The APBX 8 R loaded enclosure was developed with reflex loading, with tuning designed to concentrate SPL in the lowest frequency range. The aim was to exploit the natural boost in output found in most cars below 60 Hz known as “cabin gain”. The 8-inch single 4 Ω voice-coil subwoofer has a powerful motor that maximizes efficiency in combination with the AP8.9 bit amplifier. The low-resonant frequency of the subwoofer, matched to the reflex enclosure keeps excursion low within the entire audio spectrum, allowing also the use with a pair of AP4.9 bit / AP4 D bridged channels, capable of delivering 260 W rms.