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Audio I/O Connectors 261
connector provides an amplified signal that can power your
headphones or small bookshelf speakers. Most adapters can
provide up to four watts of power to drive your speakers. The
signals that the adapter sends through the line out connector
are not amplified. The line out connector generally provides
better sound reproduction because it relies on the external
amplifier built in to your stereo system or speakers, which is
typically more powerful than the small amplifier on the
audio adapter.
• Microphone or mono in connector—The mono in connector
is used to connect a microphone for recording your
voice or other sounds to disk. This microphone jack records
in mono, not in stereo, and is therefore not suitable for highquality
music recordings. Many audio adapter cards use
Automatic Gain Control (AGC) to improve recordings. This
feature adjusts the recording levels on-the-fly. A 600-ohm to
10KB-ohm dynamic or condenser microphone works best
with this jack. Some inexpensive audio adapters use the line
in connector instead of a separate microphone jack.
• Joystick connector—The joystick connector is a 15-pin,
D-shaped connector that can connect to any standard joystick
or game controller. Sometimes the joystick port can
accommodate two joysticks if you purchase an optional
Y-adapter.
• MIDI connector—Audio adapters typically use the same
joystick port as their MIDI connector. Two of the pins in the
connector are designed to carry signals to and from a MIDI
device, such as an electronic keyboard. In most cases, you
must purchase a separate MIDI connector from the audio
adapter manufacturer that plugs into the joystick port and
contains the two round, 5-pin DIN connectors used by MIDI
devices, plus a connector for a joystick. Because their signals
use separate pins, you can connect the joystick and a MIDI
device at the same time. You need this connector only if you
plan to connect your PC to external MIDI devices. You can
still play the MIDI files found on many Web sites by using
the audio adapter’s internal synthesizer.
• Internal pin-type connector—Most audio adapters have
an internal pin-type connector that you can use to plug an
internal CD-ROM drive directly into the adapter, using a
small, round cable. This connection enables you to channel
audio signals from the CD-ROM directly to the audio
adapter, so you can play the sound through the computer’s
speakers. This connector does not carry data from the CD-
ROM to the system bus; it only provides the CD-ROM drive
with direct audio access to the speakers. If your adapter lacks