Harmon kardon system subwoofers are active while nothing is playing and making a rattle. Video:https://youtu.be/dvDC9sg0RAs Couldn't find anything simmalar like this so had to ask what could it be. I have tried changing the sub-amp and the sub if that was the problem but it still remains, next could be the bigger amp but don't want to get a new one, if there is way of testing the problem. I have basic Harman kardon amp with business cd.

  • Do they work correctly when music is playing?
    – HandyHowie
    Aug 28, 2022 at 6:46

1 Answer 1


Clearly there is some sort of problem causing that. But it's not in the speakers themselves but in the amplification path.

  1. Check the INPUT to the amplifier driving the speaker. Is that signal there? Yes, then the problem is NOT in the amplifier. Is the signal clean at that point? Then check the power supply to the amplifier and it's that's OK then you have a bad amplifier. (It sounds like you swapped this amp out but you didn't mention that you checked its power supply.)

  2. If the errant signal is on the input then it's coming from the next thing up the line. It's your car's audio system or some other box that is in the path that is generating this noise signal. Find it, fix or replace it.

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