"johnelstad" wrote in message
ups.com...
He shoots, he scores! My amp has a three-prong plug, so I added a
two-prong adapter and the hum disappeared completely. I'm so relieved.
Thanks so much, James, for your quick and helpful response!

John

James Lehman wrote:
Does you power amp have a two prong plug? If so try adding a wire from
the
chassis to a real Earth ground. If your power amp has a three prong plug,
try it with one of those two prog adapters with no ground at all.

James. )

Do you own a fairly sensitive AC voltmeter? If so you might measure the AC
voltage on the common side of the preamp to the (now disconnected) ground
pin of the amplifier. If it's in the low millivolts region you can restore
the safety ground without restoring the hum by wiring a rectifier diode in
each direction between the 2 grounds. What this does is connect the 2
grounds for any voltage above 0.5v.

Norm