Supernait 3 Hum

I mentioned this on the NDX / Supernait thread but my new SN3 has transformer hum, not terribly loud to be fair but clearly audible (with no music on) from a few feet away. I’ve tried switching everything else off in the house but no difference, Nova is completely silent. Is this a case of some units hum and some don’t and I’ve got a hummer?

I can’t speak for the Supernait, but in general, I have found a fair amount of variation in the level of hum from the various Naim boxes I’ve owned. In general, I’d say the more recent boxes I’ve had were quieter, but that’s based on a fairly small sample. If the hum is intrusive, I would certainly talk to your dealer about it. You may be able to compare yours to another one from his stock. Also, try it in another location, maybe in your dealers demo room, as it could be that your incoming mains supply isn’t helping.

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Every transformer is unique in the way it will react to various mains pollution artefacts. Both the maker and Naim test the transformers to ensure none exceed a certain level when presented with different levels of pollution. Any that exceed this level in testing are rejected.

Ok thanks Richard, I’ll have to presume so that mine is deemed to be within ‘acceptable’ levels. Not the end of the world but a tad disappointing on an almost €4K piece of kit. An audiophile product that hums! Hmmm. I might bring it in to work and see if it’s any different.

It may not hum in other places. And maybe not at other times either. Frustrating, I understand, but that’s the nature of toroidal transformer hum. Of course, if it really is a problem then you need to speak to your dealer to see if they can help out - maybe try their demo unit at your place.

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get a good powerblock, it should stop the hum. For me it does for my 555dr.

My 250-2 had some slight hum. After a service and upgrade to DR I no longer notice any.

Been running my Supernait 3 for a week now,not encountered any hum,nice bit of kit!

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Two actual owners of SN3?

Woohoo…waiting for your reviews!

Can’t buy mine for a few months, so any impressions would be wonderful…

It needs to be a specific type of powerblock (and even then may not work - see below).

Most of the ‘mains conditioners’ are simple LC filters using capacitors across the mains to remover differential mode interference. These types degrade the sound of the system and do nothing for the mechanical hum produced by transformers.

The hum from transformers, particularly the high efficiency toroidal types that Naim use is caused when the positive and negative halves of the mains cycle don’t quite match up. To prevent this you’ll need something that is usually called a mains DC blocker. If a mains block / powerblock / mains conditioner doesn’t claim to be a DC blocker, then it won’t remove the hum at all.

It’s also possible for some toroidal transformers to just hum quietly on they own anyway, even when the mains is completely clean and perfectly symmetrical.
If the hum is caused be mains asymmetry (and can therefore be removed by a DC blocker), it will vary a bit from time to time (particularly if the increase in hum occurs at specific time of day or on certain days of the week).
If it is inherent to the particular transformer you have, it will always be constant, at exactly the same level at all times, in this case no mains device will help the hum.

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And thus was written the truth by a lady who knows her onions on such matters!

That is one of the clearest explanations that I have read on this subject.

Thanks, BF

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thanks, so should I just get over it?

I suggest you speak to your dealer as Richard also suggests, including borrowing their demo unit to try at home and/ or trying your unit out on their mains. Then take it from there, depending what you find.

Best

David

You could also ask your dealer to lend you a dc blocker from isol-8 or isotek to see if that helps.

i am lucky because the one i bought had completely shut off the hum😎

Thanks David, unfortunately my dealer only gets them in if and when ordered by a customer and they’re still a bit scarce I believe. I will try it in different locations on the weekend and see how it behaves. Sitting about 8 ft away in a quite room it’s audible.

I think the thing to try then is turning it on in different houses on different power systems. So take it for a ride round three or four at the weekend and see how the hum varies. It’s ok to run it with no speakers attached for testing purposes.

Best

David

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Hi Hollow,
There is a thread on the old Naim forum by Foot Tapper called “Suffering from those transformer hum blues”.

There is a great deal of information in there, which may be of help.

Have a look at Airlink Transformers to see if one of their balanced power supplies would suit you. I bought one and it has worked a treat every since, without degrading sound quality from the system - rather, it improved it by removing a lot of mains borne noise as well as the asymmetric waveform (or dc offset).

Best regards, BF

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When I ordered my SN2 many moons ago I specifically requested to the dealer if Naim could pick out a quiet one from the production run for me. Naim obliged and the hum was only noticeable if you stuck your ear next to it.

If I can hear hum from more than 1m away in a quiet room then I would find that unacceptable regardless of any manufacturer tolerance.

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I would definitely go back to the dealer as suggested just to check it out.

I bought a NAP200 many years ago now and I’d had the shop’s one on home dem before and was convinced my one had more hum. Took it back to the dealer and they confirmed this and ordered a new one from Naim which was much better.

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