Superline/Supercap hum


Over the past few months, I’ve upgraded my LP12 with Ekos/SE, Kandid, Keel, Radikal and the Superline powered by Hicap/DR. For 3 weeks it is operated with a Supercap/DR. So far without Burndy. This is now installed since yesterday.

After a few records were heard, the SL suddenly began to hum, not quietly but rather loudly. This was not the case with the Snaic. Touching the grounding screw of the Superline reduces the humming. Even if the tonearm is touched, the hum becomes less. However, it can still be heard, albeit very quietly. It was dead silence with the Snaic.

How can that be? An additional wire to the ground does not provide a remedy.

What can I do?

You are not alone with this issue - see a thread from the old Forum - this seems to be quite a regular event and is often cured by adding a small capacitance loading:

There several threads about this issue but the search function on the old Forum doesn’t seem (at this stage) to be picking them up. Some of us experienced radio pick-up.

Another solution may be to play with the earthing arrangements inside the LP12 and/or disconnect the earth cable lead.

Thanks for that, HappyListener. Didnt know the search function in the old forum.

The 1nF plug is allready in.

What I really do not understand is the fact that with the Hicap was absolute silence and not with the Supercap. It has certainly to do with grounding.

Hermann, how are your tonearm leads connected to the Superline? BNC or RCA Phono?

If the latter, check the connections - with the Next Gen sockets it’s very easy to get a poor contact (particularly on the outer conductor) unless you use the correct matching plugs and have them properly orientated. A poor connection will usually give you a rather loud hum! It may be that when you added the Burndy, the i/c plug connection loosened or moved slightly.

On my Rega RB2000 i/c there are locking collar RCA phono plugs. I have to ensure these are done up really tight to get a proper contact on the small outer conductor sections of the Next Gen sockets. If not tight enough, a loud hum is the result.

Thank you very much Richard. I’m using Linn RCA phono cable and airplugs for Kandid.

Disconnected all plugs and reconnected. Still hum.
Radikal disconnected, still hum.

Between SL and SC is the radical. I think the gap is big enough. Moving the SL away from rack didnt changes anything.

I do not know how the earthing is done in current spec of LP12. Before that upgrade, the ground connection to the subcassis was cut off. That was with the prefix “K” and there were never any RF interferences or hum. I guess the ground wire is connected again.

1 Like

Hermann, a good test of what I was talking about above is to use a pair of 50 ohm BNC to RCA phono adaptors (normally I wouldn’t use such things, but they can be useful as a temporary measure, and here to test, but be warned, they can eventually “break down” and cause hum. Ho hum…) just to be sure it’s not a connection issue on the Next Gens.

This is a good hint, Richard. As soon as I have the adapters, I share the result.

Does it still hum if you rever to the Snaic?

@Yeti, no, not with Snaic. The hum is only audible from about 2 o’clock but very quiet. Thats not a problem.

What have I done so far:

  1. Moving Superline
  2. Put out all the plugs and put them back in again
  3. Radikal switched off
  4. Radikal power plug turned
  5. Radikal power plug pulled out
  6. RCA to BNC adapter connected
  7. Linn tonearm cable pulled off
  8. Additional earthwirefrom SL to the earthing contact
  9. Earth line checked

None of it helped. Once the Burndy is plugged in, hum is pretty loud at 9 o’clock.

However, I must admit that the Burndy comes from a demo of the distributor and is not new. The cable has not been available for some time and it will take about 3 weeks. That’s why I accepted the demo cable.

I think it could be down to the Burndy cable.

Have you any AV kit (e.g. large TV) or alike connected to the pre-amp? If so, disconnect and result?

Like you, playing with my Radikal did nothing when I was trying to find the cause.

If it’s a demo cable the dealer should be offering some sort of warranty on it, get him to check it out.

@HappyListener, no only LP12 and PS555/CDS3.

Getting a replacement cable shouldnt be a problem.

To complicate matters, hum is gone for about 3 hours. Then it came back, not as loud as before. That is, sometimes the humming disappears, then it comes back again.

Interestingly, when it hum, every touch on the LP12 (metal) reduces the humming. That means topblade, spindle, arm also on the housing of the Superline but nothing happens by touching the supercap housing. The hum stays.

So I listened hum for about 2 hours. It has not disappeared. For me, it has to do with grounding the supercap. Alternatively it is the Burndy cable. Anyway, I’m trying to get another one.

Tomorrow I will swap the power cable.

The new cable is installed. However, it is even worse than before. Something like pattering adds up to the hum. It sounds like capacitors are discharging and recharging but irregular. With the new cable is no longer to think about playing music.

Again, Lp12 and Radikal PS disconnected from SL and power, problem still exists.

I now assume that the supercap is the cause.

All I can think of now is:

1- check the power cable to the Supercap is pressed full home
2- are there any other household electrical items e.g. fridge/freezer/something similar, which could be introducing some pollution in to the mains, which is (somehow!) being picked up via the Supercap/Superline?
3- have you given the Burndy a very good massage to eradicate any kinks/twists, especially near the ends?

Have you (or your near neighbour) got any Powerline (Ethernet over mains) network adapters in place ?

Thanks for you help.

@ HappyListener

1 - well yes, I used different cable and take care of thinks like that.
2 - The system has a separate main cable and its own fuse. Pollution into the mains is excluded. There isnt anything around. Since I am trained in this, the electrical system is fine. On the other hand Problem does not occur with 5 pin cable to SL.
3- Just a little bit to make the load on the plug not too big.

Neighbors can be excluded, since only one lives in the house, is very far away and about 80 years old without any computer or things like that. Although I use a network, but that is very far away from the music system. Nothing comes in touch with Ethernet.

My flat is an older Loft with a very good elektrical installation and a solid grounding system. Call me crazy, but I’ve put a 5x10qm cable to the system and soldered directly into a multiple plug. Mains should be ok.

I’m waiting for a response from the dealer or distributor.

1 Like

update 2 …
My last action was change of the two plugs for the pickup. Now only Superline and/or Supercap have to be exchanged. But no response from dealer or distributor till today.

After more then 4 weeks nobody seems to be interested in solving the problem. What happens with the service of Naim. I’m really really disappointed.

Hermann, I’m not sure I understand you here. Are you saying your dealer is unable to help you? I’ve tried to help as much as I can from afar, but without actually getting hands on with the system it’s very difficult to help further. I would imagine a similar situation with Naim’s support. Ultimately the best person to help you deal with the issue is your dealer. We on the forum, will try to offer as much assistance as possible, but it seems we’ve run out of possible ideas at the moment without further input.

The Superline is very high gain and is sensitive to positioning in relation to other bits of kit. All I can think of is to do a new set up and then try the Superline as far away from power supplies etc… as possible and see whether the hum disappears. My own Superline is situated on a Fraim stance that has no PSUs in it. And nether on either side. However, if I move it closer to the PSUs it picks up a hum. Also 1nF capacitance is recommended here.

When you said “new cable is installed” a week ago was this the Burndy or the power cable?
The problem only arrived with the Burndy if I remember correctly.

@ Richard.Dane, any help is very welcome and I appreciate that very much. I also understand what you mean. I know it’s often difficult to help when the situation is only described and not experienced on-site.

The German distrubutor has a helpline to which I have turned several times. The result was a burndy cable as an exchange. The dealer says with every call, the problem is solved, but nothing happens. Now I have to admit, it’s not the typical Naim dealer,but a big Linn dealer who also sells Naim. Maybe he does not have the best connection to the distributor. Unfortunately I have to fix an appointment, where the problem is solved. If it has not been solved by then, I’ll probably have to reverse the entire purchase and seek alternatives.

OTOH I’m very familiar with Naim, as I use it more the 40 years in very different setups.

However, I think those who are trying to help continue to inform what happened. However, if this is not desired in the way I do no problem. Please let me know.

I have kept the SL as far away from power supplies as possible, but nothing has changed . If it were just the humming, I could understand that this is an interference caused by the grid frequency. But it’s more than that. And only with the Burndy and not with the 5 pin SNAIC. With SNAIC its dead quiet. If it were interference, it would have to happen for my understanding with the SNAIC too but it does not.

As I wrote, it sounds like capacitors discharging. Unfortunately, I can not upload an audio file that shows it very well. The recording was made when the SL was as far away as the Burndy allowed. 552PS and 555PS are even further away, as can not sprinkle.

@Yeti, It may have been a bit vague, sorry for that. I have exchanged everything that is movable, power cord, other circuit used, even other sockets, burndy, plugs for the Kandid.

The next logical step would be to swap the supercap.