thump type noise coming out of my trunk

[Norco]

hiyas, ever since i bought my car, which came with 2 12 inch type r's and a alpine v12 amp, i hear a thump once in awhile from the trunk, found out its my subs but not sure what could be causin it, maybe a power surge? or something lose in my sub box, im still using factory deck with my subs, v12 amp has its own control display, so if anyone has any info would be greatly appreciated tghanks

[Big Joe]

Are there any bodies laying around back there? I know people tend to kick and stuff when there locked in a trunk and that could be ur thumping noise. :)

[mrjoecanadian]

I know subs thump when powered on or off, my friend has subs in his trunk and they also thump but the is when is mp3 changer is changing tracks, that is just dead air on the radio he just has an fm modulator with his changer.

[matts]

subwoofers do that. they really enhance the low notes (bass) and that "thump" is the bass. :P

a good setup shouldn't thump any time other than when it's supposed to. but some systems do it, could be your problem.

[Bjornboy81]

I think it's usually do to a bad ground (amp or signal) if it's doing it while the amp is already on.
Are you using a line to level converter? If not, use one, if you already have one, put an inline filter with it just before the amp. And make sure your amp ground is secured to bare metal. you might want to use a star washer between the frame and lug.

[airbornflght]

umm. i thoght that was the purpose of subs. to make a thump in the trunk. j/k.