"My question is at what point do you think that the extra extension of a port box outweighs the increase efficiency of a horn box for outdoors"
One of my commercial horns I designed has a cutoff of 27Hz, another of my commercial designs that is a double 18" reflex that has a cutoff of 36Hz. The horn design is only slightly larger than the reflex, so where is the extra extension from the reflex?
The reverse can also be true. You could design a horn with a cutoff of 80Hz and a reflex cab with a 25Hz cutoff. But the 80Hz horn would be 4 times smaller than the reflex. Having a port doesn't automatically mean lower extension. You will be stupid to do it, but you could tune a port to 500Hz if you wanted too.
Size for size, and if you can use enough, I'll take the horn loaded cab everyday. This includes scoops as they are a horn too. Why, because the output is radiated from a much larger area at low frequencies. Its like comparing a massive 2 meter diameter pipe carrying water to a small hose pipe. Yeah the hose pipe if pointed at you will sting a bit, but stand at the end of the 2 meter pipe and if you live, you going to get a big medical bill.
A port can be over 60 times small than the surface area of most bass horns mouths, and yeah, people might say you can move as much air in the port as it will have higher velocity, but that's like saying a 50cc moped can out run a 1000cc bike because its piston is moving faster. There's no replacement for displacement when it comes to shoveling air. There is a another saying you will hear a lot on astronomy forums, aperture is king.
Rog.
