Thanks padgettohio, you really try to help me and I really appreciate it. I wrote to ampeg several times and they answer me each time with something else to verify, excellent suport! But now they will refer me to a service center near of me, so I'll let a pro check it. Like that I'll know if I'm just crazy or something. Maybe it is the amp, maybe it is is placement, maybe it is my eq, maybe it is me doing something wrong? We'll see. Like you say, if anyone have an idea of what is causing me this "problem" tell me. 
Thanks
Thanks
