I just purchased an Ampeg B4R. I have it installed in a 4 space rack (it is 3 space) with a Rack tuner. The fan comes on as soon as I power on the amp. It never shuts off, and after a little while of running it makes some "clanging" noises. I know I probably will not hear this at gig levels, but at low volumes this seems like it will be annoying. Is this normal? I know the 4 space rack may sound small, but the rack tuner isn't deep so the ventilation should not be a problem. I am thinking of returning, but I have fallen in love with the amp, and if this is normal I will try to work through, if not it needs to go back. Let me know. This thing sounds like a small engine plane.