CB Nait 2 hum via speakers

I have an earth-ground question regarding my CB Nait 2.

I now have an audible hum via the speakers.

Until recently I used an LP12 and a NAT05 as sources, with no hum at all.

The NAT05 is gone, sold-off, since FM was cut-off here and source is now LP12 only. One quiet day (it can be busy here in the house) I suddenly noticed this hum and it has stayed.

So, is this a coincidence with somehow worse mains and/or a deteriorating Nait 2 (serviced 14 years ago), or was the NAT05 the earth-ground-anchor like the Naim CD players and is this a direct result?

Hope anyone has a possible solution.

Thanks, Maurice

The 05 has a floating earth, so everything should be fine with just the TT. Which it isn’t of course. Have you checked that the arm earth is ok and that the mains plug is wired properly.

The early Naits connected mains earth and signal ground so a lack of a source providing this connection shouldn’t be an issue. Given it’s been 14 years since its last service, I’d say that unless you changed anything and the hum immediately started, it’s more likely the sign of the Nait needing a service rather than an earth loop issue.

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Thank you Nigel, good to know.

Yes I did check the TT (as best as I could). Also, I have uncoupled and recoupled everything. Hum’s there with or without source component(s) connected. Also somewhat volume-dependent, volume off is hum off. I sort of hoped the tuner (now gone) would be the answer but I can’t check that anymore, hence my question. It not something I can’t live with at all, just slightly annoying, and would like to have peace of mind that nothing is broken or anything.

Yes I was afraid of that, deteriorating amp, thanks James.

Now that you mention it, in that same period I also changed speakers, to vintage Royd monitors. Yet, I can’t see how that could induce a hum via both speakers equally loud, but then again I’m not exactly an electronics specialist.

Try moving the Nait away from the Linn, as far as its lead will allow. I was suffering from hum when my Rega was too close to the Supernait.

I will give that a try and report back (yet, the hum is also there when the LP12 is not connected). Will do the whole decoupling and moving thing again tomorrow.

A hum through the speakers whether a source is connected or not could well be a sign that a service is due (or overdue). If you’re in the UK then you could use either Naim or Class A, who are approved to service Naim equipment.

Thank you Richard, I sort of anticipated that being the answer.

I’m not in the UK but was used to doing business with many UK companies before Brexit. The amp was previously serviced by Class A to my greatest satisfaction. I had planned to send it there again or to Naim HQ also to retain the value of the CB Nait 2. Not sure how (if?) that will work out now with repairs and VAT in EU-to-UK traffic.

You’ll need to go through your local dealer or distributor if you want it serviced by Naim, otherwise you could contact Darran at Class A directly.

I second Darren. I had a Nap 180 which I bought used and it sounded a bit dark and not great when I got it. Had it serviced by Darren and it sounded great afterwards. Probably worth doing that.

Just a quick update to wrap up this thread.

Class A informed me they now only undertake work from the UK mainland, due to already troublesome customs proceedings, which they expect to get even worse in the new year.

Dutch distributor Latham Audio showed their usual exemplary customer service and went out of their way to make sure the amp makes it to Naim HQ before the January service price hike.

I trust everything will be A-OK again after this second service. Thanks everyone for contributing.

Maurice

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