noise in speakers (1 Viewer)

[JuanNarvaez]

I hope I'm in the right forum. I work at a high school and we just got our media hook up. I mean we got the projector up on the ceiling together with a pair of amplified speakers. Wires were connected from the projector and the speakers to a connection block in the wall were I connect my laptop. The problem is that when I connect and audio from the computer so I can hear the speakers in the ceiling, there is a loud humming noise in the speakers. And that happens as soon as I connect the laptop to the connection block in the wall.

 

[JuanNarvaez]

I just disconnected the audio cable from the laptop and connected it to an ipod and the noise went away. So I guess the sound is coming from the laptop.

 

[JeremyErwin]

Is the laptop plugged in? Or is it running off batteries?

 

[JuanNarvaez]

its plugged in, I haven't tried it on batteries

 

[JeremyErwin]

Probably a ground loop. The general solution proposed on this forum tends to be "switch to optical (TOSlink)", which may not be practical in your environment, or make sure that the amplifiers and audio source are plugged into the same outlet. Other solutions include the use of cheater plugs, but that may be against fire code.