"Dave Plowman (News)" wrote:

Serge Auckland wrote:
Maybe I have lead a sheltered life since I moved to the country.... :-)
My experience is otherwise, that decent equipment doesn't hum or pick
up RF if half-decent screened cable is used. I do accept that I've had
some trouble with SOME switched-mode powered equipment which was cured
by the use of an isolating transformer. I assumed that was an isolated
example.

Indeed. I've got a pretty big installation here with some stuff in one
part of the room - TV, PVR, satellite receiver - and the main audio stuff
at another. All interconnected unbalanced. It's also linked to sound and
vision in the kitchen so I can have the same thing playing etc while
wandering between the two. And no problems whatsoever with hum. It would
be a poor piece of design which has high levels of nasties on an audio
ground.

Try measuring one. Cable screen to mains earth either on AC voltage or low
current. It may surprise you. Mind you, if it's ALL Class II equipment the
return path to ground doesn't exist so you may get away with it.

Graham


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