Noise (60 Hz hum) coming out of right speaker - Fixed but maybe coming back

[easypete]

2 days ago, I was working in the kitchen and had my 2-channel (MLO system #400) playing some background music. Not too loud... maybe about 80 dBA. After a few songs, I started to get a loud 60 Hz hum out of the right CLS panel. The sound did not come from the Kinergetic, just the panel. With no music playing, the hum was about in the 50-60 dBA range. If I turn off the system, the sound goes away.

I fixed it by switching the left and right interconnects (AQ King Cobra XLR) between the crossover and the amp. (See diagnostics below for more details how I got there). After a couple hours of listening last night, I think the sound may be coming back. I hear a hum about 30-40 dBA @ 60 Hz.

This is a schematic of my system:



Diagnostics

Turn system off --> No hum
System on --> hum
Unplug input to dbx crossover --> hum
Unplug output from dbx crossover to Ayre amp --> no hum
Unplug power to dbx crossover with all wires hooked up --> hum
Unplug power to crossover and unplug output from dbx crossover to amp --> no hum
Swap L/R input to Ayre amp --> no hum
L/R input to Ayre back to original --> hum
Swap L/R input to Ayre amp --> no hum
Keep input to Ayre swapped, swap output from dbx crossover to Amp --> no hum

So basically, by switching the L/R interconnects from the crossover to the amp, I was able to get rid of the hum. With system on, but nothing playing, there was no hum. After 2 hours of listening to music, I heard a faint hum again.

I have my thoughts, but would like to know if others have thoughts.

Thanks,

Erik

 

[MrBT]

Audio signal does not like losing ground. When it happens the result usually is loud hum, just like you are describing. I would trace ground from source, take close look at interconnects/XLR sockets and make sure that pin#1 has no ground interruption.

 

[JonFo]

Hi Erik, did you get this corrected?

Sounds like a problem in the XLR connectors / cable ends as MrBT noted.