Can you give us a little more. What are the components you are using, what sub, how connected, crossover frequency, listening level, calibration method?
Subwoofer
I noticed my subwoofer with my home theatre setup was not working. When plugged in, makes a distorted on and off sound. Replaced it with another sub and worked fine for about a month. Then it stopped working too. Has a bad distortion sound almost like its blown. Any ideas of what this could be. I hate to buy another sub if it has something to do with the home theater receiver I am using.