Transformer Hum (NAIM Unity Atom)

tony123 posted:

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

..........  agree much as posted by Huge above.     The general opinion on the forum is that Mains Conditions can dull the sound (NB I do say "can")  but as far as I can tell its the so called mains conditioners that do this & these don't claim to solve asymmetric wave distortion or DC Offset (same thing)    As Huge says the dull sound is usually associated with the capacitors used in C&D mode filters - X & Y caps connected across L-N & L-E-N.     I am aware of only one CD offset blocker that uses these,  not unsurprising given that most of these companies don't publish any circuit details.

My DC filter uses series capacitors & diodes,  an entirly different design to the C&D mode filter type(s)   This filter type (IME) does not detract from SQ if anything it enhanced it.   Its probably the most commonly used circuit when the filter is made specifically as a DC blocker.

The other method for correcting manins DC is a balanced mains transformer,  probably the best to solve all manner of mains issues.

Mike-B posted:

tony123 posted:

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

..........  agree much as posted by Huge above.     The general opinion on the forum is that Mains Conditions can dull the sound (NB I do say "can")  but as far as I can tell its the so called mains conditioners & these don't claim to solve asymmetric wave distortion or DC Offset (same thing)    As Huge says the dull sound is usually associated with the capacitors used in C&D mode filters - X & Y caps connected across L-N & L-E-N.     I am aware of only one CD offset blocker that uses these,  not unsurprising given that most of these companies don't publish any circuit details.

My DC filter uses series capacitors & diodes,  this filter type (IME) does not detract from SQ if anything it enhanced it (repeat IME)  THis filter type is probably the most common when the filter is made specifically as a DC blocker.

The other method for correcting manins DC is a balanced mains transformer,  probably the best to solve all manner of mains issues.

Absolutely and balanced mains transformers are very commonly used in industry. Look no further than you local hospital as they are a requirement for circuts that feed NMRI and CAT scanners. industrial ones are not massively expensive but audiophile ones that basucally employ massive toroidal transformers in a faraday cage with no conditioning components can cost a mint. 

The biggest problem with them (aside from the size - they really needed be installed in a basement or garage or something) is that they must adhere to local safety certifications before any sparky will fit one despite being deceptively simple devices. That sounds logical but most audiophile ones are only certified for use in the US, UK and mainland Europe. In planning to build a new home, I've really struggled to find one that certified for use in my location that does not involve simply paying the local power provider to install a 40 foot concrete utility pole with a mini substation atop it in the front driveway. The fact some audiophiles here are doing that doesn't inspire me with hope.

I'd be curios to know what Naim have on the mains coming into the factory. I'd not be surprised at all if they confirmed they use one for the site.

100% FZ,   problem is this should not be required with a simple little Naim Atom,  we shouldn't even be discussing it.     But going back to the OP first post where its said the hum can be heard at 30cm & late at night its audible at 60cm.     IME thats normal,  

ChrisSU posted:

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. 

This is true, it also depends on the quality of the transformer themselves. If Naims threshold on transformers is anything like volume pots, I am sure they let stuff through that they really shouldn't.

The OP did mention that it's on furniture so this may be exacerbating the noise, the unit itself actually being well within spec.

I'd agree with Mike - it comes with the territory.

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?

 

Got two of them and from my experience, they do not alter the sound in any way.

Moderated Post:  Please do not post unauthorised commercial links in the Hifi Corner, thanks.

He asked for the links. How can I give them to him otherwise? No PM's available here. Delete the whole post then.

To be clear, I've got no commercial connection whatsoever with that site/shop. I just bought mine from them. I don't receive any kind of compensation from them for bringing in new customers.

That's the rules - it ensures the Hifi Corner is kept as clean and shill-free as possible.  You don't need to post a link, just mention the site by name.  I'm sure anyone interested is capable of conducting a search. Thanks.

Huge posted:

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.)

Yeah, i guess I have been lucky with that so far, although I have picked the most stripped down units I could find that are mainly just DC blockers and not conditioners. Its hit and miss with conditioners for sure. Really, I just wish I could run with nothing, but apparently even a dedicated circuit won't help in my area as the neighbours appliances are contributing to the dirty power as much as my own

A search on the Airlink Transformers web site should show some products that work well for around £500-600.  They are balanced power supplies, effectively isolation transformers.

The only problem with isolation transformers is that they themselves buzz. They do stop your amps/power supplies though. I guess good if you can put it in the basement and on a dedicated line. 

tony123 posted:

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?

Kind of but they are feet designed to absorb vibrations. They are not rubber some other manmade stuff I cant remember. 

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. 

Get an Isotek Axis - quality piece of kit that solved all my humming boxes. So much so I bought two of them. Yes there are some that frown at such things but I haven’t  detected any loss in SQ and all that annoying humming has gone which really did ruin listening pleasure. 

Got Hi-Fi? posted:

The only problem with isolation transformers is that they themselves buzz. They do stop your amps/power supplies though. I guess good if you can put it in the basement and on a dedicated line. 

Hi Got Hi-Fi?,

Transformer buzz is a curious thing.  In order to stop my Supercap and especially the 555PS from buzzing like angry bees, we installed an isolation transformer.  It's a whopper (that's a technical electrical engineering term, apparently).  At its heart lies a 5kVA toroidal transformer and it sees the same mains supply as the Naim system used to.  Yet it barely buzzes at all. 

However, its errr industrial aesthetic (to be kind) would not suit a living room Naim FRAIM, Isoblue or Quadraspire rack especially well, or so my wife tells me.  The garage inside wall seems like a more suitable home for it, beneath the mains distribution unit:

Others blessed with greater electrical engineering know-how than I (e.g. Huge) are able to install a DC blocker circuit but this works really well for us.

Hope this helps, FT

SimonPeterArnold posted:

tony123 posted:

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?

Kind of but they are feet designed to absorb vibrations. They are not rubber some other manmade stuff I cant remember. 

Sorbothane ? I used to use things called foculpods under a noisy Virgin V+ box. Naim kit usually likes to be on the feet supplied though. 

Foot tapper posted:

Got Hi-Fi? posted:

The only problem with isolation transformers is that they themselves buzz. They do stop your amps/power supplies though. I guess good if you can put it in the basement and on a dedicated line. 

Hi Got Hi-Fi?,

Transformer buzz is a curious thing.  In order to stop my Supercap and especially the 555PS from buzzing like angry bees, we installed an isolation transformer.  It's a whopper (that's a technical electrical engineering term, apparently).  At its heart lies a 5kVA toroidal transformer and it sees the same mains supply as the Naim system used to.  Yet it barely buzzes at all. 

However, its errr industrial aesthetic (to be kind) would not suit a living room Naim FRAIM, Isoblue or Quadraspire rack especially well, or so my wife tells me.  The garage inside wall seems like a more suitable home for it, beneath the mains distribution unit:

Others blessed with greater electrical engineering know-how than I (e.g. Huge) are able to install a DC blocker circuit but this works really well for us.

Hope this helps, FT

This is exactly what I will do if I can ever get a dedicated line run in. Except I will put this transformer in my basement beneath my mains distribution unit. Same idea, different spot

Got Hi-Fi? posted:

The only problem with isolation transformers is that they themselves buzz. They do stop your amps/power supplies though. I guess good if you can put it in the basement and on a dedicated line. 

Mine is happily sat on the floor behind the settee, about half the time it buzzes for about five seconds when I switch the amp on,  otherwise it reduces any hum from the amp, lifts a veil or two on the music. Proportionately a cheap upgrade.

By the way, is this transformer HUM bad for amplifier? I mean, If I do nothing to prevent it, will it damage the transformer in long term?

Not half as damaging as the 'bong' or 'tick' you get from turning the transformer on.

tony123 posted:

By the way, is this transformer HUM bad for amplifier? I mean, If I do nothing to prevent it, will it damage the transformer in long term?

normal transformer hum is not harmful, however, if it gets extreme like mine did and left alone, it can be damaging. 

Huge posted:

Not half as damaging as the 'bong' or 'tick' you get from turning the transformer on.

My HiCap bongs in a huge way when I fire it up. I guess it is a good thing I rarely ever have to shut it off.