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
@noble101

I set it by ear initially based on what I thought the rolloff of the ls50 metas would be based on specs and reading and thought it sounded good. But I did not achieve my goal which was to fill in the low octave and leave what the mains delivered fine alone. There was a big bass bump from ~ 40-60 hz that was audible on most all tracks. The sound meter app clearly showed this. Room is not large, only 12X12 with lots of furnishings to help break things up naturally.  My crossover was way too high and the level way too low. Now things sound like full range speakers with extended bass. Much better though that is a subjective assessment despite the fact that the setup measures better now! You can only tell there is a sub on the tracks with extended bass to start with. I have full range speakers running in the next much larger room off the same system (no sub) to compare with.


@mike_in_nc , my solution to that problem is 1 slow the fan down, 2 change to a quieter fan or 3 disconnect the fan altogether and provide other cooling. It has a bigger processor and runs much faster.
Thanks to everyone who has participated. I’ve been reading a bunch of these DBA threads and it is causing me to seriously re-examine what I am currently doing with only one sub. For the single seating position that matters, it is invisible sonically, an REL B1 set at 23Hz with volume at 6/40 clicks, merely to augment small but deep floor-standers.

I did not hear a noticeable improvement in trying true stereo (L-R) subbing close to the speakers and went back to the single REL.

After reading and thinking, my mind (I prefer to be scientific) wraps around the DBA concept very well. I believe those who think they can localize the deepest bass are merely being fooled by other cues in their environment.

Needing at least a complete wave or more to identify pitch makes sense. Let’s throw out the ballyhooing over time coherency when you have to wait to even know what the first deep sound was…and your brain is moving off in other places already…

I’m now wondering (without any more spending) about trying three SVS sealed subs, two SB-2000s and one SB-300 in my 20.5 x 17ft deep room (with openings and canted ceiling) in place of the single REL (or two RELs with an old Storm III in my collection). Along with a really old Def Tech PF1500 sub I’m willing to make the music room best and give the extra subs to the dedicated home theater room (music rules).     Thanks again for the great discussion. Now I’m thinking.

 


Doogiehowser, people listening to my system have ZERO problem localizing 100hz. I use a stereo subwoofer system because I cross at 120 Hz 48 dB/oct.
Most bass is mixed towards the center. Because all the speakers producing bass are closer together than 4 feet and have exactly the same group delay they act acoustically as one driver. Because they stretch from one boundary (wall) to another they form an infinite line source. 

Those of you not using a high pass filter on your main speakers are missing out on a chance to significantly lower distortion in their main speakers. Just because a speaker is specified to go down to 40 Hz does not mean it stops moving at 39 Hz. It can’t project frequencies below 40 Hz but, it is still going to try , wasting power and increasing distortion. I would suggest spending some money on a decent crossover instead of buying cable elevators.
By Jove, I think he's got it! 

Only what you should do is add 3 subs to your REL to make 4. The number of subs is far more important than what kind. I thought, according to the research, each additional sub adds proportionately less. So my plan was to build 4 to replace my one Talon Roc, which would then be sold. My plan was going fine. Removed the Roc from the room, put the 4 subs in, heard the vast improvement.

But then before selling the Roc I thought what it would be like, put it back in, and there it stays! Either it was more than the predicted 25% improvement, or 25% is more than you'd think. Either way it was big enough to keep me running 5. Granted the Roc is two 12" monster magnet woofers in a ported isobaric cabinet. A much better quality sub than the ones I built. So quality does count for something. But numbers count even more.