Recently I sold a 10" Eclipse 88000 (10" aluminum cone subwoofer from car-audio) to buy speakers and a cheaper subwoofer (elemental designs e10k) to go in a 0.5 cubic foot sealed box (recommended). After the initial week break-in period, I gave the sub various tests in test tones, techno/dance, and rock music and I was quite disappointed. It sounded ok (smooth bass, no "fart", deep sound) at low volumes but with gain it just bottomed out violently and "farted" with every sound. With no time, money, or alternative, I brought the e10k with me to school and placed it under my bed facing the wall, near a corner. I crossed it over a second time after the computer output, through a passive eq, before it got to the amp (crossed over at 80Hz) with I kept the gain slightly below 1/2 (partsexpress plate amp). But now when I play "get low" (by little john) or run a sweep from 0-120Hz, I get this low (and loud) rumble at 26Hz before the sub is even close to bottoming out. Is it from the acoustics of the room, causing a standing wave? It's a bigger room, but I also have 2 crossovers to cut out upper frequencies with slightly higher gain. The response isn't flat, but I would like to make it so.