Hoping some resident audio experts can help me with a thorny 60Hz hum problem. I just bought a new Cary SLP-05 Pre-amp and balanced cables from my DS to the SLP-05 and from the SLP-05 to my BHK-250. The Cary has a cinema by-pass. In by-pass mode, I get a very loud 60HZ hum. Obviously tried disconnecting the by-pass cinema inputs. Hum goes away. Okay that’s a step. Odd because I use the device below to isolate the home theater input:
If I just plug in the RDL Hum Killer, with no home theater input to the RDL Hum Killer, the 60Hz hum comes back!! Taking the Hum Killer out and plugging the home theater directly into the the SLP-05 by-pass: the hum comes back. Basically anything with some kind of load plugged into the home theater by-pass causes a 60Hz hum only when using balanced cables. Going back to unbalanced, the hum goes away.
Couple other pieces of info:
Using unbalanced cables, I have to pull the ground pin on the BHK 250 to eliminate 60Hz hum in standard 2 channel mode. With the balanced cables, I can re-insert the ground pin and don't experience the 60Hz hum in standard 2 channel mode.
I also have a Music Hall 2 channel integrated that I use to drive outside deck speakers. I connect the input of the Music Hall to the Tape Out of the SLP-05 using unbalanced cables. With the balanced cables from DS to SLP-05 to BHK connected, when I turn out the Music Hall, I get a big thump that initiates the protection circuit in the BHK. With unbalanced cables connected from the DS to SLP-05 to BHK, the thump can barely be heard.
The Cary SLP-05 uses a pair of tubes as a balanced input buffer. I tried swapping the balanced input buffer tubes to eliminate the 60Hz hum to no avail.
I tried all the obvious things like disconnecting the cable TV connection, unplugging items on the home theater side one at a time. Unplugging the Music Hall integrated (both power and interconnects).
I have all the 2 channel equipment plugged into a P10. I tried the home theater plugged into the P10 and not. I also tried sine wave only on the P10. No solution.
I’m back in the music business with the unbalanced connectors but not happy about the investment I made in balanced interconnects. I can probably get them re-terminated as unbalanced but it does defeat one major reason for buying the SLP-05.
Hope I made the problem clear and thanks for slogging through it and attempting to help!!
P.S. Some pictures to help explain the situation.