So I bought a GK MB500 head and an Ampeg 810 cabinet, and I noticed on the low B when I play really hard on it it it kinda has a little bit of a farting noise but I don't know how to describe it really... its easier heard on high volumes, but I can also replicate it on each string, but its easier on the B string. I just have to pluck the other strings harder to make the noise, could the problem be that the strings are too close to my pickups? Or is it the 810 can't handle the low end of the B? I know the low end isn't supposed to be great on the 810... but I figured it'd at least handle it. What do you guys think the problem is?