Laptop Interference Issue, Only When Plugged Into The Mains

[MarkAH]

I've got a really big problem with my new laptop, when i plug into the mains i get a lot of high pitched noises coming through the output of any sound card i try and use into my monitor speakers.

Without the power being plugged in i get no noise whatsoever, the problem increase as i do more on my computer.

I know this is something to do with interference being introduced by the power supply i just can't figure out how to fix it.

Some people have suggested disconnecting the earth in the plug (3 Pin, UK), i dont fancy this idea!

Any other ideas from anyone? Help will be much appreciated!

[fmw]

Another option would be to buy a better power supply.

[MarkAH]

Originally Posted by fmw

Another option would be to buy a better power supply.

Thanks fmw, thats the option that i am looking atm, hopefully will solve the problem, as long as the interference is coming from the power supply and not the charging circuit in the laptop, in which case i may be in trouble!

Gonna try lifting the earth with a DI box, maybe that'll work.....

[Audio~Geek]

Are you using balanced cables for your monitors?

Have you tried different USB/Firewire cables?


The DI box won't help you in this case.

[MarkAH]

The Chain at the moment is,

Laptop > Firewire > Phonic Helix Board 24 > XLR - XLR (Balanced) > Monitors

Laptop has its own power supply,
Desk has its own power,
Monitors both have their own power.

Haven't tried a different firewire cable, but i get the same issues through multiple usb cables into my bass players tapco interface. Although the tapco is USB powered.

I get the same issues on all interfaces, even tried stereo jack to phono direct from laptop to mixer, then out on the same chain as above into monitors. But as soon as i unplug the power lead the intererence goes away, but if my laptop is plugged in and i record in from the desk i dont get the interference on the input. It is purely on the output.

[Audio~Geek]

Are all of these connected to the same outlet?

[fortyseven]

Would a ground loop isolator not work?

[MarkAH]

They were all connected to the same ring main in my house, so i tried running a power cable from downstairs, where the ring was different that didnt make any difference.

But i did discover that disconnecting the earth from the plug work a treat! Converted from english plug, to international and back to english....dodgy i know using adapters but that in turn disconnected the earth and the interference stopped.

I dont recommend this fix but it worked for me....Thank you for all your help though guys, much appreciated!

[Audio~Geek]

Thats great. I hope you don't get electrocuted.

[sparqee]

Originally Posted by Audio~Geek

Thats great. I hope you don't get electrocuted.

Why? Isn't that how you manage that wonderful hair style of yours?