What process did you use to integrate multiple subwoofers for 2 channel listening?

MC may not have patience but he did tell you what to do which you gave someone else credit for the DBA.

Proper credit where credit is due.

MC learned to build his DBA (distributed bass array) from Duke LeJeune. Check MC's posts.

Duke has been designing, selling and discussing distributed bass arrays since at least 2014. He credits Earl Geddes, and states he is using Mr. Geddes ideas with his permission. Search posts from @audiokinesis.

Like in this thread:
https://forum.audiogon.com/discussions/best-subwoofer-for-quad-2805-under-5k/post?postid=21366#21366

04-06-2014 2:05am

Ime when it comes to low bass, the elephant in the room is the room. No matter how flat the subwoofer starts out, the room will superimpose its effects. We can change the room-imposed peak-and-dip pattern by moving the sub and/or moving our listening position, but we cannot make it go away. It is impossible to find a location for a single sub that provides approximately flat response in the sweet spot, much less elsewhere in the room.

Distributed multiple subs offers an elegant solution, each sub being in a different location and therefore generating a different peak-and-dip pattern, but the sum of several such dissimilar patterns will be vastly smoother than any one alone. Instead of a few big peaks and dips that are quite audible, we end up with more, smaller, closer-spaced peaks and dips, and the subjective improvement is even greater than we might expect because (at low frequencies) the ear/brain system will average out peaks and dips that are within about 1/3 octave of each other.

While it’s possible to equalize a single sub to be flat at the microphone location, its response will be far from flat at other locations within the room. A distributed multisub system significantly reduces the spatial variation in response, such that the difference from one location to another is greatly reduced. If further EQ is needed, it is likely addressing gentle global problems, rather than acute local ones.

As a general rule of thumb, two subs have about half as much variation in in-room response as a single sub, and four subs have about half as much in-room response variation as two subs (assuming they’re spread around somewhat). Smooth bass = fast bass, because it is the excess energy in peaks that makes a subwoofer sound slow (the ear/brain system having poor time-domain resolution at low frequencies, it is the frequency response that dominates our perception). Also, smooth bass = powerful bass, because we’re likely to set the average level of the subwoofer lower than it should be if the response has distracting peaks that stick out like sore thumbs.

Dipoles have smoother in-room upper bass than monopoles do, so the discrepancy between two dipole mains and a single monopole sub is greater than what we get with conventional main speakers. If you read accounts of people who have tried subs with dipole speakers, it seems like most people who try a single sub eventually give up because they can hear the discrepancy. Most people who try two subs keep them, because they don’t hear much discrepancy. Three or four subs would be better still, and they can be small subs.

I spent several years trying to design a super subwoofer that was "fast enough" to keep up with Quads and Maggies while offering good extension and impact. I tried sealed, transmission line, dipole, isobaric, aperiodic, and more. Then a conversation with Earl Geddes changed everything, and I’m now an advocate of distributed multiple subs, in particular for use with dipole mains. I’m using his ideas with his permission.

Imo, ime, ymmv, etc.

Duke
dealer/manufacturer

You can of course do it with a test signal like white noise and a meter. That’s how I did it with 1 sub. Learned you can’t just trust your ears in this case to get it right. More subs and more controls means more complexity. That’s when automation like minidsp comes in handy to cut to the chase. Live and learn …. that’s a good thing.

I thought the Ohm blog article I linked to by John Strohbeen above was interesting. Something of a different take on optimizing sub placement for audio as opposed to home theater with more of a focus on timing of the sound waves from the subs relative to mains and listening position and how that affects what you hear than what I’ve heard from bass array proponents elsewhere where the main goal is to produce smoother bass response throughout the room including main listening position. JS’s conclusions on placement based on that seem simpler and different from other bass array proponents including Duke at @audiokinesis. 1 sub, center forward. 2 subs as stands for mains. 3 or more to the rear and set to lower SPL. Would love to hear AK’s take on that?  It seems more focused on optimizing the bass more thoroughly specifically at the listeners location.  

https://ohmspeaker.com/news/for-optimum-sound-how-many-subs-and-where-do-you-put-em/

One other thing. I know audiokinesis is big on speaker dispersion patterns and how that affects the sound.
Seems to me that benefits of a bass array is not the same in all cases. Mains need to have good dispersion characteristics to start with to match the subs I would think for best results. If mains are highly directional, there may be only so much to gain from smoother bass response across a room. Or it might just make getting things to sound right across the room impossible to start with no matter what you do with subs.
Food for thought.

@tvad Thanks. I didn't know I could do that. Makes sense. I was under the impression that MC invented the DBA and Duke just happened to be selling it. His system page puzzled me because it seemed like I should be seeing Duke's stuff in his room but then I realized he made it himself.

@hshifi Thanks for your input. I'll try the crawl again but with three subs, I better get my knee pads. Another vote for DSP -- thanks! As for bass traps or diffusers, I have many -- 4 Mondo Bass Traps, 2 GIK corner traps, 2 GIK Q7 diffusers, 4 GIK HF limited bass traps, 2 DIY absorbers 4" thick, 2 ATS bass traps, 4 ATS absorbers. I've also made several more pillows (e.g. a giant dog pillow stuffed with R38). I've moved everything around everywhere and measured all the while. Dozens of hours or more. I've moved huge amounts of furniture and even brought in more bookshelves for more diffusion. Plus, so homemade deflectors home made from wood boards to tweak reflections.
Hiring someone may be the way to go. I understand how multiple subs are supposed to work and how bass waves move in the room. It's now a question of discovering what's efficacious, given all the factors.

@powemi Good point. I will use my ears. I'm developing a sympathy between measurement and listening. The reason I am mentioning the bass hump is that I can defnitely hear it. The problem with using one's ears for a deep null is that one may not realize very easily that there is missing information, because we tend to fill in the blanks with our brains.

@mapman -- exactly. It's the complexity that makes a sub crawl or just using my ears hard to fathom.