Altec Lansing's VS4121 two-speaker/one subwoofer system is designed for computer audio. It features built-in controls for bass and treble, a headphone jack and shielded satellites for use near video monitors. Problems with the speakers can include no sound from one or more speakers, crackling sounds, distorted sound, hums and problems with distortion on video monitors nearby. Troubleshooting can be accomplished in a few steps.
Turn the power on if there's no sound coming from one or more speakers. The power is supplied through the subwoofer, so make sure it's plugged into an electrical socket.
Increase the volume by turning the volume knob clockwise if there's limited sound coming from the speakers. Check the volume level on your sound card, too. Click on the audio icon on your screen's taskbar and raise the slider to about the three-quarter level. Uncheck "Mute."
Verify that all the connections are tight and that there's no visible sign of damage to the cables if you experience crackling. Eliminate problems with your audio source by unplugging the lime green input cable from the source and plugging in a set of headphones. Listen for crackling.
Try a different audio source if you continue to experience sound problems like crackling or humming. Try a professionally produced CD to eliminate bad home-grown audio files.
Move the Altec Lansing VS4121 subwoofer away from video monitors if you experience distortion on the monitor. Unlike the satellites, the subwoofer isn't shielded, so keep it a couple of feet away from the monitor.