mains question- please help.

[godzilla1]

I just went to plug my goldring dr 150 headphones into a beresford tc 7510 dac. I accidentally touched the tip (pinnacle) of the 3.5mm headphone jack against the top of the dac. A crackling noise can be heard through the phones when I do this. The dac was switched off at the time. I also tried the same thing with my rotel ra 04 amp. Again the amp was switched off. But again, the same cracking noise could be heard through the phones. I did try touching the jack against the PC (on) but there was dead silence. In sum, the rotel & beresford seem to be noisy.

Why?

I use an mk double gang unswitched socket and tacima mains filter / surge protector.

Thank you.

[Mark.Yudkin]

I thought plugs in the UK were three-prong so that they can't be reversed and that basically all equipment needed earthing?

If any of the equipment has a plug that can be inserted either way, reverse all those that have a single gang power switch on the neutral side. You can tell this from the exhibition of the symptoms you described.

Otherwise I would suggest that you check that the live / neutral wires in the wall socket are correct. With earth on the top, live is on the right and neutral on the left.

[Alun]

It could just be a build up of static earthing itself through the amp, but you also need to bear in mind that headphones operate at a very, very low voltage compared to the mains, so any kind of leakage or induction would probably be enough to make the cones move.