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

Discussion in 'Sound Science' started by mus1cjunk1e, Mar 26, 2011.
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  1. GChief
    I haven't read thru the whole thread so this may have been covered. And up front I am not a believer in high dollar cables in an "average" set up. Better cables yes. Digital 1's and 0's are voltages that can and will be affected by material like any other voltage. Ohm's law is your friend. Then you have shielding for interferences. I work on digital controls for power generation and there are many factors we have to deal with to get good ones and zeros to and from equipment and controllers. It does matter the question is how much in your situation.
     
  2. Whazzzup
    [​IMG]
     
  3. Mediahound
    For USB audio you definitely want a cable that meets the USB audio impedance spec of 90 Ohms including connectors. Many USB cables including so-called audiophile ones deviate from the spec as much as 15 percent. You also want good shielding to reject emf / RF noise etc.

    While you don’t need fancy cable materials like silver, just a usb cable within spec. I use and recommend Supra brand usb cables myself (same brand Uptone Audio recommends) and certainly heard a difference when switching to it from a generic USB printer cable.
     
    Last edited: Dec 19, 2017
    GChief likes this.
  4. bigshot
    What was the difference you heard between your $40 USB cable and the printer cable? How did you compare them?
     
  5. castleofargh Contributor
    it's not about perfection or not, nothing is perfect and no 2 devices or components will give the absolutely identical result to the last electron. arguing that there can be a difference without consideration of magnitudes is like saying water is wet. yes we're right, but we also failed to make a point.

    a proper blind test can tell that something is indeed audible and not just some fancy placebo from sighted test.
    a few measurements could inform us on various things and give a clear idea of the magnitudes involved. which in turn could provide clues to decide if we're likely to be facing a lemon somewhere in the chain, or if the variations are of expected magnitudes.

    but asking others to trust our empty claims about how we heard differences using 2 usb cables, that's like asking me to trust the guy talking about improving his music thanks to pretty rocks. unsubstantiated testimonies aren't all false/wrong of course, but if nothing can separate right from wrong, we can't put any confidence in them.
     
    Intensecure, Magick Man and amirm like this.
  6. Magick Man
    The placebo effect is very powerful. Having been involved with a DBT involving USB cables; $3 (Monoprice) > $1000 (Audioquest Diamond), all 1m, there was no audible difference.

    and yes, my friend finally noticed that someone swapped his cables, but only because he needed to move his gear. :laughing:
     
    Last edited: Dec 19, 2017
  7. dmance
    Hey guys, here's a lesson in objective rationality...
    Some DACs come with a bit-perfect test file. If you play that file from your source (say thru USB) the DAC will light up with a green 'OK' light.
    So, try this test with a spec-grade USB cable and ...green light. Try it with a mid-grade fancy cable and
    ..green light. Try it with a $1200 audiophiles cable and ...green light.
    Repeat the same test with your ears and ...$1200 cable sounds better. No joke, same bits ...yet different SQ with phrases like deeper blacks, better sound stage, more intimacy. What's up students?? Anyone know? Raise your hand...yes you in the back.
    That's right ...'something else' is going on to affect the sound. And that something else is analog noise at radio frequencies is being conducted by the USB cable from the source to the DAC. The electronics in the source (PC, MaC, laptop, streamer) throw off RF noise ...gets transmitted on the cable and the poor DAC sees that noise as it seeps from the USB interface chip to its own ground and signal planes causing variations in reference voltage levels. So at the output of the DAC, those 1s and 0s get modulated to slightly changing output waveforms ...and dammit, we hear that. Not as pops and clicks...that would be digital noise. We hear it as slight wobbles in the transients and our brain then decides that the music is not quite real.
    So ...fix the problem of RFI getting sent along the USB and you have the beginnings of a solution. Cables block different frequencies differently. The variation in sound is the color of the cables' metallurgy and construction as a RFI filter.
     
    Last edited: Dec 19, 2017
  8. GChief
    I am new here but have been hearing the same cable discussion for 40yrs. Plus I am professionally trained in critical listening, I was also teaching a class when I retired. Short and to my point, just because you can’t hear it does not mean it is not happening. The placebo effect is a 2 way street! I have been arguing with EE’s all day and don’t feel like it in my off time so I will read everyone’s OPIONONS and maybe learn something. BTW Just because you modeled it does not mean it will work in the real world :beerchug:
     
  9. amirm
    That is true. For that reason, we try to triangulate the truth. We measure and look at system architecture. And we take into account years of psychoacoustics research. All of this currently points to statements regarding fidelity changes to not be correct.

    Sure, if you hear noises coming from your PCs as some internal DACs and even external ones do, there is indeed a problem. But then again, we can easily measure that effect.

    By the way, I don't believe placebo is the main problem. Many people who don't believe in something hear improvements they did not expect.

    The issue is a much less known but even more insidious which is the elasticity of our hearing. When we are bombarded with music signals the brain chooses what it stores and remembers longer term. In other words, it is a highly lossy process. You then get a new cable and when you insert that into the system, you pay real, intense attention to what is being heard. That immediately causes you to hear detail, "air," subtle things that you were not hearing with your standard cable. None of that is related to the cable change. It has to do with changing your state of mind.

    This is why when we perform the test blind and we don't even tell you if a change has or has not occurred, these differences disappear. During the blind test you will indeed hear differences but then the same difference is heard with both samples, causing essentially random outcome.

    This is easy to prove. Play any piece of music on your system for a few seconds. Stop, and play it again and this time pay real attention to what is being played. I guarantee you that you will higher fidelity now! Do this over and over again and in every cycle fidelity will change! Sometimes you hear more detail, sometimes you don't even though you are playing the same track over and over again with no hardware change!

    Clearly placebo is not in place in the above scenario as even knowledge of the outcome being false, causes you to still go there!

    This is why the starting point here needs to be objective measurements and understanding of the system which are far more reliable than the AB test.
     
  10. GChief
    I agree with most and understand what your saying. I had to learn and teach people how to pick barely audible man made sounds out of ocean background noise. And with 30+yrs working on digital electronics and sound processing, transmission etc I also know that the cables will be differnet, now hearing it...

    I would love to be in a study before my ears get to old!!
     
  11. bigshot
    I think people can be trained to strengthen their expectation biases too. Have you tested this blind in a controlled test? If so and it was proven you could detect the difference consistently, what kind of sound were you hearing as being different?
     
  12. Mark Bajkowski
    I agree that jitter might not normally be audible but, what's might be more important here is that USB cable does not perform its "good wire" function on its own: the rest of setup plays a role that may not be overlooked at all. We all may agree (besides those who have other beliefs here) what the "faulty" is but, logically speaking, we can't be really sure what the "perfect" means. In short, "perfect" is not the binary alternative to "faulty": USB cable is unable to determine what is perfect without some sort of a truly perfect reference and error correction because that is not a part of the USB protocol.

    We can agree (again, besides those who have other beliefs here) that external influences on the USB cable signal matter. If so, then we must agree that it will especially matter for a "perfect" cable. Additionally, if USB cable is used with an asynchronous DAC (which further eliminates jitter's influence) that such setup may actually create some audible problems using the same "perfect" cable if the cable is "too fast" because the USB cable and interface then plays a role in the asynchronous DAC sending a feedback value to the PC/streaming server effectively manipulating momentarily its too-fast/too-slow state. A too-fast cable will not be our best friend for that. In other words, some "perfect" cables may (or, per my more general "philosophy", may not) sound bad in some setups too. Let's allow the listener to decide, people!
     
    Last edited: Dec 19, 2017
  13. bigshot
    A piece of audio equipment has to be seriously broken or designed by a chimp to not work perfectly with a $5 USB cable, like an Amazon Basics cable.

    Jitter is inaudible in home audio equipment, even the cheapest. As Nick Charles once pointed out, the only piece of equipment he ever found that had numbers even approaching in the neighborhood of audible was a media server made by McIntosh a decade or so ago. Everything else is an order of magnitude below the threshold.

    Jitter is a hoodoo designed to get you to spend too much on specs you can't hear. Expensive cables are what they try to sell you if they think you're a "live one" on the hook willing to spend too much on everything.
     
    Last edited: Dec 19, 2017
  14. Mediahound
    There's a reason upgrade USB cables (and also improvement devices think Audioquest Jitterbug, Schiit Wyrd, etc.) sell; people hear improvements with them and keep buying them.

    If the cable really made no difference, people would just use the cheapest one possible and never buy anything else. In fact, if the cheapest USB cable was better, you'd see people seeking them out of office surplus, dumpsters and dumps, and turning them around on eBay since they'd be so good.

    I have always found it curious that people who truly believe that something is not possible have to go to such great lengths to attempt to “disprove” it. If I think something is truly hogwash, snake oil, or whatever else you want to call it one can simply ignore it. If there is no truth to it, said product will eventually fade into the sunset as the market will take care of it.

    The bottom line: don't like it, don't buy it. Obviously not every product is for everyone. Some cables are build for no compromise. It does not mean it's snake oil, it just means that you are not willing to spend the money vs. taking a risk on compromise and spending less. Just calling everything 'snake oil' by default because one does not understand or agree with the benefit isn't exactly going to win one any credibility awards. And if one hasn't even compared the cables themselves, and instead just blindly believes something without any of their own personal experience, it’s kinda difficult to take them seriously.
     
    Last edited: Dec 19, 2017
    GChief likes this.
  15. bigshot
    If people did line level matched direct A/B blind comparisons they would buy cheap USB cables, because in a DBT there is no audible difference. Something has to be broken to get to that level. The reason people buy expensive cables is placebo. I would be happy to ignore snake oil if people who are subject to placebo effects wouldn't go on internet forums and give lousy advice to newbies.

    Please show me a cable that has audible differences. Then show me the measurements or the DBT test that proves it.
     
    Last edited: Dec 19, 2017
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