Just toying with the Idea of a 6th order Series Tuned Bandpass cab using passive radiators for the front camber and ports tuning rear camber to front camber. So the resonator inside the box would be ports, and the outside resonator would PR's. I was going to model the 18Sound 21NLW9600C using three 18inch (will start modeling with TC Sound PR) passive radiator for the tuning of the Front camber.

My first question, In a 6th order Series tuned BP using ports the rear and front chamber ports combine to tune the cab to the lowest frequency. Anyone have any ideas wether changing the front Chamber ports to PR would effect this coupling of the two tuned resonators?

Any advise on design 6th order series tuned BP would be helpful, design and built a few 6th order BP's, but never series tuned 6th order BP's 

Anyone see any major problems in using Passive radiators in in this box? Would I have any problem tuning three 18 inch PR  in this type of enclosure?

Many thanks

Mark