By a combined method of calculations and trial and error, I've found an excellent position for my subwoofer resulting in a +/- 4.5 decibels in one of the smallest HT rooms on the forum. Dimensions 10'x11'x8 feet. With the help of a few acoustic panels, an SPL meter, and my graph worksheet it was very easy to come up with what phase, crossover, level, position did to actual room response. Feel free to visit my site for a full page of graphs as well as my updated room mode and graphing worksheet (Microsoft Excel needed). BTW, I'm not affiliated with any pop ups or banners. There you will find that there are 3 graphs to a chart so you can easily compare what each adjustment did to the response. You can also see how I made the acoustic panels. (Later I'm gonna take the panels out and see if it changes the response.) Some interesting statistics/tips: 1. To reduce a peak or null, try moving the subwoofer away from the wall (axial mode) causing it. 2. When I added a 2nd identical subwoofer to the adjacent corner it produced an extra 5-6 decibels over using a single sub in the left corner or right corner. Also, Phase needed adjustment so the subs don't cancel out any bass the mains play. 3. My crossover adjustment barely altered frequencies below 40hz and above 200hz, while significantly altering frequencies between 60-140hz. So basically, if your problems are with deep bass, then don't touch the crossover. 4. Moving the subwoofer around in the corner (equal distance to each wall) is wasting your time as the difference is small. However, moving a subwoofer along an adjacent wall starting from the corner can make a significant difference. Just to think, a few weeks ago with my single tempest and no panels I had a response that was +/- 7 decibels and the bass was rather boomy with certain notes. The setup: DIY GR-Research AV3 set to small powered by Rotel DIY Dual Tempest Adire alignments (Pyramid) 214L tuned to 15.4hz (Response goes down to 16hz at 100db) each powered by 250W Parts Express Plate amps. DIY 4" thick acoustic panels with a 7" fiberglass + 1" polyester layer suspended in air by wires with 6" spacing between panel and drywall.