Sifu i still unable to solve this problem.I already swap my amp,Hu,Rca n power cable but the sound is still there 
u swap wif other amp and the noise still there? if tats the case myb the speaker or crossover like wat craziechild mention earlier...
hve u tried taking out the speaker from the door and direct connect to amp (play active)? noise coming out from all speakers or just ur tweet?or only 1 speaker?
I've experienced this b4 and the prob was the RCA was loose.or myb the connector at ur speaker (the one tat the cables soldered wif at the speaker) touched ur car body.if this happens the amp is either switched off or u can hear noise like u listning to radio tat dont hve good signals.