Quote Originally Posted by edgewound
Ahhh....I think I follow you now. The 2 outside chambers are internally ported into the center chamber which in turn, is ported to the front baffle. This would create a primary load at 60hz on the two drivers, but I'm curious how that interacts with the secondary loading at 34Hz. I believe KEF and Mirage both use different size ports in their systems, but that is with a common chamber. Interesting.

Looks like here is the link you used (thanks, Google):

http://www.diysubwoofers.org/prt/dual_chamber.htm
I didn't use the link, I used the noted book, but yeah, that's the concept alright. When I figured tuning, I used both ports (into the center box and to the outside) in calculation of the resonant freq. I think they are only considering the outside ports so it would be lower doing it the way in the link.

My volumes are 4 cu ft, 2 cu feet, and the ports are 4" diameter and 9.5" long