Have you seen my midhorn? It is designed for Delta 10 drivers. It's made for indoors use though, so if you're going to use them outdoors, you might want to look at some horns I did for use in freespace. Check the links below.By the way, I don't know if you remember, but I've always used conical horns. I prefer their directional characteristics, so I've always used them instead of other shapes.