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Why is a 1.5-2 volt AC signal on my Neutral line?

I have several music sources e.g. DVD, Phono, DAC, Tuner etc...

I just purchased a NAIM integrated amp and I am experiencing a hum but only from the DVD player.

I have circuit tested the entire house wiring and all is well.

After a lot of investigation I found that some units have a 1.5-2.0 volt AC signal (sounds like a 60Hz signal i.e. hum) between the neutral side of the interconnect and the earth at the power bar.

Panasonic, Pioneer and Sony units I have measured all have this signal present and it varies between 1.5 - 2.0 volts

Luxman and Cambridge Audio gear does NOT have the signal present

All units have a polarized plug with no ground pin

How can the hum be eliminated using the Pioneer DVD with the NAIM Amp?

Thanks
williewonka
tvad
9,467 posts
 
I tried all the steps provided by several contributors above.

Only the Jensen RCA test adapters allowed me to identify the problem area. They cost $12.00/pair.

I reiterate my recommendation to buy them. It will save you time.
williewonka OP
1,826 posts
 
Hum Gone!

I bought a ground loop isolator by Behringer - it is exceptional since there is negligeable signal loss and the signal quality is maintained

I understand the Jensen product is also very good

Thanks for the input
williewonka OP
1,826 posts
 
UPDATE: turns out NAIM only ties the neutral side to the ground in their source components - not at the amp.

The Ground Loop isolator mentioned above eliminated the additional hum introduced by the Pioneer DVD player.

But when I connected the "Ground" screw on the Phono stage to the ground screw on the power conditioner an eerie silence came over the entire system

The manual for the phono stage does not indicate whether this is good or bad practice, but it works and I did not have to mess with grounding component chassis - just used the terminals available.

Anyhow - all is now quiet - just very pure music - I even removed the ground loop isolator.
shadorne's avatar
shadorne
7,333 posts
 
I am glad that we were able to pinpoint the problem as being due to a Ground Loop and help you solve it!
jea48
2,944 posts
 
UPDATE: turns out NAIM only ties the neutral side to the ground in their source components - not at the amp.
07-07-10: Williewonka

Williewonka,

?? Your use of the word neutral is confusing....
From reading your posts I believe you use the word neutral in reference to the outer shell of the RCA jack, the signal ground.

Are you saying on your NAIM amp the signal ground is not connected to the chassis? The chassis is only connected to the safety equipment ground?

On the rear panel of the amp is there a signal ground lift switch by chance?


Lifting the ground makes the amp hum more
06-25-10: Williewonka
That would make sense if the signal ground of the amp is not connected to the chassis.
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