Powerline Network Interference

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SRMcGee

SRMcGee

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Joined 2004
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#1
Folks:

It's taken me a while to figure out the source of the problem, but the WiFi powerline extender devices (TP-LINK AV500) that I am using to link my server to the house router create audible "popping" and "scratching" sounds when I listen to my turntable. The noises created by the powerline extender are inaudible when I listen to my server or FM radio. There are two separate 15A circuits powering my front-end equipment and the powerline extender and turntable are on separate circuits.

I cannot snake an ethernet cable from my router (third floor) to the server (basement), and the powerline extender otherwise works flawlessly. Does anyone have any idea how to eliminate or filter out the noise?

Regards,
Scott
 
#3
billshurv:

The turntable is a Maplenoll Apollo (with a Lyra Lydian Beta cartridge refurbished by Sound Smith). An SG-4 sine wave generator (circa 2017) provides platter speed control. The phono amp is Salas' UFSP, but the popping and scratching sound was also present with the UFSP's predecessor, a Pearl (MM) / Ono (MC) phono amp I completed in 2007 or so. The current preamplifier is a BA2018, but once again the popping and scratching sound was also present with its predecessor, an Aleph P 1.7 that I built in 2008 or so.

Regards,
Scott
 
#4
A phono preamp has higher gain than other inputs, and thus would be more suceptible to RF signals. That much bandwidth over the power lines is bound to be transmitted as RF. I'd try cable suppression ferrites on the cables between the turntable and the preamp, placed just before the connection to the preamp. It could be coming in from other areas, If that doesn't fix it, I'd next try such ferrites on the preamp's power cord, and the output cables to the amp.
 
#5
A friend of mine tried a WiFi extender like that one (but I don't know if it was the exact same one) that he picked up at Walmart...he had the same problem trying to use it with his Smartphone and took it back for a refund. In my experience gimmicks like that rarely live up to expectations based on the claims made about them.

Mike
 
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#6
I had a friend with this issue and he moved the powerline adaptor further away and that removed the problem. If you have a socket on the other side of the room. plug it into there. distance is your friend. They are not well tested for EMC



As it changes with preamps I think the first thing to do is check that, if you disconnect the TT and short the input and see if the problem goes away. If that is the case then you have a starting point. If it doesn't go away it's in the mains not in the air.
 
#7
benb:

Thanks for the suggestion! I've ordered ferrite clamps and will see if that resolves the problem. Either way, I'll report back.

billshurv:

Another good suggestion! I'l try moving the powerline extender to a more remote location - while I can't snake an ethernet cable from the basement to the third floor, it should be possible to distance the powerline extender from the audio racks. BTW, when I disconnect the powerline extender from its wall socket, the popping/scratching noise disappears. I'll post feedback once the change has been tested.

Michael Bean:

I wouldn't characterize the powerline extender as a "gimmick" because it does its job quite well. I have three stereos in my home and there's an extender at each one. They've reliably connected my servers to the house router for years. The fact that there's an unintended consequence with my phono rig doesn't mean the powerline extender should be dismissed as ineffective or junk.

Regards,
Scott
 
#8
...and a quick follow-up:

The powerline extender has been moved into the adjacent room in my basement, about 16 feet / 5 meters from its original location. A cement / metal screen wall, some bookcases and odd stuff found in utility rooms now sit between the powerline extender and the phono amp. The popping / scratching sound is considerably reduced in volume -- I'd guesstimate that it's no more than 25% of its former volume, perhaps less. The ferrite clamps are on order and should arrive in a week's time; I'll use them as well.

billshurv:

Thanks again for your suggestion -- I'm grateful for the improvement!

Regards,
Scott
 
#10
I use PoE adapters (non-wifi type), they do work well for extending networks without cables, but they are deliberately injecting high frequency "noise" - as most equipment will see it - directly into the mains. So consequences are unavoidable. My alarm clock radio is useless with them plugged in, interesting waking up to random noises instead of the radio, and my TV distribution amplifier seems have more interference with them plugged in.



Seems like a catch 22 compromise type device. The benefit and convenience is good, but you probably shouldn't inject noise into the mains...
 
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#11
I'd read some years ago that it was best to keep hifi on a separate ring of the mains to avoid this sort of pollution. Indeed, some people had gone to the trouble of having a separate HiFi ring wired in some rooms of their houses.

Interesting to know that some of it is airborne and not all on the mains. I gave up on a WiFi extender because of the noise it was injecting.
 
#14
billshurv said:
with the extenders most of it is airborne as they are not properly EMC tested. The noise on the line will happily cross to different circuits, so whilst a dedicated spur for audio is still a good idea it's not a cure all.
Click to expand...

All:

When we bought our house, my wife graciously turned over the large room in the basement to me for audio (in truth, she thinks its creepy down there). I promptly renovated the space and installed five 15A dedicated power lines. Two are for the amps (I run mono blocks), one was originally for the analog front-end gear, another for the digital front-end gear, and the fifth for the air pumps for my Maplenoll Apollo turntable. The air pumps are located in the adjacent utility room. In trying to resolve this noise issue I plugged the powerline extender and turntable system into the analog and digital lines, to no avail. Moving the powerline extender into the utility room and connecting it to the fifth dedicated audio circuit did the trick. The air pumps are on the far side of the utility room.

Regards,
Scott
 
#15
If you are using ethernet, it's worth trying to screen the box a bit more. As they plug into the mains you can't stick it in a tin box but there are specialist screening foils available (I need to find the thread where they are listed. A wrap of foil as a test would at least show if there was benefit in going that way.
 
#18
Just recently 'upgrade' my Gainclone LM3886 with better caps etc and couldn't get rid of an annoying crackling,scratching sound from the speakers,albet very low..was just about to rewire the amp completely thinking i'd done something wrong..unplugged my sons Powerline mains internet thing and presto noise gone!..think i'll buy him a 10metre ethernet cable and use that to his bedroom😉
 
#19
Folks:

Here's a quick follow-up and note of appreciation. The popping and scratching sound evident when using my turntable was clearly and solely caused by the network powerline extender. The powerline extender does an admirable job otherwise and I'm happy to continue using it, but moving it further away from the turntable, wrapping the powerline extender in tinfoil and adding ferrite cores to the interconnects running between my turntable and phono stage completely eliminated the problem. I added ferrite cores to the interconnects running between my phono stage and preamp for good measure, but that probably wasn't necessary.

Thanks again to billshurv and benb, whose suggestions were spot on!

Regards,
Scott
 
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