I have an Avatar B210 Delta and it has recently started buzzing when I play. It's a low pitched, distorted buzz that starts when I play a note and ends when I stop. The tweeter on the cab is off, and if I turn it up, the buzz just increases in pitch. It's almost like a very distorted sub-octave, but the sub-octave on my amp (Ashdown MAG300) is definitely off. Also, this buzz is very apparent in very low volume situations - as in playing in my room alone - in addition to slightly louder situations. Does anyone have any ideas as to how I can fix this problem?