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4 Watt Subwoofer Amplifier
The use of a subwoofer augments the bass
capability of the main speakers, and allows them to be smaller without
sacrificing low frequency capability. A subwoofer does not necessarily
provide superior bass performance in comparison to large conventional
loudspeakers on ordinary music recordings due to the typical lack of very
low frequency content on such sources. However, there are recordings with
substantial low frequency content that most conventional loudspeakers are
ill-equipped to handle without the help of a subwoofer, especially at high
playback levels, such as music for pipe organs with 32' bass pipes (16 Hz)
and some recordings with extremely low synth bass parts.
Low frequencies are not easily localized; hence many stereo and multi
channel audio systems feature only one subwoofer channel and a single
subwoofer can be placed off-center without affecting the perceived sound
stage, since the sound produced is difficult to localize. The intention in a
system with a subwoofer is often to use small main ("satellite") speakers
(of which there are two for stereo and five or more for surround sound or
movie tracks) and to hide the subwoofer elsewhere (e.g. behind furniture or
under a table), or to augment an existing speaker to save it from having to
handle woofer-destroying low frequencies at high levels.
Some users add a subwoofer because high levels of low bass are desired, as
in the case of house music enthusiasts. Thus, subwoofers may be part of a
package that includes satellite speakers, may be purchased separately, or
may be built into the same cabinet as a conventional speaker system. For
instance, some floor standing tower speakers include a subwoofer driver in
the lower portion of the same cabinet. Physical separation of subwoofer and
"satellite" speakers not only allows placement in an inconspicuous location,
but since sub-bass frequencies are particularly sensitive to room location
(due to room resonances and reverberation 'modes'), the best position for
the subwoofer is not likely to be where the "satellite" speakers are
located.
Figure 1. Simple Subwoofer Amplifier Circuit.
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