It was a race against time, but I just made it. I'm hosting my annual office party today and completed -- except for finishing -- my Theater 4s yesterday. Heavy-duty break-in today!Features include all-MDF; biscuit and yellow glue joinery, no screws (love them biscuits!); two-layer (1 1/2") front baffle; two "window frame" (if that's the right term) internal supports, one immediately above and the other immediately below the woofer cutout. Although I've seen some complaints about the accuracy of the Jasper Jig, mine worked flawlessly, both for the recess around the driver and the driver cutout itself. Vent cutout is 4 1/2", with a piece of PVC obtained from Madisound (4" internal diameter)inserted, which also fits like a glove. (In this way I can experiment with port length.) I made the cutout for the tweeter horn with a jig saw.
Since I asked about screwing in the drivers earlier -- and thanks for all your advice -- I'll report what I did. Tee nuts just weren't grabbing me (pun intented). I used hex "knife-thread" inserts from McMaster-Carr, 10-24 for the tweeter (there's nothing like overkill), 1/4-20 for the woofer, then corresponding 10-24 machine screws and 1/4-20 hex-head bolts. Although the inserts have collars, they screw flush into the MDF. Seem solid as a rock.
The crossovers will be external. I've been experimenting making some nice box joints, and the crossovers will ultimately go in some to-be-constructed wooden boxes. For the moment, they'll flop on the floor.
After a line of storms went through late yesterday (knocking out the power shortly after glue-up was completed (!!) until about 3 am), we're scheduled to have beautiful weather today in NW NJ -- perfect for a pool party.
My only remaining question (other than how to barbecue for 60) is: How on Earth do I get these things out of the garage? They weigh a ton!
Wish me luck!
Bob