Hardware Reference
In-Depth Information
support.
The jacks shown in
Figure 13.2
are usually labeled, but when you're setting up a computer on or
under a desk, the labels on the back of the PC can be difficult to see. One of the most common reasons
a PC fails to produce sound is that the speakers are plugged into the wrong socket. To avoid this
problem, most consumer-oriented audio cards color-code the jacks according to specifications found
in the PC 99 Design Guide. The color-coding can vary on some audio adapters (or not be present at
all).
A second method used on systems with motherboard-based audio is universal audio jack sensing, a
feature of the AC'97 version 2.3 audio standard and also supported by most motherboards using HD
Audio. When a device is plugged into an audio jack, the audio driver pops up a dialog box asking the
type of audio device in use, such as microphone, stereo speakers, stereo headphones, and so on. The
audio driver dynamically assigns the jack to support the device plugged in, even if the “wrong”
device is being used in a jack according to the color-coding. This feature is sometimes referred to as
auto-sensing
.
Tip
To avoid confusing the jack-sensing feature, plug in each device to the audio jacks separately,
and be sure to confirm the device type in the configuration program before continuing.
Regardless, the basic set of connections included on most audio cards and onboard audio include the
following:
•
Stereo line out or audio out connector (lime green)
—The line out connector sends sound
signals from the audio adapter to a stereo device outside the computer. You can hook up the
cables from the line out connector to stereo speakers, a headphone set, or your stereo system.
Some systems use the same lime-green color for surround audio jacks as for the
stereo/headphone jack. Check additional markings on the jacks or your system documentation
for help.
•
Stereo line in or audio in connector (light blue)
—With the line in connector, you can record
or mix sound signals from an external source, such as a stereo system camcorder, to the
computer's hard disk. In place of a dedicated line in jack, some sound cards use a multipurpose
jack (Creative calls it a “FlexiJack”) to support line in, microphone in, and optical out. See the
audio card or motherboard documentation for details.
•
Rear out and subwoofer/center or speaker connectors (no standard color)
—Virtually all
modern sound cards and desktop systems with integrated audio include jacks that support rear,
center, and subwoofer output for use in 5.1 and greater surround audio systems. Systems that
support 5.1 audio use three jacks: one for front (stereo) audio, one for rear audio, and one for
center/subwoofer audio. Systems that support 6.1 or 7.1 audio might feature additional jacks or
might reassign rear and center/subwoofer jacks with software to provide additional output.
Depending on your software driver, you might need to run a setup program provided with your
sound card or motherboard to enable surround audio. Alternatively, selecting the surround
audio setup you use through your OS's speaker configuration utility might be sufficient.
Note
