Qutest Noise into Supernait 2

Hi all,

So I just hooked up my Supernait 2 with a Chord Qutest DAC and have been getting pronounced noise (high pitched buzzing from both speakers) when the DAC is plugged in. This noise comes through regardless of which input the Supernait is set to and increases in volume as I turn up the volume in the Supernait.

The noise is completely eliminated when I remove the power cable from the Qutest. I thought it might be a cable issue so I tried both a Chord RCA to DIN into the HDD input as well as some Audioquest RCA cables straight into the Aux input. Same buzzing occurs.

This didn’t happen with the Qutest into my previous preamp/power amp setup. At this point I’m at a bit of a loss to understand what’s going on.

Any thoughts?

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What a coincidence! I’m currently trialling a Supernait 3 with my Chord Qutest DAC and was getting the same buzzing noise you mentioned.

Replacing the Qutest’s USB power supply with a Samsung Phone Charger completely removed the buzzing!

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It’s a grounding issue, pretty sure I’ve read the same here before, will search …

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Fascinating. I just received my new Rega Aria and haven’t set it up yet. Hopefully this will resolve the issue.

Like I said in my post above, replacing the Qutest’s power supply solved the problem for me. You might want to look in that as well.

I’m definitely looking into that. Thanks!

Had it a few times when connecting other equipment to Naim (Node 2i) as an earthing issue I believe.

Made up an Earth cable wired to a plug and connected to the grounding point in the back of my XS2 or SN2 solved it

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Definitely an earthing issue. On my SN1 the signal ground is connected to earth via the Turntable and I don’t have any issues with the Qutest. So it appears that the Qutest does not have a ground connection.

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How does one make this cable?

Take some 3 core mains cable and strip out the live and neutral cables. Wire the Earth to a 3 pin U.K. plug (leaving the other two pins empty) then connect the Earth wire to the back of the amp. Plug in.

For me it lowered the background noise from the amp slightly for me (especially if I run the amp up really loud when nothing playing) when no sources connected so had a positive effect, other than immediately removing the buzz I got from connecting some equipment.

Worked on both my Nait XS2 and my SN2.

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Yes, I also just hooked up a Rega Aria and I’m also getting hum. Not as pronounced but still there whether the Qutest is on or not. Not sure what to do next.

The Aria doesn’t provide a connection to mains earth. I would try adding the wire between the SN2 ground terminal and mains Earth as suggested. Does the hum go ?

I’m a little concerned about plugging a wire directly into the ground outlet. I’m in North America f that makes a difference. Is it really as simple as modifying a power cable?

There’s no problem in doing that. If unsure, then I’d speak to your dealer about providing you a suitable plug and wire to provide that connection.

So I stripped out the green ground wire and stuck it in the mains ground receptacle and it worked! Now I just need to pickup a three prong mains plug to secure the wire to. Anything else I should be aware of? Are their any special insulation or safety precautions I should take?

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Very curious turn of events. I haven’t experienced any such hum with my SN2 and Qutest interfacing (OEM SMPS or current Hynes LPS; that goes for any number of DC cables or mini-USB adapters I’ve tried). In fact, I suppose I wasn’t even aware that this was a universal issue between the two brands. Interesting.
So am I reading it right that you’re NOT using a three-prong mains cable in the first place?

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It depends on your setup. You may have another item providing a signal ground to mains earth connection which negates the issue with the Qutest. In your case possibly via the TT or phonostage ?

The SN2 has a mains earth connection. It’s there for safety and connected to the case. The ground post is signal ground. In a Naim system signal ground is usually connected to mains earth at one point and this is assumed to be the Naim source component. If you don’t have a Naim source or another source that provides this connection then sometimes hum can result when using Naim amps with devices powered by wall warts.

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Yes, I’ve read extensively on Naim’s grounding architecture. You pretty much have to in order to avoid running into this somewhere down the road. Anyway, I had wondered about that, @james_n. My Clearaudio Concept TT cable/ICs include a grounding wire and spade, which in turn is connected to my Naim phono pre, just in case. That is connected via DIN to the SN2. Funny, because when using my other phono pre, I hadn’t connected it to ground and had no hum, either.

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My two source components are the Qutest and Rega Aria. Neither it seems provides a ground connection. The only way I’ve been able to stop the hum so far has been to connect the ground screw on the SN2 chassis to my mains’ ground receptacle.

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