OT: Elec Speaker Shielding

groovedude wrote on 4/29/2004, 5:32 PM
I have two computers next to each other, with a UPS and Network Router nearby and I'm getting a lot of noise through one of my computers set of speakers.

Even with the other computer turned off I get the noise. The noise sounds as if a mic is left on and someone bumps into it now and again or it pops. But it doesn't have a mic attached and under volume the mic record/playback is muted.

The other computer gets a little noise but not as much. I'm guessing because they are a little higher quality and probably have more electric speaker shielding built in.

Are UPS or Routers speaker offenders? Or maybe is it my analog tv tuner--although I don't have it running.

Comments

jester700 wrote on 4/29/2004, 6:30 PM
CRT monitors are BIG noise generators. Just TRY to play a strat near one!

LCDs don't suffer this problem, though.
Spot|DSE wrote on 4/29/2004, 8:27 PM
TV Tuners built into video cards are noise generators, a loose or misconnected ground will do this as well, if you have audio cables run next to electrical cables, this will do it. Noise doesn't get into speakers, it gets into cables. Cables are like big antennas, so they must be properly shielded. If you run high impedance, unbalanced cables longer than a few feet, expect to hear hum/noise. If you have a CRT too close to a mixer, microphone, or audio cables, it's likely the culprit.
Depending on how badly you want to loose the noise, there are many prescriptions, dependent on budget.
John_Cline wrote on 4/29/2004, 10:10 PM
Is your analog TV tuner hooked up to cable? You may have a ground loop situation set up by the third pin of the computers power cable being at a different ground potential than the ground of the cable tv coax. Try disconnecting the cable or antenna coax from your TV tuner card and see if that makes any difference.

John
farss wrote on 4/29/2004, 11:05 PM
The UPS maybe a source of problems. Not all of them generate nice sine waves and the harmonics can make their way through the cheap power supplies into the rest of the PC. Try bypassing it and switching it off.
Maybe totally wrong of course but oftenly just switching things off one at a time is a good way to find the culprit. In an ideal world your kit should be immune to this and as SPOT said there's lots of ways to improve the situation, problem is I find sometimes some of them improve it and in other situations they make it worse.
Certainly having all your external audio lines balanced or optical is the way to go but if you're not into recording then that could add a lot of cost for only a small improvement.