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John Williamson John Williamson is offline
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Default HDMI (cable?) Noise PROOF (second youtube video)

On 14/12/2018 15:35, wrote:
A load of twaddle, linking to a useless video, due to the amount and
volume of commentary obscuring the sound of the problem.

Connects TV to laptop via HDMI, using a displayport adaptor

Absolute silence from TV speakers, even with all volume controls set to
maximum. No noise is being generated by the HDMI connection, in spite of
(Or possibly because of) neither item having a safety earth connected,
as they are double insulated, and the audio signal on HDMI is digital
anyway, so ground loops can't affect it at that point. There is a tiny
leakage current that can be felt on exposed metal parts of the laptop.

Your problem is somewhere in the analogue domain in your system. Check
for earth loops, and bad earths. You need a single earthing point for
all audio signals, and looking at the mess of spaghetti connecting stuff
together in your video, you do not have this. Tidy up the wiring, paying
particular attention to signal earth connections. Try disconnecting the
analogue path while using the HDMI path, and vice versa, as the HDMI and
analogue cable earth connections (Including any screening) may be
completing an earth loop. Check also the earthing scheme inside your PC,
as PC sound cards are notoriously hard to screen from the video and
logic signals, and you say you can hear interference when you move the
mouse. Try a USB sound interface, mounted outside the case.

Use balanced analogue audio connections if possible, as single ended
ones are prone to this sort of problem.


--
Tciao for Now!

John.