Supercap DR Buzzing Noise

Hi all

I purchased a Supercap DR a few months ago and I have been experiencing a constant buzzing noise when it is switched on. I have been through all the relevant threads on the forum and tried the advice; but nothing seems to do the trick.

I appreciate the size of the transformer means there may always be some hum/buzz but it really is quite loud. Note it is directly from the box and does not come out of the speakers.

I have the following system:

  • ND5 XS2
  • NAC252
  • NAP250 DR
  • SuperCap DR

I am using Naim SNAIC/Burndy cables and Chord Sarum interconnects. I have made sure all are connected properly.

I have also tried a DC blocker and most recently (today) I swapped out my extension block for a Puritan Audio PSM156. I appreciate this may need a few weeks to run itself in; but I am increasingly thinking it is an earthing problem with the Supercap - if I move closer to the box the humming increases. This is particularly acute if I move my hand towards it/touch it.

Any help most gratefully received!

ps. I have also tried unplugging other devices around the house one by one to see if they are impacting it. In addition, I purchased an AC voltage socket tester and this confirmed each socket in my house is earthed correctly. It delivered a slightly high reading of 244V but I understand that these devices have a 1-2% accuracy threshold.

This may need one of the Naim tech’s assistance. @NeilS


This might help.

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Thanks Richard, I have been through this a few times; but will take another look to make sure I have not missed anything.

Interestingly, I used to have a Supernait 3 which made a similar buzzing noise. When I added the Supercap DR and used the Supernait 3 as my pre-amp until I could afford the 252, the buzzing moved to the Supercap. I’m guessing this is simply because the Supernait PSU is no longer being used and replaced by the Supercap; but I thought worth mentioning as I think it highlights it is not an issue with the Supercap itself and rather a grounding issue?

It’s usually down to an issue with something on your mains - either within your home or perhaps a near neighbour?

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Yes, that is increasingly my assumption too. As I mentioned, I have tried the process of elimination in my house by unplugging things one by one. I’ve also put my EE8 ethernet switch on a separate mains block so only my HiFi boxes are on the Puritan extension block.

Next door have 3 teenagers and I am guessing they all probably have a TV/computer/phone chargers in their rooms which must be creating an overload.

The fact the humming/buzz increases when I move closer to the Supercap is what makes me question this though. Would that not indicate a grounding issue? I have zero knowledge on these things but I read this online during my (now) extensive research on what could be causing the issue.

Two things to try.
First is to take it and put in a different room and plug it in. Does the hum change in volume?

Second is to take an earth wire from the casing of the din connection point and connect it to the case of whatever you are powering or one of the din inputs.

I have inconsistencies here in France when moving just some kit from one room to another. It doesn’t make sense in that one hicap will hum yet another doesn’t. Earthing via din inputs works for me, even though it shouldn’t be necessary.

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Yes, it is a grounding issue imo.

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Have you checked the earth potential of your mains sockets?

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Hi, would you mind explaining what you mean? I have used a voltage tester to check them. Please see blurry picture for the socket in question. Sorry, it is hard to get a decent shot whilst leaning over the back of the system.

Thank you, I will try your first tip now to see if the hum changes at all and report back :+1:

A socket tester will tell you whether it’s OK or not.

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Thanks, is that different from what I have in the picture above I have uploaded?

Yours says “Socket Tester” so I would assume it checks the earth.


That socket tester will probably not tell you if Earth & Neutral are reversed - is the socket in question RCD protected?
I’m clutching at straws, as this is not something I have heard of before. The fact that the intensity of the buzz increases when you put your hand nearer sounds very odd.
Does it do it when only the mains power is connected & not the rest of the system?
The suggestion to try the SC in another room is a good one.


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I have that same hum intensifying as I approach on one particular olive hicap. The hum completely disappears if I earth the hicap to either input din on its accompanying nac 62.
Very strange.

And that hum is coming from the Hicap & not the speakers?


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Absolutely. It is noticeable above low volumes of music and is also there with no source playing. it gets louder as my hand gets near to the unit. I believe it to be only in one room on a phase that is not used in another room where only a low hum occurs on the same unit. (The house is 3 phase) The strange inconsistency is that the hum is not present on any cb hicap or hicap DR that I have, in any room. I thought it might be a circuit breakdown somewhere internally hence being only on the Olive. As said it is completely eradicated by attaching a separate earth.


How curious!



Hi, sorry I had to do the washing up before I was allowed to play with my toys again :slight_smile:

So I just tried the Supercap DR alone in 2 other rooms and the hum/buzz was still there. If I place my hand on the unit at the front I can still hear it intensify.

Re the socket tester, it seems pretty capable and has confirmed things are wired correctly. I am not sure what RCD means, but I will check now!

Thanks for all the responses, I really appreciate people giving their time to help. Hopefully I can pay it back in the future.