I know many TAs have probably come across the problem of laptops creating some kind of noise.
My problem is that whenever i have the power supply plugged in i get noise through my laptop to my speakers no matter what (actually i can lower the amount of noise by using less power on the laptop eg. turning the lcd brightness or cpu power down) but as soon as i unplug the power supply it works perfectly once again.

As far as i have learnt this is the cause of the power supply creating unclean power (not a ground loop problem!)
Iv heard of using a DI box with an isolation transformer to fix the problem but i dont know if its worth going out and buying one just yet.
Has anyone been able to fix this problem in ways other then unplugging the laptop or have they used the DI box method?
Im currently using a dxm01 as the soundcard but soon it will be a presonus firebox. From what i have read having an external audio interface doesnt make a difference.

This thread has come up a few times in past but the only thing anyone could think of was to unplug the battery.

Try using a simple adapter to bypass the ground pin on your laptop power supply (assuming you have a 3 pin plug on the power supply). That's what I do.

If that doesn't work, more study required. One of the big mixer companies, could be Rane or Xone, has a large section on hum & noise problems.

I know of several people who use the Ebtech "Hum X" device and it works great for them. http://www.ebtechaudio.com/new.html - their site also has some information about the causes of audio noise.

Last edited by tvmann on Apr-04-2006 at 05:35

Iv heard of cutting the pin or buying some kind of adaptor without it but then there is the worry of having a power surge or some kind of power interfearance that will fry my laptop.
I took a quick look at those products you recomended and the biggest problem is that they are for US power plugs and they cost alot.
I will wait untill i get my new soundcard. If not i will call acer and bitch to them and complain untill they can hook me up with something.
Atleast ill try that...

I have the same problem....

I just leave it chargig while sketching stuff but for recording or mixing i unplug it. Not ideal- but it works.

Haha.
When i saw Freak as last poster straight away in my mind i said "yes! Freak to the rescue!"
Then i see this...
Im dissapointed in you Freak.


In all seriousness though this is what i have come up with.

1. Buy a thirdparty high quality power supply. (Probably going to cost around $100US).

2. Try a passive DI box that has an isolation transformer. This cuts and DC current away from an AC signal. (So far iv come to the understanding that DC current is running through the cables and interfearing with the AC audio signal).

3. Buy one of those laptops that you can remove the cd tray and attach another battery to have two batteries.

4. Try chop up a desktop power supply down to the very bare basics and make a very large laptop ac-dc power supply with the help of a electronic engioneer in the making (Brother is in third year of uni)
(dont think this one has much chance)

5. Complain to acer and say that they suck and that they better fix it. (ok not very realistic but im going to ask nicely and they might send me a new power supply)


Since i would rather spend the money else where right now i think i will just unplug and plug in the laptop.
Its funny though because i had an old toshiba satelite with a celleron that i didnt want because it was too slow. I ended up gaving it to my brother and that never had any problems with any kind of noise atall.

quote:

Originally posted by DJ 00 Tommy I know many TAs have probably come across the problem of laptops creating some kind of noise. My problem is that whenever i have the power supply plugged in i get noise through my laptop to my speakers no matter what (actually i can lower the amount of noise by using less power on the laptop eg. turning the lcd brightness or cpu power down) but as soon as i unplug the power supply it works perfectly once again. As far as i have learnt this is the cause of the power supply creating unclean power (not a ground loop problem!) Iv heard of using a DI box with an isolation transformer to fix the problem but i dont know if its worth going out and buying one just yet. Has anyone been able to fix this problem in ways other then unplugging the laptop or have they used the DI box method? Im currently using a dxm01 as the soundcard but soon it will be a presonus firebox. From what i have read having an external audio interface doesnt make a difference. This thread has come up a few times in past but the only thing anyone could think of was to unplug the battery.

If it is a very fast popping sound, make sure your "in" and power cables are not crossed at all. This problem occurred with me using my Dads laptop which has a dodgy battery so needs to run off mains if you use it for ~1hr. I dunno if you've tried that or not, but thats what my problem was.

(I now do not use a laptop to record, I use a pc and shielded studio cables so don't have any interferance)

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I solve that problem by having the power cord far from any audio cord. Make sure they are not touching each other and try to have'em as distant appart as possible (for me about a foot or 2 is enough). Also if you're using multiplug outlets, same thing.
Have the vol pretty high with no output (hence hearing the noise), while playing around with the cables. Be patient, you'll find a sweet spot.

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I dont think your understanding what im sayin the problem is.
Ofcourse i treid what you suggested. Iv treid multiple power outlet setups but no difference.
The problem is that the power supply for the laptop is crap and it does not convert the ac to dc properly. This kind of left over part of the waveform runs through anything that touches the laptop. I dont know exactly how to explain the how the power supply (converter) is stuffing up but the dc is not exactly pure. Leaving it with some oscilation.

man this should be a sticky. This comes up almost every week.

http://www.radioshack.com/sm-see-al...pi-2062214.html

I tried searching before posting this and it doesnt come up that often...
A ground loop isolator is an isolation transformer.
Same as what most di boxes have. Except di boxes are mainly for changing 1/4" to balanced xlr.

My point is that yes i know this has come up before but i wanted to know if anyone has any other solutions.

I don't think bypassing the AC ground pin is a very dangerous thing to do, so I routinely do this almost anytime I use my laptop, like in club. Think of all the electronics/video/audio/electrical stuff that you own that does not even have a ground pin, just a 2 prong AC plug.

According to what I've read, the laptop power supply ground pin is there because they are used in businesses, and their insurance companies like to see a ground pin on all business equipment in the insured premises. Any company that makes the equipment is going to say in the user manuals that the ground pin is very important and you must use it, because they need to say that to avoid legal liability if there is any kind of accident and they might be sued.

simply unplug your laptop or get a ground loop isolator

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