I bought this head recently. It's used and I would say it's one of the older amps. I'm getting a ground type noise when the fan isn't running. When it's running, no problem. Two questions... First are the fans suppose to run constantly and if so, does anyone know who I can contact to get I would believe a new fan? I got it fairly cheap knowing the ground and fan issue. Other than that, it seems to be fine. Thanks.. GOD bless!