Transformer hum!

Watered your earth spike recently? 

If that's a serious question you'll have to explain what you mean.

My understanding is that the main cause of transformer hum is DC on the mains - and that is certainly something that could arise further up the mains supply line than your home. For that you’d need a DC blocker, of adequate current capacity. There are devices available specifically for this, though I believe some people use an isolating transformer, and certainly some of the reports I’ve read on the forum regarding DC blockers suggest that they need not have any adverse effect.

A search of the forum for ‘DC blocker’ should come up with some examples and discussion, otherwise hopefully someone with direct experience of them will spot this thread.

Another cause of transformer noise could be the mains departing significantly from a sine wave, but I don’t know how likely that might be - however I think the noise would be much more of a buzz than a hum if it were that.

If the ground around your earth spike is too dry then it won't conduct properly, which decreases the effectiveness of your mains earth. Or so I've heard... Not sure if there's much truth to it, but it couldn't hurt to try it! 

Earth rods or ‘spikes’ for individual properties are far from common in UK, at least in  areas with underground cables (I don’t know about overhead supplies), earth usually being provided by the electricity supplier’s undergroud cable armouring performing that function. (Before plastic water supply pipes now common in many areas, the mains water pipe used to be used.) However, maybe in rural Spain it could be that you have an earth rod - look to see where the earth wire from your distribution board goes. 

However, whilst ensuring the integrity of the earth connection is important for safety reasons, for which in arid places watering of it may be relevant, a poor earth connection wouldn’t be the cause of transformer hum, though it might result in hum through the audio circuits, maybe changing when you touvh instrument cases.

Mike1951 posted:

All of a sudden, my NAP250DR is emitting a loud hum, as if I've suddenly got an earthing problem.

Much equipment switching, replugging and resiting later,  it's evident that there's a mains supply factor in play. 

As I'm out here in rural Spain, this could be down to any number of factors.

 

As IB mentions it's more likely something else on your incoming supply causing problems with the mains that is producing the transformer hum. Has the weather changed recently (more aircon units on), is heavy industry or farming equipment on the supply ?

Worth leaving it a few days to see if the problem goes again.

An Isol-8 PowerLine Axis cured my "transformer blues" -- and with my modest set up (XS2/ND5XS) I could not detect any drop in sound quality. It is worth noting that the PowerLine Axis only takes care of DC off-set -- no nasty mains conditioning... So it is rather different from the Tacima thingy from Richer Sound --- also much more expensive, but it is worth the monies in my view.  

Hi Mike,

I live in fairly rural Norfolk; have a dedicated mains spur, and get occasional audible transformer hum from one or more of my 500 series p/s units.

You will no doubt be aware that Naim have yet to find or recommend a mains conditioning device which doesn't throw out the baby with the bathwater.

There is a tale of Julian Vereker being berated at a Hi-Fi show many years ago by a chap with a NAP250 which was buzzing. "I designed it to sound good" said Mr V - "if the buzzing bothers you, put it in a cupboard."

Ah; those heady simpler times eh?

Good luck.

John.

this is not a malevolent question: why bother so much about reducing the noise floor when one is ready to accept a buzzing noise/hum (which is perceptible even if within a cupboard) :-)?

DrPo posted:

this is not a malevolent question: why bother so much about reducing the noise floor when one is ready to accept a buzzing noise/hum (which is perceptible even if within a cupboard) :-)?

because xformer noise is not in the music signal path whereas the 'noise' you refer to, is.

enjoy

ken

I don't live in a rural area but my olive 180 and HiCap hum from time to time. I do have a dedicated radial spur to my kit and also an earth spike/rod in the garden which I water everyday, rain or shine when I change the dogs water bowls. 

They're both 230v units but it only happens when there's high electricity demand around dinner time and mostly in winter when heaters are on. When this happens and both transformers hum, I measure my power and the values are always bellow the norm here which is 230v. I get 217/220v every time. Really a shame  but it has no effect in sound quality whatsoever.

Just my 2 cents ...

ken c posted:

DrPo posted:

this is not a malevolent question: why bother so much about reducing the noise floor when one is ready to accept a buzzing noise/hum (which is perceptible even if within a cupboard) :-)?

because xformer noise is not in the music signal path whereas the 'noise' you refer to, is.

enjoy

ken

Hmmm, but transformer hum is constant level, so can be intrusive at low music listening levels, whereas from the music signal path only power amp noise is not reduced with volume. Noise reduced by the VC stays at a proportional level and so increasingly intrusive as you turn the volume down, whereas transformer hum gets increasingly intrusive. As for power amp noise that isn’t proportional to VC setting, at the listening distance I’ve never heard power amp hiss anywhere near the level that transformer hum can be - it would likely take the sensitivity of horn speakers for that.

kota posted:

I don't live in a rural area but my olive 180 and HiCap hum from time to time. I do have a dedicated radial spur to my kit and also an earth spike/rod in the garden which I water everyday, rain or shine when I change the dogs water bowls. 

They're both 230v units but it only happens when there's high electricity demand around dinner time and mostly in winter when heaters are on. When this happens and both transformers hum, I measure my power and the values are always bellow the norm here which is 230v. I get 217/220v every time. Really a shame  but it has no effect in sound quality whatsoever.

Just my 2 cents ...

Probably something at that time of high demand causing DC in your mains, whether it is in your house or a neighbours. The solution is the same, a DC blocker.

ken c posted:

DrPo posted:

this is not a malevolent question: why bother so much about reducing the noise floor when one is ready to accept a buzzing noise/hum (which is perceptible even if within a cupboard) :-)?

because xformer noise is not in the music signal path whereas the 'noise' you refer to, is.

enjoy

ken

it's nevertheless in the signal path to my ears :-)

but I guess what you say must be the accepted wisdom on this topic 

DrPo posted:

ken c posted:

DrPo posted:

this is not a malevolent question: why bother so much about reducing the noise floor when one is ready to accept a buzzing noise/hum (which is perceptible even if within a cupboard) :-)?

because xformer noise is not in the music signal path whereas the 'noise' you refer to, is.

enjoy

ken

it's nevertheless in the signal path to my ears :-)

but I guess what you say must be the accepted wisdom on this topic 

The mains hum is at low frequency with few and simple harmonics.

The 'noise floor' from electronic amplifiers (SS or thermionic) is a mixture of harmonically correlated distortion, dynamically correlated noise composed of frequencies that are not harmonically related to the signal, and completely uncorrelated noise.

It's much easier for the brain to process and ignore the simple and constant additional uncorrelated signal that is the mains hum, than it is for the brain to disentangle the wanted signal from all the other complex signals contributed by the amps electronic and electrical components.

A mains DC blocker will stop the hum

Tried it myself several times ...just silence..

But the strange thing was, as soon as I did stop the buzzing...it suddenly became very unimportant and I removed the blocker ( incase I was throwing the baby out ...) And just lived with it

It really isn't that distracting or important..once you know you can get rid of it if you want...or that's what I found

Huge and Japtimscarlet: different but interesting perspectives, thanks

I also have humming in my Atom. But my worry is actually not about stopping the hum, but is about saving the equipment. My logic is: if the hum is loud, then transformer vibrates more. If it vibrates more, then it should be damaged from physical vibrations in long term.

Of course a lot of people say, that the hum will not damage the transformer, bet how knows... My opinion is that vibrations are bad. And all the equipment, that interacts with vibrations serves less. For example - car parts.

There are a lot of humming trannys in Naim land, it doesn't seem to cause reliability issues but the streamers have a lot of components to shake compared to a power amp or power supply. Leave it on while it's under warranty, better to break it while Naim will pick up the tab than cosy it and have it fail later, that's what warranties are for.

DrPo posted:

Huge and Japtimscarlet: different but interesting perspectives, thanks

Actually they are completely compatible, as everyone varies, it depends on how annoying you find the hum!

In fact I actually do use a home made DC filter on my mains supply!

Has it had a deleterious effect on music playback?  Is there a commercial equivalent in terms of construction? 

I find the transformer vibration more of a problem when not listening to music.  Once the music is going - event at low volume - it is not noticeable.  However, if all is standby (and I am working at my desk), the hum can sometimes be intrusive as it fades in and out.

How easy is it to connect/disconnect a DC Blocker?

OK, then DC blocker needed! Either that or turn power a p off when not in use - personally I think half an hour warm up before playing is adequate, but the majority view on here is better left on permanently (and mineisn’t a Naim amp).

PS Audio Humbuster,,,,works 100% did it with NAP250DR as well!

Gavin L posted:

I find the transformer vibration more of a problem when not listening to music.  Once the music is going - event at low volume - it is not noticeable.  However, if all is standby (and I am working at my desk), the hum can sometimes be intrusive as it fades in and out.

How easy is it to connect/disconnect a DC Blocker?

My Isol-8 PowerLine Axis comes in the "shape" power strip.