The venerable L20T is a popular system. Containing a 115H-1 driver, JBL has made 4 variants of this system as a 18Ti, 4406, L20T and L20T3. Others have created biased networks for this little system to rave reviews but always using the same cabinet volume.
The 115H-1 is a high Qts driver. In keeping with JBL's tradition of using High Qts drivers in ported boxes the final response of the system has a hump in the midbass region, just like the L100, Control 10, and other systems. I wanted to see what this driver could do in larger cabinet. I also wanted some newer looking thin towers for HT use and higher WAF.
Comparing the original design to an optimum we see greater bass extension with higher delay times for the driver. Going from 14 ms to 19ms is a shift but a proper LF cutoff filter would protect the driver from subsonics.