so i have a 12" audiobahn sub with legacy amp. pretty ghetto but for some reason the sub just bumps when the music is off and such. like i would ahve to either turn it up to kind of stop the bumping or if i don't have hte music at a certain level it would jsut bump by it self. help please?

 

try this:
turn the car/radio on but mute the volume. now wiggle or bump the rca's to see if you get the same "bumping" sound through your sub. if so then you need to re-route the rca's or simply replace them if they are bad.

if its not your rca's, then check your amp's ground. needs to be to bear metal and should be tight against the chassis (unable to move around by pulling on it).

so having issues? at this point I would place my bet on legacy. They have a known reputation for noise issues with their amps.

 

I vote for the ground.

 

by "bump" do you mean a constant, low pitched tone?

if so, it's probably oscillation, and usually means bad ground, or bad amp.

 

use to have the same prob. if you don't have a cap, then reground the in a different place and make sure you sand it very very well, and shorten the ground if possible. also regrounding the battery helps

 

its not the ground.. because if it was the ground.. your amp wouldnt turn on.. im not 100% sure what it is.. but i know its not the ground

 

a bad ground can cause bumps/pops when the amp is off.

double-check all your connections.

 

Agreed.

 

Wrong. A bad ground can/will cause exactly what he's describing. Not having a ground at all will cause the amp not the power up.