AC Hum on Laptops

A

albert123

Expert Member
Company Rep
Joined
Aug 30, 2005
Messages
1,938
Reaction score
18
Location
Home sweet home :)
i play from my laptop to an amp to a p.a. system on a regular basis but as those who will be able to help me will be aware, plugging the charger in cause AC Noise on the speakers, if anybody has any solutions as to how to get rid of this noise please let me know?

possible ideas i have so far include,
1. behringer has a hum destroyer, however as far as i heard it will also kill some of the music played as it removes certain frequencies?
2. i have thought of maby getting a cheap UPS so the charger runs off the UPS but i am not sure if this will work?
3. i have read that cutting the ground cable will make the noise go away however 'could kill you' so this is a last option i presume :)
4. someone said that you can get a 'filter' thingy that filters the power provided by the charger to the laptop, i am not sure how this will work.

anybody ?
 
marine1 said:
Maybe the cable to the AMP is not shielded properly? Get a good cable maybe monster cable if RCA ?
Click to expand...

i assume you have no idea as this problem is not only on my laptop, its a general thing with laptops as the laptop runs off AC power when the charger is plugged in and this causes the noise. my cables is fine.
 
albert123 said:
i assume you have no idea as this problem is not only on my laptop, its a general thing with laptops as the laptop runs off AC power when the charger is plugged in and this causes the noise. my cables is fine.
Click to expand...
I dont get a hint of hum of any of my laptops plugged into the mains or not.

Are you sure of your earthing status? Many just have a dummy earth while others have a real one. Many countries don't use earthing so your laptop might not require it. What brand is it?
 
Last edited:
albert123 said:
on what kind of Amps do you plug it into and how loud to you play the music?
Click to expand...
Unless I'm at a conference its general household stuff.

The guy who works for one of the areas largest sound and lighting companies lives next door and runs his through some major equipment. I can ask him tonight if you like. I can almost guarantee he's going to say cabling.
 
bwana said:
Unless I'm at a conference its general household stuff.

The guy who works for one of the areas largest sound and lighting companies lives next door and runs his through some major equipment. I can ask him tonight if you like. I can almost guarantee he's going to say cabling.
Click to expand...

i've tried various cables, on various laptops, all does the same, some laptops (hp) does generate a little less noise, however the moment you pull the charger out on all these laptops, the noise goes away completely ruling out that it is caused by anything AFTER the laptop.
 
albert123 said:
i've tried various cables, on various laptops, all does the same, some laptops (hp) does generate a little less noise, however the moment you pull the charger out on all these laptops, the noise goes away completely ruling out that it is caused by anything AFTER the laptop.
Click to expand...
Asked the guy and he says "unearth the laptop" or you can get a "di box which will have an earth lift switch".

Hope that helps.
 
bwana said:
Asked the guy and he says "unearth the laptop" or you can get a "di box which will have an earth lift switch".

Hope that helps.
Click to expand...

di box? can you find out more about this?

i would've cut the earth cable but then i can electrocute myself cause i will be the 'earth cable'
 
This is a known issue with notebook AC adapters, because they are small they run at a higher frequency .. or something, I can't recall as I read up on this years ago.

http://ask.metafilter.com/20028/Laptop-Audio-Hum

There's some info there, plenty on Google.

Unground your notebook and hope for the best :)
 
albert123 said:
di box? can you find out more about this?

i would've cut the earth cable but then i can electrocute myself cause i will be the 'earth cable'
Click to expand...
All the laptops I own have removable cables leading up to the brick - the manufacturer even included earthed and unearthed cables. What kind of laptop is it?
 
bwana said:
All the laptops I own have removable cables leading up to the brick - the manufacturer even included earthed and unearthed cables. What kind of laptop is it?
Click to expand...

the cable comes with a 3point plug, Acer, Mecer, IBM and HP all have same problem.
 
albert123 said:
the cable comes with a 3point plug, Acer, Mecer, IBM and HP all have same problem.
Click to expand...
If any of them are designed to work in Europe or US they should be able to run unearthed.

BTW - looking at the cord that came with it I only just realised now the 360 is also unearthed.
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X