60 Hz Hum from Powered Sub

Are you using the low or high level inputs to the sub? If you're using the low, it's probably a bad cap in the subwoofer. You might just try the high level inputs if you have them. I know that cured the hum in my older Sunfire sub years ago. I replaced all big electrolytic caps and it still hummed, no matter what I did. This just might work? It would be a temporary cure until you either upgrade to a newer and better sub, or decide to send it in for repair. Good luck.

Power your sub from the mains plug which is also connected to your other devices. Basically, all the earth potentials of all the devices must be on the exact same potential. If there is even a few millivolts difference, you will get the dreaded hum. Every device must be on a STAR connection, meaning plug everything into the SAME mains outlet with the shortest possible power cables.

spacecadet65   said:

08-30-2021 9:13am

The hum is present whether there is an audio source connected or not.

Funny, I was using my sub's Line Input/LFE connection via RCA cable from my loop out right/left connections on my power amplifier and all was well.

Now using the high level speaker input connection with the amps plug adaptor off my speaker terminals and I get the 60Hz hum.

Need to mess around with it more, but why would the power amp to the LFE be fine, but not the high level speaker terminals (producing hum)?

Have not read all responses. So at the risk of repeating, the most common cause for a subwoofer hum is cheap cable or a cheap cable that eventually went bad. Poor shielding is the most common exact culprit on a cheap cable. Power cord is also a possible culprit. Solid copper 75 ohm Quad Shield RG6 terminated with a RCA plug is an inexpensive alternative to all the other types of subwoofer cables that are offered, sold or recommended as being the best. None of those offerings will be quad shielded. The solid copper coax RG6 cables are easily found and are probably the least expensive of all the options.