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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
ieales's avatar
ieales
1,201 posts
 
  • 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.
clio09
3,355 posts
 
@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.
audio-union's avatar
audio-union
179 posts
 
I don't agree with much of anything written on this thread, except for if you like it then you got it correct. On the other hand, bass sub frequencies are felt more than they are heard and you feel directionality in your sinuses, medical science. Proper phasing of the bass frequencies makes a huge difference to the quality of the performance and the power requirements to achieve a great performance. When the bass image is in the same plane as the rest of the image it is magical. Typically this is a achieved with a speaker management system. There are manufacturers who specialize in such equipment. You could say it is all in the science and the knowing.
mapman's avatar
mapman
22,198 posts
 
+1 @audio-union

Totally true but look every obsessed audiophile must choose their obsessions and overlook certain truths to keep it all reeled in or go totally bonkers. Or do they? From the sound of things, perhaps not. 😉
millercarbon's avatar
millercarbon
12,531 posts
 
hleeid-
@mike_in_nc  -

Firstly, heed the advice from MC/Noble101/and especially Duke LeJeune.

Secondly, I will divert from phase, crossover frequencies, gain, etc. and instead share my experience regarding subwoofer placement.

I am running four subwoofers (yes, the AudioKinesis Swarm). Two are mounted up high facing the ceiling. Their heights vary with one 12 '' and the other 18 '' below the ceiling.

Duke mentioned in an earlier thread that any subwoofers mounted above the room mid height contribute to the vertical plane, thus further reducing standing bass nodes.

My A/B testing (4 on the floor vs. 2 on the floor with 2 up high) in 2 rooms (10 x 12 minus closets and 12 x 16 living room) at my previous house along with over a year at my new house (also A/B testing between a 13 x 16 vs. a 15 x 19 room) all clearly confirm a noticeable all around improvement.

Hope this is helpful to you!


mike_in_nc, Hope you are paying attention (to the whole thread) because this is typical of what happens every time. A small number of us have experience and knowledge. A whole bunch more talk as if they do. Sift though the chaff to sort out the wheat and you will be fine.
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