Constant Rumbling Noise from Subwoofer

[connordelaney]

Ive just installed an active sub to my stock radio using a line out converter. However after wiring it up there's a constant loud rumbling from the subwoofer but it still works fine when music is on loud. Any one know what can cause this? All connections have been checked and they're fine. The noise goes away when I unplug the RCA leads. I'm hoping it's a bad ground on the amp but if it was wouldn't it still make the noise when RCA leads are removed?

Cheers

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[YukonXL04]

What vehicle? Does it have active noise cancellation?

 

[connordelaney]

What vehicle? Does it have active noise cancellation?

Ford Fiesta MK7 and I'm not sure 

 

[winkychevelle 10+ year member]

Old pioneer radios used to do this if you unplugged the radio rca while the radio had power

If the line out converter has a ground wire, ground it there. You can also take a short wire from your amp ground and touch it to the outside barrel of the rca or the rca ground. That should get rid of any noise but is not the best solution.

Which hi/low convertor did you use? Cheap ones often fail