Strange Hum from Right Pre Channel Only


My tube preamp has developed a peculiar hum problem only in the right channel, and it began only after I switched to XLR cables running from the preamp to the XLR inputs on my Krell FPB 300cx amp. I never had this problem when I used RCA’s from the pre into a RCA/XLR adaptor attached to the amp inputs.

Strangely, when I switch L/R channels for the XLR cables attached to the pre, the problem goes away, but now I have Left pre out to Right amp in, and Right pre out to Left amp in, not an optimal arrangement.

Please advise what could be causing this right channel hum and how I can remedy it, other than by reversing the channels on the pre end.

Thank you.

Neal
nglazer

Showing 1 response by steuspeed

Ground loop. Try using a two prong adapter on your power cables until you find it.