Originally Posted by Jacob B
But front corner loading both low and mid bass woofers (E15HP and FM8) should should make the omni-directional, long wave length low and mid bass waves bouncing off the floor/front wall/side wall arrive phase-aligned at the seats, right?
It's not the nulls and peaks I would try to minimize, it's an attempt to optimize the precision of the bass (to complement the Rythmiks :-) )
Corner loading should eliminate interference on the direct wave from the neighboring walls. It does not eliminate room modes, though. Placing subs opposite each other helps with room modes. If you place 2 subs on the front corners, it eliminates all but one horizontal room mode, but does nothing to help room modes on the front-back axis, which can be a big problem.
2 subs in opposite corners eliminates a lot of room modes (all but one) on both axes. But, because the subs aren't a mirror image on both axes, you don't get very consistent response between seats. Still, I have found that this is one of the best overall approaches with 2 subs.
2 subs in center wall positions along the long axes gives you excellent natural response without EQ and consistent seat-to-seat response, because the subs are mirrored on both axes. The downside is that this is much less efficient, due to no corner loading. If you have lots of sub output for your room volume, this is probably the best option.
I haven't had good luck with center wall placement on all 4 walls in a rectangular room.
If you have 4 subs, there are 2 optimal layouts, IMO:
4 corners is great for the benefits of corner loading, eliminating most room modes, and high output.
1/4 3/4 positions on the front & back wall eliminates an additional horizontal room mode, but leaves a single room mode front to back. You sacrifice output, but eliminating that extra room mode helps the natural EQ.
Both of these are mirror on both axes, so you get excellent seat to seat response.
Balancing output and eliminating room modes, the 4 corner placement + EQ was the best for my room.
From a technical perspective another interesting layout is the double bass array. This uses 8 subs. 4 in 1/4 3/4 positions horizontally and vertically (suspended) on the front wall. This eliminates all horizontal and vertical room modes. Then, there are 4 more subs suspended on the back wall, except they are delayed and out of phase, to act like active room treatment. This eliminates the front back room modes. So, ALL room modes are eliminated, for a perfect natural response and time alignment for all seats. You'd have to DIY this, though. I wonder if anyone has done that with Rythmik kits?
It's also worth noting that for the 4 sub placements mentioned, if you sit in the middle, good room EQ can cancel out the bass energy, except vertically.