Naim Xs 2 and Arcam Irdac - Ground loop ?

Posted by: Den83 on 22 January 2016

Hello everyone,

New to the Naim world.

We recently completely changed our hifi setup and did some extensive listening with various set-ups at home.
My wife and I quickly fell in love with the Naim Xs 2 (compared to the other amplifiers we tried at home, including Rega Elicit R, Hegel H160, Roksan Caspian, ...).
We had a bit more trouble choosing the speakers and were really hesitating between the Focal Aria 926 and the PMC twenty 23.
We finally decided on the PMC as they are better fitted to our room acoustically-speaking.

We also bought an Arcam irdac as our source since we blew our budget with the PMC twenty 23 (3300€ in Belgium with the recent price increase).

The Dac is connected to our Macbook Air via a Chord usb cable, the tv with an optical cable  and a media streamer with coaxial cable.

We are quite happy with the results but we are unfortunately experiencing some noise issue.

When the volume of the Naim Xs 2 is higher than 9,  there's a hum that appears from both speaker. It's very subtle but when I put the sound louder (say 10/11) then it becomes quite disturbing (especially when you have silent moments in the music, movies, ...).

I have read up on the subject on the forum and on internet and discovered that it could be due to a ground loop.

After some plug-pulling sessions I realised that the hum appears as soons as I plug in the Irdac (without anything else connected to it).

I'm a bit confused because the Irdac plug doesn't have a ground connection.

Does anyone have an idea of what could be the cause and how I could solve it ?

Thanks in advance for your replies.

ATB,

Den

Posted on: 22 January 2016 by Richard Dane

You could try running a thin ground wire from the DAC to the NAIT chassis. Your dealer who supplied the Rega and Naim is no doubt familiar with the issue, as it can be quite common, and will have a solution at hand.

Den, does it happen with the IR DAC connected to the NAIT but nothing else connected up to the IR DAC? Just wondering if it could also be coming from one of the other connected devices.

Posted on: 22 January 2016 by Adam Zielinski

Den83 - the ground loops are not actually caused by a 3rd pin (the so called 'ground')

Posted on: 22 January 2016 by mpw

when i started my turntable for the first time - i too encountered a humming noise from my speakers which would not go away despite doing everything.

By chance, i happened to pull out the TV set top box plug from its socket and the hum stopped.

I realize you have a DAC but i thought my example could help you think a little out of the box - if & as necessary.

It should be simple enough to solve once it gets solved 

Good luck !

Posted on: 26 January 2016 by Den83

Thanks everyone for the replies.

I did some more testing this weekend.

I don't have any noise when the Xs2 and Irdac are both plugged in but without anything in their inputs (besides speaker for Xs 2).

From there, as soon as I connect the dac to the XS 2 with RCA then the noise appears (nothing is connected the dac's inputs).

So it's not related to any other components.

Posted on: 26 January 2016 by Adam Zielinski

Well - you have identified the offender then. Time for a new DAC perhaps?

There is of course a way of isolating the DAC (via isolating transformer on the RCA connection between DAC and the amp). You could test it. A decent isolating transformer should cost no more than EUR 20 / GBP 15.

Posted on: 26 January 2016 by Den83

Could a linear power supply with grounding solve the problem ?

Posted on: 26 January 2016 by Adam Zielinski

I doubt it.
Or in other words - I would be very surprised if it did. If you read a bit on a theory of ground loops here...

https://en.wikipedia.org/wiki/...op_%28electricity%29

.... you will understand why I'm hesitant.

The funny thing about the ground loops is that only properly earthed (3 prong sockets etc) equipment, connected to the same, properly earthed socket stands a chance of avoiding ground loops. iRDAC is not earthed / grounded and this is where the tiny difference in voltages occurs, which you now hear as humming.

 

 

Posted on: 26 January 2016 by Hal

irDac looks like a floating design. Grounding wise these types could prove problematic using with a Nait. I remember that some years ago I connected a Marantz CDP (again a floating design)   to my venerable Nait 5i-2 via RCA and there was a bad buzz out of the speakers.  Bringing in a properly grounded MF M1Dac resolved the issue though.