Possibly the finest horn on the market today, these EV 9040's have a very long flat throat and excel in smooth dispersion of the critical high frequencies...
LaScala vs "XII" MWM midbass unit - The Klipsch Community
If you need to cross at 500Hz, I would suggest looking at the Electro-Voice HP horns. ... and one 9040. I had a bunch of the EV drivers at one time, still have one...