Wow, I havn't visited my own thread for a while since I've gone skiing vacation. Thanks everyone for the great posts. My friend also pointed out to me that two or stereo subs works much better than a single sub. The current issue of HiFi+ has a great article of this that my friend showed me.
My large room is about 1,500 square feet of space that has to be filled. Beyond the listening poisition there are three adjoing rooms that makes up the total space in a cross like shape.
To smooth out the room modes, I will go with two subs positioned behind the main speakers against the front wall. I've got into a pilot program with a subwoofer manufacturer who will actually provide me with two subwoofers that are sealed 15 inch paper cone drivers with some kind of loading, factory provided Rane dsp processor and 3 day rental of professional test equipment that the factory will dial into the test equipment remotely and set up my system. This ought to be interesting.
I did listen to the JL Audio Fathom F113 at local dealer Atlantic Audio who carries Dynaudio Evidence Temptation, Masters, and JL Audio Fathom F113 along with SIM Audio electronics in their main showroom. It was only one F113 subwoofer in the showroom. It was being crossed at 40hz to augment the main speakers. I played around listening to Temptations and Masters comparing the sound both with and without F113. First of all, since the room was smaller than my listening space both of these speakers did darn well in the low frequency range and there really wasn't any need for subwoofer augmentation with F113 subs especially with Master model that has 4 each 10 inch drivers per speaker. What little difference it made with Evidence Temptation seemed insignificant. I did try just listening to the subwoofer output as I have done with other subwoofers and played around with different crossover points and gain of the front panel. F113 seemed to sound pretty quick in its prodigious bass output and from my memory it might be a little better than Velodyne DD15 bass. Still F113 didn't bowl me over with its integration with Temptations and it didn't sound like the coherent bass sound of the Master model. I think digital subwoofer and room correction with Rane, Tact, or DEQX could have made this integration much better.
So, I'm waiting for delivery and trial of these new subwoofer designs which should come in 3 more weeks.