Sorry - Noisy Transformers Again - Advice Welcome - Update that could be controversial

Just over three years ago I installed a dedicated supply to the hi-fi. Henley block, separate consumer unit, etc. I have three good quality unswitched sockets on the end of it into which all my equipment is plugged (XPSDR, SCDR, 250DR, NAPSC, Xerxes & Roksan Tuner).

I was surprised from day one that SHMBO’s hair dryer was still able to generate transformer noise in my system (though oddly not consistently) - but aside from that things have been ‘quiet’ but with occasional short lived ‘noisy’ periods that I assumed were down to external factors rather than anything in the house.

Last three days things have suddenly - and consistently - turned noisy and it is across all three of the major transformers. I switched down for 12 hours but the noise was there as soon as I switched on again. Very little variation in the noise which is verging on a buzz rather than a loud hum.


I had an Orbi Satellite near the hifi, to get a cabled connection to the ND5 XS.

It produced a lot of noise, a buzz through the speakers.

Maybe you have something wireless in the vicinity creating the noise?

(Shifting the orbi a few feet away solved it for me.)

There is a FAQ on transformer hum. Useful info there.

Seems to have disappeared

Apologies thought it was there. Have you searched anyway for previous posts? Been discussed numerous times here.

Yes - it is an often discussed topic, though sadly with very few obvious ‘solutions’. I have ordered an Isotek Evo3 Isoplug to see if that makes any difference. The issue will probably disappear just as the Isoplug arrives - that’s what I am hoping anyway.

Best of luck anyway. I cured my hum, which was a dc offset issue, with a dc filter. Again, it was the wife’s dryer and light dimmers. I actually removed all dimmers in the house anyway.

I never worry about them, they come and go and generally disappear as quick as they came.

Sorry with Naim amps, no short cut it requires a dedicated mains spur.

He’s got one.
Infact it shows that a dedicated mains isn’t the cure in all cases.

Maybe Neil meant this great work by GadgetMan?


Weird, I have one standing close by as well and no issues. Was it plugged into the same power block?

Have you switched off your other mains circuits in order to eliminate other home devices as the possible cause?

Yes and it has no effect. As I said in an earlier reply nothing has changed in my house for 18 months. Kitchen appliances were top of my list to investigate - but no change when I took the kitchen ‘off line’.

Thanks - missed it when it hit the Forum - smug in my ‘quiet’ environment! Very interesting. It has actually become a little better over the course of today - so I’m hoping my prediction holds true, it goes as the Isoplug hits the doormat.

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I use an ‘Isol-8 PowerLine Axis’ DC-Blocker to great effect.


I had it next to the stand. Once I figured out it was the Orbi I played around with the power supply and then eventually tried waving the Orbi around near and further away, bingo that was the source. The buzz was loudest when it was in held on front of the volume knob. Curiously, the buzz almost disappeared when I touched the volume knob (but only the volume knob, touching the amp case had no effect on the noise).

I hadn’t appreciated how much effect a wireless device could have. It’s now about 6’ away and no buzz for me.

That’s some good sleuthing.

Mine is just under a meter away and no issues. But a while back it was standing tight next to my Star and nothing.

Read somewhere that some transformers are affected more than others so perhaps that?

I did get some really audible hum from my Star’s transformer by either plugging it on the same power bank as the TV or having a hair dryer on ontheven same power line upstairs.

So guess what - just entered my main living room and my gear is as quiet as I have ever heard it! Isoplug not even shipped yet.

So it must have been external - I.e supply grid - factors at play.

Can close this post.


Adding this to my original retitled post so that I don’t have to repeat things.

So the Isotek Evo3 Isoplug arrived. The transformer noise had returned, though not as continuously as before. So I unplugged the Xerxes from the bottom of my three double power sockets into which all my gear is plugged (happens to be the first socket the dedicated supply sees) and inserted the Isoplug. Things were quiet at that moment - but I popped in and out of the room over the next few hours and it was clear that when there were noisy periods they were still there but definitely tamed - and bearable. Had that not been the case the Isoplug would have been out - only £110.00 wasted.

I thought I better now check the effect on the sound quality - expecting the worst and therefore a difficult decision. What followed was a three hour listening session to make sure that I could believe my ears! Yep - sound quality was obviously improved from the very first track to the last. It is like the bandwidth of the system has been widened. Same glorious sound as I have been used to but with more top and bottom information and definition.

This probably falls into the shelf height, stacking order, plug order and cable dressing theatre of improvements - but to my ears it is definitely there. Might just be my setup - but for the cost it’s worth a try.

No brickbats please - just passing on my experience.

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