He is using a passive crossover. When we built the speakers we divided the networks into two separate boards. They are tied together only with the strap on the dual set of speaker binding posts. With the straps removed you can bi-amp the speakers and still maintain the crossover points. Not the best crossover approach, but the least expensive. At the point in time that we built the Linus Array, the Active EQ's from Barrenger and others were controversial and expensive. We also built them kinda in a hurry for competition in the Southeastern United States DIY speaker building competition...They did win First Place in Atlanta, beating even the Linus Array pair entered by the designer, Dr. Griffith....we did a few things differently on our pairs than the Dr.'s plans called for....used really nice film and foil bypass caps, flush mounted the planar tweeters, and had actually broken the speakers in by playing the dog$#!^ out of them..The surrounds were more flexible. I do think it upset the Dr. that we beat his own Linus Array with our build...
Compared to the Altec VOTT A-7 they are not nearly as efficient however. They Altecs have to be about 100 db + while I think the line arrays are still high at about 96 db..