Distributed Bass Array configuration

1. Doesn't matter. It is all mono. Proved it by running both ways. No difference. There is a lot of BS around subs. Stereo bass, for example.

2. This one is a misunderstanding of phase. The phase of the subs in relation to the mains doesn't matter. Timing does not matter. The importance of phase is in that the output of all the subs with the room, it all interacts. Each sub has its own set of room modes. These room modes move around when the sub is moved around- or when the phase of the sub is moved around. 

If you do your sub setup, place the subs asymmetrically at different distances from the corners, set crossover 80 or lower, and then set level, you are basically done. These are the big ones. Phase, I have it on my Dayton amps, as well as on my Talon Roc, and it is easily the lest significant of all the things you can do. 

All my subs by the way fire into the wall from about 2" away. They are asymmetrical, and I never have any idea where they are or indeed if they even are on at all! No one does! Yet the bass is beautifully 3D and seamless with everything else.

@millercarbon - Thanks for your comments.

Regarding sub phase, I have experienced its making a big difference in FR (measured and audible) between sub and main, but it’s easy to believe that with 4 mono subs not all set to the same phase, this would lose its importance.

I never thought of firing the subs into the wall. Interesting idea!

I do agree that with proper setup, subs can and should be undetectable, and I’ve accomplished that with 2 subs. Should be easier with 4.

I can imagine that using mono subs, one loses the need for symmetry, thus it should be easier to get smooth response.

Thanks again.

Hey Millercarbon, just copy that and paste that from now on.  Most straightforward, no bs explanation I’ve heard to date.

And for the record, I still hate subwoofers as much as I love them

REW measurements definitely show a difference. I guess it's up to each person if it matters or not.
Here's some example of in-phase vs out-phase graphs. Scroll down in the link to view all 5 screen captures.

First graph is comparing dual subs in and out of phase.

Next 2 down include the phase graph for dual subs in and out of phase.

Last 2 dual subs for the Group Delay for in and out of phase.

https://imgur.com/a/RSQiBMi

From REW author.

The vertical lines for the phase graphs are called Wrapped Phase:

" Phase is cyclic, due to the periodicity of the sine function. When it is increasing and reaches 180 degrees it wraps around to -180 and continues with -179, -178 etc. When it is decreasing and reaches -180 degrees it wraps around to 180. The vertical lines show those wrap points. If you look in the graph controls you will see a button to "unwrap" the phase, which allows it to go to 181, 182 etc rather than wrapping, but you can end up with extremely large value ranges in unwrapped phase, partly because any time delays create a frequency-dependent phase shift that gets ever larger as frequency increases.

All that changes at the wrap points is the way the graph is drawn. Think of it more like reading the second hand of a clock, after 59 secs it starts again at 0 and counts up again, but time has not jumped or done anything other than progress as usual. The part of phase that gets plotted when wrapping is used is like showing only the seconds of a time."

Group Delay
" The Group Delay at a frequency is the slope of the phase at that frequency. It provides an indication of how the envelope of signals at that frequency is delayed in the course of passing through the audio chain - if everything is delayed by the same amount the shape of the signal is not changed, it simply arrives later, but delays that vary change the shape of the signal.

Anything that affects the phase will also affect the group delay, which includes crossovers, the response of drivers, the low and high frequency roll-offs of the various parts of the audio chain, any time delays in the system and the filtering effect of the room, its modal response and the frequency-dependent absorptions of its surfaces and furnishings".