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As soon as I plug in a standard 3.5mm jack cable into my speaker AUX IN port they produce a loud disturbing noise exactly as this one: https://en.wikipedia.org/wiki/File:MainsBrum50Hz.ogg. I don't even need to connect a cable to a computer, it's enough for it to be connected to speakers only. My speakers are Creative Inspire S2 Wireless. When I turn up volume, humming is louder. I tried connecting a power supply to another wall outlet, turning off my router but it didn't help. My current guess is that power adaptor is broken. I could get a new one where I live for a couple of dollars. It's worth mentioning that Bluetooth connectivity works completely fine, there is no humming when a device is connected to the speakers that way.

Does it make sense to get a new power adapter in such case?

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  • Are you using an old-style "wall wart" linear supply? Modern switched-mode AC adapters are more compact and should not generate this kind of noise.
    – bwDraco
    Sep 9 '15 at 21:36
  • I am using Creative stock power adaptor: i.ebayimg.com/00/s/MTIwMFgxNjAw/z/mKIAAOSwBLlU8erR/$_57.JPG. And would be the same one. Sep 9 '15 at 21:39
  • Well, this definitely does not sound normal. What you showed is a switched-mode supply, and chances are good it's subpar quality allowing some small quantity of mains to reach the device. I'd want to replace the adapter, but don't get a cheap one.
    – bwDraco
    Sep 9 '15 at 21:42
  • @misha256: The problem is that these speakers used to work some time ago. What's strange here is that humming is produced as soon as a cable is plugged in the speaker, most people reported that they hear humming after connecting a cable on both ends Sep 9 '15 at 21:46
  • @DragonLord: I am not sure if it's possible to find a power supply with identical parameters and plug type and if it is how much more expensive it would be Sep 9 '15 at 21:47
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Why are you plugging a cable into the speakers without having the other end connected to anything?
That's the very definition of 'make a hum noise' - a game played by every guitarist who ever lived, at some point in their career.

It will get worse if you hold any single element of the plug at the other end & get better if you hold both elements with damp fingers, closing the circuit. If it doesn't stop when you do that, the cable or the speaker's socket is broken.

It has nothing to do with your PSU at all.

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  • Why are you plugging a cable into the speakers without having the other end connected to anything? - I don't get it. In order to connect speakers to my new computer I need to plug a cable into the speakers first, right? Sep 10 '15 at 10:40
  • No. Plug into the source first, the destination last. Golden rule.... otherwise you get hum.
    – Tetsujin
    Sep 10 '15 at 10:42
  • You're right - humming is louder if I hold both ends with a finger and even louder after plugging in an other end into a computer. Do you think my speakers are just broken and a new PSU won't help? Sep 10 '15 at 10:43
  • There is still a loud humming if I plug a cable into computer first Sep 10 '15 at 10:45
  • As I said, first suspect the cable; then the socket. If the speakers are silent with nothing at all plugged in, they're the least likely to be at fault.
    – Tetsujin
    Sep 10 '15 at 10:58
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Try to plug both in the same wall outlet to see if the humming disappears. This post probably answers your question:

It's caused by the electrical ground on one piece of equipment being at a slightly different voltage than at other equipment. This causes something like a DC current between your equipment, which your speakers interpret as a hum. The quick and dirty fix is to use a long extension cord (with a 3-prong plug for ground) so your speaker system and computer are plugged into the same wall outlet.

Try to connect the plug to your phone. If the noise vanishes, it is probably the problem, since your phone is eletrically isolated.

You can also try shielded RCA cables to prevent some kind of interference, but it doesn't look like your problem.

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