Hey got a bit of a problem that i cant seem to fix, i got alpine type s 6.5 inch door speakers in my back and when ever the bass hits theres this really high pitched noise i have the door panel off and theres nothing vibrating or loose and i have no idea what it is it did it with the kenwood speakers i had in there to, the only way so far i was able to make it stop was by putting pressure on the outside door panel behind where the speaker is. its only that door to none of the other 3 doors have that problem