Rig: Genz Benz Shuttle 6.2 on top of an Acme B2, series 2. All this perched on a wooden barstool so it's close to my ears. Bass: Tobias Growler 4, 1st gen. Problem: If I stand to the side of my rig with my bass strapped as usual, I suddenly get high pitched whine/feedback, rather loud. Bass is at cabinet height. It doesn't happen if I'm positioned between the bass and rig. Not string vibration related. This is a somewhat manageable problem (i.e. don't stand there) but it constricts my movement at times, and if it's without a stand I can't lean my bass against the cab during a break. I don't understand why it is happening to begin with. Ideas?