Jazzeren

Hi guys Well, this is maybe a bit weird thread, but I really need some ecperiences/advices. I just bought the GK MBE 212 lightweight cab. ( for small/medium gigs). I got it with parcelservice from thomann, Germany. The problem is, when the horn is on it buzzes and is very noisy. is this normal? BUT...without horn it sounds good, and there is no problem. My question is: Do you guys use the horn a lot? Never thought about it ( maybe because my old Mesa Boogie 400+ cabs, did'nt have a switch - they were just ON). If i send it back to Thomann it will probably tske weeks to get fixed - and I can't wait that long. What are your experiences?