Not heard this one, can you expand further please?
We havenât had 220 in at least a decade on the mainland. E.g., mine in Berlin is ~237 V whenever I measured it (having been provoked to do this by the forum 
)
Until 1987, mains voltage in large parts of Europe, including Germany, Austria and Switzerland, was 220 ( ± 22 ) V while the UK used 240 ( ± 24 ). Standard ISO IEC 60038:1983 defined the new standard European voltage to be 230 ( ± 23 ) V.
From 1987 onwards, a step-wise shift towards 230/â23/+13.8 V was implemented. From 2009 on, the voltage is permitted to be 230 ( ± 23 ) V. No change in voltage was required by either the Central European or the UK system, as both 220 V and 240 V fall within the lower 230 V tolerance bands (230 V ±6%). Some areas of the UK still have 250 volts for legacy reasons, but these also fall within the 10% tolerance band of 230 volts.
https://en.wikipedia.org/wiki/Mains_electricity#Standardization
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We even have mains water here too.
You donât seem to be understanding the point I was making.
Iâm fully aware of voltages around Europe and also the variations from country to country, that was all part of my pre retirement business.
, & I can assure you that what you might have in Germany is not the case in many other counties, even today.
My point in my post is that I expect UK users with voltage that can as high as 250v are more troubled with noisy transformers than are areas in Europe with the lower end of the EU voltage harmonisation range.
Maybe I didnât understand this point because you mentioned âusers on the mainland with 220 Vâ which arenât really a thing anymore and havenât been for a decade.
Yes, UK may be closer to the upper end of the tolerance range, but thatâs a different thing. So if you meant this but said something else it is hardly my fault to understand what you did say
Thank you for this post. I have tried to establish a component causing DC offset on the electricity in my home but to no avail. I then considered a large Airline Transformer to correct the mains DC offset but I decided against it because I could not find any definitive answer regarding the benefit to reduced or complete hum removal. If anybody could offer any advice regarding confirmed gains they have experienced by correcting the DC offset and whether the 1.5k outlay would be worth the investment it would be helpful.
I will also add that power conditioners have never worked well for me. They seem to reduce the excitement we get from a Naim setup.
You never will as there are so many variations between different households. The best you can do is try and see
I rather suspect my humming is likely related to voltage rather than dc offset having both isolating transformer and dc blocker available with little result.
The voltage measured by my UPS software (for pc) albeit on a different circuit to the hifi, is currently 248v. It tends to rise as the evening progresses (as does the hum) presumably as demand drops.
Wouldnât like to say how accurate the measurement is though.
You donât need to spend 1.5k to sort Dc on your mainsâŠ
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The ifi dc blocker looks a very neat solution.
Whether it works, or has an impact on SQ can only found out by trial in your own situation.
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Assuming you are in the UK, 248 wouldnât be high enough for the electric company to do much - ideally you need to be touching 254 for them to really take notice - but perhaps take a few measurements then give them a call. If you are on the limit, then people closer to the sub will be getting higher values still.
Had a chance to take our noisy NAC 552 power supply to another property today. It all measured about the same noise wise at 25 DB room noise before powered on and 35 DB close to power supply when powered on. This was on the other house mains supply old looking switched plug, not dedicated, fridge plugged in boiler on etc. So unless the whole two town area has overly high voltage itâs a power supply issue.
Unfortunately when I got it installed back at home the NAP 500 wouldnât power up, perhaps all this on off switching has blown an internal fuse, the Powerline is fine. Any suggestions?
Did you check the fuse?
By the way, you can easily measure the mains voltage with a digital multimeter from Amazon or whatever, for 25 euros or so. (Itâs the other stuff like waveform distortion that is difficult)
Bear in mind I worked at a Naim dealer in the UK for over 6 years. Never heard the hum once in the shop and no customer ever once mentioned it.
I do think the forum (and this is a good thing) amplifies any problems because anyone who has them can compare notes. Itâs natural that on a thread about hum, 99 or even 100% of anyone who posts has had the same problem.
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It might be interesting to know how many people on the Forum have experienced Naim Transformer hums. Perhaps we need a Poll that says âHave you ever experienced Naim Transformer Hum? Yes/Noâ
It would. Better still, ask what voltage they are on and whether they are in an urban or rural area.
My perception from the forum is that this is more common in rural 230v locations.
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Hi @Suedkiez , I swapped over the Powerline cables from one power supply to another and the plugs both worked. Is there a fuse in the 500 somewhere else? Everything is switched off now, no music 
Have you checked the internal fuse in the pop-out section next to the mains inlet?