Just curious if anyone has had this problem.

dmangrich · Post by **dmangrich** » Mon Nov 10, 2008 3:46 pm

I have two laptops, one with XP and one with Vista. The one with Vista makes a very bad howling noise out of my speakers when hooked up to my equipment. Does/has anyone heard of this? If so what needs or can be done to eliminate the sound? If anyone knows of the direction I need to be sent please do.

alfalfa4381 · Post by **alfalfa4381** » Mon Nov 10, 2008 4:03 pm

Sounds like accoustic feedback. Try disabling the laptop's built-in mic. Sorry, I don't use Vista, but, if there is a speaker icon at the bottom right in the system tray, you can right-click on it and choose properties and mute the mic from there. Otherwise you will need to go to Control Panel and find the applet that pertains to Sound Settings and doubl-click it, and then go to Sound Properties and mute the mic.
Also, make sure that you are plugging the audio cable to the speaker jack on the laptop, usually the green one, and not the pink mic jack.

Bigdog · Post by **Bigdog** » Mon Nov 10, 2008 4:05 pm

The only thing you are changing is the laptops and all the other equipment configuration is the same?

Does the noise stop if you disconnect the Television wire? If you are using one.

My first thought is a ground loop either from the TV hook up or from the audio. They sell ground loop eliminators for both the audio and visual connections. I have both installed in my system. But at certain jobs I can still hear ground loop noise and have to use another isolator on one of the bar TV hookups.

I don't think it has anything to do with the operating system. It's a hardware compatability problem. Dealing with electricity.

dmangrich · Post by **dmangrich** » Mon Nov 10, 2008 7:44 pm

The noise stops only if I unplug the power. Otherwise it doesn't matter if I have a monitor hooked up or not.

alfalfa4381 · Post by **alfalfa4381** » Mon Nov 10, 2008 9:14 pm

The reason I am thinking feedback is that most laptop built-in mics are by default turned on. When the laptop in plugged into the sound system, the laptop is probably too close to the powerful speakers and the mic is picking up sound from the speakers and re-micing it and re-amplifying it, and re-micing it, and on and on. He said "howling" not "buzzing" like a 60 hertz ground loop would make. Dmangrick, is it a loud buzzing sound?

DanG2006 · Post by **DanG2006** » Tue Nov 11, 2008 11:55 am

If it stops when you unhook the power it sounds like a groundloop think with the power unit. I had that with my laptop and eliminated it by changing to an outside USB soundcard.

Bigdog · Post by **Bigdog** » Tue Nov 11, 2008 12:34 pm

I don't mean computer monitor, I mean television.

letitrip · Post by **letitrip** » Wed Nov 12, 2008 11:09 am

Are you saying that you don't get the sound if the latop is running off battery power (i.e. still on and running but not plugged in)? Then there is a power supply issue. I doubt it is a ground loop however because you're dealing with an AC to DC transformer and without getting too far into the electrical engineering details it is very rare that you'd find a ground loop generated through a modern-day transformer of that type. Additionally, going through the sound card, the audio ground is typically well isolated from the DC ground and so having the type of ground potential mis-match that creates a ground loop is not very likely.

My guess would be something internal to the laptop. I've had other laptops where noise from the hard drive motor spilled into the sound card which became very apparent at the high volume levels of a PA. It could also be an issue with an internal transformer or even noise from the CPU fan motor (these sometimes shutdown and run only periodically when the laptop is on battery power).

dmangrich · Post by **dmangrich** » Wed Nov 12, 2008 10:01 pm

OK I get a horrible sound when I hook it up to my equipment. When I unhook the power cord the sound goes away but everything sounds fine until i replug it in. It does all the same on a friends laptop also. They both have everything the same except his is HP and mine is Dell. It does it even if the mic is on or muted so that isn't a factor. I will try the external sound card this weekend also to see if that will solve the issue. I was thinking about removing Vista. Maybe it works maybe not but have no clue and a laptop that doesn't do what i need it to do.

myau · Post by **myau** » Tue Nov 25, 2008 2:24 am

I've experienced the same thing with different laptops. Running the laptop on battery power is fine right? Yeah the external soundcard should work. Also, you can try this: use a 3 prong-2 prong adapter for your laptop power adapter and see if that changes anything.

letitrip · Post by **letitrip** » Sun Nov 30, 2008 5:55 pm

Sounds like interference from the the battery charger (part of the power supply) is being picked up in the sound card. Before you spend money try a couple things. Go into the volume control and mute all sources going to the sound card except for "Wave". This should allow your software to still send signal to the card but ensures any other inputs to the sound card are muted in case the interference is isolated to one of those sources (like maybe the internal microphone). Also make sure the volume control for the Wave input is all the way to the top. This helps maximize the final signal to noise ratio at the point the sound card's pre-amps get ahold of it. You can also try adjusting the overall volume control higher and lower, making the appropriate adjustments to that channel's input attenuation (gain, trim, it has many names) on the mixer to keep the proper input level. See if you're able to eliminate the sound in any of those ways.

If those don't work then look at the USB sound card. They're not very expensive and should definiately correct the issue.

alfalfa4381 · Post by **alfalfa4381** » Sun Nov 30, 2008 10:32 pm

Well, since you said that the bad noise goes away when you unplug the power supply, then it must be power related. I have a few other ideas for you.
1. Is this environmentaly related, ie., only happens in the one establishment? If so, maybe a bad circuit. If the laptop is plugged into one circuit, and the sound system in another, then a ground loop can happen.
2. Is the transformer (the big bulky box-like part) of the laptop power supply near a piece of equipment where electromagnetic inductance can cause this problem? If this is the source of the problem, the noise should change as you move the laptop powersuppy around. Having it close to a CRT, such as your karaoke tv monitor, can cause a horrible noise because it uses a fly-back transformer that works at a very high frequency. Florescent lights use similar HF xformers. Dimmer switches in the room can cause noise from inductance.
3. Lastly, and probably a stupid question, but are you sure that the power supply you are using is the one designed for the laptop? Maybe it is bad? Compare the numbers on the laptop as far as what it needs from the power supply. It sould be stamped on the computer near where the unit plugs in and should show the voltage, probably 12v, the current type, probably DC, and the power rating, something like 1500ma. It should also show the tip polarity, either the tip is positive + or negative - . Verify that the numbers on the power supply shows that it is putting out what the PC is looking for. It could be bad, try another PS.
4. I dunno.

Marlena · Post by **Marlena** » Sat Dec 20, 2008 6:19 am

WOW great discussion.. i also purchased a new laptop today and am having the exact same issue...

plugged in - bad feedback noise
battery - no noise
Shure beta pg 2.0 On - Noise
Shure beta pg 2.0 Off - No Noise

I remember some time back where someone mentioned a problem with the laptop power cord needing to be replaced for This problem.. could this be it? should I try it? or am i imagining a thread? (I could be, i dream a lot)

Marlena

Bigdog · Post by **Bigdog** » Sun Dec 21, 2008 3:35 am

You need those ground loop isolators on all your wires.

My Friday job keeps messing with their TVs. Last night I had interference lines on the TVs all night long. It's something they did and I refuse to try to do anything to fix it. First of all I don't know where to begin and second of all I don't feel like I should. It's making me look like I am running crap equipment and that's the part that's making me mad. They can never be happy they always have to screw with stuff and never think about the consequences for their actions. They did something so they could watch the hockey games.

I'm the only entertainment that has lasted and makes any money. So now we can't see the words on all the TVs like before and the picture quality is screwed up on the ones that are left. Who does the brain work for these idiots?

letitrip · Post by **letitrip** » Thu Dec 25, 2008 12:01 am

Bigdog wrote:You need those ground loop isolators on all your wires.

Sorry, but I disagree with the notion that seems to be implied here that in order to have a rig free of ground loop interference that you must have some type of special isolation devices installed.

Buying quality equipment and understanding how to properly deal with AC power is more effective than any specialized devices. Understanding the power being supplied to your equipment is priority number one. Use a tester. Make sure there is a good ground and that the hot and neutral have proper polarity. All of your equipment should have grounded connections and those grounded connections should all share the same ground (i.e. read they should be plugged into not only the same circuit but ultimately the same outlet). Some equipment may have DC transformers, these often do not have grounded connections but given their isolation from the AC ground shouldn't cause an issue.

The way I deal with this is for my Karaoke rig is very simple, all my audio equipment plugs into a single 8 outlet power distribution center. Extension cords and 3-way splitters ensure that I can connect all the audio devices to the same single ground connection thus avoiding the dual path to ground that causes ground loops.

Honestly folks, considering the value of the equipment you deal with, one of the most basic aspects is the AC power supplied to it. Any good audio engineer will understand and stress this point. If you AC distribution is flawed you're doomed before you ever start sending audio signals to any devices. If you're going to do a professional job, you really ought to have some understanding of how AC power works. You don't need to be an electrician but you should know more than simply 110 Volts will flow through this cord if I plug it into this outlet here.