Since it is tough for small-sized loudspeakers to reproduce frequencies under 40 Hz, and really tough for under 100 dB, people often choose to use a loudspeaker just for this purpose. Hence the subwoofer, a kind of loudspeaker that reproduces bass frequencies ranging most generally from roughly 20 Hz to around 200 Hz. DO you need one? Depends upon how well you want to hear deep bass, if your music or audio is reproduced under 40 Hz.
Subwoofer drivers, known as woofers, average between 8″ and 15″, and can run 34″ even. And drivers begin at 4″ those under 8″ generally don?t reproduce lower frequencies with good quality and usually have higher distortion.
Use high-powered amps with subwoofers and an electronic crossover with a low-pass filter. There are two types of subwoofers; those with an amp in the subwoofer cabinet (active), and those without the amplifier (passive). Typically active subwoofers will be clearer and stronger.
With regards to the use of subwoofers in home theater systems, they come mounted in a sealed enclosure. Some people like to focus attention of their systems around satellite speakers, hiding their subwoofer; hence it may be packaged within the system. Others build the subwoofer into the theater cabinet.
Why the separation? To keep them out of site, for one thing. Plus for sensitivity issues dealing with the areas? sound compatibility and mode. Some people prefer to place the subwoofer near the listener.
Bottom line is, if you want to be able to hear low frequencies, you need a subwoofer. If you don?t care, don?t? worry about it then.
When will this come into play? Lower frequencies are needed with older sound formats, like with vinyl records replaced with digital formats, like CDs, mainly with 5.1 formats Dolby Digital and DTS (where the “.1” channel is for the bass frequencies, for the subwoofer), common choice of mixed artists.