Do powerline adaptors effect hi-fi sound quality?

https://forums.naimaudio.com/topic/using-homeplugs-

Frenchman

1 year on and I'm still using them but I haven't experienced the issues described by some. That is why I quoted HomePlug AV200 certification which I believe was a considerable improvement on the initial products that were available.

Dave

I use them - it is impossible in my place to hardwire, and I have wireless dead spots. Performance depends on how "clear" the AC line is from end to end. They won't like circuit breakers, etc.

They create some noise on the line; how this will react with your components can be difficult to judge. The noise was significant on my Burmester 100 phono preamp. It is quite possible you will need to use some form of power conditioning. PS Audio, Isotek and Shunyata conditioners all get rid of the noise. 

For me, they are invaluable.

I have RFI and EMI meters, and do not find any excessive radiation which I did see referred to in other threads. There is much more radiation from wi-fi, and even more from cordless phones.

I use Netgear AV2 plugs - the primary chip set is the same in all certified products.

I use NetGear av's 200, as a better alternative for wifi/airplay for 2 years on. I've not experienced any quality loss or noise, or dropouts. IMO the transfer from my upnp server to my uq2 is digital, so why should I've any loss or noise?

I agree, there is no loss of any data transfer, or noise in the data signal itself.

But some equipment, specifically the power supply in that equipment, can react to the high frequency signal that is being carried on the AC line. It is obviously some sort of harmonic, as I certainly can't hear the carrier frequency. In addition to my phono preamp, all my guitar (which are all valve based) amps also pick up this noise on the AC line. But it is easy to get rid of if it is an issue.

I can hear RFI from devices like Powerline adapters, and it does affect my enjoyment, but then perhaps I'm just fussy.

Powerline adapters use a massive comb like set of RF frequencies covering up to 100s of MHz with gaps in certain protected parts of the RF spectrum. (Because your mains wiring will radiate like a radio transmitter) Each of this spot frequencies are modulated. They can cause a vast range of intermodulation  frequencies, and can appear as a rich hash of RF noise in affected equipment. This in itself is not usually directly audible unless extreme distortion is occurring or you are very unlucky but it can modulate the negative feedback of amplifier stages and the stability of precision clocks. ( and therefore add jitter). These can rob the affected audio of fine detail and micro dynamics and therefore naturalness. Some however don't appear sensitive to this.

Simon

Simon

Out of interest what specific powerline adaptors have you used?

Dave

Hi Dave they were Comtrend devices that I had issues with.

Simon

Simon

Have you experience of HomePlug AV200 certified products?

Dave

I use the Homeplug to good effect to supply the MacMini but not for carrying music files. In addition it's on the domestic circuit so doesn't interfere with the HiFi.

No, but I have seen them measured.. To cut a long story short my first episode with these devices involved Ofcom, and I was shown the issues they *can* cause.. And this is common to the technology used in these devices. I then got involved with a group measuring the side effects of these devices and lobbied standards groups and other organisations. These people were mostly EMI professionals ( not the recording label!). The main concession we helped in part to secure was the RF blanking of protected RF spectrum in recognition that  the devices do transmit as a 'side effect'... but I am afraid the hifi fraternity seemed to carry no weight.. And also they would appear not universally impacted by the RF energy.

Different chipsets can reduce interference when no data is being transferred and reduce RF power levels when able to, but when transferring data they by the laws of physics do produce relatively large amount of RF energy and can effect sensitive audio and radio equipment.

Simon

To demonstrate that the produced RF has a field strength in the air - you could use a EMI meter at a  distance from your mains or appliances whilst you switch a PLA on and  transfer data, or go into your garden with a SW radio and tune up and down. You will hear a screeching metallic sound - probably also overloading the RF front end on your radio in places. This is the radio field strength that your house wiring (unless shielded in steel/aluminium  trunking) is radiating. This is why certain protected RF spectrum is blanked out from allowable PLA modulation radio spectrum.

I used them for around six months when I first got my uq2 and they did their job really well. I dont know if they introduced rfi, I honestly wouldn't know what to listen for, but I can confirm that there was a noticeable improvement in sq when I replaced them with cat 6

dayjay

Which powerline adaptors were you using?

Dave

They were tp link, I think av 500, and I got them from maplin 

Was this demonstration using your Comtrend devices? Have you tested AV200 certified products?

Fused said earlier in this thread he had used RFI and EMI meters and did not detect any excessive radiation.

Dave

Dave, I and many have done this with a whole multitude of devices, yes the Comtrends were particularly appalling (IME) . Have a gander over at the 'tube to see many people's experiences.

i'll have a look at what is out there on the 'Homeplug AV200' but they sound ominous .

Dave, it all got a bit dull. But I found some amusing videos on a pressure group site of some Devolo Homeplug AV200 devices transmitting data wirelessly between two completely separated mains circuits (one was on a generator) to demonstrate they do produce and can receive modulated RF .. 

http://www.ban-plt.org.uk/videos.php

The Homeplug AV format was developed in 2005 so I understand, and several manufacturers build to this format..

Simon

I saw the videos, well some of them. The amateur radio fraternity is the only anti-PLT group that I've heard of. I don't have an AM radio anymore (thankfully) so can't run around the house looking for EMI/RFI hot spots.

Dave

Indeed I do, as with teenagers in the house demanding internet access in every nook and cranny for their computers and phones, I was getting a little concerned about RFI and EMI for ourselves, not just my systems.

In terms of radiation output, the worst offenders are, starting from worst, are microwave ovens, DECT phone transmitters (disturbingly high), 802.11 wi-fi devices, computers and crappy generic SMPS power supplies. My Netgear AV500 home plugs are not emitting external radiation above ambient levels, so I am not quite understanding some of the comments here. All current Home Plug products are, I believe, using the core Atheros chipset. Some products do also contain 802.11 wireless transmitters, so perhaps this is causing some confusion??

But I will re-iterate, Homeplugs do generate noise on the AC line itself - it is how they work. I do use power conditioning to get rid of this noise. So I agree completely with Simon on them increasing the noise floor on systems, just not on how the noise is getting into the system.

If you use an AM radio to "sniff" out noise, you will find that just about most electrical circuits will create some noise. But the most noise will come from when you tune into a station. If you think about that for 5 seconds, it can help create some perspective 

Yes we are talking specifically about the modulated RF on the attached mains lines themselves - i.e. your domestic home wiring - it is this RF that the Homeplugs create and is the basis in how they work and communicate with each other. By the laws of physics you can not pass a current at RF and it not radiate electric and magnetic fields from the conductors unless you screen or balance the conductors. This is how radio works... if you shape and size the conductors specifically you create antennas and the radiated field becomes optimised.. luckily the house wiring is generally not optimised and so does not efficiently/effectively radiate over longer distances but produces a relatively strong near field strength.

Here is a UKAS test lab EMC result summary from the mains wiring attached to a power line device from the above site.

http://www.ban-plt.org.uk/reports/Belkin-F5D4076.php

Simon

Ouch, that's a serious EMI problem!  Quite scary really, that much distributed hash.

I'm not affected by EM fields (and I've briefly been exposed to a 3 Tesla field modulated at 120MHz!), but I'd be concerned about that in my house pulsing for every broadcast frame.

I now have a clearer understanding of what we are dealing with. It's the noise in the mains wiring generated by the PLA RF signal we are concerned about and whether this increases the system noise level floor to the detriment of our audio equipment.

As a simple test, if I turn the amplifier volume control up very high, without any input, wouldn't that tell me if I had an usually high noise level floor?

Dave

Dave it might be - the effect of PLAs could be considered a more extreme version of using noisy switches or unshielded Ethernet leads. Each environment will be different - the areas that were night and day for me was with my tuner and turntable cartridge - where I could hear a low level warble and increased hiss.

However I don't subscribe to fancy Ethernet leads - but many on here do swear on the improvements that reducing very tiny amounts of RFI compared to the large amounts from PLA brings.

Simon