About Subwoofer Speakers

A subwoofer is a specialized speaker that produces sound with only low frequencies. It is an essential part of a complete sound system and includes other speakers with specific frequency ranges. This specialization in speaker design is from advances in sound technology.

Definition

The specific frequency range that subwoofers cover depends on their application. Most subwoofers for the general consumer have a frequency range between 20 and 200 Hz, which is at the lower limit of human hearing. Professional live sound systems use subwoofers that produce sounds below 100 Hz. THX systems such as those found in commercial theaters use subwoofers that produce sounds below 80 Hz.

Design

Subwoofers consist of an enclosure containing one or more speakers. The primary design consideration for the enclosure is that it must resist the high air pressure the speakers produce without being deformed. Additional design considerations include the efficiency, size and cost of the subwoofer. A passive subwoofer receives its power from an external amplifier, while an active subwoofer has its own amplifier.

History

The first commercial subwoofers were made in the 1960s for home sound systems. Some entered commercial theaters in the 1970s with the development of Sensurround systems. The film Earthquake was released in 1977 and was the first commercial film that used Sensurround. The development of compact discs in the 1980s provided the practical reproduction of deep bass, which made sound systems with subwoofers more desirable. DVDs often have a low-frequency effects channel that carries a sound track specifically designed for subwoofers.