box/enclosure , vent/port ?

6th order " series-offset "hybrid - bass reflex is probably V E R Y L O U D.

https://www.youtube.com/watch?v=CZaRQT3Rvaw

https://www.youtube.com/watch?v=jN-E1dfMfO0

https://www.youtube.com/watch?v=HIg5knLNRNo

Maybe a fun project ^^^^^^^^^^