800watt, 12' long 16" diameter Bass Cannon.

Step 4 Install the sub woofer.

As seen in the photo, the sub woofer faces downward. It can go either way around without too much issue..
I screwed the sub woofer securley onto the lower flange, added the second flange ontop then added the second length of sonotube.

I worried that the wind would possibly snap the tube out of the 1/4" grooves so re enforced the tubes with ply triangles made from scraps.

I used marine Sikaflex to glue the tube into the grooves, then screwed the ply rib triangles from inside the sonotube. I used more sikaflex to bead between all the support ribs. It ended extremely strong.

I did have to drill a hole through the lower flange to let the sub woofer cable pass through. This was an oversight. In future I'd run the cable to the sonotube wall and pass through to lugs on the outside.

Comments

[Omega13Shadow]

Does the orientation of the subwoofer have any effect on sound? Is it best to put it facing the shorter end or the longer end? 

[NastySpill]

No that wont have any effect. I had it facing down, but in hindsight it should have been facing up, that way I could have run the wiring right up the inside of the lower half of the tube.
The travel of the subwoofer is equal in each direction so you get equal sound in each direction.

[bigtreehouse]

What is all the cool stuff in the background of the pic? Looks like an aluminum bridge...

[NastySpill]

Yeah it is a bridge. Its my assembly workshop - just joking.. I worked for a general engineering company at the time I built it. Used the place afterhours to make it.