Finally! I think I've discovered the cause of pc-sub interference


Well-known Member
For a long time now, I've battled with a low "rumbling" interference noise from my sub when my pc is connected to my receiver (by hdmi). I have gone as far as to connect a ground lead from my receiver chassis to a wall socket, with no success. In the end I just gave up, split my HTPC and sold off the components. Then at the weekend I connected up my everyday pc to my tv to check out a bluray disc I'd made of my daughter's wedding. I had forgotten all about the rumbling up to that point. Then when it kicked-in again, it doubled my resolve to find the cause. And I think I just have.

After ruling out multiple hdmi cables, I started to think about ethernet. I have a Virgin Media Superhub 3 running in modem mode, connected to a Linksys router. This in turn connects to a HP 8-port switch. All my ethernet cables are of the standard un-shielded type. I had never bought shielded cables, thinking it was just a money-making ruse. But just for curiosity's sake, I reached down and unplugged the ethernet cable from my pc. The rumbling stopped immediately. I tried a few of the everyday things I do on my pc, like running Word, Photoshop and a couple of other apps. The rumbling would always be there, but would stop for a while if the pc wasn't being used for any length of time. But when I would open an app, the rumbling would go nonstop. I have often linked it to hard drive activity, as it would correspond with the hdd led blinking on my pc case. Now there was nothing. And when I reconnected the ethernet cable, the rumbling was still absent. EUREKA!

Now I'm not going to kid myself that I have discovered a total fix. I'm not going to buy a dozen shielded ethernet cables of varying lengths. I don't even know for certain if shielded cables are the answer. But I am going to start with buying a couple of ferrite clamps for my pc and receiver power cables, just to see if they make a difference. But right now, I'm beginning to think I see an end to this infuriating issue.

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