This is one of those that just simply won't happen. I've been over and over the schematic, but there is no way to do it on stripboard. The active DI by itself would occupy most of the 1590BB..
The documents for complete PCB project is here:
https://sites.google.com/site/plexilandia/tech12bassdriver.rarI would still strongly recommend getting a behringer. The sound is more or less 1:1 with Tech21 and the price is less than the parts for the project.
+m
fyaelectronics.com