Constant speaker buzzing, trying to find cause

[Searinox]

I've installed a new harddrive and fan about a month ago, and have since been getting a constant buzzing(NOT humming) noise in my speakers that doesn't really change with volume(it starts low, peaks at around 50% volume, then drops again). It is noticeable enough at reasonable levels, especially as it amplifies when I hold my hand over the volume dial for some reason.

I've since tried disconnecting the harddrive and fan, aswell as all the other drives, starting the computer with just the power cable and speakers in, plugging the speakers into a different outlet etc. with no results.

I noticed however, that if I touch the case while holding hand over the volume dial, the buzz dies down. Since I've been reading on google about grounding I had a sudden idea and took out my TV tuner card from its box and put it inside my PC. The moment I plugged the TV cable into the back of the computer, the buzz died for good. Also if I put myself in between and hold my fingers on the PC case while holding the TV cable connector, I can feel enough current flowing through me to make my fingers twitch. But if I take the TV cable out, buzz returns.

To produce the buzzing I don't even have to put the audio jack in! If I hold it about an inch away from the computer case, I can hear it!

I'd like to note that I also tried a different set of speakers, a cheaper set, and they buzz much more loudly, and with them the buzz DOES scale with volume. At the same time, I have a set of SONY speakers with an amplifier plugged into the same port(I'm using a splitter), and plugged into the same electric outlet, and they get NO buzzing WHATSOEVER.

What do each of these clues point out to? Current leaking through TV cable, buzz dying when I bridge myself between the case and speaker volume dial, the fact that the buzz doesn't really change with volume, and that I don't even need to plug the speakers in to hear this? Also, since the Sony(which might I add, are superior, and have an amplifier aswell) do not buzz like the other two sets of speakers, might there be a way to filter this noise out?

[samar69]

First unplug everything and check for the proper electrical room support. It is also possible that the current flow for speaker is not proper. I will recommend you to change the phone charger and cable first. This can be due to that also.
If your amplifier is plugged into a multi plug transformer then that can be the reason for the humming sound. You can try this also. Unplug all electrical appliances in the room, serving only the amp. Change the connected terminal (the 2 are not taken on the same fuse). Use an EMI filter multiplug.