I've completed the lash up from 18mm chipboard, with 18mm MDF baffle. It will test the new crossover and sealed chamber, the chamber is somewhat smaller than the original ported box. I fully stuffed the chamber with fiber glass loft insulation and  mounted the crossover on the back for easy access and to duplicate what will happen on the final build. I made a wide baffle to match the width of the design proposed and give a good representation of what it will sound like.

The baffle is also the same width as my Yamaha NS-1000M. With the Yamaha's turned upside down and the lash up placed on top, the drivers are spaced similar to my proposal. I have each of the drivers in my active Yamaha's wired separately to its own set of binding posts, without an internal crossover, so the Yamaha's bass driver is borrowed here for the sound test.