Powerline Causes Audio Hum

[airickm3]

Hello -

I installed a TrendNET powerline adapter to bring better download/upload speeds to a far corner of my house, and it's causing a hum/buzz/popping in my speakers. I've spent hours trying to troubleshoot this with no luck. Would love any advice on how this might be solved. Here are the facts:

- The ethernet cable from the powerline adapter is running into my Mac Pro 4,1 tower.
- The speakers on my tower are connected via the 3.5mm jack on the back of the machine.
I have tried the front headphone jack as well, the hum persists.
I have tried headphones on both inputs as well, the hum persists.
I have tried an alternate set of speakers on both inputs, the hum persists (Bose Companion 20 and and old Altec Lansing 2.1 setup).
- The buzz/hum from the speakers intensifies when internet activity increases.
- The buzz/hum exists even if the ethernet cable isn't plugged into the Mac Pro.
- The buzz/hum vanishes completely the moment I unplug the powerline adapter from the wall.
- The powerline adapter, the speakers, and the computer are all on the same circuit. My office has only one, so no possibility of moving the adapter to another circuit.
- I have tried the adapter in each of the four wall sockets in my office, all produce identical results.
- The computer and the speakers are powered through a Cyber Power 850G UPS (again, same circuit, but separate wall socket)

Please help! It would be so nice to have the internet and sound at the same time
Thanks.

 

[username214]

What kind of ethernet cable are you using? If it is UTP, id suggest switching over to the STP ethernet cable.

 

[airickm3]

What kind of ethernet cable are you using? If it is UTP, id suggest switching over to the STP ethernet cable.

Thanks username214, but the sound exists even when there is no ethernet cable involved. When I plug the powerline adapter into the wall, without any ethernet cable running out of it, it still creates the sound on my desktop speakers. So it doesn't seem like swapping the cable is going to make a difference.

 

[bill001g]

Run the computer and the speakers on the UPS..ie unplug the UPS from the wall. This will show if the interference is coming in via the power. I suspect it is wire between the computer and speakers picking it up.

 

[airickm3]

Run the computer and the speakers on the UPS..ie unplug the UPS from the wall. This will show if the interference is coming in via the power. I suspect it is wire between the computer and speakers picking it up.

Terrific test! Not what you expected though - when the computer and speakers were running off UPS there was no hum from internet activity. Not sure what that gets us though...

 

[bill001g]

This means it must be coming in over the power. The UPS all claim they filter the power even when it is running on the mains, obviously they don't do such a good job.

Maybe a surge protected power strip or a extension cord between the UPS and the speakers/computer might help. Since the powerline units say to not plug them into either of those because it degrades the signal maybe you get lucky and it will filter some of the signals coming in from the powerline units.

Many times hum in audio equipment is caused by poor grounds. Still your UPS should complain if the ground in the house were bad.

 

[airickm3]

This means it must be coming in over the power. The UPS all claim they filter the power even when it is running on the mains, obviously they don't do such a good job.

Maybe a surge protected power strip or a extension cord between the UPS and the speakers/computer might help. Since the powerline units say to not plug them into either of those because it degrades the signal maybe you get lucky and it will filter some of the signals coming in from the powerline units.

Many times hum in audio equipment is caused by poor grounds. Still your UPS should complain if the ground in the house were bad.

Tried two different power strip from UPS, and pugged in computer and speakers to new strip. Still the same hum. :/

 

[bill001g]

Not sure what to suggest, it is either coming in via the speaker power or it is some issue with the grounds in the computer and the speaker power that is allowing this noise to get in.

The simplest test would be to hook your phone to the cable going to the speakers and see if you still have the hum. If it makes noise it is just the speakers that have the issue if it does not then it is some relationship between the speakers and the computer power.

Still I don't know how you would solve this. Maybe plugging speakers directly into the wall and leave computer on UPS would make a difference.

 

[Hunter_20]

Can you try wrapping the audio input in a ferrite bead?

Not sure what to suggest, it is either coming in via the speaker power or it is some issue with the grounds in the computer and the speaker power that is allowing this noise to get in.

The simplest test would be to hook your phone to the cable going to the speakers and see if you still have the hum. If it makes noise it is just the speakers that have the issue if it does not then it is some relationship between the speakers and the computer power.

Still I don't know how you would solve this. Maybe plugging speakers directly into the wall and leave computer on UPS would make a difference.

 

[airickm3]

For all future readers:

I solved my problem by getting an external USB sound adapter. The hum is gone, the internet works great. For now I grabbed one of these:
http://www.frys.com/product/8351707?...H:MAIN_RSLT_PG

A sabrent USB sound card. There are much higher quality solutions out there, which I'll be exploring soon, but this worked as a quick fix.

 

[joshleeman]

For all future readers:

I solved my problem by getting an external USB sound adapter. The hum is gone, the internet works great. For now I grabbed one of these:
http://www.frys.com/product/8351707?...H:MAIN_RSLT_PG

A sabrent USB sound card. There are much higher quality solutions out there, which I'll be exploring soon, but this worked as a quick fix.