I had two Alpine 10 inch subs and a 500 W Sony Xplod lying around. After several experiments and MANY questions on instructables.com and google I took apart my psu to clean it out and see if I could put the green (on) short to a switch (which I haven't cut a whole for yet). I then cut down all the leads and tied them together with some crimping connectors (for ease of experimenting). I connected the amp and put the two subs in series and used the stereo outputs (100 W @ 4 Ohms) to connect the speakers with one speaker out of phase (reversed polarity). I used a cardboard box about 22 inches long to create the tube by rolling it by hand to soften it up and then laying it down flat again, before actually rolling it around the speakers I took some small pieces of cardboard and taped them to the magnets to help align them while rolling the larger box around them. I taped the cardboard to the INNER piece of framing of the speaker, NOT just wrapped around the outside. This becomes important in the next step. I finished rolling the box then wrapped it in tape TIGHTLY at both ends with more tape, as close the metal as i could get it. I took some old speaker wire (cuz I couldn't find my twine ball) and ran it through each of the holes (where the bolts usually go) and tied it together at both ends. I wrapped some tape around the center to tighten these crossing cords, then I taped up any gaps I could manage.
It now goes BOOM!!
I will remake this in a clearer fashion upon rebuild.
Gonna remake once I find a taller box and I promise to put up more pics.