Mains extension blocks


Thanks Simon - mine is first gen too. I’ll ask my dealer and Chord about swapping out its PSU. I know Chord don’t like use of third party ones. I use it mostly unplugged as a portable, but noticed it sounded a bit off when I used it plugged in a few weeks ago - hence I tried the test. Quite surprised as Rob Watts seems very keen on minimising RFI in his designs.


Looking online it seems difficult to find any domestic use mains extension blocks without surge protection. Years ago when we had those large tower computers, it was recommended to put them on something with surge protection to protect its hard drive. Nowadays with most using laptops, it seems superfluous to needs - or am I missing something ? I have my Unitiserve and sky box plugged straight into the wall socket and their hard drives have been fine (touching a lot of wood).


ISTR there’s a 20dB drop (about) when the homeplug signal goes from one ring to another or one CU to another. The signal noise is around 10-20dBuV/10KHz which is pretty darn low anyway but after it’s been from one CU to the other it’s nearly undetectable. Saying that I have homeplug devices going from one ring to a separate CU in barn 50 yards away and I can still get an IP camera working! This technology is really quite amazing.


My BT HH6 SMPS is not that good Simon, but I have heard worse with other BT products in the past. That said the BT plug together with Siemens (phone) & Cisco (switch) all live on the same power strip thats powered via the UPS & its isolation transformer - plus a herd of ferrite clamps & a RA thingy. So for the SMPS’s physically & electrically close to the Naim, they are somewhat isolated & suppressed.

My view on SMPS’s - good bad or whatever - are part of everyday life. TV’s, radio’s, Muso’s, phones, computer, phone, tablet chargers, LED’s … practically every modern electrical device has them.
I’ve checked all mine, including the many LED’s, with my little obsolete tranny radio. Can I do anything about whatever I find, not a lot really other than make a decision to do nothing or find an alternative. Do they actually affect the Naim ?? errr no, or at least not that I can hear.


I always turn off chargers if they are not in use. BT HH! Hope the Innuos Zen Mini MK 3 is ok. I shall move it further away from the HiFi even though not on the dedicated supply.



I’ve just checked my Hugo 1, and the wall wart isn’t silent. It doesn’t have the same aggressive buzzing sound that some lights etc. have, but still…also, I can trace the same noise along the DC wire into the Hugo, which I suppose I could address with ferrites, but I favour the ‘prevention is better than cure’ approach.
I bought the Hugo used, so I have no way of telling if it was supplied with the original PSU or not.


So just to be clear in simple to understand language if one has something like this on the house mains (even if the hifi is all plugged into its own dedicated mains supply):

Does that potentially undermine all the effort to get dedicated hifi mains installed?

My, perhaps naive, understanding was that the whole point of installing a dedicated supply was to avoid the effects of other devices etc which are plugged into the normal mains circuit compromising performance of the hifi system.

If this is actually not the case then I question why we bother with dedicated mains?


ah you sure that is going via the wires and no through the air… I saw an interesting test with Homeplugs where propagation was through the air as opposed to wires - but not as far as 50 yards.:grinning:

Of course for network use, you really need ethernet or wifi for many other than basic elastic data transfer activities and these devices are definitely not ethernet… but I agree they can be a good kludge/workaround for temporary setups or none demanding setups where the RFI is not an issue

As far as RF emissions, here is a doc from the EM journal

It is a few years old now, and later devices have a wider spectrum and slightly better behaved apparently - but the basic issues are the same.


Well I am little obsessive - as noisy electronics interferes with my radio based activities. Currently there is only one set of devices I currently have that can make my 552/250.2 sound a little off - and they are the electronics ballasts in my kitchen under cabinet lightning.

I found my NAT03 was more sensitive - perhaps for understandable reasons - and there was an errant Netgear SMPS that was the issue there - but I wrote about that on the old forum. Easily fixed.


spot on!!!


I’ve just found that my main system (NDX/282/250) passes the radio test with flying colours, but the Atom is really quite noisy. I might have to do a bit of digging.

I guess we should probably have opened a separate thread by now!


Probably the power supply. Out of interest what DC voltage and what current/power is the Atom PSU?

Forget that just seen it’s IEC input.

Perhaps a ferrite on the mains lead might help?


What about a metal box (biscuit or sweet tin with holes) to put the offender in to cut out the RFI?



I’ve removed the extension block with the red light and plugged the monitor, laptop and desk light straight into the non-dedicated mains wall plugs in my listening room. However the laptop power supply remains.

Phil - to your idea of metal tins what about wrapping the PS in some Faraday tape?


Guess that does the same thing.


Has anyone tried a Mains block or Mains Lead with built in RFI filtering ? I’ve been looking into aftermarket mains leads recently for my Active speakers and one of the options I looked at was from Mains Cables R Us . They recommended their number 5 cable which features a ceramic RFI filter ( ceramic rings apparently that dissipate RFI as heat ) , any filter is against my better judgement but I was assured of no adverse effects… I suppose they would say that though …I haven’t got around to trying just yet but wonder what others may think ?


I know how you feel. I know think I have to listen in complete darkness with everything else other than the hifi unplugged to get my system at 100%. Ridiculous.


I noticed this too. I did an RF test using my phone as you can get a few apps to monitor it. It gave off more than my i7 roon core below it.


I’m listening in complete darkness too now. All I can see is the Naim green logos but I’m fretting that they might be giving off RF and ruining the SQ. I’ve disconnected the fridge, all TVs, washing machine etc. The kids have been told that we are eating take aways by candlelight from now on. And I’m checking into the Priory in the morning :rofl::rofl:


Out of interest I got out my old Yaesu portable scanner this afternoon and went walkies around the house, I tuned to around 500khz AM, Philips LED’s that I have in sidelights we’re pretty bad but an Osram was fine, a CFL was bad as were pelmet fluorescents in the kitchen. The worst was a small Samsung LCD TV I have as a CCTV monitor, even in standby it was horrendous. Now for the irony, as I approached the Nova display it started screeching quite badly! Presumably this has been filtered out in the design and has no negative effect. Otherwise plug-in power supplies for my router, Apple stuff etc seemed pretty good bar the charger for a portable Dyson which was pretty bad