hi, i just replaced my rear speakers and one is unclear compared to the other.
i checked all the wiring to and from this speaker and its all fine.
I cut off the factory harness and hooked the black and white car wires to female connectors and then hooking those up to the prongs.
I have the black wire to the negative terminal (black speaker wire) and the white wire to the positive termianl (red speaker wire). I tried switching and the sound was even more distorted. Thanks

 

if possible try switching the two rear speakers. this will let you know if the problem is the speaker, maybe faulty or blown, or if it is the wiring. or just use another speaker that you know works fine.