Apple Macintosh Performa 6400 Series - Manual (Page 51)

5 Turn on the computer.
Now you’re ready to hear full-range stereo sound coming from the speakers
and bass sound coming from the computer’s internal subwoofer.
To adjust the overall volume, use the sound control buttons on the front of
the computer or use the Monitors & Sound control panel, which uses
software inside your computer to adjust volume. (For more information, see
“Adjusting Volume and Sound” in the previous section, “Using Your
Computer’s Sound Features.”)
To adjust the subwoofer volume independently of the speaker volume, use the
subwoofer balance control (Ï) on the back of the computer. (The subwoofer
balance control works only when external speakers or a monitor with built-in
speakers is attached.)
For more information about using speakers attached to your computer, see
the “Sound” topic of Macintosh Guide, available in the Guide (h) menu.
Subwoofer balance control
51 Connecting Equipment and Expanding Your Computer