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

other than the normal ground loop problems due to bad cabling/mains/ground etc...

Yep other than the normal problems from using RCA.

Please understand that stray voltages ALWAYS exist but for the majority of cases the micro-currents are small enough so that they do not induce much audible hum as they circulate through your interconnects. The only proper solution is balanced - invented ages ago - but the desire by manufacturers to reduce cost means you often get RCA - even on expensive components.

I second Shadorne's comments.

So it sounds like you are saying that the 1.5 to 2.0 vac that you measured was between the circuit ground/chassis ground of each component and ac safety ground, WHILE THE COMPONENT WAS NOT CONNECTED TO ANY OTHER COMPONENT. Given that, what you were seeing was simply the voltage to which the component's circuit and chassis grounds (which are usually common) "float" in the absence of a direct connection to ac safety ground (such as via an interconnect to another component which in turn has a 3-prong power plug).

That level is typically determined by the happenstance of stray capacitances within the component between circuit ground/chassis ground and each of the two sides of the incoming ac line ("hot" and "neutral"). The most significant stray capacitances are usually in the power transformer. Sometimes intentionally present capacitors and/or stray resistance paths may also be significant.

A good quality ground isolator, such as those offered by Jensen Transformers, should solve the problem. Also see this paper at their site.

Regards,
-- Al

You have a ground loop problem between one or more units. Also if you have a separate line and breaker but use the same ground at the box, it is all still connected together. If you know this please forgive me but you must drive a new ground rod at least 8 feet away from the other ground or where the water pipe goes into the ground. This could be shorter or longer away depending on the soil; hard or soft - wet or dry, etc.! Back to the ground loop. Disconnect one unit at the time until the hum is gone. That is the one that has the difference of potential. Sometimes you can connect a wire between the two units, under chassis screws and solve the problem and sometimes you have to sell the problem and get something else. Ground loops are one of the hardest problems to fix. There is another way to fix or at least remove the noise but it takes a lot more electronic work. However, like said too already one of your rca's could have lost it's ground. With locking RCA's this happenings a lot more because the IC is pulled or heavy maybe and breaks the cheap little pin and hum! It does not matter if you are using that RCA's or not because the broken ground acts like a antenna for noise. Good luck!

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