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If you indeed have a ground loop problem, instead of using a ground lift adapter, you could try transformer isolating the laptop from the mixer. Look for an Ebtec Hum Eliminator. Or I could sell you the one I have.

Tuite wrote:Where do I get a ground lift adaptor guys? Which one do you use? Should they be available in good electrical shops?

You can get them anywhere at all. Probaby even 7-11.

...and actually, most laptop AC adapters have no ground, so I'm guessing lifting the ground that doesn't exist probably won't do anything anyway.

So what should I do? Should I buy something or just change my plug set-up! By the way, Im Irish so that Canadian law won`t affect me!

I read on another topic that when some guy plugged some of his effect pedals in with an AC adaptor he got an electrical hum! Some suggestions were:

To use the Ebtec Hum Eliminator but one guy said it wasn`t a ground loop cos they have no ground! He suggested there was ripple in the DC power from the wall wart! What is a wall wart? How could this be fixed?

Another guy said he opened up his effects pedal and inserted an RC filter in the input! Could this help here?

Scott, I can`t plg and unplug because I connect the line out of my laptop to the monitors and the hum and crackle interferes during playback too!!

Ray J, did you have hum from a laptop too or was it something else? Is that a picture of a ground lift adaptor in Endofanera`s post? Where does it go in the chain? What do I plug into it and it into?

The power adapter you use to power up your laptop when you aren't running it off the batteries...when you plug it into your AC outlet, does it have two or three prongs? If it has 3, it is grounded. The purpose of the adapter delineated in the photo above is to interrupt the ground ('lift' it). Try that first, as it is a 60-cent fix.


If you are running the monitors out of the analog headphone jack on your laptop, or indeed anything out of that jack other than crap headphones, you should definitely pick up a laptop DI (laptop audio interface, PCDI, whatever. Whirlwind and Rapco make them, as do many other manufacturers). Try it out at the store.

Does running your laptop off batteries fix the problem?

I had definite 60-cycle buzz, and it went away when I lifted the ground.

The plug I use to power my laptop has three prongs! Does this mean that I should try lifting the ground with an adaptor or that I dont need to and thats not the problem?

I am running the monitors from a powr amp that is connected to the phones out of my laptop by a Y-cable! However, when I use the batteries on my laptop, this sounds fine!

Also, when I plug the control outs of the desk to the line in on my laptop with another Y-cable, this sounds fine too but as soon as I plug the laptop in, I get hum and crackle from both the signal goin in and the signal going to the monitors!!

Do you think its a ground lift problem?

Tuite wrote:The plug I use to power my laptop has three prongs! Does this mean that I should try lifting the ground with an adaptor or that I dont need to and thats not the problem?

I am running the monitors from a powr amp that is connected to the phones out of my laptop by a Y-cable! However, when I use the batteries on my laptop, this sounds fine!

Also, when I plug the control outs of the desk to the line in on my laptop with another Y-cable, this sounds fine too but as soon as I plug the laptop in, I get hum and crackle from both the signal goin in and the signal going to the monitors!!

Do you think its a ground lift problem?

I think it might be two problems. Use the ground lift. It should accomplish the same thing running the laptop off batteries does.

Then try the laptop interface for the monitor feed. It will decrease your noise floor(which you will notice if you crank up the inputs on your mixer), but, as you are dropping some iron into your signal, it will degrade the overall signal a little bit.

Or, you could get a firewire/spdif/whatever digital output to a 50-dollar A/C converter box and take your output from that (the ideal solution). Look at BSW's catalog for cheapies...

Rightio!! I`ll buy a ground lift adaptor and see what difference it makes! Are there any special types of adaptor I need to buy or anything?

Im not too sure about buying an interface cos I am saving up for a pair of active monitors and a firewire equipped desk to solve these prob so i dont really want to be spending too much money on things!!

Tuite wrote:Rightio!! I`ll buy a ground lift adaptor and see what difference it makes! Are there any special types of adaptor I need to buy or anything?

Good god, no. It's a 2-dollar piece of hard rubber with some metal bits in it. Get it anywhere, or break the damn ground tine off your cable...

Wots a ground tine? Is dat the third prong?