I have an SVS 20-39PC sub which I have owned for about 2-3 months. I get a vibration or buzzing sound from the sub at certain bass frequencies. It is very apparent in certain movies such as Last of the Mohicans, The Phantom Menace, and others with significant base. It is not a constant sound and only comes at some mid to low frequency. I can reduce it by lowering the volume, but that kind of defeats the purpose of having a good sub. I tried reversing the polarity and running the power to a separate circuit in the house based on other buzzing threads that I read. That didn't help. I also don't get a constant humm which it sounded like others were getting. My sub volume was calibrated with Video Essentials to about 4 dB above the rest of the speakers. Has anybody else experienced this problem or have any recommendations to solve it? Let me know if I need to provide more information.