my kicker L5 15'' subs make a like whisle noise when they play low notes?? help?

[uros b]

you cant hear it from inside the car but when i pop the trunk to go look at them, i hear it...only on low notes, the box is tuned to 38 hertz alont wiht the subs and the amp is a kicker zx1500.1
they cant be blown because thas just enough power fo those subs 750 rms to each sub

 

[patrick g]

check your ground wire,

make sure its not mounted on metal thst may have paint on it.

the paint could drain some sound