Just got the amp, got it installed. In the manual it says the H/P Crossover is marked 20hz 33hz etc. up to 150hz. The L/P crossover is marked 30hz.......250hz Mine AIN'T. It has 20hz and 150hz with nothin' in between. How the hell do ya' set it for the box tuned freq. if there is no scale??? Am I that stupid or have I missed something???