Appreciate hearing from you, CM!To the best of my knowledge, Paiste pioneered the crimped bottom (Sound Edge) in the 1960s. Bonham played Paiste 15" Sound Edge hats. Zildjian refers to them as Mastersound hats. I have Zildjian Mastersounds and love them. They give a stronger chick sound and never suffer from airlock.
Until Paradiddle Pete, made mention of his sound edge hats from the 60's, I was oblivious of the fact that sound edge design existed that far back.
Would have been sometime around the mid to later part of the 70's, I came across a picture of a set of sound-edge hats and remember thinking, never would I buy a set of those, what ugly looking hats, and why in the dickens would they ruin a perfectly good set of hats by crimping the bottom cymbal edge.