popping and crackling sounds

[sammytheman]

Hey fellas I don't know what is going on. My logitech speakers are messed up. 1st off, I have to play around with the base volume on the center channel to get any bass whatsoever. The place where you have the power button, volume, M3D, etc buttons. 2nd if I change the sound volume from the "Center Channel" or whatever its called, I hear this loud popping and crackling sounds. Sometimes its like a lightning storm. I don't know what model my speakers are but I bought them is 2003. They are Z-series, I believe. I looked up logitech but they only show the latest models on their site. Any help would be greatly appreciated. Thanks.

Oh I found the model:

Logitech Z560 THX Certified 4.1 Speaker System - Hot Hardware: HotHardware.com