I encountered the same symptom in case of my front speaker. Now I have the solution.
These doesn't necessarily have to apply to your problem, however, it could be at least an indication.
"rattling of speaker", if the speaker itself removed from the door sounds ok, in general occurs if particular bit of nearby matter acts as a secondary source of sound transforming absorbed mechanical energy of sound emited by the speaker into distorted rattling sound.
Thus your primary task is to locate this source(s), while the secondary task is to eliminate them by mechanical adjustment.
Here goes the replication of my action:
- I completely removed inner plastic door panel (how? http://www.206gti.net/front_speakers.shtml - last paragraph)
- while playing bass sound causing the rattling I inspected area of polystirene layer covering the inner side of naked door by pressing on it with my fingers
- finally I issolated a small area (5x5 cm) pressing on which eliminated the rattling completely
- I glued appropriate block of polystirene on inner side of removed plastic door panel, so that it would act by continuous force on that resonating area after mounting back on the door.
Conclusion: Ratling was caused by the construction of the door that makes it inadequate as a speaker casing.
Hope it helps.
Peter Drienovský, May 2005
