Subwoofers and Phase Question For You Sub Experts

@millercarbon thanks for the informative and entertaining post.
Just for a bit of context, I sold a pair of full range speakers last week that didn’t really need subs. The Dunlavy 3 is a great speaker that will cover well until I reinvest in new speakers.
I’m not new to the perils of sub integration nor the DBA theory, and I’ve conversed with Duke a couple times over the years about his Swarm arrangement. I’ve setup a few successful 2+2 systems and had pretty good results with so-called difficult speakers like Magnepan and Apogee.

So with that out of the way, to benefit from the content of your post I also need some context - I’m curious to know what your mains are and whether or not you run them full range. Also, you make no reference to sub quality, only quantity. Are you saying that 4 cheapish subs can produce tight, articulate and extended bass, or is there a requisite standard or level of quality and if so, can you suggest a make/model that you see as the entry point for a successful distributed sub system.

As for the ‘phase’ affect, I only hear what I hear and see what I see. With subs inline, I hear no issues other than that stated. With subs elsewhere, there is a downside, as stated. It may or may not be phase but it sure seems like it based on the effect that I hear.
Lastly, my pair of HSU have been pretty much everywhere in the room including perched up on table tops; presently they’re against the left and right walls, tight up and with one behind the front plane of the speakers and the other closer to the listening position.

It would be cool to hear from people using subs with inbuilt room equalization to see just how successfully they integrate in a 2+2 setup.

Cheers!

@kenjit  Same applies to you as to what i posted to millercarbon above.

@rooze   +1

@rooze ,
Well, there is always Vandersteen.
The new Sub 3 has a built in equalizer. 
BTW, I own both the Hsu and Vandy subs (2wq) for 2 systems, and the Vandersteen subs are by far more subtle and better integrated than I can get with the Hsu's. 
Don't get me wrong, I like the Hsu's, but when it comes down to seamless integration, the Vandy's have it hands down.
Bob

You should also consider the Rythmik subs. These have one of the best servo control systems on the market and are reasonably priced. The servo control amps include a variable phase control which makes it easier (using REW and a calibrated mike) to optimize the integration with your mains. 

If you have the room, you might also consider the GR-Research open baffle subs. These use the Rythmik servo controlled amps in an open baffle system. I have stereo triple-woofer subs which provide very natural sounding bass that is very deep and detailed, but these need to be at least a few feet from your front wall. These are sold in kit form, but if you don't want to build them yourself, GT Audio Works sells complete subs with from one to six drivers in each.

The theory behind the swarm is that by distributing the bass needs across 3, 4 or more subs, each one doesn't have to work very hard (so you can theoretically get away with lower quality subs) and each excites room modes differently so the amplitude of the peaks and valleys as you move around the room is reduced and the bass can be considerably smoother.