Humming Uniti Atom. Is this normal?

The iFI DC blocker has had some poor reviews - are you able to try a different one (perhaps the Audiolab which is around £100 in the UK, or a loan from your dealer to prove the point) ? If not, it sounds like you need to talk to your dealer about a swap - different samples can produce different levels of hum, as I discovered with the Nova.

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Yes, its quite normal for Naim equipment to hum mechanically (so, not via the speakers), due to their large toroidal transformers. But - do get your unit checked by your Naim dealer. As @TallGuy says - some samples of units do this more than others.

Its is possible that its due to noise on your mains. Opinions differ as to whether Main Conditioners help - or are worse than living with the hum.

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Transformers will hum, some will be more audible than others.
If a DC filter did not change anything, it means your Atom transformer naturally has that hum.
All my Naim units hum, but its only audible from the listening position with a totally silent room.
My other equipment with transformers also hum, some may appear to be silent, but listen closely & you can hear it.

Re DC filters, if you have so called ‘DC’ on your power, it will not be constant, as such it will cause the transformer hum to change volume & pitch/tone. If you transformer hum is constant & unchanging, you do not have DC offset.

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In contrast, none of my Naim units hum. That includes over 6 units - several with some of the largest Naim transformers (250 & XPS). But - I am not saying that @Mike-B is wrong, in any way. His hum, mine do not.

There can be occasional bursts of hum/noise - due to something weird on the mains - but that’s about it. Otherwise - near silence.

Maybe I am lucky…? :slightly_smiling_face:

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Hi @IanRobertM, yes lucky I guess, but I know someone with an all olive multi-box system with PSU’s & he too is silent.

To add some flesh to my Naim hum.
As I said its only really audible these days in a ‘dead of night’ silent room.
But go back a few years; I did have real mains power distortion (DC offset) so I designed & built my own DC blocking filter. That stopped the variable volume & tone, but still had hum audible from the listening position.
Meanwhile the cause of my mains distortion was fixed, I still had the same hum, but as the DC filter had improved SQ, I kept it, & still have it.
The worse hummer was my (ex) CDX2 & this unit has a small transformer, so hum levels are not necessarily related to transformer size. However the CDX2 hum was solved very nicely indeed by adding a (non Naim) XPS, that was done for SQ reasons & very successfully I have to say. The CDX2 was replace with an NDX, its transformer was just about silent, but its powered by the same XPS so obviously no problems.
Finally my power voltage was normally at least 248v & sometimes as high as 252v. This has been lowered locally in the last year & is now between 238v & 240v. This has lowered the hum further & is now completely acceptable

Worth having a read of the following Discussion

@Mike-B - Thats me… lols. Actually I have mix of CB (converted to Olive), Olive & ‘Black’. I certainly have had short term ‘buzzes’, but nothing continuous - ever.

One trick oft quoted, was to listen very late at night - when the mains should be ‘cleaner’. If that cured your hum, you had a mains problem. Some people have had success in contacting their electric supplier, who adjusted their voltage, lower. Much as you suggest.

@GadgetMan - Yes, well worth reading the Guide.

Thanks @TallGuy @IanRobertM @billywindsock @GadgetMan @Mike-B for the valuable input. This made a lot more clear.

I’m wondering if there ever has been an input from Naim on the fact that what i reported here seems to happen also to many others?

I think Naim is not the only user of ringtransformers. And like i said in the OP: it is only now after switching to a Naim product that i am facing this issue. I’ve used amplifiers from Vincent, Cambridge Adio, Denon, Ayon, Linn, Lavardin, McIntosh and a few other brands. Never had a humming transformer.

Please allow me this question: Isn’t this more or less a design matter that can/could/should be solved by Naim in the first place?

The standard answer to your question is that Naim specify their transformers for sound quality first & foremost.
Also keep in mind that these days a transformer is becoming less common, a lot of modern equipment has switch mode power supplies which are practically silent. So far to date, this is something Naim have chosen not to follow, again for SQ reasons.

In my system the 200 and CDX2 hum a little too. It’s audible if your ears are about 50-60cm from the units in a quiet room. My tube amps before Naim also hummed. All of them. The obvious question is, how loud is the hum? I guess your dealer should be able to assess if its ‘normal’ or not.

I don’t know if the Atom manual specifies AC phase/polarity but if you’re in a ‘Shuko country’, you could check if the polarity is correct. Should be like this:

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My Atom sits in the corner of the living room by the TV and the hum is audible from the sofa 4 or 5 metres away. It’s only noticeable when no music is playing, so I keep it in network standby mode to silence it when not in use.
Naim power supplies hum. There’s no easy way round this. Having said that, not all boxes are the same. My old Superuniti was worse. I’ve had a 200DR and a 250DR which were both pretty quiet.

Just for completeness, Naim had to change the supplier of their Transformers arouse end 92/beginning 93. Previous supplier withdrew from making transformers, I believe.

Original supplier was Holden & Fisher, new (and current) one is Nuvotem. Who I understand are used by many other high end audio makers…?

My experience is that all Naim units have audible transformer hum. Some people are more susceptible to this than others. I am very sensitive to this and have been able to hear the hum on every Naim transformer I have every heard from approx 6 feet away. I don’t notice this when music plays, but I have found it distracting when on standby. On the worst offending units I can hear it from across even the largest of rooms. It’s definitely something I struggle to come to terms with and wonder how I would deal with this if I were to purchase a Naim unit.

I should add that I had to return Kef LSX speakers (with painfully loud coil wine or transformer hum) and I also often turn off the milk frother in our kitchen because I can hear it whining. I can also hear those high pitched cat deterrents that people sometimes have in their gardens. The only other people who seem to hear them are my kids!

I’m definitely an outliner on this, so the experience of others may differ. I suspect the average age of a Naim customer makes this less of problem for many :wink:

Definitely not all Naim units in all environments. I have 555, SC, 300PS and most of the time can only hear them in a totally quiet room from at most 50 cm, or less, if I really try to. And my hearing is OK. Sometimes, usually in the evenings around 10, once or twice a week for an hour, I can hear them in quiet room from 3 meters. God knows what it is that someone turns on at these time.

But seeing your avatar, maybe it is different in your body and that’s the problem :slight_smile:


I have to be right near my Atom to hear it, can’t hear it from listening position. Funnily only hear it from the back of the unit to.

Atom and Nova definitely the quietest to my ears. Supernaits and other PSs I have always been to hear from within 6 feet, sometimes only just, other times quiet loudly. I was recently at a demo for some non-naim gear at my dealer and they had a stack of Naim gear (555, 500PS etc) warming up in the same room for a demo later that day and I could hear it from the other side of the room (20+ feet). Found it quite distracting!

Try some kryptonite :wink:

@Suedkiez I wish I could trade super hearing for the ability to fly :airplane: Much more useful :grinning:

Superhearing is the most wimpy superpower and am sure is predominantly annoying, best to trade for nearly anything (except for Daredevil)

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If anyone wants to trade super powers then PM me…

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