What would cause a rear door speaker to buzz at low volume but work perfectly fine at higher volumes ? This happens to only one of the speakers. I have eliminated the possibility of this being a resonant buzz within the door. And the problem exists with cd, tape and radio so I think the head unit is not the problem. I just don't see how a speaker could be defective only at low volume levels. Any ideas ?

 

Rubbing, off-center voicecoil. Probably needs replacement.

 

yep