I'd love to see the NEHD measured.
Unusual construction for the LAT 250 driver. It looks like parallel dynamic units? Hard to see.
View attachment 95993
View attachment 95994
View attachment 95992
10x 2.5" or so diaphragms. It works like conventional H-frame or derived subwoofers with the motor on each end connecting half the membranes via connecting rods. The membranes operate in reverse direction but same polarity to squeeze the sound through the surrounding slits. This means vibration cancellation as well as higher output.
Heil had the Transar woofers way back, and BohZen has their similar version now. It seems Tymphany sunk a lot of change into that direction and they did not last long. Alpine used a 700 series LAT in an offering for the car awhile back too.