Forum: General Discussion - Topic: Very loud humm sound when using laptop

Hope someone can help with this one..

When I have my Laptop + DJ Console plugged into my amp/mixer it creates a very loud humm sound. If im playing Dance or R&B usually the song will drone it out but its quite noticeable on slow melody songs. If I unplug the laptop from the power and just run on batteries the humm dissapears, but as soon as I plug the power its back again. I have tried another laptop and same problem. Anyone have any ideas about how to remove or lower the humm noise?

Cheers
Grug

Do you have a earth on your laptop AC/DC converter ?

Yes

So try to unplug the earth (directly if you can, or simply use a powercord without earth). I think this will kill your humm noise.

Usually this hum is due to a earth loop between the mixer and the PC.

Switched to a cord without earth. Cheers :-)

Grug

Glad I could help you ;-)

Go to the hardware store and get one of those little plugs that converts the 3 prong to a 2 prong AC plug. Works for me.

Very common problem. My budgo way is to remove the ground pin from a double adaptor and plug the ac power from the laptop into that.

Yo guy's, it's not smart to unplug your ground, it can build static electricity that can kill your units! Instead, use Ground Loop Isolator: http://www.bcae1.com/glisoltr.htm or http://www.epanorama.net/documents/groundloop/ . If you don't wanna make it, buy it: http://www.audioallies.com/getitem.asp?Item=B-25N&Sys=FR .
Cheers

dj-alf has a very good point i had this problem before and got the isolator... much safer

Funny, my laptop doesn't have a earth at all.
As they don't work in 110/220 (depending on your country) earth seems to be less important for laptops.
But in the studio world its pretty common to see devices with their earth cord cut out (static microphones, preamps...)

In fact when you cut this ground wire, you make the mixer 'provide' ground to the other devices.
Instead of multiple ground points, there only one. So no loop.

But I agree, it's less safer for the high tension part...

I just ordered two of those isolators here: Boss B-25N Ground Loop Isolator @ 4.95 a piece. I hope it comes with directions, because it seems to be laid out strangely. It looks like one male and one female rca plug on each side of the box. Can anyone explain how and where it is connected? I am using a maya44 and a denon x900 mixer.

You will connect it from your "Master Out" from mixer to the Amplifier. You can connect it before your mixer because you will have two of them for each channel.