaker cable to my speakers... because it was the cheapest at the store for the length of cable that I needed, and I wanted to set them up the same day. Honest.


Edited by gsilver - 3/26/11 at 9:01am
post #7 of 256



 

Quote:
Originally Posted by Wildstar View Post

Note that SPDIF cables do affect the sound, because of jitter. In SPDIF, not only is the clock is recovered from the signal, it uses biphase mark code, which makes the jitter also signal dependent. There was a paper explaining this very well, but I can't find it at the moment.

 

This will have to do, but it's a bit too technical:

http://www.tnt-audio.com/clinica/diginterf1_e.html

 

Because of this, cable bandwidth, noise, reflections from the connectors, even kinks in the fibre (when using toslink) will all affect the sound. If any of this applies to USB as well, I don't know, it will depend on the protocol.

 

A true asynchronous connection, on the other hand, can never have this problem, as the clocks are independent. It can, however, occasionally lose a sample.


But are any of these differences verifiably audible ?

 

To date the empirical evidence is no except in the case of actually faulty cables, to date published evidence of audibility of jitter places audibility at levels well above any sligthly iffy cable viz several nanoseconds, digital kit measured by stereophile at 14, 9, 3 and 4 ns of peak-to-peak jitter has been subjectively reviewed as fine, i.e these massive levels of jitter have not caused reviewers to flee clutching their ears. Published peer reviewed AES articles from researchers at Dolby Labs and NHK (Japan)  have tested listeners' ability to detect jitter, in both cases very high levels of jitter (up to 250ns random jitter, 10 - 20ns correlated jitter) were extremely hard to detect.

 

I'd simply not worry about jitter until I had better evidence that it is audible at levels found in competent digital audio kit.

post #8 of 256
Quote:
Originally Posted by nick_charles View Post



 


But are any of these differences verifiably audible ?

 

To date the empirical evidence is no except in the case of actually faulty cables, to date published evidence of audibility of jitter places audibility at levels well above any sligthly iffy cable viz several nanoseconds, digital kit measured by stereophile at 14, 9, 3 and 4 ns of peak-to-peak jitter has been subjectively reviewed as fine, i.e these massive levels of jitter have not caused reviewers to flee clutching their ears. Published peer reviewed AES articles from researchers at Dolby Labs and NHK (Japan)  have tested listeners' ability to detect jitter, in both cases very high levels of jitter (up to 250ns random jitter, 10 - 20ns correlated jitter) were extremely hard to detect.

 

I'd simply not worry about jitter until I had better evidence that it is audible at levels found in competent digital audio kit.

Yor are one of a few who tell the truth!! 
 

 

post #9 of 256

Well, random generated jitter is not the same as cable induced jitter.

I can say that there is definitely an audible difference between a plain OEM cable and a pure silver Siltech or Kimber cable, between a Audiolab 8000CDM and a Sonic Frontier SFD-2 (DAC) or a HHB CDR-850 (for headphone listening). I can tell which is which, blind. At least I could, back in the day, it's been many years since I've tried it... Of course, I have no way of proving this scientifically.

post #10 of 256



 

Quote:
Originally Posted by Wildstar View Post

Well, random generated jitter is not the same as cable induced jitter.

I can say that there is definitely an audible difference between a plain OEM cable and a pure silver Siltech or Kimber cable,

 

You do know where we are ? - here we can ask for stronger evidence for these claims, how did you tests this , how did you avoid bias created by simply knowing what you were listening to, how come the differences between copper and silver or between two (even very) different "normal" cables do not show up when someone measures the FR ?

 

 

between a Audiolab 8000CDM and a Sonic Frontier SFD-2 (DAC) or a HHB CDR-850 (for headphone listening). I can tell which is which, blind. At least I could, back in the day, it's been many years since I've tried it... Of course, I have no way of proving this scientifically.

 

This is more likely but unless you carefully level match two devices the most likely cause of perceived differences is volume, I have 4 CD players/DACs, no two have the same output levels, I can blind test (14/14) at least two of them, until I adjust for level differences (0.7db).

 

Since the CD standard properly implemented produces sound that is perceptually noiseless (contingent on a good DDD recording) and with imperceptible distortion and amazingly even frequency response, why (invoking only the laws of physics and our current knowledge of psychophysics) should we expect two competent CD players to sound different ?wink.gif



 

 


Edited by nick_charles - 3/26/11 at 12:46pm
post #11 of 256

I did not explain myself properly.

The source was always the 8000CDM. The CDR-850 was only used as DAC, for it's headphone output.

The cables were swapped by my father, who wanted to know my opinion on them without telling me which was which. He is a great cable fan, and has tried a very large number of them through the years. In my opinion, from what I've heard (my father disagrees), there is indeed little to no difference between copper cables, but the diference between them and silver cables is noticeable, specially high-end ones like Kimber or Siltech.

Like I wrote, this not scientific at all, nor do I have the means to provide scientific proof. However, I don't believe the "scientific tests" featured these kinds of cables.

 

post #12 of 256

did you measure the resistance of these cables to ensure the difference you heard was not yet another simple difference in volume? 

post #13 of 256

We are talking about a digital connection.

post #14 of 256
Thread Starter 

That's exactly my point -- it's digital. By definition, it can't make a difference. Just like gold plated connectors on an HDMI cable can't make a TV's picture look better. It's all ones and zeros. Any difference must be placebo. Silver can't make 1001001011100101 sound better than copper confused_face.gif
 

Quote:
Originally Posted by Wildstar View Post

We are talking about a digital connection.



 

post #15 of 256

 

Quote:
Originally Posted by mus1cjunk1e View Post

That's exactly my point -- it's digital. By definition, it can't make a difference. Just like gold plated connectors on an HDMI cable can't make a TV's picture look better. It's all ones and zeros. Any difference must be placebo. Silver can't make 1001001011100101 sound better than copper confused_face.gif


Oh please, not again. It's not just "ones and zeroes". That's a gross oversimplification of what a digital connection is. An hardware implementation of "digital" is way more complex than that, especially when you carry or have to recover a clock. Under that respect, it has many aspects that are pretty much analog in nature.

 

For most USB devices (except the asynchronous ones), the USB cable is part of a system which can be affected by noise, jitter and the like in more subtle ways than making a 0 into a 1 or losing a packet. It's not a matter of silver vs copper of course  rolleyes.gif  However, as I pointed out in other threads, it's probably quite safe to say that the cable is usually a very minor contributor of problems in a typical USB connection, compared for example to the poor quality of the clock found in the source computer. While I do bother about low jitter (maybe beyond audibility but it's another topic alltogether), I wouldn't bother playing with USB cables. A decently built one is all that's needed imo.

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