A subwoofer is a type of loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be generated by a woofer
. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX- certified systems
. Subwoofers are important for high-quality sound reproduction as they are capable of producing the low-frequency sounds that regular speakers and surround sound systems cannot
. They are commonly used in home theater systems, car stereo systems, and sound reinforcement systems in nightclubs and concert venues
. Subwoofers can be either active or passive. Active subwoofers are self- contained speakers and amplifiers, while passive subs need to be powered by an external amplifier or A/V receiver
