Hardware Reference
In-Depth Information
•
Coaxial PDIF (also called S/PDIF)
—The Sony/Philips Digital Interface receives di-
gitalaudiosignalsdirectlyfromcompatibledeviceswithoutconvertingthemtoanalog
format first. The SPDIF out interface might be built into the sound card using a dedic-
ated or multipurpose jack. Most motherboards include an SPDIF out jack on the rear
port cluster, whereas others, use a plug-in header cable to provide output.
Note
SPDIF interfaces are also referred to by some vendors as “Dolby Digital” interfaces. Coax
SPDIFconnectorsusecableswiththestandardRCAjackconnectorbutaredesignedtowork
specifically at an impedance of 75ohms—the same as composite video cables. Therefore,
you can use RCA-jack composite video cables with your SPDIF connectors. Although audio
cables are also equipped with RCA jacks, their impedance is different, making them a less
desirable choice.
•
Optical S/PDIF out
—This supports home theater and digital speaker systems with
opticalinputs.Typicallocation:rearofcardorexternaldevice.Motherboard-basedau-
dio solutions may include optical S/PDIF out on the port cluster (as in
Figure 13.2
)
or on a header cable that uses an expansion slot. Cards made for audio recording may
also include an optical or coax S/PDIF in connection.
Advanced Audio Features
Sound cards designed for audiophiles and sound producers typically have additional con-
nectors designed for their specialized needs, in addition to the standard connectors listed
in the previous section. These might include
•
Aux in
—Provides input for other sound sources, such as a TV tuner card.
•
MIDI in and MIDI out
—Older sound cards with game ports (a 15-pin female con-
nector) also supported MIDI in and MIDI out through adapters that plugged into the
game port. With current high-end sound cards, MIDI ports might be connected via
a proprietary breakout cable (see
Figure 13.3
) or a proprietary I/O port adapter that
might occupy a 5.25-inch drive bay or be placed on a tabletop.
Figure 13.3
The M-Audio Delta 1010LT card is designed to work with up to ten channels of analog audio
and can also work with MIDI and S/PDIF digital audio sources.
