Interesting points. What I am using is JBL 2225H in PiAligned cabinet. So Vb=47L and Fb=53Hz. The port is placed a diameter away from surrounding walls.

The cabinet is 9.5" deep - and I have two ports, 3" diameter each and 5.67" long each. So that means distance from back wall to back of port is 9.5-5.67 = 3.83". Does this sound like it is going to be a problem?

Is there any difference at all between using the ports found by the formulas in the PiAlign.doc paper, and the ports I've selected above? (which tune to same frequency). The formulas in the PiAlign paper for the ports, really did not make any sense to me - only the cabinet ones did, so I selected my own ports to use. But is there a difference such as Qd?

Thanks!
Adrian