N-Vi + NAIT 5i-2 50/60hz Buzz on AV input

This sounds like a hum caused by a 'ground loop', the audio path has two earth connections when both the Nait and the N-VI are on. It is quite common for this to happen when using Unity Gain and connecting to a home cinema system which has multiple earth points ( AVR, Cable box, TV etc) though It is unusual for it to be a result of connecting two Naim boxes together.

If you are using your setup as a way to wach TV and DVD etc you may actually be getting the hum from your cable or satellite box. Try leaving the Nait and the N-Vi connected and remove the cable box connection to your TV etc. If the buzz goes away that's where the ground loop is actually being generated.

It is possible to buy ( not expensive and found at sites like Amazon or Maplins etc) a 'ground isolator' which you can attach in the audio signal path either in the path from the cable box or in the path from the N-Vi to the Nait. Do a search on Google.

G

Thanks G,

I solved one problem to find another.  Today I systematically removed all sources including the cable TV and to my surprise, the source of the noise on the UNITY gain was the NAIM CD3.5!

Even when I turned the power off to the CD3.5 with the rear switch, I it created a ground loop.  The only way to remove the noise was pulling the plug on the main or disconnecting the DIN.

Why would the CD3.5 put so much noise on the ground?

Naim uses a 'star' earth concept in it's systems so that all the individual internal audio earths end up going to one final audio earth point. I am not sure what Naim's exact audio earthing strategy was in the days of the CD3.5 but with the likes of the CDX2 and CDS3 etc the CD player is the preferential location of the final earth with continuity to it provided via the interbox DIN/RCA leads.

For this reason I am surprised the hum goes away when you disconnect the CD3.5. I woud have thought the opposite would occur and hum would increase on disconnection.

Time to send Naim an e-mail perchance ( if Richard Dane doesn't see this thread).

Richard Dane has picked up on this quite quickly.  Amazing response time really.  Appreciate all the help.

Roberto

What did Richard say?

G

We are still debugging, however I'm leaning towards ground loop isolator. Kind of weird since problem is between 3 Naim components. 

In my case, my CD5x "added" hum to my system, when connected to AV components.  In fact, it simply exposed a grounding problem elsewhere.  Dealer suggested disconnecting Cable TV where it enters my home.  That killed the hum.  Cable TV were very responsive and sent a tech out to improve the grounding at no charge, which helped a lot, but I still ended up needing isolators between the AV and Naim systems to achieve silence.  A low-cost happy ending.

Good luck,

Nick

I have no Naim audio sources at all, just an optically connected Mini, but still had ground loop issues with Bluray/DVD/Cablebox connected to my SN. Ground loop isolators fixed it completely. Like a new system. 

Yes, but it is multiple earths that are the issue. The CD3.5 should be the only earth.