Hum in New Classic

I dont know. But the only devices I have that had hum-problems with have been made by Naim so I guess they selected some product that produced the best sound in exchange for hum-reliability. I recently had an NVA amp which also used big toroidals and it was really silent. The Aavik I use right now use SMPS and some psychedelia from Ansuz (Tesla Coils and other stuff) and is more than silent.

I tried a DC blocker on my Atom HE but the hum remained at the same high level. I have had a number of products from Linn and Rotel with big transformers that have been dead quiet. But musically Naim is totally superior to them.

I’m not sure why so many describe this as a Naim specific issue. I’ve had many amplifiers from many different brands and most would hum at times. The only amplifiers I can think of that never hummed were McIntosh models simply because they use potted EI transformers instead of toroidal.

1 Like

Same here.

Puritan PSM156…….nuff said :ok_hand:


I guess I have lucked out (Or maybe it’s less of an issues in North America) I have only had one humming transformer and that was an un-serviced 250.2. It was fine after being Re-capped/DR’d.

Sorry to hear that. If not solved, you will ask the 3 items to be replaced or you will take something else ?
Maybe you can try this famous Puritan 156 ?

The puritan is another 1800 eu. I feel like I should not need such gear for my amp to be quiet when off.

Can someone please explain the hum while off? The transformer is not active in standby. A loud hum seems really weird to me.

Maybe try a socket tester before spending any serious money on this problem? With a socket tester you can see whether there are any problems like DC etc

Well actually power is connected to the transformer but the bits after it downstream are not active. That’s the only way it can still hum.

A linear transformer will have a nominal loss of around 2% just being plugged in with no downstream load.

The older gear had a physical power switch broke the mains circuit before the PSU. I was certainly under the impression the the SMPS controlled a physical mains AC switch to the linear transformer but if it hums while off, it must be after.

There are for sure relays that disconnect most of the gear. No humb here but I did not have it either on older gear that is with afew exceptions over some days or specific time of days. I doubt that the transformers can humb in standby on new classic, but who knows.

Hum is very rarely any fault of the amp/power supply, but caused by mains issues, though some transformers are more prone than others. As others have said, humming, especially intermittent or variable in intensity, is commonly DC on the mains but it has also been said on the forum that mains overvoltage can also cause it. It and solutions have been discussed at length on the forum! And is NOT a problem confined to Naim, so changing for something different might not necessarily stop it and could even result in louder hum, though as torroidal transformers seem to be the type most prone to audible hum, there may be more chance of avoiding hum if the choice of replacement avoids them.

1 Like

In my experience humming can vary a lot from unit to unit. I’ve had a fair number of Naim components in the house over the past few years and none of them hummed significantly except for one box: an XPS power supply. This could be heard throughout the lounge when no music was playing and in quiet sections of music. It was the only thing my long-suffering wife objected to about my HiFi obsession.

I think XPSs were a bit notorious for humming and I did wonder about replacing it with a 555 on my 272, but was unconvinced that would have cured the hum for sure. In the end the hum became a factor in my jumping ship in the main system.

I did consider having a dedicated mains supply installed, but I remembered the disruption when we had our house rewired not long after moving in and thought again. It rather smacked of the tail wagging the dog. And according to some experiences related here, it’s not a guarantee of correcting the problem.

So sympathies to @Steinwerck and @ChrisSU. I hope you get the issue resolved and soon.


1 Like

I have had great success with the iFi DC Blocker. Was suggested getting a DC blocker in the FAQ of one of Naim’s competitor’s websites to solve transformer hum on their integrated amp.


When I had a multi-box system, only my two NAP 250s hummed. One considerably louder than the other one, so much so, that you could hear it when sat down and not playing music.

I got an iFI DC Blocker and tried it on the loudest of the two. It worked well, virtually stopped all of the hum, so you could only hear it when your ear was close to it.

Problem now was, that you could hear the second one. So did the same.

I was pleased with the results, essentially all was now quiet and no detriment to the SQ.


You’re right, the AC supply to the Linear PSU is switched on and off. I suspect the unit is not in standby if transformer hum is still audible. If you press the power switch when the unit is on, then it switches off the logo and mutes the outputs (and according to @keltiks post below uses less power). A longer press results in a click of a relay, the linear PSU turning off and the SMPS turning on - the device is now in standby.

@ChrisSU, my 350s hum. Not too problematic but it’s there, albeit at a very low level from my usual listening position when all is quiet and no music is playing. The hum is constant and doesn’t change and nothing in the house affects this. After quite a few years of complete silence with SMPS powered kit, I suppose it a consequence of having a couple of hefty toroidal transformers back in the rack…

As a comparison, the NC250 I had for a week, was quieter, my NAIT 50 and NAIT 1 are only noticeable with an ear pressed to the case. The 350s are still quieter than my old 300PS which would hum, grunt and make other noticeable noises depending on what was happening on the mains. The Supercap was quiet as a mouse.

I keep seeing this comment ,press the button and it just turns off the logo.
Wrong on the NC250 at least .Pressing the button switches off the logo ,but more importantly it switches off the output to the speakers ie no more sound no hiss .It also halves the power consumption of the unit ,when measured .
Holding the button in takes it down to 0.5 watt usage

1 Like

Interesting- I’ll have a look at this again when I get home later. Are your 250s set to Instant On or Auto Standby ?

Edit - indeed it does. Has it been mentioned elsewhere as that mode is not mentioned in the manual ? I’ll edit my post and thanks for the info :+1:

1 Like

To my surprise the NSC222 does seem the power down more with a long press. Not sure if this resolves the issue since it is not constant. I will try the full power down more.

My NC222/250 are perfect with no hum. My previous SuperUniti did not hum. Previously, I had a pair of Musical Fidelity P270s which did hum at times. In previous times, I had a BD250 which hummed badly and was replaced by one which was much quieter. It seems that there is a dependence on mains quality and device quality.