Possessed Alpine sub

Hi all,

Very annoyed as a friend last night decided it would be a good idea to play about with the amp (which is not mine) powering my sub.

From what I saw, he touched one of the bridged channels, 1+2, whilst music was on, with a screw driver and my Alpine sub went, 'bump'. Thinking nothing of it, I let the music carry on for a minute or less. I did not notice the sub seems to be possessed until I had the music OFF. All volume on ZERO, treble ZERO, gain/distortion ZERO, however when the bass is turned up on the amp, then sub starts to pump. It's just a 'thud, thud, thud', a lot like a hearbeat.

God damn I don't know what is wrong, if I run the sub of one channel it doesn't do it as violently and the only way it will work is if I turn the bass down and up quickly. Both channels do it, but its obviously violent when bridged.

The thing is, it's not even my amp!

Anybody had any similar problems or have any idea for a fix without spending pennies? I have disconnected and rewired EVERYTHING I could possibly do in the dark last night.

The only thing I could blame it on is the earthing points on the amp, or head unit?!

Please oh so mighty Fiat friends, help me!

You need to check that the amp is the problem - any chance you can wire it up to another sub? Otherwise I think you might have shorted something, which might mean a trashed amp.