Buzzing sound from speakers
 

I've just moved back home recently from college and setup my computer. the thing is that when i turn on my lamp, not a typical bulb, perhaps halogen or something.. the light intensity works on a gradient knob as opposed to the typical on/off.

When I turn it on, the speakers on my computer start buzzing. They are plugged into the same surge. Any ideas? Perhaps the speakers are grounded weird or something? Thanks

it's probably the dimmer knob. I'd not be surprised if you don't hear the buzzing if you turn the knob all the way up, or turn the light off. Move the light.

lights and other things can effect that... i have a similar desk lamp that is close to my speakers, and when i first started using it, it would make my speakers pop and crack when it went on and off, i ended up turning the speakers offf in order to turn the light on and off, but then i moved em apart and swapped the lamp into another outlet

What Shakran said.

Dimmers are notoriously noisy when set to anything but maximum. I can't have them on the same circuit as any of my equipment.

Bah. I was hoping for some easy fix to this. I like my setup right now =P

So let me rehash... it's happening cause the dimmer is using the same outlet as opposed to actual physical proximity.

Anybody know the rationale behind this? Is it a result of the changing load or something or other? Just curious.

ThaNKS

From my understanding, it's actually the physical proximity. If you've ever had a cell phone near speakers, you've probably heard the humming too. It's simply the electromagnetic interference because the frequency happens to match those used by the speaker. That's MY understanding, but it could be entirely wrong.

It can be either, or both.
Depends on the dimmer but they generally cut the AC wave to reduce power to the light. They'll use a little thyristor which delays then switches power on rapidly at some point in the wave, thereby reducing total output. This now hard ramp, switching at AC frequency, causes the interference. It can come back through the line or be picked up as RFI by other parts in your audio system. You probably noticed it's worst at half brightness? That's because at half power the switching occurs halfway through each wave - at peak amplitude.

You're sure it's proximity and not coming through the wiring?

Dimmers in lamps are usually junk. Better ones have shielding and coils to reduce interference. Have you tried an external dimmer? If you don't need the dimming you could replace the dimmer knob with a switch, or just an external switch.