Probably start with modern neodymium magnet drivers and there’s a lot of chat about how 15” stuff is often better than 18”. What mains are you matching it to?
EVa5, 1000w 15" bass driver, 250w Tweeter. So there's no need for a sub in smaller venues but I do a few outdoor events so I'm always looking to raise the capacity.
Probably start with modern neodymium magnet drivers and there’s a lot of chat about how 15” stuff is often better than 18”. What mains are you matching it to?