Calculate external dimensions, taking into consideration the limitation on height and width of a car boot.
Line out a MDF sheet according to the required proportions and begin to saw it with the help of a circular saw or a fret-saw. Do not forget, that the box shown on the photo, is double. Thus, you get parts for making a subwoofer box.
Then take the bottom part of your future box and put the front wall to it. Drill holes and screw two or three drywall screws, which are typically used for gypsum board fastening:
The same procedure must be done for the top cover. It is better to set the future box to the side:
After that, subtract MDF thickness from the bottom depth of the box and mark in the bottom the stripe, before which the material will be removed. Do the same on the top, only subtract the thickness from the top external dimension. Mark the bevel with the help of a pencil and a ruler, joining these points:
Join points on the internal surface of the cover in order to see before, which level one should work with a plane. Repeat the same for the bottom part of the future box.
It will be more interesting further. Take a power plane (or an ordinary plane if there is no a power one) and remove excesses of MDF basing on marks drawn previously. As soon as you finish, screw down the back wall:
Remove the extra projecting parts with the plane. Is it ready? Take the box, set it on the side on a sheet of MDF and draw the future sidewall with a pencil from inside. Draw the other side too. As this subwoofer box is intended for two heads, the middle wall would not be out of place for it:
Insert the sidewalls and the middle wall (if you have a box for two subwoofers) and attach them. The foundation is ready; it is time to make holes for drywall screws in order to connect walls of the subwoofer box. If they do not enter into depth of material, ream spaces for blinding of heads with the drill, the diameter of which is 8 mm. The craftsman from the example did not have to do that, because everything peeped into with a swing:
Here is an example of how drywall screws are started and liquid nails are applied to improve impermeability of the construction. As you see, the lower and the front walls are already glued together:
Remove the "nail" residues by pieces of carpet and continue to fasten sidewalls:
You have a little left to do: fasten the top and afterwards - the rear cover:
Do not forget to process edges in order to get them as in the photo. Create marking for subwoofers and cut holes for a phase inverter (inverters):
Uh-oh, let`s saw, but saw in large! Do the victory lap with the fret-saw and check correctness with the help of a loudspeaker:
Phase inverters. Saw from a plastic pipe, paint black from inside. . . And add rings on the top and at the bottom from the firm DLS. Attach also everything with the help of liquid nails:
Before covering process, process the box by a glaze disc for smoothing of sticking up parts and irregularities. Moreover, use a vacuum cleaner inside and outside it. Cut off the carpet with reserve by the sides so that it could be folded. Gluing:
It is worth handling carefully with sidewalls in order not to cover the carpet with the glue, which is already on its place:
Insert ends and cut the carpet "in wedges" in the place of fastening of subwoofers:
Glue the "wedges" of the carpet with a spray and fold them inside. And do not fear to dirty hands with "liquid nails" – they can be washed with the solvent 646. Anyway, the phase inverters must be glued inside to create the full hermetic state on connections:
The homemade subwoofer box (or even the one for two subwoofers) is ready. The amplifiers are attached to its rear side and the wires for subwoofers come through drilled (and afterwards "nail"-filled) holes:
Thus, the scheme of the subwoofer construction is shown. Have a Nice bass!