Radio Hum


I just hooked up a pair of conrad-johnson Premier 8A monoblocks to a c-j PV-11 preamp, and I have a wicked hum, even a zero volume, in only the right channel, and it is picking up a radio station. I have changed and moved speaker wires and interconnects to no avail, though it does get better and worse with movement. It will not happen in the other channel. What am I missing? What else should I check? Is something wrong with my preamp, cables, power supply???

Thanks, Brian.
bkrpdx

Showing 2 responses by bkrpdx

Thanks for the response.

I have connected the right preamp output to the other monoblock (call it left), and the hum follows it. Connecting the left preamp output to the original monoblock (call it right) results in no hum. So it is not the amps.

I have switched the left and right speaker wires, and the hum remains in the speaker connected to the monoblock connected to the right channel. So not the speakers.

I have switched the interconnects with each other and with different one with no change. Not the interconnects.

I suspect though you may be correct on a ground problem in the preamp right output, and I am looking into that.
All the tubes have now been replaced, a solder ground repaired, and a blown cap replaced. On a reference system, the preamp is now silent. I bought a new, shielded power cord. My amps were just cleaned and serviced by c-j. The major right side hum is gone. But there is still hum, which is much softer, and is now volume-dependent. And I still hear the radio. Even when I unplug my tuner entirely and there are no other radios around. Any other ideas?