• Malfeasant@lemmy.world
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    7 months ago

    For my desktop, I have a monitor with built-in speakers and the audio is carried by HDMI - but its speakers are such junk that I have powered speakers connected to it via a headphone cable. I haven’t noticed any weird noises before texts or phone calls, but I do get a faint buzz that changes with the contents of my screen… Oddly enough, bright white makes most noise, dark is quiet. That would make sense for analog video, but for HDMI it baffles me.

    • MystikIncarnate@lemmy.ca
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      7 months ago

      It makes sense, the DAC is in the monitor, but the monitor is an electrically noisy place, so the IC that’s responsible for the DAC/AMP is picking up noise from the power circuitry in the monitor. It’s common with cheap DAC/AMP chips, like what they use in low end motherboards and monitors.

      Basically as power usage is increased the noise should be greater. Unfortunately it’s a design flaw, so your only real option is to replace it to resolve the problem. You may see improvement with a ferrule, or you could try doing some hardware hacking and adding shielding around the audio circuitry.

      The ferrule is the easiest and cheapest, but it may not fully resolve the issue.

      • Malfeasant@lemmy.world
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        7 months ago

        Oh no, I get why the interference happens, it’s more the content of the interference that surprises me. With analog video, a white screen is basically a 15 kHZ full amplitude square wave, but HDMI is encoded so regardless of the balance of 0s and 1s in the original content, the data stream should be just noise either way.