I am currently running a 12in. Memphis M1 in a 1cu ft sealed box being pushed by a kicker zx400.1 (true output 490 watts rms). It is firing towards the rear of the car. I have already set the gains using the tutorial (all crossovers off, 60hz -3db test tone . . .) The deck is an older premier deh p770mp.

When the LPF was set to 80hz on the head unit, the sub seems to run out of steam and just does not want to play loud or low. A single 10inch infinity ref powered by 300 watts was playing louder/lower and hit harder then my memphis. However, after tuning the cross over to approximately 60hz on the kicker amp, the sub plays lower and louder.

Could there be a problem with my sub/sub box design?

Also what is the typical crossover setting for a 12inch subwoofer?