Distributed Bass Array configuration


Please, I don't want to debate the merits of the DBA nor of those who espouse it. I am considering adding two more subwoofers to a system that has two already. To those who use a DBA,I am interested in how you have configured them, specifically--
  1. Do you run in mono, or do you split the array to run in stereo?
  2. What is your approach to setting phase (delay) among speakers that may be facing different directions and are different distances from the listener?
Thanks!
mike_in_nc
Hilde45, very poor choice of experts. Mr McGowan is a businessman with poor hearing. His objective is to make money by any means possible. He is reasonable good at that. I suck at it. 
Most of these people making comments here on this subject are using 3rd if not fourth rate equipment and are running their subwoofers without a high pass filter on the main speakers, people who listen to Yello on Tekton loudspeakers.  There is no way in ---- you can get decent bass out of a system that way. The main weakness of a distributed array system is that there is no way to control time with it. You can not get the impulse from the subwoofers and your main speakers to your ear at exactly the same instant. The result is a mess. But, it really does not matteras none of these people have a way to deal with the problem anyway. They would rather spend their money on cable elevators. 
@mijostyn Both the experts cited have extensive experience in audio, i.e., it’s their profession. Neither are subwoofer salesmen. In both cases, their answers were detailed, and in both cases, they explained pretty carefully -- in Poes’ case, with great detail. In both cases, neither proffered sweeping generalizations about stereo bass, Indeed, the case was pretty well established that in many cases, mono bass was better for room acoustics and might be the only thing hearable, anyway. The information they provided is not susceptible to ad hominem remarks. To be clear, they are not offering arguments that are "pro stereo bass" or "pro mono bass."  They rebut the claim that there is NO such thing as stereo bass and it can NEVER matter. There is, and it can, with all the qualifications provided. I thought that the OP's question was seeking to learn about this topic, so I provided what seemed like good information, rather than just my experience, which is meager.
I run one pair crossed over at 150hz (in front) and one crossed over at 80hz, so I do run stereo, but I doubt it changes a huge amount in the end. I've played with the phase but don't notice any effect. Like @heelid I placed my Swarm at different heights, two lower, one ear level, and one close to ceiling. I experimented with different orientations, and firing toward the wall produced by far the smoothest results. These were very easy to integrate beautifully in my system.
  • mc’s formula is a rip from Floyd Toole’s book, the focus of which is setting up a home theatre, not a HiFi. Read the book and find that the mid wall location works for rectangular rooms. Not all room are rectangular.
  • 80Hz XO and no main roll off is a sure recipe for a mono low end which is fine if you like it. Lots of level, no detail. mc’s Moabs claim 20Hz. Adding 4+ subs from 80Hz is going to create one hell of a bass bump.
  • Floyd states that DSP & EQ can get perfect bass in one location only which is my preference.
  • Phase matters and is both audible and measurable.
@mike_in_nc place a phone call to Duke Lejuene at AudioKinesis who manufactures the Swarm which he'll tell you was based on a theory by Earl Geddes. If you search the web I think there is also a white paper out there by Earl that explains the concept and placement ideas. Duke provided a placement guide based on the Golden Ratio that I dug up somewhere. It is a good start but with some experimentation you can dial it in. He has gained a wealth of information on this topic and is more than willing to share.

I did my own swarm using 10" woofers in sealed boxes. Crossed over at 70 or 100 Hz depending on the mains speakers using an Accuphase F-25 frequency divider. Two woofers firing towards the walls, two woofers firing into the room, one of the four woofers raised to ear level. I put the woofer nearest the corner out of phase by swapping the leads.

Since you have line source ribbons @mijostyn has an interesting set up for that type of arrangement I used with my Acoustat Model 2 speakers. His theory in effect creates a line source for the bass. You can chat with him as well to get more information.