Hi Neil, I also messaged Puritan Audio today about this and they too thought it very peculiar and not something they had heard of before…
Apologies for the Hicap diversion but I thought it might throw some light.
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RCD is a protective device usually found in your consumer unit, that essentially detects an imbalance of current between Line & Neutral & would trip instantly if your Earth/Neutral were reversed at the socket.
Regards
Neil.
No problem at all, it has been very useful to hear someone else has a similar problem and not something I am doing wrong!
Thanks Neil, this socket tester has an RCD test function on it. I will report back after reading the instruction manual on how to use it given it is an electrical test 
Check that you have an RCD first, if you haven’t, the test function won’t do anything.
Regards
Neil.
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Thanks Neil, I will go and check now. I used it to test the socket polarity again and after reading the manual I can confirm the results conclude the socket is wired correctly.
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We do not have an RCD unfortunately. I live in an old Victorian terraced house and we had the living room and dining room dividing wall knocked through a few years ago. A good electrician replaced all the sockets in the resulting enlarged room. One thing he did say to me is that whilst it works perfectly fine, our fuse box is very old and could do with replacing. I’m not sure that would cause this though?
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I will ask around tomorrow & see if anyone has any theories.
Regards
Neil.
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Much appreciated. Have a good night.
Hi Neil, no problem if you haven’t; but I wondered if you’d had a chance to see what the team think the issue could be?
I’m still baffled; but increasingly I think it’s a combination of a grounding issue combined with electrical noise from the mains with three teenagers living next door.
I know it’s a simple task to connect a ground wire around the DIN sockets as suggested above, but I’m very wary of doing so given the value of the equipment and how long it took me to save up and acquire it piece by piece.
I have ordered a professionally made ground cable that has a spade plug at one end I can attach to the 252s grounding post and a 13A plug with only the earth pin included at the other end.
Probably won’t solve the issue; but it was a nominal amount in the bigger scheme of things and may exclude another potential cause of the issue
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I haven’t forgotten, some people took advantge of the Easter break & took an extended holiday, so the factory was a bit thin on the ground last week.
I will ask some questions over the coming week.
Regards
Neil.
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Thanks Neil and absolutely no problem, I’m grateful you’ve even offered.
I’m the meantime, I’m leaving the system powered on 24/7 as I’m conscious the Puritan PSM156 may need several days to bed in and have the desired effect.
Worst case scenario = I live with the transformer hum when not playing music. It’s not a massive issue in the bigger scheme of things; but it would be nice to eliminate if I can.
Well I’m sorry it’s been such a long wait for so little! I’m afraid the human body influencing transformer hum has foxed everyone.
All I can suggest is that if you have any doubts about the electrical system in your home, employ an electrician to carry out an EICR for peace of mind.
Regards
Neil.
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Hallo,
I have been working with Naim as a importer and in retail for more than 20 years. Naim has known about buzzing transformers for many years. The answer has always been dirty electricity or the transformers themselves. They had to scrap many of them because of the buzzing problem. Naim continued to use them because they thought them better sounding in their equipment than other manufactors. I can’t understand why Naim has not solved the problem after such a long time.
Stefan Mether
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Thanks for trying Neil. As an update I picked up a UPS from eBay for £40 on Sunday and it just got delivered. I’ve plugged it in and the very loud buzzing has now dropped down to an audible but far quieter humming sound.
I need to listen to some music to test the sound quality but it’s hopefully a good solution.
I live in an old house on the north side of Chicago. Whenever i had large amps with big (MOSFET) transformers i heard an audible “hum” from it - and this includes power supplies.
DC offset was the culprit.
The problem was 100% solved when I purchased an Emotiva CMX-2
I recently purchased a Naim Classic 250 and NSC 222 and they are dead quiet and I also have dedicated mains with its own ground.
Emotiva was only $150!! They also have a model with 6 outlets.
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That would suggest dirty mains, then. Do you have any friends with new houses that you can try the PS plugged into their mains? (I don’t think you need the rest of the system to test for this hum)
Is the SC new? If so, I’d take it back and have them replace it.
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One customer / 2 has a Naim ps humming. Then it would be a very big list of returning components lol.