SuperCap DR hum

My 5 year old SuperCap DR has always had a hum as soon as it’s powered on. I know that this is very typical or Naim kit. I have tried plugging it into a Shunyata Denali power conditioner that is on its own dedicated mains circuit (to give it the cleanest power around) but this doesn’t change anything about the hum.

What else should I try to reduce or eliminate the hum? Does a service from Naim fix it?

I think the hum issue is very random. My SuperCap DR was the quietest Naim power supply I have owned. The HiCap was the noisiest. The 552 PS hums much more than the SC ever did. A service did not change that at all.

If the hum comes through the speakers, it is usually a ground loop hum, which will heed further investigation. Plenty of info on here, just search for ground loop hum.

If the hum cannot be heard through the speakers, it is usually DC offset, caused by other equipment. You could investigate, switching off all electrical equipment to find it. Or you could add a DC Blocker to see if that works.

I have added to IFI DC Block and that stops most of the hum.


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The hum comes from the SuperCap DR itself and not through the speakers

My older SC hums. Naim’s official response was, “They do that.”


My XPS2 (2003) went for a service this year, which made no difference to the humming sound.

In addition, in my (2020) 555PS DR, there is no hum.

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Is the hum noticeable when sitting 6 feet away from your system? How annoying is it? You’ve written a thread about it so it’s obviously bugging you. I have had XPS, XPS2, HiCaps, Supercap 2, 555PS and have had no real hum problems. I did have a hicap that ran hot which bothered me so much I sold it, although there was nothing wrong with it after tests were carried out.

Other option is sell it and buy another one. A service may or may not fix it.

Thanks for the update.

Either speak to your dealer to borrow a DC Blocker and try that, or order one on-line, try it and if it improves, keep it, or if not, return it.

Both my NAP 250s hum and I put the IFI DC Blocker on them.

Didn’t get rid of all the hum, but improved it, so that I can’t hear it when sat down with no music on.



Here is a few ideas for you to investigate

I don’t have any hum or buzz from any of my Naim equipment.

I can hear it from my listening position about 6-8 feet away from the Supercap DR. I have had a hi cap DR in the past that also had a hum. My 555PS doesnt hum and is silent. It is annoying and I may now try a DC blocker that others have mentioned

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You have alot of cabling with an active system. Could that contribute towards hum? The cables look very neatly but somewhat tightly dressed. Cable dressing could be a contributing factor.

Have you had a Naim dealer have a look?

The DC Blocker seems to have worked but has it impacted SQ?

You have probably resolved all your issues. My experience is with a multiple box system spread over two racks it is very difficult to separate the sensitive signal path cables from the power cables and power supplies.

Do Naim recommend DC blockers? I thought that they affected SQ.

But in complex systems what are you supposed to do?

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It’s obviously annoying and higher than it should be.

The cabling has been re-dressed since then.

As with anything, there always compromises.

Did some investigations and found that it is DC Offset hum. There are seven transformers in the power amps and power supplies. However, it is only the 250s that hum, which you can feel through the case.

As previously advised the IFI DC Blockers don’t remove all the hum, but you can only hear it now with your ear right next to them.

With the investigation I did, I found no change to the SQ. There is no mains conditioning that you get on some other DC Blockers, hence, why I chose them.

It is a result for me. But may not be for others as all systems vary, but for the cost and potential improvements it is worth trying.


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Should’nt one be to ask such qualified manfacturer as Naim that their units are completely silent? I had a Atom HE that hummed so much that I sold it back to my dealer. I tried with a DC blocker but it does’nt help. Also owned an Atom that was completely silent. Now I have a Nova and NDX 2 that are completely silent. I am completely satisfied with both of them. Fantastic players!

It looks like a successful compromise has been achieved. Alot of work goes into these active systems
Trying to get the cable dressing neat is very fifficult and time consuming.

I have also noticed in your profile that you have dedicated mains supply for your system. Effectively, you have done everything possible to eliminate the hum.

It doesn’t help that the power cables are so long and with so many of them. Plus being PowerLines, there are thicker too.


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I’ve had a 10 plus box system for a few years and cable management is a nightmare. Yours even more so. I do sometimes contemplate 1 box amplification albeit non Naim.

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I had a hum on my supercap and it was a faulty lamp i had plugged in the wall socket nearby.