SUBWOOFER horns are built underneath the floor in a cavity of 1 meter deep. Each horn is driven by 8 x 18" (47 cm) woofers. A total of 16 woofers.Each horn is 9.5 meters long and has a floor mouth area of 2.2 square meters and reproduce starting from 10 Hertz FULL POWER. The real mouth area IS NOT the one on the floor. The real mouth have to be considered together with the side vertical frontal panels. The total horn is calculated onto the listening point considering the side walls and the ceiling loadings. This reduces the floor mouth that is not in open air.The SUBWOOFER efficiency is 120dB/ 1 Watt/1 meter. So the need of external regulation to adapt to the remaining audio system. The total electrical capability of the 16 x 48 cm woofers is about 400 W peak power per woofer that means about 400 x 16 = 6400 W peak total (practically uselss). Each woofer features a 100 mm coil. The real maximum power fed to both subhorn measured with an oscilloscope at the highest musical peak was 6 watts per channel when a pair of tube amps were used to drive the 16 LAuras, while up to date the electric power can reach 60 watts per channel using the 4 x 50watts/ch BLU EYES amps. In this conditions, peak levels are much higher and undistorted than any live concert at all. Walls and ceiling seems to fall down, but fortunately don't. The sound pressure is concentrated at the listening point and stopped by a 2 meters high woolglass anechoic wall on the back of the listening position. We should remember that the total diaphragm surface of the woofers is 2.89 square meters (8.67 square feet) and with the drivers horn loaded (not direct radiating), distortion at 60 watts is practically negligible. If for instance the real maximum rated power (6400 watt) would be used the pressure level would reach 160 dB, but I wonder who could survive. Not even the house built in steel & concrete maybe would stand up.SUBWOOFER horns are built underneath the floor in a cavity of 1 meter deep. Each horn is driven by 8 x 18" (47 cm) woofers. A total of 16 woofers.Each horn is 9.5 meters long and has a floor mouth area of 2.2 square meters and reproduce starting from 10 Hertz FULL POWER. The real mouth area IS NOT the one on the floor. The real mouth have to be considered together with the side vertical frontal panels. The total horn is calculated onto the listening point considering the side walls and the ceiling loadings. This reduces the floor mouth that is not in open air.