NAT01 servicing

Hi-Fi Corner
1

Hello all,

My NAT01 tuner has developed an annoying transformer hum. I gather from my dealer that Naim has now stopped servicing this tuner and was wondering if any denizens of this site might be able to recommend an alternative.

Aidan

2

Hi that is news to me. Had my 01 serviced about 6 months ago. @NeilS should be able to give you advice.

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3

Thanks.

I’m not entirely surprised that they have. I’m surprised that there was no warning. Maybe there was and I missed it.

4

I think this has already been answered if you perform a search. Here’s Neil’s answer from 27 days ago.

Maybe you should tell your retailer.

It sounds like the problem you describe is possibly in the PS, so it must be worth sending it back to Naim Audio for servicing.

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6

Thanks Clive. I will do that. I also have a problem with the display, which I can live with on its own. The hum I can’t live with, so I will want to get both fixed at the same time.

@NeilS would you confirm that nothing has changed wrt servicing recently and I’ll get my dealer to dispatch?

Aidan

7

Nothing has changed that I’m aware of.

Please note though that we cannot fix the early vacuum displays & I do not know if we have transformers for the PST.

Regards
Neil.

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8

Thanks very much Neil. I have informed my dealer and I guess he will be in touch.

Aidan

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9

If the problem is a mechanical hum from the transformer in the power supply you might ask yourself if you’ve changed where you plug it in or whether you’ve recently added a device to your household system which might be injecting noise.

One customer rang in to say that whenever he plugged in his golf cart (!) charger he experienced mechanical hum from his system. Another his fish tank heater. Hardly needed my advice.

Have a ponder.

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10

But…but…I don’t have a fish tank!

I will indeed ponder but nothing has changed recently that could explain it.

One interesting symptom is that when the tuner input is selected on my amplifier (a Devialet) at the ‘safe switching’ level (-40db), and the tuner is OFF, the hum is very loud. When I switch the tuner on, the level of the hum drops markedly and then increases ‘linearly’ as I increase the gain on the amp. That may suggest something to someone with the patience to read my effusions.

Aidan

11

Transformer hum is a mechanical vibration - originating physically within the NAT01 power supply.

Is this a hum audible through the speakers - i.e. not the transformer hum?

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12

Hi Adam

Your diagnosis was spot on. Transformer hum was a misdescription. It was a hum through the speakers, not from the tuner itself. A friend suggested disconnecting the turntable earth from the amplifier and like magic the hum was gone. I am left with the display fault, which I can live with but will get fixed while I still can.

Thanks again.

Aidan

13

Yes, if the hum comes from the device as opposed to audio outs, that would suggest so called DC on the mains, or asymmetric mains. Some devices, often those with heating elements of some type can cause this.

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14

Yes indeed - our washing machine causes a big hum on my Naim kit.

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15

Hum cured by disconnection of a source usually points to an earth loop.

If you did not have an earth loop and then you did - it is VERY likely that you changed something. You changed something that I would notice and you don’t think relevant.

Often it is the connection of AV, non-audio components to the amplifier. Here you might have a DVD player connected and you have no problem but you connect the DVD to a television and the television is connected to a communal aerial system - etc, etc. It’s not the connection direct to the amplifier but ALL the daisy-chained AV bits and pieces that hang off it.

Although problems that originate in the AV side can be alleviated by disconnecting earthed elements of the audio side you are best advised to unplug all the AV leads and reconnect your audio components. Then see if you still have a hum problem.

If you don’t, your problems are caused by the AV side. If this has proved the case you should be able to preserve all you audio connections by fitting a Ground Loop Isolator (a 2 x 1:1 isolating transformer) to the lead from you AV equipment. Most cheapish ones will degrade the signal somewhat - which is why I’d advise treating the less valued AV signals - rather than any of the hifi sources for which you’ve paid so much.

If you still have a hum problem with all the audio sources connected to the preamplifier and the mains:

1: Check again that you don’t have ANY AV stuff still connected (I used to encounter connection-blindness all the time)
2: Keep the AV disconnected and let’s look at the new problem.

If we are to do a dealer’s job you’ll need to detail the system exhaustively and accurately.

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