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Several weeks ago, I moved into a new home. In office, I have my computer set up with a set of media speakers (older model of Logitech Z-550's). Every now and then the speakers will make a popping sound that is quite painful to my ears. I can recreate the sound when I flip on light switches that are not connected to any actual light or electrical devices, i.e. the outlets they're associated with aren't used (they're blocked by furniture). Other times it happens randomly -- I'm actually not sure if it's truly random or if it's caused by activity of other people in the house (in the event that it actually is a electrical wiring issue).

So I was wondering if this was a electrical wiring issue, which wouldn't be a DIY project by any means, or could it be possible that the popping noise is caused by the speaker wires coming into contact with other cables from my computer, printer, and other electronic devices. Or is it something I haven't thought of?

Any help would be appreciated!


  • The speakers all connect to the subwoofer, and the subwoofer is plugged into a Tripp Lite surge suppressor that was designed for audio/video equipment (I forget the model). The surge suppressor "grounded" and "protected" lights both check out (both show a green light).

  • The sub does not have a ground pin (assuming that means a 3-prong plug). It only has 2-prongs.

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Are the speakers plugged in to a surge suppressor, UPS, or other similar electrical device? Is the receptacle that the speakers are plugged in to grounded (does it have a ground pin, that is being used)? – Tester101 May 21 '13 at 19:18
Are the light switches that you're flipping on and off on the same or different circuit as your speakers? What other major appliances do you have that have electric motors (e.g. refrigerator, freezer, AC, dryer) and is there any correlation with them turning on or off? – Niall C. May 21 '13 at 21:16
Have a look at my answer on similar topic. – Peter Ivan May 23 '13 at 8:41
You're correct that 2 prongs means no ground. So this means you don't have a ground issue, but there are still a ton of other things it could be. Any progress with the other suggestions in my answer? – Henry Jackson May 24 '13 at 5:02

This could be a bunch of problems, from a missing ground to a voltage spike, to dying speakers, etc...

First of all, it would be helpful to rule in/out the computer as the source of the popping. It's possible your computer's sound card is not great and is sending those noises to the speaker, which is faithfully playing them. Try plugging the speakers into a different device (e.g. an iPod), AT THE SAME OUTLET. Then see if you get the popping noises.

If you still do, try moving the speakers to a different outlet somewhere else in the house. Event though the light switch doesn't control the computer's outlet, they could still be on the same circuit and causing some other kind of interference.

If moving the speakers to a different outlet solves the problem, there may be issue with the wiring. (Could be the switch is bad and is causing a ground fault or something. Or maybe the unused switched outlets are bad. Or something else.)

As @Tester101 says in his comment, problems with the ground can cause audio issues. Do the speakers have a ground pin (3rd prong), and if so, is the outlet properly grounded? You can also get so-called "ground loops" when different components have different grounds, which can cause a voltage difference—are the computer and speakers plugged into different outlets?

An outlet tester is an easy and safe way to do quick sanity checks on outlet wiring. You just plug it into an outlet and the lights will tell you if there are some common wiring problems. If I were you I would pick one up and test all of the outlets, including the unused switched ones.

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Your first test is very helpful; I never considered it wasn't the speakers' fault. For me the problem turned out to be that my USB keyboard was plugged into the port right next to my audio input. – Noumenon Dec 31 '14 at 22:58

Static noise can be generated from many different sources...poor grounding, bad connections, internal PC components, etc. It could be difficult to determine exactly where it's coming from.

  1. Check all PC connections.
  2. Re-route speaker wires with as much separation from/perpendicular to other cables/wires.
  3. Keep speakers as far away from other components as possible (tough to do, but might be necessary).

That's the easy stuff. If those don't work, then you'll have to start eliminating things like internal noise, bad sound card, and grounding problems to name a few.

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Well, I just came upon this similar kind of problem yesterday, and had a whole afternoon-evening struggle on finding the problem's cure. So I write my own solution here as I, or others might encounter the same problem again later.

(Ungrounded electrical outlets in the room, Creative t6100 5.1 system, connected to PC via integrated Realtek soundcard, Win10) As beforementioned, try keeping your speakers or the primary speaker connection component (as for me, the subwoofer) away from power strips with consumers. For me it meant only about 3-4 centimeters away from the box's usual place... :/

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