I bought a Tempest several years back along with a PE 250 W plate amp (the one with the remote) with the intentions of building a great new sub. Didn't get to it until this weekend. Used WinISD and built a vented box that is close to 13.5 cu ft after driver and ports. I tuned it to around 18hz with 4" diameter 13.5" length flared ports. I tried it out last night and it did not seem to have near the punch I thought it would. I played Toy Story 2 several times and it doesn't sound great or give any real punch. I have a huge volume room because it is vaulted to the second story and open everywhere. The sub was sitting out in the middle on it's side, driver facing me. I know it will give some more impact in a corner, but I wanted to fire it up and make sure it worked before putting it there. I get a terrible noise that sounds distorted when I hit it with with TS2 where Buzz blows up all the robots in the beginning. I'm pretty sure that I have leads or speaker wire slapping the driver also. I'll find a way to get those out of the way. It may sound a little better when I stuff the ports, but not a lot. I play my old 4.4 cu ft blaupunkt based sub I built a long time ago tuned to about 27 and it rattles the house. I really expected more out of it. WinISD says it should be flat to about 17 Hz, but I included some numbers measuring it vented, stuffed, and the old sub. Used RS digital SPL meter C weighted about 3 foot from the drivers facing them. I used the NCH tone generator program to drive the subs. It looks like it should be loud, but it doesn't seem even half as loud as the old sub even though it measures higher. I did change volume between tests, but not during. Freq vented sealed old 60 110 113 109 56.6 109 112 107 53.4 110 111 107 50.4 112 112 107 47.6 111 113 107 44.5 110 112 105 42.4 109 110 102 40.0 108 109 100 37.8 109 108 100 35.6 106 107 103 33.7 107 107 104 31.8 105 105 102 30.0 104 104 101 28.3 105 105 104 26.7 105 104 102 25.2 104 103 102 23.8 102 101 99 22.4 100 98 97 21.2 97 96 94 20.0 95 93 91 18.9 92 90 86 17.8 90 86 82 16.8 87 84 78 Any ideas? Does the sub need some break in time? Is the through the roof group delay killing me? I know fixing the leads to get rid of the slapping sound and putting it into a corner will help, but I measured the little on a couple feet from the walls too. Thanks, Dennis_H BTW, should I ask this on a different forum since the DIY section here seems to have died?