Purpose of Dome on Tweeter...


What is the purpose of the "Dome" on a dome tweeter? Will a dented or dimpled dome effect the sound dispersion coming from the tweeter? If not, why aren't they just pushed in at the factory? Better yet, if a dented dome doesn't effect the sound, it would seem as if it's a non important part in a tweeter so why not just build a tweeter without the dome at all?
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Speaking of domed woofers, has anyone else noticed how much the whizzer cone vibrates and buzzes? That's obviously due to higher frequencies that get in through the crossover filter. But has anyone tried to damp the woofer whizzer cone and prevent this rude distortion? I have. I used one of those little triple stacked discs Acoustic Disc thingies from Golden Sound. Surprisingly efficacious.
Addendum. I meant dust cap not whizzer cone. Oopsy daisy. It's the dust cap on woofers that buzzes and vibrates.