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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. RRod
    It would seem the simple solution is for the party making the claim to provide a) a sound clip where a difference can be heard, b) a reference signal and its reference measurement for setting the sound level, c) the noise characteristics of the room/chamber/headphone enclosure used for the test, d) the equipment used for all measurements and playback.
  2. bigshot
    In my sig Ethan Winer puts the most annoying noise possible under music and dials it back a notch at a time. It ceases being audible LONG before it hits -110dB.
    Last edited: Jan 2, 2018
  3. castleofargh Contributor
    I understand that not everybody can visualize what a log scale really means, after all dB are not linear they don't even really have a unit because it's a ratio. but we use them to discus so many different subjects, sometime positive, sometimes negative, sometimes it's a dynamic range, sometimes a loudness level, sometimes a voltage and often all of the above. and when everybody keeps arguing about some values beyond -90db like in the farce that is 16 vs 24bit audibility arguments, it's understandable that people would assume those magnitudes to be easily audible. add marketing to all that and people go from being unclear to getting misguiding or plain false ideas put into them. so I really don't blame those who have a hard time visualizing the magnitudes we're talking about sometimes.
    but anybody can find some player where the volume is displayed in dB instead of %, and fool around to experience what is -30, -50, -80, -110dB below their usual listening level. it's not the same as noises at those magnitudes while playing the music at normal level, but it's a start to get an idea of how loud those things really are. if after doing that and reading just a little bit about auditory masking, the person still decides to believe that -100dB stuff is what's ruining the soundstage or making the sound unnatural in his music, then I doubt any explanation will ever work on him.

    meanwhile, I at least, need evidence of things happening before I come to change my mind on said things. and claims from sighted tests aren't going to be even anecdotal evidence anytime soon.
    I can't tell people what to do with their money, but somebody who would be ready to invest a few hundred dollars into a USB cable for the sake of improved fidelity, should really consider investing into at least a nice soundcard to be able to measure a few things in his/her system. that way instead of hitting our chests to decide who wins, we could maybe get recordings and measurements of the signals coming out of the DAC with different cables in whatever conditions that resulted in audible changes for the user. it's only a start but at least it's something. and for the user, the soundcard can be a tool to check many more things in practice instead of relying on audio myths and marketing. I've been doing just that with a cheap Scarlett 2I2 and have tested many things, most of which ended up being vastly irrelevant to me and my playback system. but at least I know.
    no luck for -110dB noises, that's like the limit of the device with nominal gain setting, so it might be a little too low to measure on that particular ADC depending on conditions. after all the 2I2 was only made for people to record themselves singing and playing music ^_^. we'd need a better soundcard or an actual measurement device to go below with confidence.
  4. danadam
    This might be helpful:
    amirm likes this.
  5. bigshot
    It's always good to know what those numbers represent as real world sound! Playing around with an equalizer can teach you a lot too- like which frequencies are more important than others.
  6. gregorio
    No, that is absolutely NOT what those two videos are showing! They show that the noise interference can be measured but they DO NOT show it can be heard. The noise is measured at roughly -110dB but in the audio of the video the noise isn't at -110dB, it's at about -10dB. That's a difference of roughly 100dB (100,000 times) between the noise on the video and the actual noise level!!! How did you fall for such an obvious trick, especially as it even states at the beginning of the video that the noise has been changed (amplified)?

    He's either a complete idiot, just clever with words or both. I've seen him state that he can perceive differences of up to -300dB, which is not tough at all, in fact it's trivially easy to perceive an obvious difference even when the actual difference is -infinity dB (IE. No difference whatsoever)! This has not only been "thought possible" but actually known and easily demonstrated for many decades. However, perceiving a change/difference and actually hearing a difference are two, often completely unrelated things!!

  7. amirm
    I chased down that video which actually got triggered by a discussion in this very forum! He is hearing the same interference through his IEMs and documents such in his video:


    It is an interesting case of common mode noise travelling through to the shield of the USB cable to the output of the DAC whose negative connection is connected to same. Once there, such noise will travel downstream to rest of the audio chain which uses unbalanced connection. So the problem is real but it is the fault of unbalanced architecture in audio and a higher-end DAC (Chord) which doesn't isolate itself from such.

    I plan to duplicate this and investigate. So it is a good find by the person who created the video and Mediahound who brought it to our attention.

    Poor guy is having a real problem here and as much as I could read that long Chord thread, no one offered to help him from Chord, not any acknowledgement of the issue even though company principal was there and responding to other things. He is a real customer with a real problem he has identified. You can read more of his posts around here: https://www.head-fi.org/threads/cho...n-3rd-post-◄★☆.784602/page-1998#post-13228642
  8. amirm
    BTW, he later said that the iPurifier didn't fix it despite what it says in that video. For anything to fix this, it needs to isolate the ground, not filter USB.
  9. Mediahound
    Or try a better USB cable, one with better shielding, since that's where the noise is entering the signal path.
  10. amirm
    Since there are no measurements for this for any cable out there, it is not a viable path other than trial and error. A better DAC that makes it immune to this problem, or using balanced audio output is a more foolproof way. Alternatively you can avoid DECT technology phones near your audio gear. :)
    gregorio likes this.
  11. bigshot
    Or just don't use your DAP when you're near the generators at your local hydroelectric dam.
    Killcomic likes this.
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