Last night I tested my DIY Down Firing 54L DPL12 w/ 16oz of polyfill. The results were encouraging and frustrating. Parameters: Sine waves from 20-70 @ 5 Hz intervals until 40 Hz In corner of room with SPL meter @ 1 meter away Phase set to 0 Crossover set to ~90 Hz Sub Volume @ 40-50% Amp PE 250W Yamaha RX-V2300 set to -44 (Found 30 Hz started to bottom out at -40.5) Pioneer DV-440 for movie and test signals Results: dB Freq 95 20 104 25 102 30 102 35 111 40 112 50 103 60 103 70 DPL12 bottomed out at 30-35 Hz before any other frequency. A little strange since it played 20 Hz well. Played several tracks on Avia and calibrated the sub. I had to turn it down a little during the asteroid chase in Episode 2. The second sonic charge hits the 30-35 Hz range while breaking asteroids and sub was bottoming out. Conclusions: Probably should have tested this in the center of the room or outside to try to match the response curves. In addition, the strange shape and size of the room (as seen in attachment) makes me think the ported might give me a better response. However, for best results, I think a second sub might do a good job of pressurizing the room. Budget does not allow for this, however. Sub volume must be set at 25-30% for audio calibration. Receiver cannot exceed -30 without affecting sub performance. This is the Avia calibrated volume for my system. However, actual listening will not exceed -35. I may attempt to move sub to a different location, but this corner has always been the best location. What do you think? Should I expect more? Why would it bottom out at 30-35 Hz?