Ok I just got my fi bl 18 and we have it hooked up to a hifonics bxi1606 and it is ran by a pioneer deh 5900, but anyway it worked good when i first got it 2 days ago, then it started making a weird noise and stopped working. Then after we took the whole thing apart and couldn't find the problem we put it back together and it magically started working again. Then today it stopped again. We took the whole thing apart and the amp still works and the sub isnt blown, and it isn't the auxiliary. Idk we've been messing with it for like 4 hours and the only thing i could think of is that a door speaker is messing up or the rem wire is messing up.

Any help much appreciated, Mikey

make sure all speaker wire connections to the sub are TIGHT.

Make sure the power\ground\remote line from point A and B and secured tightly.

Make sure you have the sub wired to an ohm load not lower than 0.7

make sure your voltage is not dipping super low.

I would definitely make sure you have a good ground. I had a problem that sounded kinda like that, and it turned out that it was my ground.

Well i took your advice shizzon. And it ended up being that my power wire that goes to the battery from the amp wasn"t tight at all so i tightened that and now it works perfectly.