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

Lifting the ground makes the amp hum more

This is a "Stereo" setup only - amp tuner, DVD(i.e. CD) and PHONO - no TV/AV components or connection to cable equipment.

Thanks for the info though - I'll tuck that away for future use

Thanks all for the feedback - just to clarify the situation

The house is 23 years old and the supply comes in from the street via a subterranean cable.

The breaker box is earthed to the water supply pipe - and I could not detect any grounding problems at the breaker box or anywhere else in the house - I have verified there are no spurious voltages between neutral and ground anywhere in the house (tested with a very good digital meter for resistance, continuity, AC and DC Voltage) - particularly at the outlets with appliance connected - BTW all appliances are new this year - so no old lunkers are causing problems.

I also tested the equipment with only the dedicated line to the hi-fi turned on - YES - I took all of the other breakers offline.

Each piece of equipment (has a two pin polarized plug) was tested without connecting it to the amp and found that Sony, Panasonic, Pioneer and Toshiba all had a 1.5-2.0v AC voltage between neutral of each phono socket (and also the chassis) and the ground of the outlet they were plugged into - I also verified that the outlet did not have any spurious voltage present before plugging in the equipment - However on testing the Cambridge Audio sources and the Luxman sources I found they did not produce any voltage between their phono neutral or chassis - so they work well with the amp.

I have spoken to NAIM tech support and they indicated that their design philosophy is somewhat different from that of the consumer electronics manufacturers and that difference results in a hum when used with them.

Their solution is to use a ground loop isolation device which are commonly available, between the amp and DVD player.

I would guess that other hi-fi oriented manufacturers adopt a different design philosophy that allows consumer electronics to be connected without a problem, because I have not found too much on this topic - other than the normal ground loop problems due to bad cabling/mains/ground etc...

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

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.

My use of the word Neutral does refer to the outer shell of the interconnect/phono socket

Using a multi-meter continuity tester and resistance settings I placed one probe on the outer shell of the amp and the other probe to the earth pin on the amp and there was no beeping from the continuity tester and the resistance setting showed a completely open circuit.

I asked NAIM about this and they confirmed this was how they designed the amp.

The ground on the amp is connected to the amp case/chassis for safety

They ground the neutral side of the signal in their systems at their source components

I did try "lifting the ground" on the amp and the hum got louder, but NAIM did not condone this practice and warned against it sighting safety.

Hifitime -

One thing I've done in the past is bond all...

Be careful about doing this - components are designed very differently e.g. NAIM and Luxman - this could cause other problems that may be damaging - although I've read this solution many times on several forums- NAIM warns against this approach.

Cheers