Filtering noise from powerlines and finding a better headset

[TheForumTroll]

I have had problems with noise while using a microphone for a long time now. At first I tried using another sound card which did little to no difference. Now I'm getting really annoyed by it again and was hoping I could get some advice in here instead of just throwing money at it again and again with no luck. First let me add what I have done (or not) and what I have tested:

Grounding: There is no ground on any of my components since there isn't any in the outlets in this old building (except in the kitchens 360v outlet). I tried temporarily with ground via the water pipes but it made no difference.

PC components: I have tried removing everything from my computer to see if it made a difference in noise level (it didn't).

External components: I have tried turning everything off -like TV, stereo, server, lighting, etc- and it removed abound 20-30 % of the noise.

Microphones: I have tested with two different headsets. One uses USB and optical and one uses jack. Both were pretty much evenly noisy.

Testing: I then tried connecting mic in and headphone out directly with a jack to jack cable. I measured the noise level with Passmark SoundCheck and Rightmark Audio Analyser. Now the noise was pretty much gone.

What can I conclude from this? Logic tells me i need a new headset/mic and something to remove some of the noise from the powerlines. But how do I know which headset to get and does anything actually help with "dirty power"? I were even looking at a UPS but read that they make it even worse. So what are my options? I'm going crazy not being able to solve this!

[Jon Gerow]

You need a ground.

Are the 360V outlets in the kitchen at least going to the same breaker box as the rest of the outlets?

Is the wiring that goes from each outlet to the breaker box steel conduit or are they just sheathed cables like Romex?

[TheForumTroll]

I, uh, I have no idea how things are wired, except that I have a single box in the basement for everything with some RCBO or GFCI breakers or whatever they are called. It is a rented flat so I can't really change anything either. All the wiring in the walls are in plastic.

I'm in the EU if that makes a difference (guess the outlets and breakers are different?).

[Jon Gerow]

All the wiring in the walls are in plastic.

So it's not metal conduit? They're PVC conduit?

Plastic's non-conductive, of course, so my idea for you isn't going to work.

I wasn't going to ask you to make drastic changes. If the wiring is housed in metal conduit and your boxes are metal, you can just anchor a ground wire to the conduit. That would, in turn, eventually ground your outlets to the breaker panel in the basement.

Depending on how easy it is to feed wire through your walls, you could try feeding a single ground wire from the outlet in question down to the basement and ground that to the panel.

[TheForumTroll]

Yeah it is a PVC pipe. Unfortunately this is an old flat with the breakers in the basement and I live on the 3rd floor, so no way to get wires all the way down there

Wouldn't grounding through the radiator (temp. for testing only!) be enough to see if it made a difference? There were what looked like tiny static discharge when I put a wire from the radiator to the case, but no change in the noise floor.

What do you think about the test I did with turning stuff off and then using a cable directly between mic in and headphone out, which removed pretty much all the noise? With that and the noise affecting both analogue/jack and digital/USB, doesn't it point to a problem with the headsets and/or their wires?

I was ready to put ferrite cores on everything, buy a UPS, etc. but now I'm in doubt if it would do anything at all.

EDIT:
Here's some pictures from a test I did. Directly in the front jacks versus headsets and monitor speakers (ACE is jack, Tritton is USB):

Noise level, dba



Total harmonic distortion %:

[Oklahoma Wolf]

You need a ground loop isolator.

Incidentally, if you think that's annoying, try a ground loop issue with an 1850W pro audio amp powering some very powerful home theater subs. That one just about drove me up the wall. On that one, I made a cheater cord for the XLR inputs on the amp as per this article: http://www.rane.com/note110.html

[TheForumTroll]

That reminds me of back when I did a little studio recording on an old 24 track analogue mixer. I wish I had all that balanced equipment instead..

Thanks for the advice. I'll see if I can find a ground loop isolator right away. Now just to figure out what it is called in Danish, hmm...


EDIT:
I think I got a JitterBug somewhere. I wonder if it would help.