Subwoofer cable causing interference between left speaker and FM? source

[Wabi]

So this is kind of strange:

Regardless of what input my receiver is on, when i plug in my sub-woofer cable (sub doesnt need to be connected), music plays from my left speaker. It sounds like an FM channel of some sort. Depending on how I move the sub cable, the channel gets more or less clear (as if it's acting as an antenna).

I've tried:
- Swapping L and R speakers, and it's always from the L output.
- Unplugged the other end of the sub cable, so that it's not even connected to anything, still the same issue
- Connecting the sub cable to a different port to see if it replicates, apparently it only happens when i plug the cable into the sub out.
- Moving the cables around so nothing is tangled with power, each other, etc.

How do would I resolve this, and why is it even happening in the first place?

Thanks!

 

[jsmithepa]

I assume this is a powered sub, if so you should have a shielded RCA cable, and make sure that shield is properly grounded on both ends, and perhaps the cable length is at the perfect resonance frequency, so get a longer one, coil it if necessary.

 

[Wabi]

I assume this is a powered sub, if so you should have a shielded RCA cable, and make sure that shield is properly grounded on both ends, and perhaps the cable length is at the perfect resonance frequency, so get a longer one, coil it if necessary.

I am still getting this even when the cable isn't plugged into the sub. Also, just checked, this cable is apparently "dual-shielded".

 

[jsmithepa]

If a shielding is not grounded, it becomes an antenna.

 

[americanaudiophile]

http://audiosystemsgroup.com/SAC0305Ferrites.pdf