Transformer hum - what to do?

Foot tapper posted:

Hi Markah, very sorry to read of your situation.

First, as others have said, try disconnecting the likely culprits that are polluting the mains at home to isolate the villain. .......

Finally, if all else fails, do a search on this forum for a thread called "suffering from those transformer hum blues?" It is one of my threads. I tried several options before finding one that works beautifully for us.

Hope this helps, FT

Sounds logical to me, clean up the juice be fore it enters the home!

And if that device hums, who cares, it's a good distance from your listening area!

Allante93!

Markah, you have my sympathies and understanding.

I have the same issue with the electrical supply in my house and the buzzing was sadly unchanged by a dedicated spur arrangement ( though the music definitely improved).

The problem has proven completely intractable in my house. Frustrating, as I can take any of the power supplies to my neighbours house and they don't buzz 

In the end the only solution I found was to move the power supplies out of the listening room completely. I was very lucky to be able to site the brain stack such that they sat back to back with the brawn stack in another room,  separated by a wall with a couple of holes in the wall to  allow cable connections. Extreme, but effective. If this might by any chance be feasible for you I fully recommend it!

Many will say that when the music is played loud enough, the buzz is drowned out. Yes and No in my experience. I certainly was only consciously bothered by it in quiet passages, but having now got to a point where I now have zero buzz and heard the musical uplift that a silent backdrop brings, it's now clear to me that even when you don't directly hear the buzz, if it's audible at quiescence, then it's always there, adding a colouration and distortion to the sound that amounts to a permanent 'downgrade' of your system. If something can be done to minimise the buzzing then I strongly recommend doing it. 

kevin J Carden posted:

Markah, you have my sympathies and understanding.

I have the same issue with the electrical supply in my house and the buzzing was sadly unchanged by a dedicated spur arrangement ( though the music definitely improved).

 

Yes a dedicated supply does improve sound quality, but it does Jack s**t at alleviating transformer hum. Plus a dedicated supply seems to measure the worst in customers homes (and including my own) when tested with a Blue Horizon Mains Analyser. My dedicated spur read 'Max' on the dial for mains noise and two radio stations could be heard coming through the analysers speaker. Others have measured similar results on dedicated spurs.

Many here seem to poo poo mains conditioners. All I can say is try one if you can in your own system and hear for yourself what the effects are. I'm not sure if any other manufacturers apart from IsoTek make a DC cancelling product that rebalances the mains sine wave to help reduce transformer hum, but if you could try their Synchro cable it may help.

A good conditioner will lower the noise floor and increase dynamics (likewise a poor design will decrease them). It will also make any time of the day a late night listening session. If you want to spend bigger bucks a good regenerator will cancel a lot of transformer hum. These types of products have come a long way in development since they first started appearing years ago, and I simply don't accept that they ruin sound quality when used with Naim. My experience in my own system and in customers systems say other wise. This great hobby is always evolving.

Check it out and see how you go.

Cheers

Rick.

Iv'e  had two humming PSUs-- and my latest CD555PSU was only slightly the worst--it was still annoying especially during late night low ambient noise times /etc

My PurePower Regenerator 2000i completely eliminated any residual of hum from the Naim PSU and with some tests /in/out of the system

--I suffered no loss at all of Dynamics/ Sonic presentation whatsoever when the  PP was inserted in the Power line.

The unit is set for 230V operation. On my current model unit the Frequency adjustment is user determined from the front panel-- with the later updated 3000i's this function is

microprocessor  controlled automatically .

Recommended to try.

D41

My Turkish grandfather used to ask to see the owner of every restaurant where he was served a bad meal. Upon seeing the owner he would give him a big hug and when asked about the purpose of the intimate embrace he explained that it was a goodbye hug since they were never going to see him there again. Now, I am sure that if my grandfather had owned a humming megabucks Naim system he would waste no time to look for the dealer to hug..

Luckily, my modest music system is well behaving, producing hums only when Glenn Gould or Keith Jarrett are being played. 

Perhaps Naim should design a double casing for its power supplies with sound insulation material in between. That could save a lot of hugs in the long run.

Luckily none of my Naim equipment hums, though it seems to be a common issue.

I am sure the dealer can fix it. As far as I know it is very simple, for the Technician to fix.

Ricky Dasler posted:

Yes a dedicated supply does improve sound quality, but it does Jack s**t at alleviating transformer hum. Plus a dedicated supply seems to measure the worst in customers homes (and including my own) when tested with a Blue Horizon Mains Analyser. My dedicated spur read 'Max' on the dial for mains noise and two radio stations could be heard coming through the analysers speaker. Others have measured similar results on dedicated spurs.

 

That makes very little sense, if at any, and not at all my experience with dedicated spurs. I'm finishing one in my current house now and it's my fourth troughout the years in different houses. 

I use a mains noise analyser too. Here in the Netherlands there are usually 3 phases (live) entering the CU. Not sure about the UK though. You pick the quietest on the noise analyser to feed the spur. After that, a clean run with quality components (RCD, MCB, fuse, whatever is used), and a good shielded cable can't result in more noise than the standard in house/walls wiring that usually directly feeds a bunch of other stuff too. A well setup dedicated spur should be more quiet than the rest of the house. But never ever more noisy.

[@mention:1566878603941226] I've had very good results with the DC X-Terminator from Kemp Elektroniks. It's specifically designed to eliminate transformer hum caused by DC offset on the mains. Everything went completely silent immediately. Very reasonable price too. 

I had the same problem as you. In my case I just put a DC filter between mains and the SU and the problem was solved. It seems that small DC componnents in our mains make toroidal transformer to hum.

...Javi

Moderated Post:  Unauthorised link removed.

KTMax posted:

Ricky Dasler posted:

Yes a dedicated supply does improve sound quality, but it does Jack s**t at alleviating transformer hum. Plus a dedicated supply seems to measure the worst in customers homes (and including my own) when tested with a Blue Horizon Mains Analyser. My dedicated spur read 'Max' on the dial for mains noise and two radio stations could be heard coming through the analysers speaker. Others have measured similar results on dedicated spurs.

 

That makes very little sense, if at any, and not at all my experience with dedicated spurs. I'm finishing one in my current house now and it's my fourth troughout the years in different houses. 

I use a mains noise analyser too. Here in the Netherlands there are usually 3 phases (live) entering the CU. Not sure about the UK though. You pick the quietest on the noise analyser to feed the spur. After that, a clean run with quality components (RCD, MCB, fuse, whatever is used), and a good shielded cable can't result in more noise than the standard in house/walls wiring that usually directly feeds a bunch of other stuff too. A well setup dedicated spur should be more quiet than the rest of the house. But never ever more noisy.

 

 

And you'e used the analyser on the dedicated spur at the hi fi socket end to measure differential and common mode noise?

Hi Marhah 

 I had the same problem when I moved to 300 it drove me crazy,

eventually after trying different locations around the house just before I thought I would sell 

everything I brought a Honda generator down and put it in the garden, so I could see if off the mains grid was the answer,

plugged in a long extension lead, plugged in 3 power supplies, 300ps,xps2, supercap all DR, 

Fired up the genny came inside shut the back door and switched on the system and hey presto not even the slightest hum....

all this did was prove that the equipment was fit for purpose but the incoming mains supply was very poor, probably due to living 100 meters from a dry dock which runs 24/7.

still we sent the worse culprit 300psu back to the mothership and had it rebuilt,

This did help.

best thing is a balanced supply. (Airlink) in the U.K. If you have the room the have one fitted by a qualified electrician.

it doesn't stop the hum it collects it the unit hums but you get a clean supply to you naim equipment and the don't hum , hence it all depends where your incoming supply is as to whether you can fit one in.

hope this helps ( easy to test hire  a genny and fire it up)

regards Hiary

Ricky Dasler posted: 

And you'e used the analyser on the dedicated spur at the hi fi socket end to measure differential and common mode noise?

The noise analyser I use detects EMI/RFI, high & low frequency and narrow & wide band interference as well as DC offset and translates that to different noises through a speaker. It plugs in any socket you want. It's from Kemp Elektroniks and specifically designed for audio/video purposes. Works a treat!

markah posted:

stuart.ashen posted:

Is it possible to rearrange the room so that you are further away from the boxes? My 300 hums but 2m away I never notice it.

Stu

Hi Stu,

Initially I was going to jump in here with a big "no", which holds true for the half of the room where the hifi is situated at the moment. It could be a possibility though to move the listening area to the other half of the room (that's basically what we use as a formal dining area, separated by a big archway). Food for thought................ and thanks for the suggestion.

Mark

Not a solution by any means, but it is worth bearing in mind that, exactly as with speakers exciting room nodes or causing cancellation, the precise position of the offending unit in the room can emphasise or reduce audibility - corner location likely to be worst - and even moving only a small distance might make a difference to the loudness at the listening position.

KTMax posted:

Ricky Dasler posted:

Yes a dedicated supply does improve sound quality, but it does Jack s**t at alleviating transformer hum. Plus a dedicated supply seems to measure the worst in customers homes (and including my own) when tested with a Blue Horizon Mains Analyser. My dedicated spur read 'Max' on the dial for mains noise and two radio stations could be heard coming through the analysers speaker. Others have measured similar results on dedicated spurs.

 

That makes very little sense, if at any, and not at all my experience with dedicated spurs. I'm finishing one in my current house now and it's my fourth troughout the years in different houses. 

I use a mains noise analyser too. Here in the Netherlands there are usually 3 phases (live) entering the CU. Not sure about the UK though. You pick the quietest on the noise analyser to feed the spur. After that, a clean run with quality components (RCD, MCB, fuse, whatever is used), and a good shielded cable can't result in more noise than the standard in house/walls wiring that usually directly feeds a bunch of other stuff too. A well setup dedicated spur should be more quiet than the rest of the house. But never ever more noisy.

[@mention:1566878603941226] I've had very good results with the DC X-Terminator from Kemp Elektroniks. It's specifically designed to eliminate transformer hum caused by DC offset on the mains. Everything went completely silent immediately. Very reasonable price too. 

 

 

Actually it can make complete sense, dependant on the layout of the mains distribution wiring inside the house.

A dedicated spur gives a more direct low impedance path to the muck present on the incoming mains feed.
If you eliminate internal noise sources, other, longer, higher impedance circuits will act as DM capacitative filters and reduce mains noise.

999 euros for this thing? Gosh...

As far as my experience is concerned, you have three sensible options (I say sensible because there are people, in this world, who would keep the system and change the house): a), a power regenerator, like PSAudio or the like; b), accept that the thing is Naim-inherent and live with it; c) change brand.

Best

M

Max_B posted:

As far as my experience is concerned, you have three sensible options (I say sensible because there are people, in this world, who would keep the system and change the house): a), a power regenerator, like PSAudio or the like; b), accept that the thing is Naim-inherent and live with it; c) change brand.

Best

M

Did you deliberately omit the option of a DC blocker?

Re b) accepting it is inherent when with Naim when bad mains is causing it doesn't make it acceptable in use if it is interfering with enjoyment of the music or the room!

And re c), it is important to be aware that it is not a phenomenon unique to Naim, and if the cause is a mains problem there is no guarantee that choosing another make will avoid a transformer hum, though very likely different brands will differ in their susceptibility,, and indeed different models (also very likely there will be variation within the Naim brand or possibly even between different examples of the same model).

As for moving home, that of course is a balance for the individual, as in how critically important to enjoyment of the home might be enjoyment of the music unfettered by annoying hum vs whatever other factors may be at play...  but if someone has a loved but susceptible piece of kit, then take it with you when home hunting!

Max_B posted:

As far as my experience is concerned, you have three sensible options (I say sensible because there are people, in this world, who would keep the system and change the house): a), a power regenerator, like PSAudio or the like; b), accept that the thing is Naim-inherent and live with it; c) change brand.

Best

M

d)  Fit a DC blocking filter in the supply to the audio system.
e)  Get a professional electrician to fit a large isolating transformer near the consumer unit (7500VA for typical UK mains circuits).

Huge posted:

Max_B posted:

As far as my experience is concerned, you have three sensible options (I say sensible because there are people, in this world, who would keep the system and change the house): a), a power regenerator, like PSAudio or the like; b), accept that the thing is Naim-inherent and live with it; c) change brand.

Best

M

d)  Fit a DC blocking filter in the supply to the audio system.
e)  Get a professional electrician to fit a large isolating transformer near the consumer unit (7500VA for typical UK mains circuits).

Huge - as per my previous post one of the power supplies is now at my dealers and suffered the same hum there. As you say all transformers hum to some degree but I never heard it before (before in my previous house and before the servicing/DR upgrades) and the noise from the NAP300 PS in particular but all three cumulatively can be very distracting. I'll wait for more feedback from my dealer but if it turns out that it is purely down to the mains then I will have to weigh up the whole situation and look at the various solutions being offered.

I don't want to give up on this system as I absolutely love it so as you suggest some sort of DC filtering sounds like a place to start. A large isolating transformer near the consumer unit would have been a possibility in times gone by as that is all situated in what used to be the garage - this has now been converted into another living area within the house.

Innocent Bystander posted:

 

As for moving home, that of course is a balance for the individual, as in how critically important to enjoyment of the home might be enjoyment of the music unfettered by annoying hum vs whatever other factors may be at play...  but if someone has a loved but susceptible piece of kit, then take it with you when home hunting!

 

 A better words sequence to regain some sanity here would be: 'As for moving home, that of course is for the unbalanced individual..'

Chrissw19 posted:

Hi Markah, you have a great system! I suffered from a randomly humming Hicap DR and similar on the 300PS but less frequently. It was quite annoying so I've bought an Isol-8 DC blocker (high current version) on an auction site just to see if it was going to work and it did, the humming is completely gone! The hicap was also suffering from a constant very low level hum that has disappeared. 

That sounds promising - I see they do an "Axis" range for DC-blocking, was it something from that?

I have an Isol8 Axis, it reduced the hum , not entirely,  but now the hum is not so obvious.  No noticable SQ difference 

Bob F 

Xs2 hicap lp12 etc

I don't want to spoil your promising expectations Markah, but I have less positive experience with dc-blockers.
About 2 years ago I tried 2 Nait 5si's and they both sufferd badly from transformer hum. I had the chance to try two DC blockers. One from Supra and the so-called 'AH! DC-offset killer'. Both indeed killed the hum, but.... unfortunately, also the sound.

Although both to a different extend, they immediately softened the treble, and dynamics, making the music sound dull and lifeless.
Perhaps a more expensive dc blocker like the Isol-8 Axis won't harm the sound-quality. In your system it's worth a try!

markah posted:

Latest update - the NAP300 power supply is still humming at the dealers, they even tried fitting a felt pad at the transformer but no improvement. They will be in touch with Naim on Tuesday to see what they say. 

In my experience, hum seems to vary between Naim components and may even vary between different serial numbers of the same component for all I know. I had a slight hum on a Supernait and Hicap, a horribly distracting hum on an XPS which you could hear at the other end of the room but no hum unless you press your ear close to the case on a Supercap and 300PS. All were/are sited in the same place on the same power supply extension! I can't explain why the boxes hummed to different degrees (doesn't relate to transformer size) so I'd suggest asking your dealer if they have another NAP300 you can try. At least that would rule out that particular unit and its transformer...

markah posted:

Chrissw19 posted:

Hi Markah, you have a great system! I suffered from a randomly humming Hicap DR and similar on the 300PS but less frequently. It was quite annoying so I've bought an Isol-8 DC blocker (high current version) on an auction site just to see if it was going to work and it did, the humming is completely gone! The hicap was also suffering from a constant very low level hum that has disappeared. 

That sounds promising - I see they do an "Axis" range for DC-blocking, was it something from that?

The one I got is the Substation axis which is rated for larger systems. I checked with the designer if it was suitable and he said that was the one used by owners of larger Naim systems. Luckily there was an ex display one available on an auction site.

I've posted on this subject before.  (try a forum search)    Bottom line is you need to determine if the hum is constant or variable.   If the hum is constant & unchanging it means you probably (might) have a naturally noisy transformer - & all transformers make a noise to some extent, even the so called silent ones.  If the hum tone and/or volume changes for short periods or at different times of the day,  then you might (might) have asymmetrical waveform distortion (DC).