@rauliruegas I never said that! From the second I first fired them up I knew Sub model 3 was deficient, but I did learn a lot from building them. Sometimes you have to know what does not work to know what might work. Sub model 4 was inspired by Magico's Q subs, except I took it several steps further.
The most efficient location for subwoofers is in a corner followed by up against a wall, 6 to 9 dB more efficient. The problem with these locations is you can not integrate the subs properly with strictly analog equipment. It requires digital bass management. You are putting the subs where they sound best. I am putting the subs where they work best then making them sound even better.
My subs are not transmission lines. They are a balanced force, acoustic suspension (sealed) design with resonance free (and I mean totally resonance free) enclosures. The walls are 1 7/16" thick. The 10 sides are only 4" wide and they are arranged in a cylinder, an inherently very stiff structure. They are much smaller and lighter than the Magicos making them more practical in all situations. They weigh just over 100 LB each. There will be four of them eventually forming an 8 driver linear array. They are 2 dB down at 20 Hz without any processing. @skoss heard them yesterday. You might ask what he experienced. The picture is up on my system page.
The sound is not where I want it yet. The system is now dead flat from 20 Hz to 12 kHz. I can boost the subs by adjusting their volume relative to the stats, but this makes the bass too warm. The sound is also on the bright side, again because to is corrected to flat. There will be a EQ program in the DEQX and it is supposed to be in the next upgrade. That will allow me to program the amplitude curve to my taste, bass increasing 3 dB/oct below 100 Hz and a shallow drop from 1000 Hz so that 20 kHz is down 6 -12 dB.