Subwoofer question

For the most part it is a practical consideration in that it looks better. Low bass is non-directional so there really isn't any great difference either way. 

Swarm is a low cost system and it is smaller than most DBA subs. The 20hz -3db is consistent. It's easy to place and it is very inexpensive compared to some DBAs.

DBA doesn't say 4 for the system. DBS says more is better and placement is dependent on mode/node. Huge rooms can have subs hanging on the walls, floor, stacked columns or built in. The number of cabinets is not the issue, the results of smooth, deep bass is.

Swarm and Debra are actually a brand more than a way of doing bass. DBA is a concept of implementation, not a Name Brand. I'm sure I'll be corrected if DBA means something else. :-)

Time to feed the chickens..

I've never seen or heard a swarm. 

I keep yapping about 'stereo pairs' of subs, front facing, no ports, locate adjacent to mains: giving/preserving bass directionality, by virtue of both the fundamentals and overtones of those fundamental notes.

It finally occurred to me: those that use SWARMS must be adding them to systems that already have bass directionality, they are adding more to a system that has more bass than most of us have. i.e. my woofers, 15", 37lb monster magnets, I could add more below what they do if I wanted, SWARM might be best.

Adding a SWARM to a system that does not have decent bass directionality is what does not make sense to me.

in the context of higher end Home Theater multi-channel systems, more that 2 subwoofers is common place. the reason is that more than 2 subwoofers, up to 4, will even out the bass nodes in your room. and each sub is more linear than a single sub. even with only a single low frequency channel. and with movie soundtracks having so much low frequency information it’s a natural fit for that application.

there is lots of information on ways to integrate multiple subwoofers into a system out there to find. the SWARM approach is a very good one.

i have three Funk Audio 18.0 subwoofers in my Home Theater room (on a single LFE channel) and it’s awesome. and i have only level matched them so far, no fine tuning.

forget about deep bass directionality; while it exists really it’s higher frequencies that are mostly giving you directional clues. your deep bass priority should be to even it out as best you can so doubling and such is not overwhelming the music. and 3 or 4 subwoofers around your room will help with that.

"What is the rationale behind facing the subs toward the wall?"

Boundary (driver-wall) reinforcement is increased, thus more bass.