In EY, Ashkenazi pronunciation of the kamatz is more of an Oh or sound, not oi like a cholom. The patach is what has the Ah sound. It does not matter if it is for the name of a person or the place (EY).
The Sefardim have no significant difference in the pronunciation of the patach and the kamatz, both sound like an Ah.
In America, many people pronounce these vowels like Sefardim.