To anyone interested, I repeated the out of phase/phase setting experiment using the on-line tone generator posted above and a Radio Shack SPL meter positioned approx. ear level at the listening position.
I ran measurements from 200 to 10 HZ for the Silverlines alone with volume at 200 Hz set to 80db. Observed values generally less than 70db for 50 Hz and lower (a slight bump to 70 & 74 db for 40 & 35 Hz, respectively). Decibel levels at 80 Hz were virtually identical (i.e., 82/83 db) for 0, 20, 80, 100, 120 & 140 Hz. At 160 degrees, a slight reduction to 80 db was observed. A value of 77 db was measured at 180 degrees. I did not find a huge null created by running the subs out of phase to the main speakers. I wonder if this has to do with the great disparity in speaker sizes (one 12" SB1000 driver vs four 3.5" mid/woofer drivers in the Preludes) or if it is due to "reinforcing" room effects. I did listen to quite a bit of music afterwards with connections properly matched between subs and mains and with the phase now at 180 degrees. Did not notice any of the negative effects previously reported with phase at 140 degrees. Possibly the ("sub") bass was a little better at 180 than at 0 degrees but it was very subtle if not a placebo effect.
I ran measurements from 200 to 10 HZ for the Silverlines alone with volume at 200 Hz set to 80db. Observed values generally less than 70db for 50 Hz and lower (a slight bump to 70 & 74 db for 40 & 35 Hz, respectively). Decibel levels at 80 Hz were virtually identical (i.e., 82/83 db) for 0, 20, 80, 100, 120 & 140 Hz. At 160 degrees, a slight reduction to 80 db was observed. A value of 77 db was measured at 180 degrees. I did not find a huge null created by running the subs out of phase to the main speakers. I wonder if this has to do with the great disparity in speaker sizes (one 12" SB1000 driver vs four 3.5" mid/woofer drivers in the Preludes) or if it is due to "reinforcing" room effects. I did listen to quite a bit of music afterwards with connections properly matched between subs and mains and with the phase now at 180 degrees. Did not notice any of the negative effects previously reported with phase at 140 degrees. Possibly the ("sub") bass was a little better at 180 than at 0 degrees but it was very subtle if not a placebo effect.