The cooling duct fittings were made long ago, and the ball has been in my court. As soon as I am able, I intend to take those fitting and make some measurements. Then we'll be able to use that information to know what size the orifices in the one way valve needs to be. For anyone that doesn't remember what I'm refering to, see the posts called "12π and 15π horn loudspeakers" and "Loudspeaker Venting and Cooling Techniques."

In the time that has passed, I've realized that I want to make a 10π version with two 10" drivers in addition to the (dual 12") 12π and the (dual 15") 15π. Each will use a pair of drivers configured push-pull to reduce distortion. I also plan to make versions with and without the cooling system. That will keep it simple for those that don't need the extra power. But first things first, I'm hoping to have a prototype built from my collection of parts by this summer.