I've got a couple of Optimus condensor mics (each powered by a AA battery) and a low end Peavy mixer. If I go from the mics to the mixer to the 1/8" microphone in plug on my camcorder, I get a high-pitched hum in the background.

If I connect the exact same set-up to my computer or to the RCA input jacks on an 8mm VCR, the recording sounds just fine.

My nephew just got some sort of a mini-disk recorder, and he borrowed my stuff to record a friend's garage band. When he connects the mixer to the disk recorder he gets a high pitched hum. I believe he is going from the mixer into a 1/8" microphone in plug.

Is there something we can do to eliminate the hum?

Thanks!
Rob Fish