Construction of T20 has now begun.
I've paid extra attention to the area where the drivers are mounted. There are two main issues with a sub. One is dealing with vibration from the drivers, the other is dealing with acoustic pressure. The area where drivers are mounted are given extra attention because that is where mechanical vibration is transmitted. Dual opposed design reduces this a great deal. You can't see it here, but the driver baffles sit into a groove in the end to firmly hold them in place. At this point they are attached with polyurethane glue which is very strong. Dual baffles and as much bracing as possible.
Drivers will be installed via external hatches.
Progress has been slower than with F20 and the bass bins because a little more care has been taken over certain details, some of them now shown. Driver cut outs were cut all the way through with the router.
This is intended for a permanent installation under the floor. If I'm happy with the result then it will stay for quite some time.