I've read over the plans and several of the posts, and am confused  as to which  is right.  The plans say to model the closed section on a regular 4th order single reflex cab (vented), and some of the posts say to use the 4th order Bandpass formula for calculating the area of the sealed section.  Which S factor for the bandpass is being used for the calculation? I don't remember which post it was (should have written it down), but it says something to the order of use the OPTIMUM 4th order bandpass, which would be the S factor of 7.  Thanks to anyone who can clear this up for me.

Thanks!!!!!! That's what I wanted to know.  I'll just follow the recommendation in the plans as well as yours.  Now for some sawdust.

uhh..

1st order = no volumes, OB/IB
2nd order = one volume, sealed
3rd order = one volume, vented or BR or PR
4th order = two volumes, sealed back, vented front
5th order = two volumes, sealed back, sealed front (dunno why one would build it, but its on the list)
6th order = two volumes, vented front, vented back
7th order = 3 volumes sharing 2 drivers with 2 ported
8th order = 3 volumes sharing 2 drivers with 3 ported
9th order = same idea as 5th order
10th order = depends on who you talk to, some call it series loading, BOSE calls it thiers, others call it a waste of time, usually some arrangement of volumes within volumes and lotsa ports etc. very good at making loud BP style bass (peaked)

so you model the WO on a BP4 alignment, aiming for a perfect Q of .707 to balance extension and power handling.

Just goes to show you that there is Order in the universe

gex