Preparing to Calibrate Your System's Audio
Once you have your system's video display looking picture-perfect, you can turn your attention to the sound. Audio calibration is a matter of configuring your audio/video receiver or preamplifier for the type and position of your speakers, and then adjusting the system's overall frequency response to match the particular acoustic characteristics of your listening room.
First things first. Most A/V receivers and preamps have some sort of setup menu, displayed either on a front-panel display or on your TV's display. You use this menu to configure up your receiver/preamp for your specific speaker system.
You start by telling your receiver/preamp what size speakers you're using. This setting determines the specific crossover frequency below which low bass signals are sent to your subwoofer. If you select "small" speakers, the crossover will be set to a higher frequency, so that more of the low audio signal is handled by the subwoofer. If you select "large" speakers, the crossover is set to a lower frequency, so that more of the bass reproduction is handled by your main speakers (which presumably have larger woofers designed for better bass). For most bookshelf and satellite speakers, use the "small" setting; for most larger floor-standing speakers, use the "large" setting.
Next, you have to tell your receiver/preamp how far away from the main listening position each of the speakers is, which helps to adjust the relative volume of each speaker. For example, if you're 10 feet away from the front-left speaker but 12 feet away from the front-right speaker, the volume needs to be boosted slightly for that more-distant front-right channel.
That's about it for the automatic settings. What comes next involves using some audio test signals—and your ears.