The subwoofer shall be a tuned, ported enclosure with acoustic bandpass filter design. The enclosure shall be compact and suitable for flush-mount installation in a space 14.17" x 18.9" (360 x 480 mm) and occupy a maximum depth of 4.1" (103 mm) including board thickness. The  loudspeaker component shall have a diameter of 8" (20 cm) with ferrite magnet, rubber surround and a nominal impedance of 8 ohms. The rated power handling from 40 to 200 Hz (-10 dB) shall be 240 W Continuous Program and 80 W Continuous Pink Noise. The frequency response shall be 45 - 200 Hz (-10 dB, 1/2 space). The output sound pressure level shall be 91 dB SPL (half-space) at a distance of one m with one W of input power applied. The subwoofer enclosure shall be steel plate with a black paint finish. The grille frame shall be constructed of fire-resistant ABS resin with a white, paint-ready finish. The mounting bracket shall be of heavy duty steel construction. The input connector shall be a removable terminal block with screw terminals allowing two pairs of speaker wire for input and loop-through terminations. An optional low pass filter module shall be available for system equalization. An optional matching transformer shall be available for connecting the subwoofer to a distributed speaker system. The transformer shall mount inside the subwoofer enclosure with selectable Wattage taps of 60 W, 30 W, 15 W and 7.5 W at 70.7 V line and 60 W, 30 W and 15 W at 100 V line. Dimensions (W x H x D) shall be 16.93” x 21.42” x 5.32” (430 x 544 x 135 mm) and the weight shall be 24.25 lbs. (11 kg).

The subwoofer shall be TOA model HB-1.
The matching transformer shall be TOA model MT-S0601.