Nait 5 AV Connection blues

Posted by: SB on 06 July 2001

I Have recently required a Nait5 and while stunning in Stereo, I am having a nightmare of a problem integrating my AV system.

The problem occurs when I connect the pre-out of a Yamaha DSP-A592 into the AV Input into the Naim.

One switching to Any AV mode I get a significant 50 Hz hum across all speakers.

There was no hum with the A592 on its own. Note the Yamaha is a double insulated design with no direct earth connection.

My dealer is working with Naim to get this resolved, but I thought I would try the forum to see if anyone else has had similar issues.

Most recent suggestion which I have tried is to plug a DIN plug with an earth lead connected to centre PIN to ground the NAIT. This made no difference.

Any help would be appreciated

Posted on: 06 July 2001 by David Dever

...as these may be what's generating the hum, esp. cable TV or satellite inputs. You'll need to disconnect every item from the Yamaha AV receiver, reattaching each input/output individually.

Dave Dever, NANA

Posted on: 06 July 2001 by SB

I systematically went through this.

Even with no connections at all, no video leads, no aerial connections, etc.

I still get the hum.

Posted on: 06 July 2001 by Mike Hanson

If you're sure that it's not your video sources causing the problem, then you might want to try putting a transformer in-line with your signal between the Yamaha and Nait5. There's a bunch of info regarding these issues in the following thread:

http://forums.naim-audio.com/eve/forums?q=Y&a=tpc&s=67019385&f=48019385&m=9711992322

-=> Mike Hanson <=-

Posted on: 06 July 2001 by David Dever

- The NAIT 5 signal ground does not connect to AC mains ground nor to the chassis itself.

- Other Yamaha power supply designs (those without a three-prong IEC mains cable) use a capacitor network to space the chassis ground at equal potential from the incoming AC signal on the primary side of the transformer (depending on the item in question, this may or may not connect to the signal ground). If chassis and audio ground meet, you may try connecting the chassis ground directly to mains ground (most Yamaha AV receivers still have a ground tag).

Funny, my DX7 synthesizer had this same problem until I re-built (simplified) the power supply last month (these had captive two-prong AC mains cables).

Dave Dever, NANA

Posted on: 06 July 2001 by Ron The Mon

Ess Bee,
You don't say in which country you reside but I remember doing an installation in which the neutral and hot connections of one of the outlets of the hi-fi were reversed and had the problem you mention. Have you tried something as simple as checking all outlets with a polarity and ground tester? Or even swapping power cable connections or outlets? Do you use a power strip which could be faulty?

HTH,
Ron The Mon

Posted on: 08 July 2001 by SB

Thanks for the input.
I am based in the UK. I didn't think of reversing Live & Neutral on the power plug. I will try it when I get home. I am currently on business in the US and have managed to obtain the Radio Shack Isolator mentioned above. I now have two options to play with. I will update on progress next week.

Posted on: 09 July 2001 by Arthur Bye

This might be more information than you want, but try this site for diagnosing ground loops.

"http://www.epanorama.net/documents/groundloop/index.html"

Arthur Bye