laptop problems...

[Dragon Slayer J]

when my laptop is plugged into any sort of amplification (from pc speakers to PAs) and plugged into the mains there is a sort of static hum. Now, this hum is not there when its not plugged into the mains. i have tried it in different places and the hum is still there.

it seems to have nothing to do with the sound card as it is still there even if i mute everything so i was wondereing if maybe it has something to do with the power supply. Has anyone ever heard of anything like this before? Any suggestions on how to fix it?

[Aris_T]

Operate on battery. I had the same prob and one day I accidentally pulled the power plug. The laptop went into battery mode and the noise disappeared.

PS: A friend told me that you don't get problems like that with an external sound card, and he does use one without any noise. Other solution is to get a macbook (I'm told that they're noise free)

[Dragon Slayer J]

thanks... i had thought about the external sound card but i wasn't sure.

[voodoo_child]

Laptop power supplies can be pretty bad when it comes to interference...because of the way they operate (switchmode), they can send interference back into the mains, and possibly anything else connected to the same supply.

As suggested, try running off battery, or plugging the laptop into a different outlet than the amplifier. Get it as far away from the amps as possible, both physically, and also in terms of it's location on the ring main.

[seaninsjca]

My tech department supports laptops. I've heard of this with various models. The best recommendation I've found so far is to purchase a "Hum X". Do a Google on them, most of the music retailers sell them and it generally solves the problem.

[seaninsjca]

Forgot the product link... http://ebtechaudio.com/humxdes.html

[shogun]

sometimes has to do with the converter.. mac's do not make these noise BUT if your converter goes, your laptop is done.

[IbanezFreak777]

Yeah i had a problem with an lcd monitor making weird lines, and when i pulled out the power supply for the laptop the lines went away...