The molecular structure of metal changes a bit over time(hahaha, Bullcrap talk)
I don't know the exact term pero un ung ngyayari.
Its only true for cast cymbals. For sheet cymbals the sound stays consistent(the dirt and shin of the cymbals affect the sound, once you clean it babalik ung tunog)
Cast cymbals' sound changes through time.
Now ung "maganda na tunog". Its relative bro. depende sa definition mo ng "maganda"
As far a I'm concerned, Mas gumaganda ung tunog pag masmatagal. Sumasarap ung tunog, Parang wine. Or parang pagkakaibigan. LOL to the second one.
Hahaha. Hope this helps
Try Cleaning your cymbals giving them back their shinny finish. You'll hear a big sound difference, maybe thats the sound your after.