Laptop Noise

[hrasco]

If I hook my laptop up to an external sound system it creates noise along with the playback. The noise goes away when I unhook the P/S and run off batteries. Is it possible to get a laptop P/S that won't cause noise or will I have to isolate the audio with a transformer?

Enquiring minds want to know.

[Sonic Vampire]

I have the same problem when hooking into PAs when it is running unbalanced (tip & sleave) as opposed to balanced (tip, ring & sleave) is this how you are running your gear or are you using a decent sound card with balanced ins and outs?

too get around it I have a plug that lifts the earth on the laptop, not the best (safest) solution but it works

technically your idea of the transformers is the best

[hrasco]

Thanks for your reply. This is not balanced audio or even a decent sound card. It's just the headphone out of the laptop. I will sometimes use it as an audio source for testing installed systems or if I just want to do a quick patch to my home studio monitoring system. My laptop P/S doesn't have a grounded plug so there's nothing to lift. As I mentioned before, it works fine on batteries. I thought maybe someone else may have had the same problem and a better/different P/S might cure this.

[WOK!]

You can use a DI-Box with ground lift to connect the audio out with the amp/mixer input.
It helped for me.

[BaRaKa]

1. Rip the ground prong right off the triplug.

2. Plug into powerbar/ surge protectorth

3. Ground laptop to something such as the back of a DJ mixer with good guauged wire, maybe with an alligator clip.

EDIT: sry I missed this part...
My laptop P/S doesn't have a grounded plug so there's nothing to lift.

However this is a useful technique I have used before.. guess I'll leave this post up anyways :)

[Guod3]

You can get really inexpensive stereo iso transformer cables. The audio transformer is encapsulated inline. They have RCA female connectors on the input side. High spec, 20 to 20kHz and cost <$20 (made for car audio systems).

[hrasco]

Good suggestions. Thanks!

[strata189]

Got a supplier for those stereo iso cables? Love to get some.

Thanks,

Randall