Why do I get hiss on an external DAC?

Discussion in 'Computer Audio' started by M76, Jan 16, 2020 at 8:22 AM.

  1. M76

    M76 [H]ardForum Junkie

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    I bought an external DAC with balanced output exactly to avoid noise from the PC, but now I constantly get hiss or hum or whatever you call it from the speakers and it is affected by what the PC is doing. If the GPU is occupied the hiss gets worse. If the screen displays bright colors the hiss is less pronounced than when the display is dark.

    This is an external USB dac, how can the noise propagate through a digital interface from the PC? Or is it possible the noise is collected by the cable going to the speakers? Or through the mains?

    What can I do to get rid of it? Would connetcing the speakers to different electrical outlets help?
     
  2. criccio

    criccio Fully Equipped

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    Does the DAC have an optical input? USB is still electrical.
     
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  3. M76

    M76 [H]ardForum Junkie

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    USB is ones and zeroes with integrity checks it can't collect noise like an analog connection.
     
  4. criccio

    criccio Fully Equipped

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    I know, but its still metal on metal so its possible. I mean it has to be that if you're getting feedback based on what the PC is doing.
     
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  5. grim4593

    grim4593 Limp Gawd

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    Although the transmission is digital the power lines can still have power supply noise on them that makes its way into the speaker outputs. If the DAC does not have its analog circuitry properly isolated from the digital circuitry it can definitely end up with hiss.
    I've had this happen with noisy GPUs and lower quality speakers. You might be able to fix it with a USB cord with an integrated ferrite bead or buy a clip on ferrite bead.
     

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  6. M76

    M76 [H]ardForum Junkie

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    I have multiple ferrites tried playing around with them, but no matter where I put them they didn't seem to affect the hiss.

    The thing is intermittent too, one day its fine, next day I get the noise. It's not going on right now for example.
     
  7. N4CR

    N4CR [H]ardness Supreme

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    Ground maybe? Probably not if hiss but worth a try.
    Try isolating it on amp end.
     
  8. DoubleTap

    DoubleTap 2[H]4U

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    Are you using any kind of analog input to the PC? Either a 3.5mm Mic or a 3.5mm Line in?

    I use the 3.5mm Line in to mix the output from my Amazon Echo View - I found that if I just leave the 3.5mm cable disconnected from the Echo (but plugged into the PC) or if I have a dirty power source, then I get induction or power noise going in through that port and it gets inserted to the digital stream.

    The previous Echo I had was USB powered and most USB chargers were super noisy. The little Apple one worked great and didn't introduce noise.
     
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  9. travm

    travm Limp Gawd

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    Did you buy a shitty DAC?

    Check the power supply (wall wart?) And try a ferrite there too. If it's a shitty amp design or a bad PSU it just is what it is.
    Could also be dirty power. Is the amp usb powered? If it is you could try a powered usb hub to get the power supply right out of your PC.
     
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  10. Lastan010

    Lastan010 Limp Gawd

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    what DAC and Power Amp are you using?
     
  11. thesmokingman

    thesmokingman [H]ardness Supreme

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    I'm using a Fiio K5 Pro with usb cable (along with a Micca OriGain amp) and its unfortunately sandwich between a bunch of power cables with no noise/distortion. Maybe its your unit?
     
  12. Lastan010

    Lastan010 Limp Gawd

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    Last edited: Jan 20, 2020 at 12:09 PM
  13. GotNoRice

    GotNoRice [H]ardForum Junkie

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    I get minor hiss when using my Maverick Audio TubeMagic D2 on either USB or Coax S/PDIF. It's definitely coming from the computer as it changes when I move my mouse. It's not as bad as the similar hiss I would get when using my X-Fi Titanium by itself inside the computer, but it's still there.

    I don't get any hiss whatsoever when I use optical S/PDIF between my X-Fi soundcard and the DAC. I sort of expected that this would be the case, even before I got the DAC, which is why I made sure to get a DAC that had optical input.