Weird hum thing

Since the beginning of the year I’ve been using Tellurium Q Black Din interconnects to connect my NDX2 and Nat 05 tuner to the Supernait 3, with everything working perfectly.

A couple of weeks ago I swapped the 05 for an 02. Immediately a 50Hz hum appeared when using the NDX2. There is no hum when using the 02 or the Rega.

The hum goes away when I replace the TQ lead between the NDX2 and SN3 with a standard Naim lavender 5 pin Din.

Obviously I have a solution - use the Naim leads - but I’m curious to know why this happens. As far as I know, both tuners have a floating earth. If I toggle the grounding switch on the NDX2 the hum reduces but doesn’t go away fully, so is still unacceptable.

I know the TQ lead has some sort of resistor in the Din plug at one end, and the Naim of course doesn’t, but why I get hum on the NDX2 with the 02 and not the 05 escapes me. Very strange. I wonder if anyone has any idea?

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Nigel, I have no answer for you, sorry to say, although it does seem to indicate that the TQ interconnect is the possible cause of the issue. Just because the hum didn’t manifest itself with the NAT05 doesn’t mean there wasn’t still an issue.

Have you tried re-positioning the NAT02 and seeing of the hum increases or decreases? I’m just wondering whether it’s picking up interference from the SN’s transformer.

Hi Richard. I’ve tried everything I can possibly think of. I’ve put the 02 as far from everything else as possible, no change. I’ve tried removing the system automation lead (why it would possibly have an impact I’ve no idea, but I tried it just in case), no change. I held off posting until I’d been able to get the 02 on the dedicated mains along with everything else, which I did earlier, no change. In all scenarios adding the TQ between NDX2 and amplifier causes loud hum. Immediately I put the Naim lead in, silence returns. It’s just odd that the 05 is unaffected.

OK thanks Nigel. Perhaps the TQ interconnect is faulty or unsuitable? Have you tried it the other way around?

Good idea! Unfortunately no difference. If you don’t have any idea either I suspect it’s time to give up.

It is either a) magic, or b) witchcraft.

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Hi Nigel, have you tried changing the NDX2 grounding default/floating switch position.
The NAT-05 has the power earth connected to the chassis case & I don’t believe NAT-05 signal
(-ve) is connected to that earth.
I’m not at all sure of the NAT-02 power earth arrangement, but as thats the only thing thats been changed when the hum started, its logical enough to try a flick of the grounding switch.

if the TQ cable has added attenuation (you mention a resistor?) integrated at the DIN part, it may be that something there has moved and not isolated 100%? DIN plugs with these added bits can be quite tightly packed? just another thought if of any help? and if the 02 is more sensitive to this if at all the case

Afraid so :slight_smile:

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Nigel – A bit strange. A couple of things –

With the TQ in place between NDX2 and SN3, do you get the hum only when the NAT 02 is powered on or do you still get it with the 02 powered off (connected to the mains but the power switch off) ?

If you move the TQ cable to between NAT 02 and SN3, do you now get hum when using this (NDX2 connected via Lavender, Signal ground at chassis) ?

Has the tuner been serviced at all and what cable are you normally using between tuner and SN3. Not Morgana is it ?

What are you radio aerial arrangements?

Are they in any way shared with an AV set-up or floating earth devices?

It may be that the TQ has the shield common to the DIN ring and signal ground and thus exposed the signal to earth ground.

You can possibly test this with a multimeter in continuity mode and compare with the Naim DIN.

Thank you James and Adam for those questions. Somehow they set my addled brain off at a tangent, and I realised that I’d been swapping between the lavender and one of the Telluriums. The other TQ was hidden away. So I got that one out and tried it, and lo and behold, no hum.

My scientific conclusion, therefore, is that one of the TQ leads is buggered. This particular lead has a strange lump under the sleeve at one end, which it’s always had ever since I bought it used. It must be that the jiggling around when I swapped the 5 for the 2 has damaged the lead, possibly whatever was a bit dodgy over the edge. I shall see if I can send it to TQ to be fixed.

It did seem very very odd that the 05 was fine yet the 02 wasn’t, when they both (presumably) have a floating earth. I know for sure that the 05 does, and given that when the 02 was introduced a Naim system would have its signal earth through the turntable, I can only assume that it too has a floating earth.


Yikes. Hope it wasn’t mine? I can’t say I ever noticed a lump.

Glad you’ve got to the bottom of it.


Graeme, you are in the clear. It’s the other one!



Just to finish this little story, I mailed Tellurium Q to ask them about the hum, with my conclusion that the lead had broken. They suggested I sent it to them for investigation, pointing out that as it’s out of warranty any repair would be chargeable, which seems fair.

So I sent it off in the post yesterday lunchtime, and today received an email saying that it was indeed broken - a broken wire 4cm from one end, presumably where the lump was - and that they had fixed it. Total cost £30. I’ll end up with a lead 4cm shorter but it was a little over 1m anyway.

I thought this was fantastic service - fixed on the same day it arrived with them. So a big shout out for Tellurium Q’s service. I wasn’t sure what to expect in dealing with them but they have done really well.


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