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Speaker Systems Overview :
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There was a time when "good PC speakers" was something of
a contradiction in terms. But companies like Cambridge SoundWorks,
Klipsch, and Polk Audio have dramatically improved the sonic scene. |
The arrival of multichannel sound cards, which support
four-, five-, six-, seven-, and now eight-channel output, created a
market for multichannel speaker systems. In the late 1990s, the driving
application for multichannel audio was the 3-D positional audio in
games. This ushered in a new type of sound design for games, which
improved players' abilities to interact with imaginary worlds. Noise
from a character positioned behind you and to your left would actually
come from the left rear speaker, for example.
Initially, most multichannel setups consisted of
controlling electronics and five speakers in what were called 4.1 (four
dot one) systems—four speakers positioned with one left/right pair in
front of you and the other behind, and a separate floor unit, commonly
referred to as a subwoofer (although in most cases, bass speaker
is a more accurate term), for low-frequency sounds. The floor unit is
the 1 in 4.1. The arrival of DVD-ROM drives and the DVD format's support
of Dolby Digital audio brought 5.1 sound cards and speaker systems to
the PC. The fifth speaker sits on top or in front of your PC monitor and
provides an outlet for Dolby Digital's all-important center-front
channel information, which contains nearly all film dialogue. A sixth
speaker—either a dedicated bass speaker or subwoofer—is the dot-one.
When playing Dolby Digital content (movies, usually), this sixth speaker
is the output for the Low Frequency Effects (LFE) channel and delivers
rumble effects.
Although you'll hear the bass speaker that comes with
many PC speaker sets called a subwoofer, it usually isn't. It reproduces
low frequencies, but a real subwoofer is specially designed to handle
signals of from roughly 10 to 50 Hz—very low frequencies that are below
what typical home audio speakers can properly reproduce. Home systems
use subwoofers to beef up low-end response. Crossover circuitry
sends signals that are below a certain frequency to the bass speaker or
subwoofer, whichever you have. The crossover frequency depends on your
speaker system, and some systems let you adjust this value.
The arrival of THX certification brought another level
of sophistication to the PC speaker world. Star Wars creator
George Lucas founded the company THX to test film playback equipment.
The goal was to insure that audiences would get the optimal
entertainment experience possible. The company extended its testing to
home theater equipment and now even tests PC speakers. Several makers,
including Altec Lansing, Cambridge SoundWorks, Klipsch, and Logitech,
have speakers that carry the THX seal of approval.
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