I've owned a few Bozak models over the years and wish I stilled had the Concerto VII's. They were manufactured in Connecticut and had the classic New England signature sound where the highs were more than adequate but not sizzling, like JBL, Altec, and Klipsch. Their last in house tweeter was the B-200Z which had a little more sparkle. What Bozak was known for was their excellent midrange drivers, some of the best in their day. The B-312 was a two way design but could be upgraded to a B-313 by adding their six inch midrange driver and X-over network...a much better sounding speaker.
Bozak 312s from 1968
My first hi-fi speakers were a pair of Bozak 312s purchased in 1968 (from Lee Kramer of High Fidelity SSS in Atlanta for a whopping $310). About 3 years later I upgraded to the B-4000 Symphony and packed up the 312s in their original boxes. There they've stayed all these years until this August (2020). Amazingly, they still work! And sound fine. I'm surprised at how much bass those 12" woofers put out. I'll likely put them up for sale soon here in the greater Knoxville, TN area.