Interference caused by lan cables?

[SeaZz]

Firstly i have to apologise if the thread is in the wrong section Anyway Recently i bought a cheap 2.1 sound system for my desk. Sounds great but there's one problem..
The speakers make some kind of scratching noise when i have ethernet activity. I have a powerline which goes to a router (for wireless devices) and my computer to one of the ethernet ports on router. Only when i use ethernet or wifi the speakers make that scratching sound.
Should i buy shielded ethernet cables? (I'm using regular cheap cat5e cables)

 

[Dugimodo]

It's more likely there is an earth loop problem causing noise in the power supply of the sound system, if you don't get the same issue plugging a pair of headphones into the PC output I'd be fairly certain of that. If that's the case shielded cables won't help (and ethernet cables are pretty good even without shielding and not using an audible frequency anyway).

If you do still hear the problem it may be the sound card that's not well shielded being the problem. An external USB sound card might help, maybe. The inside of a PC is a naturally noisy place in terms of RF and needs good design for clear audio.

If the sound system runs off DC via a plugpack a better power supply might help, if not an old fashioned isolating transformer would probably do the trick if you can find one somewhere. Unfortunately the problem might have no easy solution with that combination of devices. you may be able to find audio cables that have an isolation circuit in them but I'm not sure if that's true, I know such things exist for car audio systems.

I had a cheap amplifier I tried to use off a PC that introduced a 50hz hum (the AC frequency here) if plugged into the same supply as the PC. There was no fix and I had to use a different amplifier in the end.

 

[SeaZz]

It's more likely there is an earth loop problem causing noise in the power supply of the sound system, if you don't get the same issue plugging a pair of headphones into the PC output I'd be fairly certain of that. If that's the case shielded cables won't help (and ethernet cables are pretty good even without shielding and not using an audible frequency anyway).

If you do still hear the problem it may be the sound card that's not well shielded being the problem. An external USB sound card might help, maybe. The inside of a PC is a naturally noisy place in terms of RF and needs good design for clear audio.

If the sound system runs off DC via a plugpack a better power supply might help, if not an old fashioned isolating transformer would probably do the trick if you can find one somewhere. Unfortunately the problem might have no easy solution with that combination of devices. you may be able to find audio cables that have an isolation circuit in them but I'm not sure if that's true, I know such things exist for car audio systems.

I had a cheap amplifier I tried to use off a PC that introduced a 50hz hum (the AC frequency here) if plugged into the same supply as the PC. There was no fix and I had to use a different amplifier in the end.

My bad i didn't say about the power supply. The speakers are powered through usb power and a 3.5mm jack for audio. I bought a new 3.1 Amp usb charger which i use for the speaker power (That's not the problem.I tried to connect the speakers to pc power or another usb charger the sound is the same) The problem starts when the speakers are on my desk , if i move them away from the cables no problem whatsoever.

 

[Dugimodo]

Ok sounds like I got it all wrong then I'd still be surprised if it's the LAN cables and not something else nearby but you might be right.
Does sound like the speakers are picking up noise from something nearby though. Not sure what the solution will be.

 

[SeaZz]

Ok sounds like I got it all wrong then I'd still be surprised if it's the LAN cables and not something else nearby but you might be right.
Does sound like the speakers are picking up noise from something nearby though. Not sure what the solution will be.

I think i fixed it myself. I saw that if you place a clamp-on ferite bead on cable stops the interference.I had one arround so I tried it on the usb cable and it works at least for now .There is no scratching sound anymore maybe that was the fix. But i will change the ethernet cables because i need to move the powerline to another wall socket about 2 meters away from the desk. Anyway Thanks for your response!