AC noise problem

[rustzone]

Hey, guys! So, here’s my problem. Some time ago I noticed that when I connect AC adapter to my MBA, quiet continuous noise appears in my headphones. It's not loud and isn't heard with music, so I was ok with that. But when I connected an external usb sound card and tried recording guitar, I heard the same noise in the recorded audio. Tried recording without adapter - noise became quieter, but didn't stop. The problem is not in sound card (I tried it with other MBA and there was no noise) so I figured it must be in my mac. Any thoughts?

 

[DmbShn41]

Sounds like this is electrical noise through the line voltage. Is the charger plugged into a properly grounded outlet? What about a surge protected outlet? If you have one or both available, try it and see if the audible noise goes away.

 

[rustzone]

The thing is that I tried my friend's mba with exactly the same power outlet and it worked without any noise.

 

[case2001]

Did you use your AC adapter with your friends MBA?

 

[rustzone]

No, I used his. But anyway, the noise is heard even when recoding without adapter.