Noise/hum issues - help

[strat+ac30]

I've attached an mp3 with a sample of the noise problem I have. I've run across it in my monitors (Alesis M1 Actives) but only when the volume is at the upper limits. The place where it's unworkable, however, is when I use a newly-acquired Pearlman TM1.

My system:
Sonica Livetracker laptop
Presonus Firepod

I've found out where the hum/noise is coming from. If I unplug my laptop's power adapter, it goes away. Clean, clear. When I plug it back in, the noise returns. But obviously I don't want to have to unplug my laptop every time I record with the Pearlman (which, being my nicest mic, will be used frequently.)

I've tried plugging the laptop's power into five different outlets - three of them in different rooms. No dice.

Has anyone else had this issue? How can I get rid of it without having to unplug my laptop every time I record?

Dave

[kafka]

Could be your hard drive. I can hear my laptop's hard drive in my guitar pickups very clearly. There are plenty of other sounds, too - too many to catalog. The universal solution to all of them, I've found, is distance. Get away from the computer, and things generally get better.

[Snatchman]

I agree. Must be something going on with your laptop. Especially if the noise is following you around. ( other rooms).. Good luck..

[eliguitar]

I've been having the exact same problem. Tomorrow Im gonna look into grounding, maybe borrow a couple of good power conditioners to see if there's any difference.
The weird thing is that I wont hear that noise when I connect small computer speakers to my laptop. I tried using different monitors, interface and nothing got rid of the noise.

If anybody has an idea of how to get rid of it let us know

thanks

[drBill]

It's really quite simple (yet, very difficult at times to implement) - make sure there is ONLY one path to ground. This will fix the problem. (60 cycle hum) Solutions include: Telescoped wiring, no gear touching each other, all grounds coming to a central point (star grounding), no metal rack rails, etc., etc., etc. This has been covered a lot here. Do a search for "star ground". Also, balanced power MAY help. Or it may not. Depends on your particular circumstances.

[Kiwiburger]

Most laptop PSU's i've seen are switching power supplies, and they don't have a ground. So it's hardly likely to create a ground loop.

I understand that true ground loop hum sounds like a real hum with plenty of the fundamental (50 or 60Hz).

RFI induced hum tends to be a buzz - with far more harmonics, and little or no fundamental. Much more annoying.

What i'm hearing in that sample doesn't sound like hum or buzz to me. It sounds like hash - I might have thought motor noise. I would swap out the PSU with a better one - these things are built very cheaply and it's probably just faulty.

I had problems with the cheap chinese PSU that came with my Portico. I replaced it with an off-the-shelf laptop PSU and that fixed the problem. I was getting a different type of noise - more like pink noise that got louder with time. It also radiated this noise as RFI, so dynamic mics would pick it up.

If it's not the PSU - I would wonder about any fans or motors in the laptop. Computers are often a grounding nighmare - so many components, so many screws that could be left out ...

[drBill]

Good advice!! Switching power supplies are notorious for inducing hash-like trash into the audio.