One of my LDS cabs has a horn (Selenium) that's buzzing when the dial is turned to add 'high range'. Don (@LDS) suggested replacing the diaphragm, which I did. The sound persists. Meanwhile when the horn is zeroed out, the speakers are bassy, solid and punchy. Awaiting another reply from Don but thought I'd throw to you guys for any thoughts you may have. Replacing the whole horn is about $30.00. But, what if it's an electronic gizmo issue rather than mechanical? There's a whole mini-circuit board in there which the crossover runs through. That stuff baffles me. Thoughts?