[SOLVED] Powerline adapters create PC speaker interferences

[Kruppe75]

Hey all,
I recently bought the Devolo Magic 2 WiFi Powerline system. Installation was easy and without any issues. Then (right after synchronisation between the two PLCs) I noticed an intermittent knocking sound in the background as well as irregular static sound (interference) coming from my PC speakers (Sound Card is on board on an Asus Z97-A MB and Speakers are Altec Lansing 2.1). PC is connected via Ethernet to PLC. Power comes to the PC through a surge protection multi socket.
The knocking sound gets louder when the speaker volume is raised and is there, even when the Ethernet cable is disconnected.
The static interference is not affected by volume level and gets more intense when browsing or with internet activity in general (it gets lost of course when Ethernet is pulled out and there is no internet).
When disconnecting the speakers from the PC, all is normal.
This problem is not there for my laptop's built-in speakers or for my Kingston HyperX Cloud II headset (which connects over USB though).
I tried moving the PLC to a socket outlet further away from the PC (still in the same room though) and though the knocking sound somewhat subsided, the static interference remains and is really annoying.
Next test: To try the Devolo to a friend's house to see whether the problem comes from the PC sound card or from the electrical wiring in the house.
I was wondering if someone else has had any similar experience and if there is a way to solve the issue (something like a noise filter in-between socket outlet and PC - I don't know if it will isolate the correct frequencies though - or a UPS - the cheaper ones do not make the AC - DC - AC though, and I'm trying to find some low budget solution first).
I would appreciate any help on the matter.
Many thanks in advance.

 

[bill001g]

It is not likely getting into the pc via the power cord it is likely directly bring picked up by the wires running between the computer and the speakers or someplace in the speaker electronics. It not being affected by the volume level indicates the interference is entering past that point.

Not sure if you can get different wires for the speaker system. For many years before everything was hooked up via optical or HDMI cables audio people used shielded cables.

I used to have a cell phone that caused interference on my speakers if I placed it too close and never did figure out how to stop that.

It could be the power to the speakers but that is unlikely since the output of the power block is regulated DC power. I suppose you could try a different power block if you have one.

There really is nothing cheap that filter the signals on the wires. As you found you need a online type of ups to totally isolate power and I am not 100% sure it is isolated even then because the new powerline units use the grounding wire for signals also and that is commonly connected everywhere. Many types of surge protectors actually block the powerline signals but nobody documents that ability.

Be sure the PLC unit is plugged directly into a wall outlet and not into any type of surge protector. It will not cause interference but it many times affects there performance.

Maybe changing the layout of the speaker wires will have a affect. Maybe wrap them in aluminum foil but I not sure if that would do anything.

 

[Kruppe75]

Many thanks bill001g for your prompt reply.
The PLC is indeed plugged directly into the wall outlet and I even tried different ones (right now it is plugged to the opposite wall outlet from the one that powers the surge protector multi socket).
I did not mention that I already followed your logic and thought that this would be a speaker problem (either due to wiring or poor shielding, as you say). So, I brought a friend's set of high quality speakers (over 500€ worth) and shielded wiring and tried them out. The result was exactly the same. When the 3.5mm Jack that connects the speakers to the PC is pulled out the interference is magically gone. That also proves that the cause is not the speaker's power, since the interference is there only when they are connected to the PC. The funny part is that the interference (and the knocking sound) is there, even when the PC is powered off! Which eventually leads me to the conclusion that this is probably due to poor electrical wiring in the building. Hence the inquiry on whether there are solutions, such as filters or whether a UPS would work.

What I do not get is why would the interference signal be passed on or boosted through the PC soundcard (the 3.5mm jack connection) and not through the power cord of the speaker's amplifier.

As I said, I will be trying the system in another house to see if the effect is being reproduced there as well. But for now, I am at a loss.

 

[bill001g]

The powerline unit you are using are not the ones I have used. They are based on g.hh and not homeplug which I am more familiar with. They likely operate on different radio frequencies.

I assume it does this with the PC unplugged as well as just turned off.

I would bet the signal is coming out the wires in the wall directly into whatever electronics it is affecting. Not sure how you would filter that since it is passing through the air

 

[Kruppe75]

The powerline unit you are using are not the ones I have used. They are based on g.hh and not homeplug which I am more familiar with. They likely operate on different radio frequencies.

I assume it does this with the PC unplugged as well as just turned off.

I would bet the signal is coming out the wires in the wall directly into whatever electronics it is affecting. Not sure how you would filter that since it is passing through the air

That is correct, the interference is there even if the PC is unplugged. The interference clears out only when the 3.5mm jack that connects the subwoofer (where the amplifier is) to the PC is disconnected.

You're probably right about the signal's source, that's why I want to try the plc out in another house and see the result.

Many thanks again!