Karaoke Forums

Ok Folks, here it is,,I'm running my toshiba laptop with " Just Karaoke v1" and I'm getting a grounding hum when the laptop is plugged into AC outlet. Now I don't get the hum when the laptop is running off the battery..My host it ru nning the volume at full on the laptop so i told him to back off to 50% and modify PA settings. Any suggestions? thanks in advance.......staffer

Ebtech (Sound Enhancements) Hum X Ground Hum Exterminator

http://www.audiomidi.com/Hum-X-Ground-H ... 3C131.aspx

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Are you sure it's not the audio cable going from the laptop to the PA? If it's got a bad spot in it could cause a hum.

I don't think that is it, he stated that he does not get the hum when running on battery only when plugged into ac.

staffer, go to the hardware store and for around $.79 you can pick up at 3 prong to 2 prong adapter...mind you I do not recomend this as a fix, though some will, but it should get rid of the hum and if it does then I recomend the Ebtech Hum Eliminater, it will eliminate the hum yet still keep your laptop grounded.

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Music speaks to the heart in ways words cannot express.

Hi Staffer

This topic has been answered a few times on this forum. See the following link:

http://www.karaoke-forum.com/viewtopic. ... highlight=

Yes there are differences of opinion, but I can tell you what worked for me.

1. I broke off the ground pin on the plug of my laptop adaptor.
2. Hum all gone.

Now I do not claim to be an electrician or an electric safety expert of any kind, but I can claim that I got rid of that irritating hum by doing this YAYYYYYYY!! I have been using my laptop like this for over 4 years without issues and humfree.

If you are not too happy about breaking off the pin, try taping it up with some electrical tape first and see if it stops your problem.

Cheers

Vic in Sydney.

Many Many THANKS all reply's are considered and appreciated.......staffer

I would recommend not pulling the ground tab, that is a dangerous way. There are other safer alternatives, like ebtech link above or even Rat Shack has a filter that goes inline with the audio cables between the computer & mixer.

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I had the same problem and this worked great for me

Not saying it doesn't work, but the ground tab is there for a reason. It's not safe to remove there ARE safe alternatives.

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It's called a ground loop. It's usually caused by different equipment being plugged into different outlets and running extension cords of different length. The inline filter is one way to alleviate the problem and does pretty much the same thing as breaking off the ground tine on the end of your computer adapter mentioned above. The difference ii, with the inline filter, you are breaking the signal ground which is where the hum is originating.

If you can't find the inline filter, try running everything off one outlet and use a outlet strip.

I had this same problem in the video business. I was taping (obsolete term) a school musical and ran the sound directly from the audio board. Got a ground loop from there. Had to record on batteries to alleviate the problem until I acquired an adapter that filtered (cut is a better word) the signal ground.

I, for one did the same thing. My first night at the club and the irritating loud hum. The bartender suggested pull the ground pin off the power cord of the laptop. So I did, and hum disappeared completely. 'Probably not safe to do this but what the heck, been using the same laptop at the same club for 4 years now and so far, no problem (yet! knock on wood).

I agree.....Get the "Ground loop eliminator" from Radio Shack..(Maplins in the UK).......but next time ...get a Laptop with a 2 pin power adapter

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What's strange is that laptop power supplies deliver DC (direct current) power, and the filtering of the DC is done within the power supply. So you should do this:

With the laptop running on battery, introduce a hum by plugging just a single wire into the mic input and holding it with your fingers. Note the pitch of the hum. Then plug your mic back in and connect the laptop to the power supply. Note the pitch of the hum. Is it the same as when you touched the wire, or is it higher pitch? If it's a higher pitch then you need a new power supply unless you can get it fixed. Most likely a defective filter capacitor or a problem in the voltage regulator.

If the pitch is the same as when you touched the wire then your mic is picking up hum from the power supply. Try relocating the power supply box and note the intensity of the hum as you move it. You may have a defective mic cable or the computer's audio section may be poorly designed so that stray hum is being picked up. Try another mic.

Never, EVER, remove a ground pin. That's like jumping out a fuse with a nail. It's there for your protection so that you don't get killed if the hot wire from the AC supply shorts to the frame of the equipment.