The bass tube can also be mounted at the back provided the speaker is not directly beside the wall. The default settings of the controllers are as follows:
DSM 50 FFL: 11 o'clock position
DSM 25 FFL: 11 o'clock position
The crossover unit is mounted on the panel behind the bass port.

As shown in the drawing, the three upper chambers are loosely filled with damping material. The lowest chamber remains empty. It is easiest to roll or fold the mats before pushing them through the four openings between the stiffeners and thus prevent them from slipping later.