Home Theater/home theater systems
what is the purpose of the center channel speaker in a home theater. i have sound coming thru the front speakers but nothing from center or the back two speakers. do i have a bad center on a 2 mos old system?
The center channel speaker is meant to reproduce dialog and other "on-screen" effects, and work in conjunction with the main/front speakers to create a more convincing sound-stage for effects. However functionality requires the material being played back to have been mixed in 5.1, and the 5.1 signal to be sent into the A/V receiver (or whatever device is providing equivalent functionality in your system). The majority of broadcast television is stereo (2.0), as-is the majority of music; so reproduction via just the main/front speakers is appropriate.
Similarly, the rear (or "surround") speakers are designed to fill a similar role in reproducing effects from 5.1 soundtracks.
Depending upon your A/V equipment, you may simply need to engage a 5.1 decode/output mode, or you may need to change settings to enable the center/surround speakers, or you may not be providing a surround sound signal and the system is (properly) providing a stereo output based on the media being played back.
I would need more context to provide an opinion regarding a defective speaker, or troubleshooting tips to pursue that avenue.