Originally Posted by Manfish

Hello

That sounds a bit different. As I understand the internal sub and external sub are not conected except for the air space they share.

So a sealed sub box (2nd order) and a ported sub box (4th order) if you put the sealed box inside the ported box it becomes a bandpass 6th order(maybe).

The subs would not work as a direct pair as in an isobaric design, they would work as two competing systems acting on each other. Is the idea of the internal sub to improve linnerarity or extra db.

I keep thinking of this design and feel that internal box needs to be ported into the next box to make a quasi bandpass 8th order.

If you have two internal subs matched with the external ones and have two out of phase you should get some huge air movment (twice-ish X-max) But how you calculate this box and port size I don't know.

No i can't figure it out i'm going to have to build one. unless you're giving it a go you can let us know.