I just got a new speaker cab with a horn in it. When I play the low notes on my 5 string at moderate volumes a crackling sound comes from the horn. Im sure its the horn- when I turn the horn's attenuator all the way down I can't hear it. I don't think it is what people refer to as "farting" as this sound is more of a broken glass type of crackle. Its weird because it sounds fine when I play above low E. Did I get a bad horn?