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Forum: General Discussion

Topic: Speaker interference when laptop charging

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Hi folks!

Title says it all I think lol. If using laptop only in the house, one soundcard style, all is grand ..... but when I have to plug the laptop in to charge an awful buzzing/crackling interference is heard from the speakers :( Unplug power supply and it is clear again.

Any ideas on how to remedy this issue?

Thanks in advance :)
 
Inviato Wed 20 Mar 13 @ 8:11 am
You need a GLI (ground loop isolator). They cost from around €7.
 
 
Presumably, your power supply is 3 prong, which includes a ground prong. Get a 2 prong adapter, connect to the power supply, and plug into a surge protector, and the problem is solved. This is known as "lifting the ground." The Wiki which is linked in the prior thread advises against removing or isolating the ground, but I believe this is something different. I've never experienced any danger since the 2 prong adapter is being plugged into a surge protector.
 
legaldeejay wrote :
The Wiki which is linked in the prior thread advises against removing or isolating the ground


Yeah, for a good reason - your life.

If a product has a ground connection, it's there because it's needed. They didn't just add it for fun.
 
A surge-protector is a peak (or over-voltage)-protector, and has nothing to do with grounding. It will NOT protect you from ground-malfunctions or the risk of being electrocuted...
 
ferrite chokes, ground loop isolator, try a different wall outlet, lastly (and probably best solution) buy a new laptop power adapter.

but while we're here, lets address the issue without spending any money. depending on your speakers and how you have them hooked up, i'm assuming your running a 3.5mm headphone jack to said speakers. Sometimes (especially with eBay/Chinese male to male plugs) the plug doesn't "seat" into the receptacle 3.5mm properly, ive had to alter some of my plugs by simply cutting away some of the rubber at the base of the plug.

give us some more details on what "speakers" you are using, how you have everything setup, plugged in, and wired. I try to do a process of elimination before spending money.

-cheers
 
I had the same problem and after trying many things, it was a 2 prong adapter that saved me.

I am 90% certain this will solve your problem.
 
I use one of these to avoid the problem.
Very well worth the $ 15 that it cost.
 
+1 on using an Audio Isolating Transformer (AKA Ground loop isolator).
The fact you have interference means that you have power going down your audio cables. The Earth connection is likely keeping it at a safe voltage. I have measured dodgy Switchmode Power Supplies supplying 90VAC between the output and Earth. This will give you a mild shock not to mention potentially kill expensive PA gear. Don't risk your safety using 2 pin adaptors.

DI boxes also usually have a ground lift feature and are great for connecting Line level Mixers to Live sound desk Mic inputs.
Also note that isolating the Mains input with a Mains Isolating transformer is an option but it's a heavy and expensive option.

We had issues at work connecting via Serial to dodgy Air conditioning systems (frying serial ports) and found that a good solution was to buy Laptop Power supplies designed with a 2 pin supply. Dell makes them for Latitude Laptops as a combo Mains / 12V Car Power supply. I don't know about other Laptop brands.
 
Cheers for all the replies here folks, tis appreciated :)

First answer in the postbag was a winner :)

groovindj wrote :
You need a GLI (ground loop isolator). They cost from around €7.


Picked one of these up on eBay for £5 and it does the job perfectly :) Thanks again!!
 


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