It seems like people have been asking for more ported subwoofer boxes, so I decided to make up some easy to assemble models. They all go together pretty much the same exact way, so I took photos of the assembly process. This one happens to be the 15" model. I spent a lot of time making sure this design went together as easy as possible and pretty much fool proof which makes assembly very easy and fast. As with all my flat pack designs, there is no need for drilling holes or using screws to hold anything together. I use Titebond wood glue and an assortment of different clamp sizes. If you don't have enough clamps, believe it or not you could use some strong masking tape to hold the pieces together while the glue dries. Some people like to use a brad nailer to hold the pieces together so they can move to the next step quicker. I just wait about 30 minutes in between each step before removing the clamps and installing the next piece. It is very important to dry fit each piece in place and see how you're going to clamp it down, and where to put the wood glue. Any place that wood touches another panel should have glue. Instructions: Lay the bottom panel on your work bench as shown and glue in the long thin pieces making sure they are flush with the front of the bottom panel. These are the sides of the slot port. Next glue the top of the slot port on while making sure it is also flush with the front of the bottom panel: You have three smaller pieces of wood in your kit. They're used for the port extension that runs up the back wall inside the box. Glue these 3 parts together like this: Once dry, glue that port extension into place just behind the longer port section. This is a side view of how the angles should come together once the port extension is glued into place. Keep in mind the ones in the photo are held together with tape. You should have a nice 90 degree slot port now.
You are now ready to glue on the rear panel of the box. Make sure you put glue on the part of the port that touches the rear panel so that you don't get any air leaks. Your port is complete. If you're worried about any air leaks around your port, you can simply run a small bead of glue around all the angles, or use some type of caulking. Next glue in the inner brace that fits nicely inside the rabbet joints cut in the bottom panel. If any glue squishes out of the rabbet joint, you should probably wipe it off so it doesn't keep the side panels from sitting in place. Next you will want to glue on the inner front baffle the same way you just glued in the brace. Make sure everything is nice and flush on the front of your subwoofer when gluing the inner baffle in place. Your subwoofer is now starting to take shape.
Once the glue dries it's time to install one of the side panels. Make sure you put glue everywhere wood touches, including where the side panels tough the bracing. The side panel will be the exact height as all the other pieces you have glued on. You can now add your other side panel: Let all the wood glue dry and you're now ready for the top panel to be put on. Simply run a good bead of glue along all of the wood pieces you can see when looking at the top of your box. That includes the sides, brace, back, and inner front baffle. Go ahead and sit your top panel in place. It will try to slide around a little bit, but don't worry, you'll get it lined up just fine before the glue starts to dry. Having a friend help you with this step always makes things a little easier, but certainly not needed.
The web archive has all the photos here: http://web.archive.org/web/20160521...eads/ported-subwoofer-flat-pack-assembly.565/