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Spargett's avatar

Tips for minimizing or reducing electronic noise?

Asked by Spargett (5343 points ) May 29th, 2008

I installed a new flat screen last night. In addition to the TV, there’s a PS3 and some computer speakers plugged in below.

I also have two small halogen lights that backlight from behind the TV to create a subtle glow emanating upwards from below the TV.

There’s a noticeable a bit of hum that comes through through the speakers regardless of the volume of the speakers. The halogens seems to amplify the hum as well.

The power outlets are by default a two prong, non-grounded outlet, but I’ve installed a grounded adapter (screwing the faceplate screw through the adapter to properly ground it) which is then run to a power strip/surge protector.

Does anyone have any advice or tips for issues like this?

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9 Answers

Wilhelm's avatar

Looks like your speakers are picking up some EMI. Try going to Radio Shack and pick up some of those magnetic cuffs to clip on to your speaker cables. They’re pretty cheap and should help out. :)

mac316's avatar

It’s unlikely that the center screw will actually ground the two prong outlet. You need to check it or have someone check it for a true ground. Wilhelm has a good idea as well.

Spargett's avatar

@Wilhelm: I’m not familiar with the magnetic cuffs. Can you tell me a little more about them?

@mac316: I’ve always been skeptical about the effectiveness of the grounding adapters. I hear mixed opinions about them constantly.

I’m not sure if this helps for anyone reading, but here’s a photo of the setup’s layout.

Spargett's avatar

I looked into this more. The magical component (which I belive Wilhelm was referring to) seems to Ferrite Coils. Ferrite is the element they paint the B2 and F-117 to absorb RF and RADAR frequencies. Which is also applicable to consumer electronics oscillating RF and EMI output.

Another potential issue is that in addition to my 1940’s era power box not being properly grounded, is that it may not even be metal. Apparently bakelite was a common material to use back then. Crazy.

xyzzy's avatar

If it is a low frequency hum, then it sound like you have a ground loop problem. The simplest thing to try is to plug everything into one outlet.

Try a google search on “ground loop hum”.

JasonH's avatar

get rid of the lights bro. also use a multi plug adapter run the lights 5 feet from the TV and speakers Especcily the speakers, i know where to get “Ferrite” running to many applinaces on 1 plug is a no no with electronics, just my Experance anyways,.

sndfreQ's avatar

I’m with xyzzy on the ground hum-any device with improper grounding in the chassis or at the circuit in the wall will create a ground potential/hum; if you have devices in the chain that only have the “2 prong” plugs, then they may be potential carriers/amplifiers of ground hum. At the power source/wall, you may want to test for proper grounding.

As a musician, I have also invested in power conditioning, such as those made by companies such as Furman to mitigate ground hum. I would suggest reading up on their power conditioning tech (there are other companies that manufacture these btw). My studios have Furman PL-Pros and they seem to kill RFI/EMI in an otherwise noisy 40A home circuit.

mvgolden's avatar

Tracking down ground loops can be a royal pain. I would suggest unplugging everything (including connectors) and then plugging things back in until you hum starts again. That way at least you know where the problem is.

itsjustmatt's avatar

xyzzy seems to be the only who knows what he’s talking about. Putting ferrite cores on your speaker cables is at best laughable. I wish people would not try to give help on a matter they have no knowledge in. The lights are unlikely to be your problem. Focus on a ground loop problem, as mvgolden says, they can be hard to get rid of.

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