audio hum (ground loop hum)

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moxielll
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Joined: Mon Oct 29, 2007 5:51 am
Location: connecticut

audio hum (ground loop hum)

#1 Post by moxielll » Tue May 06, 2008 8:20 am

I;ve begun to use my new laptop to DJ at the local swing dance, and found that strong speaker hum when using the A/C wall plug. Understand
it comes from the transformer (no hum sound when using battery). I've read lots of solutions on the net, but wanted to hear from the swing DJs
in the know. Sheilded audio cables, isolation transformers, ground loop isolators, ground fault circuit interruptors.....? Any suggestions to eliminate the Hum while still using the A/C plug....?

moxielll

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JesseMiner
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#2 Post by JesseMiner » Tue May 06, 2008 8:43 am

Just discussed weeks ago in the behemoth Laptop DJing thread.

Jesse

moxielll
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Location: connecticut

#3 Post by moxielll » Tue May 06, 2008 11:20 am

Thank you, Jesse

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CountBasi
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#4 Post by CountBasi » Mon Nov 17, 2008 1:55 am

There's a case for some tech/admin extracting that and putting it into this thread.

I was (trying) to DJ a non-dance event Saturday night and was getting horrible noise from the speakers. I was plugged into the mains, had my wifi detection turned off, going through a mixer and my Turtle Beach sound card. The sound card didn't seem to matter as I tried without, same buzzing and humming sound. This is the same laptop I DJ from regularly at a weekly dance in Portland, and I also DJ'd from elsewhere (London, Vegas, Utah) with no buzz or hum.

I'm guessing it's not my laptop.. but would dearly like to know how to go about troubleshooting as it was pretty bad. I certainly couldn't go on DJing from it on Saturday. Thankfully there was a backup laptop someone else had I was working the gig with and we used that.

Any clues as to where I should start to look? Windows sound settings (they're set to No Sounds). Any piece of hardware/cable I could buy to take along to gigs as a failsafe?
It don't matter if your clock is broke - it's the right time somewhere : Slim Gaillard

Toon Town Dave
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#5 Post by Toon Town Dave » Mon Nov 17, 2008 11:25 am

To summarize what came up in the laptop thread, there are two options:

1) Buy (or fabricate) a ground loop isolator to go between your audio output and the mixer board.

2) Be cheap and get a 3-prong (NEMA 5-15) to 2-prong (NEMA 1-15) power adapter to go between your laptop power supply and wall power. The thrifty alternative is to cut the ground pin off an extension cord.

Surreal
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#6 Post by Surreal » Tue Nov 18, 2008 12:17 am

At one place I was playing at recently, they had a very long speaker cable coiled into a loop. I just stretched the cable out and this reduced the hum significantly.

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