Transformer Hum (NAIM Unity Atom)

Transformer hum/buzz is normal Naim says due to the high quality ones they use. I can hear mine humming away from 3m distance. Only remedy is to play loud I guess...

Drikus posted:

Transformer hum/buzz is normal Naim says due to the high quality ones they use. I can hear mine humming away from 3m distance. Only remedy is to play loud I guess...

Hum is not really linked to the quality of the transformer, but more by its design. Toroidal transformers especially the larger ones that Naim use in their PSUs and Poweramp are relatively efficient and have a good transfer performance, but at the cost that they can saturate easily. A saturated transformer will buzz at the point it saturates. Off centre mains, or so called DC in the mains will easily tip the transformer into saturation and buzz. There are numerous designs that some manufacturers use to remove this off centre mains effect, I assume Naim feel these detract from the overall performance so don’t use them. Other techniques used by some manufacturers including Naim include covering with material and careful mounting to reduce the audibility of the hum and in this regard I have noticed there is some variability from Naim, however a heavily saturated toroidal transformer is going to buzz loudly what ever.... so the only cure is to use a DC offset remover if it troubles you and you are plagued. You might well find the DC offset occurs from another house sharing your phase from the substation.

Got a DC-offset remover on both my power supplies. It helps but it's not totally gone.

I have an XPS - somewhat famous for buzzing!  I lived in places with very “busy” mains (a large city-centre apartment block and, later, a town centre street) and had a lot of buzz - sometimes, loud enough to distract from the music and, at one point, loud enough that putting my system in the bedroom caused sleepless nights!  I tried balanced mains, which didn’t work and removed the fun from my system.  Now I’ve moved home again, to a more rural location, I barely ever hear buzz and if I do, it’s very low-level.  Sadly, this experience did confirm that  noisy powersupply is the cause. Move house? ;-)

I built my own DC blocker,  I over spec'd it for A/V load with high current diodes & 105'c low ESR caps (plus other stuff) .   It stopped the variable hum tone & volume (since found to be caused by a neighbour who has since moved) but it did not fix the low'ish residual hum.  Bottom line is some toroidal transformers hum,  & sorry to say Naim seem to be more afflicted than others,  However hum is not true of toroids persee as they can be spec'd as silent,  I've used them in my work life.   If Naim are convinced their transformer brand gives best SQ,  thats OK for me,  although I'm still wondering why Linn seem to have successfully moved to SMPS.  

My sense, from reading a great deal about hifi over the years, is that a cornerstone of Naim’s philosophy is very large, completely over-specified, linear power supplies that are so capable of dealing with sudden and sharp demands for current that they always deliver  fast transients and never reduce the power and immediacy of the musical signal.

Linn, however, have a different philisophy and their equipment plays music differently - some say with less passion and immediacy, although I’ve not heard a Linn system for a long time. Perhaps we have to accept the downsides of Naim’s approach, if Linn doesn’t deliver to our own tastes?

Hi Seth,  I've heard all the pro's & con's of both power supply systems,  & I'm very familiar with both in a non-audio field.

I hear a Linn system on a regular basis,  KDS front end & Klimax power amp (200W/4ohm 110W/8ohm per channel = the different sort of thing a SMPS can do)  driving Neat Ultimatum XL6's  ............   sounds pretty OK to me,  refined & dynamic & not much sign of the less passion & other Linn sound negatives we read on this forum.    That said my Linn mate likes my Naim,  but all very different rooms.

Perhaps I should have a Linn listen. I do  struggle with the bulk of my Naim system, as does my living room floor, and would prefer something less imposing. Still, it seems Naim’s new streamers have both switched-mode and linear supplies, due to recent legislation, with SMPS only allowed to take stand-by duties - Naim do seem to feel the SMPS still don’t give them what they need, even in a source component.

Don't here my Atom buzzing at all and my rooms not that big. I do have it in isolation feet, not sure if that helps or not.

One thing I would say, is DC offset is nothing to do with whether you are in a city or middle of the country side... only if you have your own dedicated mains transformer / substation can you be sure of removing asymmetrical mains. I live in the country with an overground supply and I still get DC buzz from time to time. Also transformer buzz is not related to dirty or noisy mains, it is the laminates vibrating when saturated  from the mains being asymmetrical .. which occurs when loading is not consistent across both sides of the sine wave.

Drikus posted:

Got a DC-offset remover on both my power supplies. It helps but it's not totally gone.

Where can I buy this "dc offset remover"? Can you paste the link, please?

SimonPeterArnold posted:

Don't here my Atom buzzing at all and my rooms not that big. I do have it in isolation feet, not sure if that helps or not.

By saying "isolation feet" you mean some kind of rubber base below amplifier?

Do these thing remove buzzing?

https://www.naimaudio.com/power-supplies

I understand that his is NOT for Unity Atom's price range, but for the more luxurious systems. But anyway, would these power supplies remove buzzing?

tony123 posted:

Do these thing remove buzzing?

https://www.naimaudio.com/power-supplies

I understand that his is NOT for Unity Atom's price range, but for the more luxurious systems. But anyway, would these power supplies remove buzzing?

These PSUs all contain large toroidal transformers, generally larger, and potentially noisier, than those from which they are an upgrade. (Although none of the Uniti players can use an external PSU. )

tony123 posted:

Drikus posted:

Got a DC-offset remover on both my power supplies. It helps but it's not totally gone.

Where can I buy this "dc offset remover"? Can you paste the link, please?

 

Look at Emotiva's website for the CMX-2. They work wonders. I  use them as well. 

But some people say, that they do NOT experience hum/buzz from Naim equipment. 

So is it some kind of lottery. Sorry man, you have humming one, but it is in NAIM's specifications, so live with it. And congratulations, yours is not humming - it is also in specifications.

Doesn't all humming units have to be replaced (because there are ones without hum)?

tony123 posted:

But some people say, that they do NOT experience hum/buzz from Naim equipment. 

So is it some kind of lottery. Sorry man, you have humming one, but it is in NAIM's specifications, so live with it. And congratulations, yours is not humming - it is also in specifications.

Doesn't all humming units have to be replaced (because there are ones without hum)?

That is dependant on the power that they are feeding their Naim equipment. All of it hums to some extent, but most at levels that some don't notice. The loud ones, like mine, are due to other issues like DC offset. Has nothing to do with the kit. 

I've tried to put fabric mouse pad under my Uniti Atom. And it reduced the vibrations from transformer hum. I hear it less. Seems the mouse pad stopped the vibration transfer from unity to furniture under it.

I'm thinking to put something more serious under my Uniti. I know, that there are so called "audio equipment isolation platforms and feet", but as I understand they are only vibration absorbing.  I think I need vibration+sound absorbing platform (like mouse pad, but more serious).

Does anybody use something like this?

Got Hi-Fi? posted:

tony123 posted:

Drikus posted:

Got a DC-offset remover on both my power supplies. It helps but it's not totally gone.

Where can I buy this "dc offset remover"? Can you paste the link, please?

 

Look at Emotiva's website for the CMX-2. They work wonders. I  use them as well. 

I've read these DC offset removers can impact quality of the sound, removing dynamics. Is that true?

tony123 posted:

I've tried to put fabric mouse pad under my Uniti Atom. And it reduced the vibrations from transformer hum. I hear it less. Seems the mouse pad stopped the vibration transfer from unity to furniture under it.

I'm thinking to put something more serious under my Uniti. I know, that there are so called "audio equipment isolation platforms and feet", but as I understand they are only vibration absorbing.  I think I need vibration+sound absorbing platform (like mouse pad, but more serious).

Does anybody use something like this?

Yep, I do. I got some Laptop cooler balls, they break in half and are meant to raise your laptop for cooling, but, they are made of this good silicone rubber that is great for vibration absorption. Some furniture, especially the hollow IKEA stuff can easily amplify transformer hum if your kit is sitting right on it. 

tony123 posted:

Got Hi-Fi? posted:

tony123 posted:

Drikus posted:

Got a DC-offset remover on both my power supplies. It helps but it's not totally gone.

Where can I buy this "dc offset remover"? Can you paste the link, please?

 

Look at Emotiva's website for the CMX-2. They work wonders. I  use them as well. 

I've read these DC offset removers can impact quality of the sound, removing dynamics. Is that true?

As long as they aren't current limiting, you are good to go. I have noticed no negative effects of the Emotiva, or PS Audio units at all. If anything, its said the sound should improve only because loading the transformer with DC is causing it to overwork at other things than making great music. 

Got Hi-Fi? posted:

tony123 posted:

But some people say, that they do NOT experience hum/buzz from Naim equipment. 

So is it some kind of lottery. Sorry man, you have humming one, but it is in NAIM's specifications, so live with it. And congratulations, yours is not humming - it is also in specifications.

Doesn't all humming units have to be replaced (because there are ones without hum)?

That is dependant on the power that they are feeding their Naim equipment. All of it hums to some extent, but most at levels that some don't notice. The loud ones, like mine, are due to other issues like DC offset. Has nothing to do with the kit. 

Having tried 4 Naim power amps on the same mains circuit with different levels of hum, it can’t be just the mains quality that determines this issue. 

Personally, I would not accept a unit that had a distracting level of hum, although fortunately, I have found newer amps to be quieter. 

have lots of audio equipment over the last 50 years i cant recall any hum present with any equipment that couldn't be cancelled by moving equipment around , it seems naim equipment has more issues  

You may find something helpful in the following thread:

Suffering from those transformer hum blues?

However, the solution in this case may be too expensive for a Uniti Atom.

Hope this helps, FT

Got Hi-Fi? posted:

tony123 posted:

I've read these DC offset removers can impact quality of the sound, removing dynamics. Is that true?

As long as they aren't current limiting, you are good to go. I have noticed no negative effects of the Emotiva, or PS Audio units at all. If anything, its said the sound should improve only because loading the transformer with DC is causing it to overwork at other things than making great music. 

The problem isn't so much current limits as the 'mains filters' or 'mains conditioners' that are quite often built into such units (some are pure 'CD blockers' though).  My experiments have found that it's the differential mode capacitors in the filters that are the cause of the dulling of the sound.

(I designed and built my own unit to deal with the asymmetric mains waveform at my house and that had inductors but no capacitors.)