Again: HiCap DR humming

I know it has been discussed many times. And I know that humming is “normal”. But I can hear the humming of my preloved Hicap DR in the whole 50 m² livingroom. The humming is not comming via the speakers, it ist just the HiCap DR.

What solution is best?

  1. send the Hicap DR to Naim for service
  2. sell the Hicap DR an try another one
  3. buy an DC-Blocker (Supra LoRad)
  4. abandon the Hicap an d accept the less good SQ
  5. buy an no-naim not humming Power Supply



That’s not good - What is the Hicap sat on (rack or something else) - just wondering if this may be making things worse ?

Could you borrow another one from your dealer just to see if you have a particularly bad example ?

1st choice for me is 5
2nd choice is 2 but only after testing at your home first

Regarding 3: If you have a naturally humming transformer, a DC blocker will not help. If you do have a DC problem you will most likely hear the hum tone & volume change at different times.

I would take it to a dealer and listen to it there, and compare it to one of theirs. Then you’ll know if you have a particularly noisy one, or if it’s just that your mains is the cause.

Yes at least try it on someone else’s mains. I have one and it’s totally silent (going tomorrow, but that’s another story). I get a short hum from the balanced supply when the Hicap is first turned on due to the current surge but after that just silence.

Option 3 — try a DC blocker. It cured the humming in our living room. I went for Isol-8, but only after trying at home to establish whether the thing would stop the humming that was driving me nuts…

I had the same problem with a hicap on SN2 but was lucky as actually preferred the sound without it. Also tried option 5 which didn’t hum but although it brought more clarity I lost some impact in the bass so again it was removed.
When i had the hicap I bought a balanced mains unit to see if it would stop the hum and it didn’t so would be cautious of throwing too much money at it.
I can’t comment on a DC blocker though as never tried one.

I had the same problem.
I would rule out 1 and 2, as well as 5 (I tried, the non-Naim PS didn’t hum, but it made little difference to the sound of my SN2).
Things improved a little after I changed the mains block (I had the basic Netzleiste - I now have a Musicworks Matrix 2 with Powerline).
I have never tried a DC-blocker; it’s been suggested on another thread that this was the best solution.

If it more than 10 years since a service then get it done.

NB a service is more than just new caps

For me, it is mains. However, some transformers react more to the mains than others and I have noticed that a well placed amp having well routed cables hums less than wrongly placed amps.

Something in my old house is not good. Even when all Naim is switched off, I hear something especially late night. Even one specific lead which is connected to the doorbell and the jacuzzi hums. Cannot disconnect them, they are built-in.

On a day I brought my humming amps to my parents place and the humming was only 10% there. Others have recommended this as well on this topic, and it is worth to try since it is an important parameter in the troubleshooting. If not for this amp, then maybe for later.

It could be an issue with the substation/local earth. ISTR that the Neutral coming to your house is the earth at the substation. This can be different from your local earth which traditionally done via a local spike though also sometimes by the incoming water feed pipe. If there is a difference between the substation earth (neutral) and local earth then you can sometimes get a hum. In my house there is a c. 1.5V difference between local earth and neutral. In fact I can see a tiny spark if I touch a neutral wire to ground; BTDT in the loft once doing a light socket. For some equipment a difference between neutral and earth can cause a hum. Anyway that’s what I read in hifi choice a year ago. Hence why I installed a balanced mains supply.

I don’t experience humming with my Hicap DR so it is not normal that your unit shows humming. As others have suggested, perhaps look at the mains.

My Olive HiCap for the NAC hummed more than the olive HiCap for the Prefix.The HiCap DR now on the NAC hums not a jot, unlike the 250DR which is like a hive in direct noontide summer sun most of the time.

Same electricity supply, different units.

All my Naim amps until recently have hummed and my hicap dr hummed on my sn2. I could hear it with no sound on from the system or TV but not when listening to music. On my 282 it doesn’t, so far, hum at all and neither does the 250dr

Thank you for all your answers and suggestions. The Hicap DR is humming on itself. The Humming is not depending on interconnects to other gear. I tried another Hicap DR, lent from my dealer. This one was Humming differently, but also to loud. A DC-Blocker (Supra LoRad) didn´t help. I then tried different wall sockets. On most of them the HiCap DR was humming loud. Only in the kitchen it was totally silent.
I think a separate power circuit will be the solution for my problem. So, I have a new project. In the meanwhile I use the Hicap DR in the kitchen to pimp my toaster.


Try on the end of a long mains extension lead from the kitchen to where the hifi is located. If it doesn’t hum then sounds like something horrible with the mains at the hifi location. Next stage is from a socket near to the hifi but not the one you normally use. So hopefully on the same ring but a different socket. Hums then it’s the ring. Doesn’t hum it’s the socket. You follow?

Is the kitchen on a different circuit to where your Hi-Fi is ?

If so what other items are on the circuit which causes the Hi-Cap to hum. Any heaters, motors, other electrical equipment ?

I think this is because of the electric current. Sometimes my HCDR and NAP200 are also humming, I mean loudly, but it’s just temporary. After a little while it will be gone and maintain at a low humming level. If you want I think you can audition a power generator or something like (such as from PA audio or Isotek) and you will see. Hope this helps you

mine , 555dr, humming sometimes at night and on weekends, holidays.
But after 3 or 4 meters, i don’t hear anything.

That is the solution - and you may have inadvertently identified a problem with your HiFi mains circuit as you presently have it. Naim products are (over-) sensitive to ‘bad’ mains - but love good mains.

Since you have shown by your excellent experiment (I wish more people would do this sort of thing) you have shown the Mains delivered to your house is not the problem, but that something is causing a problem on the mains circuit the HiFi was using.

Two solutions:
1. Un-plug everything one at a time on that problem circuit until you identify the culprit - or if still humming after nothing else is on it the circuit itself is faulty.
2. Put in another ‘Hi-Fi’ mains circuit.

Since the latter will improve your system in itself it is the way I’d go. But I’d still want to identify the problem with the existing circuit as it may be worth getting that resolved for safety reasons.