Passive Subwoofer Enclosure

Passive subs are called passive because they need to be powered by an external amplifier or Audio/Video (A/V) receiver . This is similar to traditional speakers. The important thing to remember about a passive sub is that since the sub needs more power to reproduce low frequency sounds, the amplifier or A/V receiver needs to be able to send enough power to sustain bass effects reproduced by the sub without draining the power supply in the A/V receiver or amplifier.