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View Full Version : Filtering Powerline (aka PLC) audible artefacts?



epoch1970
2015-07-01, 06:10
I've recently played with a few powerline adapters and in my home there is one adapter that causes audible clicks in the neighboring audio source when it is powered on.
I've looked around but unfortunately most "powerline filtering" conversations seem to concentrate on improving adapters throughput, and not on reducing audio artefacts.
I've read ludicrous advices like putting a $500 online UPS in front of a $50 adapter...

I know the issue can be solved with a little luck and using another power socket for either the audio source or powerline adapter
I understand nothing about EMI and live well with that.
Intentionally, I post this message outside the "Audiophile" forum.

I'm looking for a simple, diy, inexpensive recipe that would work in case the "power cord extender/long ethernet cable" one is not practical. Ferrite beads on power cords?

Thanks for your thoughts.

EDIT: To clarify. The amp in question is not sh*te and the adapter is not at fault. The issue resides in the topology of the electrical wiring at this specific place in the appartment; which is a shame but cannot be cured.
In addition, my project is to use this set of 4 adapters in another (large, with thick walls) home. There is no practical alternative to using PLC there; ethernet wiring would be a nightmare, there is no cable, and wifi repeating does not perform as needed. My question comes in anticipation that some of the adapters might interfere with some of the audio sources in that house.

DJanGo
2015-07-01, 07:34
hi get rid of this Adapter....

i knew from my parents something about the french powersupply and the (dont take this personal) french Laissez-faire :o

My Parents Phone line is thrown (by the company) over the street and was "plugged" with insulating screw joints. (really these cheap f*ck things not a terminal or in a case to get the water out of the joints)

If you found a working adapter use it, but didnt trust them cause i bought nearly 20 of them cause after some time they just out of order...

edit
may the one that clicks has had best days?
/edit

epoch1970
2015-07-01, 09:33
Actually power supply in FR is rather good. Home wiring standards might be another story, esp. considering older housing.
I cannot do without PLC in this case. And I hope it won't prove as fragile as you say...

DJanGo
2015-07-01, 12:09
Yupp Power supply is "good" (my Dad gets an "older" APC PDU from my office that shown ~248 and 255 V) ~230 should be the std. (in germany)

And in the other thing: Its not The House its the departement. The cable is owned by France (dont now the right company Name) and the nice craftman ship is made on the Outside of the building.


Not "that" fragile i used them since the early 2ooos and they are not really build for 24/7 hours a day.
There is no real cooling and the got hot and then the soldiering gets worse and you have a fragile Unit.

My Dad has build a big aluminium case with fans, router (antenna on the outside) and so one.
That PLC works since 2007 or so (it might be not the newest std.) if thats gone it has earn his money.

EDIT: To clarify.
Ahhh is it attached to 1 one by three(or more) Adapter?
Is there a FI (german Fehlerstromschutzschalter) thats used in bathrooms and kitchen?
Is it the same building or is a electricity meter (from your powersupplier) between this and the other Adapter(s)?

epoch1970
2015-07-01, 14:38
1) is it attached to 1 one by three(or more) Adapter?
2) Is there a FI (german Fehlerstromschutzschalter) thats used in bathrooms and kitchen?
3) Is it the same building or is a electricity meter (from your powersupplier) between this and the other Adapter(s)?
1) I don't understand what you mean.
Here is the topology:
- one wall socket with a PLC adapter connected to it (pass-through design) and a wifi AP (or nothing at all) connected to the adapter.
- another wall socket 2 inches apart, with a basic power strip connected to it. The amp, DAC and SB3 player are connected to the power strip.
- elsewhere in the apartment, 3 other adapters.
The problem: power up the amp, and when nothing is playing you can clearly hear clicks.
What I have tried, that did not solve the issue:
- swap 2 adapters
- run with 2 adapters instead of 4
- plug the amp directly through the adapter's pass-through socket.
(There are 2 wall sockets next to one another because one of these is permanent, and the other is controlled by 2 wall switches.)

2) As far as I understand what I see (I'm renting the place...) the panel includes 1 larger circuit breaker that works with -and probably came with- the meter.
Below that, there is a panel including an RCD (Fehlerstromschutzschalter, disjoncteur différentiel if you'd prefer), a bunch of fuse holders, and 1 resettable circuit breaker (for the water heater).
I believe the RCD protects all the circuits in the house.

3) Yes, there is only one meter. All adapters on the same circuit.

epoch1970
2015-07-01, 14:57
Its not The House its the departement. The cable is owned by France (dont now the right company Name) and the nice craftman ship is made on the Outside of the building.

Our potent public services rarely miss an opportunity to outsource a job to the private sector :) Small jobs, slim pickings, sometimes terrible execution...
For a natural gas distribution job you'll be ok. An electricity job will normally be ok. Telecom wiring can go wrong.

P Nelson
2015-07-04, 16:18
First, I assume that this click you hear does not occur when you are not using the power line adapters (PLA). This probably means the PLA are the source of the problem. You mentioned you swapped some of them to rule out a defective PLA. These PLAs work by transmitting a frequency into the house wiring and then receiving it on the other end, so they introduce a source of line noise. I am going to guess to avoid audible interference they generally use high frequencies outside human hearing. Which brings us back to why are you hearing this?

My first though is they are defective.

My second thought is maybe they are simply poor design. Trying a different brand may test this theory.

My third thought since you only hear the click is when there is no audio source is that it is a faint harmonic from the PLA. Your amp should filter the power source to clean up power line noise. But what if the noise is coming through the audio signals? Disconnect the audio input to the amp to see if it goes away. If yes, you have a harder problem to solve. If it is the power source then you should be able to filter the noise by using capacitors or a choke. Look up filtering for ham radio equipment or contact a local club.

I know this doesn't answer your question, but I hope it may point you in the right direction.

Paul

epoch1970
2015-07-05, 03:44
Paul, thanks for your time and advice.
Yes, the amp does not click from day one :) The click is faint enough to be noticeable only when nothing is playing, but it is definitely there.
The adapters I've used follow the AV2 Homeplug specification, so they should modulate a signal in the 1.8MHz to 86MHz band.
I resisted many years using this technology and was mildly amused at the "gigabyte" class claims, but I have to say I was quite satisfied with the results overall. All my attempts at testing performance under adverse wiring conditions (deliberately plugging the adapters via extension cords) came up with more than adequate performance for (multiple) AV streams.


My first though is they are defective. My second thought is maybe they are simply poor design. Trying a different brand may test this theory.
I will rule out that all 4 are defective. I terms of design, I am a bit reluctant to point the finger at the TP-L*nk adapters I chose, considering their overall compliance and performance; although I could have gone for Dev*lo adapters just the same. My choice was a matter of price point (these things are not exactly cheap) at the time of purchase.


But what if the noise is coming through the audio signals? Disconnect the audio input to the amp to see if it goes away. If yes, you have a harder problem to solve.
I missed testing this hypothesis; unfortunately I've packed up everything so I can't test anymore. Here the SB3 is connected via toslink to a V-Dac which RCA outputs are connected to the Rotel amp. I should have put the SB3 and the V-Dac out of the chain to test (both have flimsy *looking* switching PSUs -esp. the V-Dac.)
I have 4 SB3 in the home powered by either slim-era or Logitech-era PSUs, but the issue appeared at this location only.
(If someone insists I can unpack and test for the sake of advancing science...)


If it is the power source then you should be able to filter the noise by using capacitors or a choke. Look up filtering for ham radio equipment or contact a local club.
Excellent, thank you again.

Julf
2015-07-14, 03:09
If it is the power source then you should be able to filter the noise by using capacitors or a choke.

A first, simple step would be a cheap X10 powerline filter.

epoch1970
2015-07-16, 03:50
Thank you, Julf.