Computer sounds(feedback)
 

I am getting feedback from my laptop when it is quiet between songs. Dell sent me a new AC adapter because it only happens when it is plugged in, now they are sending me a new motherboard because I am still getting it. Is this a common problem?? I have to unplug the computer to get rid of the sounds and plug it in when the music starts. I don't run music between songs (yet) and it is very annoying.

I run a Dell Studio 2.18mghz, 3meg ram, 320HD... that I just bought and hope to not have to buy another amp/mixer.

Your problem is a floating ground. This is either in the outlet or the power supply of the laptop. My guess is it is probably the building wiring.

i've never heard of a feedback coming from an a/c adapter or a power cord, most of the time you'll hear a hum,and you can get a hum elliminator from www.wbtech.com, are you sure it's not from your eq settings, feedback occurs when your eq's high setting is up, or the mic is infront of the speakers..try going to control panel, sound speach & audio devices, click on sound, and on the sound scheme type in no sound

Besides the other good advice already posted, I would also check the internal mic volume on the laptop.

What is precisely meant by that term, Dale?

I know I'm not Dale but....A floating ground usually happens when you have a properly grounded device, and one that is not, hooked up on the same circuit. The ground "floats" between the 2 devices. This is almost universally caused in a bar by older neon lights. The older ones don't have a ground. As they age, it exacerbates the problem. Electricity, like water, takes the path of least resistance. If your laptop/amp is closer (wiring wise) than the grounding rod (if there is one) that goes to earth, your equipment will act as the ground. Bear in mind, path of least resistance can also include wiring size as well as distance. This can also be aggravated by the wall wiring being undersized. This is not limited to neons. It can be anything that is not working properly, or is not properly grounded.

In other words Bryant it is a lack of ground somewhere in the AC power that the laptop is also plugged into. To go any deeper would require you have an electronics background.

When Karl said feedback between songs I immediately thought of 60 HZ hum, but you are right he could have his internal microphone on.

What is meant by internal microphone?? As for a ground, I have that feedback when just the windows screen is up and no other programs are running...it doesn't matter which bar I'm playing in. My original computer didn't have this sound just some hiss. The sound sounds lilke the old movies when computers were making a "computer sound" when they were trying to figure something out. Thanks for the help and keep the sugestions coming please.

In your hardware audio properties under Volume/Advanced, you will find some sliders to set individual volumes for certain devices. Mic should be set to lowest volume or off. I set my line in and CD to zero also.

The other thing is, are you using wireless microphones? They are susceptible to interference also.

I disabled the mic and also muted it and that doesn't work either. It just doesn't make sense why I get that sound only when it is plugged in???? Also, that sound comes even when my cordless mics aren't hooked up to the system. Thanks everyone for the ideas and keep em comin.

Get the little 3 prong to 2 prong adaptor, and use on laptop.
see if that helps.

That is a good idea, but I would only do this for testing purposes. If that is indeed the problem, come back and ask about isolating the ground.

Bobcox, you're a genius...that worked great. Now the only thing left is a slight hiss, but it is way better than that feedback sound and might not even be heard in the bars. Thanks so much and I will keep looking on this forum and maybe help someone else someday.

Is it a problem to run this way all the time??

That goes right back to what I was saying. Apparently they do not have the outlets grounded correctly.

That may be, but I have the same problem at home and I know that all my outlets are grounded properly cause I did the wiring myself. Is there something that I can get to clean up the power in the bars that I'm playing at??

I have been doing it for years. no problems, Bob

Hey Carl,
Bob, Dale and Mark are all correct. Since the problem went away when you lifted the ground (this is what the three prong to two prong plug did) there is a ground loop somewhere. (this is what Dale explained, the path of least resistance)

When ever you set your system up, be sure that EVEYTHING is plugged into the same power strip which will go to one outlet. Since you have the same problem at home it leads me to believe that the ground loop may be occuring in your system somewhere.

There are plenty of power conditioners availabe but I have been running PA systems for more years that I like to talk about and find that ground loop problems can be delt with by following this one simple rule. I have never had to use a power (or line) conditioner, I just eliminate the ground loop.

I Hope This Hekps.

Jim

Let me be a little clearer here Karl. When I said "in your system" I do not mean that your stuff is broken. Here is an example.

Let's say your laptop is plugged into one outlet and your TV is plugged into an outlet that's on a different breaker. Buy using power from two different breakers, you are creating at circit between the two breakers that runs through your system. This creates a loop. What nomally would go to ground gets caught in this loop. In non-sound aplications this causes no problem. In sound aplications it creats a hum or buzz. Buy plugging your TV and your laptop into the same outlet, you eliminate this loop which stops the hum.

Jim :g

It is a real danger risk. There is a ground for a reason. It can be done to test - your feedback was a 60hz hum. But wouldn't use it for any long term. On the rare occurance that something happens where a spike turns up in the system, normally would go through the ground, without it, it will now find it's way to the electronics or worse the person touching the electronics. This is an old sound man's trick to eliminate hum from amps in clubs that would create it, but not recommended anymore.
The Ebtech unit linked to earlier (wrong link btw) is a safe way to eliminate the hum without hurting the grounding connection. http://www.ebtechaudio.com/humxdes.html Those 3 prong to 2 prong adapters aren't meant for eliminating the ground, the little tab that gets bent back (for those trying to lift it) is supposed to get screwed into the middle plate screw on true 2 prong only (no ground) plugs in older buildings.
The eliminator is not much at most music retail stores. But the equipment or life you save could be your own - yeah most are lucky and nothing happens, but there is always a chance once the protection is not there!!!

in my opinion, he's better off getting a hum eliiminator instead of a 3 prong to 2, he can get one at radio shack for $15.00 ,theres a danger in using that type of an adapter (3 prongs to 2 ), not just for him and his equipments and not to mentioned the people around him..this is just my opinion..