so i hooked my fi ssd 18 up and it sounds good till i start bumping and then i hear a little whistling sound .... then if i turn it up louder i hear a rattling and idk if its the sub or if it is the car... im also freaking about if that whistling is from that little hole that i filled up from my previous forum... i had a little hole in the surround that i sealed with silicon... i havnt got my amp fully tuned right yet but i dont think that could cause any of this and what is the low pass filter and the subsonic filter