From Mark Seaton:
"While there's been plenty of discussion of the Terraform XL product in Johnsteph10's thread, I thought with the production version of the Terraform XL out in the build area, it was time for a dedicated Terraform XL thread.
Note the version for Johnsteph10 was custom built to fit his specific installation, but is the identical internal volumes and tuning, having the same performance. I intend to attempt keeping 1-2 Terraform XL enclosures as shown below in house ready for loading, but it is possible to do custom versions where one dimension is traded for another for some additional cost. The monster you see here is 22.5" x 54" x 28" deep (yes, I look even shorter than usual here):
I am awaiting the new amplifiers to finish these up, but testing thus far has been quite impressive with just how clean and powerful the 11-20Hz output is, with plenty of thanks to the PR loaded bandpass design and 3" radius flares on those huge ports.
More to be added later.."
Also, Mark has mentioned the new custom amps are ready....and even better than originally planned! I'll check in with him or let him comment on these new amps...