Distributed Bass Array configuration

      Here's a good article on the subject of multiple subs that I think is worth reading.  
https://mehlau.net/audio/multisub_geddes/

     My general advice is to also learn as much as you can about how sound waves behave in smaller, domestic-sized rooms and how humans detect sound waves through our body and how our brains interpret/process these inputted senses before creating the perceptions of sound in the room.  Spoiler alert: bass sound waves behave quite differently than higher frequency sound waves in our rooms and we perceive them differently based on their frequency range, too.

Tim 

Well, I am going to join the DBA Swarm club, will, let’s call it the “Magnum” Swarm club. Instead of 4 10” subwoofer driver cabinets, I am getting 4 12” subwoofer driver cabinets in 36”x14”x14” dimensions. 
 After speaking with James Romeyn about my room and equipment setup, my subwoofer experiences and experimentations over the years, and my listening preferences, the Swarm Magnum was the best option for me. 
I am overwhelmingly curious to see what type of improvement and listening impressions, and affect it will have in my room. I have used Velodyne SMS1 EQ and Rives Audio professional measurement kit for years to dial in the bass. With the recent acquisition of my humongous Classic Audio T-5 Reference speakers, I found myself using less subwoofer bass due to the larger speakers excellent bass output capacity. But, and this is a big caveat, I am okay experimenting with the Swarm Magnum to evaluate its efficacy in my room and for my particular tastes. 

For those listening sessions when you want to hear Aerosmith Back in the Saddle and crank the system up to hear the kick drum of that song, it’s glorious with lots of bass…no one at those loud music levels cares about stereo bass or mono bass, just the fact that you can jam out to this badass rock song. For more subtle music, such as Stevie Ray Vaughn, Tin Pan Alley, then, subtle rolling bass that is more articulate and defined makes a huge difference. Playing this song at louder volumes, I tend to want to be immersed in the music entirely with the bass enveloping you in a different way than the rock you this way that Back in the Saddle can do. 
Because I straddle variety of genres of music, the Swarm Magnum seems like a solution that can solve my need for deep and loud bass zone with one song and not so much with another type of music as the Swarm Magnum is able to rise to the occasion without resorting to turning up each sub to get louder when I want to rock…just simply turn up the master volume and the bass should equally support the music, no matter the genre. Mind you, I have been utterly satisfied with my methods for years; however, after overwhelming positive feedback and the scientific approach that the DBA method uses to achieve satisfactory bass, I guess I should finally explore this in order to ensure that I am maximizing my listening pleasure. 

Hello audioquest4life,

     Congrats and welcome to the DBA Swarm Club, be prepared to be amazed! 
     I wasn't even aware AK offered a larger Magnum version of their Swarm system.   
      James Romeyn, of Audio Kinesis, was also the person who convinced me to give their 4-sub Debra DBA system an audition in my room. He and Duke really know their stuff and are very helpful. 
     Congrats on your humongous and impressive Classic Audio T-5 Reference speakers, too!  I wouldn't think those huge things needed any bass help.  But that's the amazing thing about the whole 4-sub DBA concept, it'll integrate seamlessly with virtually any pair of main speakers and in any room, when positioned and configured properly. 
     My only advice is to configure the volume and low pass crossover frequency filter settings as low as possible with the bass still sounding very good to you ("very good" meaning powerful, detailed, dynamic and natural).  Oh, and don't forget to make sure your chinstrap is securely buckled.

Tim    

Hi Tim,

Thank you. Appreciate the good vibes and feedback. Yes, the Classic T-1.5s produce great bass as is, but having lived with augmented bass for so many years and my frequent excessive need for an over abundance of bass when rocking out, I felt that the 4 sub DBA concept is at least an almost perfect solution for my needs. At least worth experimenting with after speaking with James. Augmented reality is a good thing when done appropriately. I know a few on this forum and other forums who have Uber main speakers and still use augmented bass ala DBA. 
The new Magnum DBA Swarm is in initial production that will probably hit the streets around August, pending parts availability. It was designed by Duke for those folks who have larger rooms and thus a greater need for bass. 12” drivers all the way around. My room is nearly 19 feet wide x 33 feet deep x 8 feet high. It is the total cubic volume in feet that the DBA works it’s magic up to a certain total volume…the Magnum is for large or extra large rooms:j. The original concept behind DBA was to address bass issues in smaller rooms. The Magnum advances this concept further for larger rooms. 
Glad you are enjoying your system with the DBA. 

Big room + big DBA = killer bass!

I feel sorry for the rest of the spectrum.

It’s only a problem if not properly implemented. So, Not me, I am not worried, at least for low level listening where bass smearing might be more noticeable if not properly implemented. At way louder and extreme listening levels…the way I listen, I have learned that when I play very loud I could care less about bass smearing, because I want to feel the kick drum.

For those low level wine sipping moments, yes, one should be very careful about messing with the frequency spectrum in order to enjoy in solitude the crispness of a cymbal. I think that if the DBA system is integrated properly it affords one the ability to integrate bass effortlessly, no matter the listening level, which is highly appealing to me.

At way louder and extreme listening levels…the way I listen, I have learned that when I play very loud I could care less about bass smearing, because I want to feel the kick drum.

DBA is a level invariant low end Loudness contour? I'd always suspected it might be for some.

I think that if the DBA system is integrated properly it affords one the ability to integrate bass effortlessly, no matter the listening level, which is highly appealing to me.

The beauty of DBA is the "integrated properly" happens almost automatically. With one sub it is impossible, the peaks and nulls are unavoidable and draw attention to the bass. With four they are so small and smooth the bass disappears, the subs disappear, and all you are left with to "integrate" is their level. 

When it comes to that, there is no escape from the reality of human hearing. Equal loudness contours are a thing. DBA is no magic bullet.  

It does however get a lot closer to what you described. With normal no, one, or two sub bass the really low bottom end either falls off to nothing, or else you have way too much above that. Either way you notice big changes with volume. With a DBA the contours are still there but nowhere near as big a problem due I think to the smoothness factor. 

What I did, once the initial phase is done, was listen to a lot of different music at my normal levels. I abhor meters. Most of the time I listen at a nice satisfying volume level. Sometimes not that loud. Occasionally I listen Supertramp Loud. Gradually, over time, I make really small level adjustments. Really small. Like I turn the knob but about half the time not really sure it did anything. This works because the meaning of the equal loudness contours is we go from being relatively insensitive to bass at low volume to hyper sensitive to bass at high volume. The same 2dB change in other words seems completely different (a lot more) from 98 to 100dB than from 88 to 90.   

Took a while, but most of the tweaking was in the first few weeks and now it is pretty close to what you said, effortless no matter the listening level. Never quite gets there, but close enough I never give it any thought any more- until it comes up like this. 

ieales,

     I get similar results from my 4-sub DBA as millercarbon, seemingly effortless bass that is seamlessly integrated with my main speakers regardless of volume level, that is as solid, powerful and dynamic as the source content dictates.
     Bass smearing and bass masking of midrange frequencies occurs when the deep and mid bass frequencies are accentuated, meaning the lower frequencies are artificially boosted, are not in relative balance in volume intensity with the rest of the frequency spectrum and, therefore, not accurately and faithfully reproducing the recorded source recording.
     Of course, this assumes the source material was well recorded with the full frequency spectrum in accurate and natural relative balance without any frequency portions being exaggerated or attenuated.
     Whether a 4-sub DBA system over emphasizes the bass frequencies, resulting in smearing or masking of the midrange frequencies, or accurately and proportionally reproduces the bass frequencies, resulting in no smearing or masking of the midrange frequencies, is completely determined by the user’s sound quality preferences and the subsequent sizing, positioning and configuration of the DBA system.
     The specific size and bass output capacity of the subs utilized, the specific positioning of the 4 subs in the room, along with the specific volume and low pass crossover frequency settings, allows for a wide range of bass reproduction options which, as a result, allows for a wide range of overall system sound quality permutations. Flexibility and scalability are just another couple of advantages of the DBA concept.
     For example, my overall system sound quality preference is accurate, detailed, dynamic, well balanced and natural. My 4-sub DBA system, the Audio Kinesis Debra model, utilizes relatively small, 1’wx1’dx2’h,subs that are rated at 4 ohms and have 10" drivers. My room is 23’x16’ with an 8’ ceiling.
     Based on my overall system sound quality preference for high quality, I positioned and configured my DBA system so that the bass would be perceived in the room as being accurate, detailed, solid, powerful, dynamic and well balanced with no portion of the audible frequency spectrum accentuated above another.
     I accomplished these goals, of optimum bass quality rather than bass quantity, with the DBA’s bass by positioning 2 of the subs along my front 16’ wall, with each at opposite ends about 1’ in/away from each corner. I positioned the other 2 subs toward the rear of the room, with one placed along each of the 23’ side walls and, again, about 1’ in/away from each rear corner. I also placed 2 stacked GIK Tri-Trap bass traps in all 4 corners of my room.
     Avoiding placing any of the 4 subs in corners and utilizing multiple bass traps in all corners is a good start. But my goals also required the proper configuration of the DBA system for my overall system sound quality preferences to be attained. I precisely matched the volume of the DBA to that of my main speakers, running the mains full range down to their rated bass extension of only 35 Hz, and set the low pass bass filter to 40 Hz.
     The result? Music and HT reproduction that is accurate, detailed, solid, powerful, dynamic, well integrated and well balanced with no portion of the audible frequency spectrum accentuated above another.
     The only exceptions worth mentioning occurs on some HT Blu-Ray discs during LFE channel reproduction when the DBA’s bass can become so decidedly unbalanced and overwhelming that it shakes the seats and walls in the room to very enjoyable and satisfying levels.

Tim

I'm almost always talking about my DBA in terms of music. But I have to say, the effect with movies is if anything even more impressive. A good movie soundtrack through a high end stereo with a DBA is really something.

Why is there never any mention of level matching these DBA systems with the main speakers using an SPL meter? Otherwise, wouldn’t it just be guessing what the volume level should be on the subs?

I think its a fallacy if some are asserting setting up multiple subs properly is easier than one. That’s pretty simple math. You now have more adjustments to deal with and each one has some effect on the resulting sound. You can gloss that over to whatever extent desired but you can’t deny the facts.

I agree, using the 'throwing darts' method isn't the way I'd install a $3200 subwoofer system.

Why is there never any mention of level matching these DBA systems with the main speakers using an SPL meter?

There is. All over the place. I've never done it. I listen with ears, not meters. So why would I care what a meter wants?

Otherwise, wouldn’t it just be guessing what the volume level should be on the subs?

Is that really what you think? Do you "guess" what volume level you like? "I think I'll try 12 today. Wow that's way too loud! Guess I'll try 4?" Is that what you do? Of course not. You know perfectly well what volume you want. So why would subs be any different?

Otherwise, wouldn’t it just be guessing what the volume level should be on the subs?

For some Way Too Much isn't enough.

You're twisting it around MC, the whole purpose of level matching is to prevent you from trying to figure out what the volume on the subs should be. That's why its called level matching.

@mapman wrote:  "I think its a fallacy if some are asserting setting up multiple subs properly is easier than one."  

@golfnutz wrote:   "I agree, using the 'throwing darts' method isn't the way I'd install a $3200 subwoofer system." 

I realize that it seems counter-intuitive to think positioning four subs in a room is easier than positioning one, but consider this:  When you change the location of a single sub, you have changed the way ALL of the bass energy is introduced into the room.  With four subs, when you change the position of any one of them, you have changed the way ONE-FOURTH of the bass energy is introduced into the room.  By following a few guidelines you can probably end up with excellent results after one or two adjustments, if not from the get-go (which seems to be the case about half the time).  I include six different setup strategies in my guidelines, most of which are very forgiving, and all of which have been used successfully.   

Regarding setting the levels, either ears or measurements can give excellent results, but in either case (and regardless of the number of subs involved) finding the exact setting IS critical.  The reason is, the ear's heightened sensitivity to changes in SPL at low frequencies.  A little bit of change in gain on the subwoofer amp translates to a disproportionate change in PERCEIVED loudness.   So it may take a while to find that magic setting on the amp's gain knob.  Note that measurements alone may not be enough - Geddes and Toole and others have observed that most listeners prefer slightly elevated bass compared to the rest of the spectrum, but the amount of elevation preferred varies.  I got excellent results fairly quickly in a challenging situation by using measurements as a starting point and then having an experienced bass player guide me as I fine-tuned the settings.  

Note that the improved in-room smoothness of a distributed multisub system allows more flexibility in setting the level.  It is the peaks which stick out like sore thumbs and are the limiting factor in how loud we can set the bass before it starts to sound unnatural.  Smaller peaks means that we can set the level a bit higher for more satisfying bass because we don't have to sacrifice a truly satisfying level across the rest of the bass spectrum to avoid over-energizing the peaks.  

Duke

I have found the best and most efficient way to set up a sub is to measure first to get things in the ball park and then fine tune by ear from there.
What I get out of the whole DBA thing is measure before doing anything. It may be a waste if peaks are not a big issue. There will always be some though so it’s all a matter of judgement.
If the goal is to smooth things out at just one spot, DSP is probably the most straightforward solution. Or a good old fashioned analog parametric equalizer.
For smoothing out across the room then the more heavyweight dba solution might make sense, but only if the mains are capable of delivering across the room as well ie they have wide dispersion characteristics otherwise you might have smooth bass across the room but everything else falls short.

Then there is the alternative where you have multiple subs set up not  primarily to smooth out response but for best soundstage (smoother response is a secondary benefit).  That means if 1 sub front dead center,   2 subs at or near position of mains, 4 subs the two behind you are set to a lower level than front.  

I agree, level matching the subs to the mains is a good starting point, especially from someone installing their own subs. Where you end up doesn't mean the same position is necessary. At least you'll know where you are with reference to increasing or decreasing gain. Each time you add an additional sub, the SPL increases. So if having 4 subs (or more) in a room, I would think level matching becomes even more important, especially, as you said, if you have a difficult room.

Flat in room and or at listening position is just a starting point for great bass. Time, phase and Harmonics and the superb transition to mains with high pass is crucial. More sources ( subs ) in the room is a simple averaging machine for amplitude… great for sine waves… not so great for the rich harmonics above the magical oft cited 80 HZ line.  This is a big hint…. Play a decent recording of a scaling acoustic bass w eyes closed… image move ? (!Wales gets it, Eric surfed up next to it w Orchestral, a small Cello ensemble… I am guessing it aint all mono for them ) Glad the OP is at 95%, wonderful place to be but like any good audiophile questing for even better !!
of course use test tones, rta, good microphone… and listen. 
Fun thread but needs more cowbell and bass players…

audiokinesis

Regarding setting the levels ... finding the exact setting IS critical. The reason is, the ear’s heightened sensitivity to changes in SPL at low frequencies. A little bit of change in gain on the subwoofer amp translates to a disproportionate change in PERCEIVED loudness ...

That is completely false, notwithstanding your use of ALLCAPS for emphasis. See any basic audiology text for proof, which will show the range of increased sensitivity is typically in the midrange, 2000 - 5000 kHz. And that’s why the midrange of a hi-fi system is so critical to fidelity, even for those of us who also expect to hear the bass.

There is just so much misinformation about LF on these threads, but this was an especially glaring error.

@cleeds wrote: " That is completely false, notwithstanding your use of ALLCAPS for emphasis. See any basic audiology text for proof, which will show the range of increased sensitivity is typically in the midrange, 2000 - 5000 kHz. "

My bad for not explaining where I was coming from.

I do understand what you are saying, but what you are looking at is where the ears are the most sensitive; that is, where sounds of a given SPL are perceived to be the loudest. And indeed that peaks exactly where you say it does (with the peak centered around 3.5-4 kHz).

What I’m talking about is different, and is not nearly so obvious.  I’m talking about the ear’s sensitivity to CHANGES in SPL (and I would use italics instead of allcaps if that was available here). A change in SPL does not produce the exact same change in perceived loudness across the frequency spectrum; it produces more of a change at low frequencies. Go from a low volume level to a high one and the deep bass goes from being inaudible to being thunderous. The unit of measure of perceived loudness is the "phon", and by definition at 1 kHz the loudness in phons is the same as the SPL in decibels, so the two curves share that data point:

http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/eqloud.html

Now take a close look at how the equal-loudness curves bunch up below 100 Hz. A 5 dB change in SPL at 20 or 30 Hz results in a change in perceived LOUDNESS of about 10 phons, comparable to a 10 dB change in SPL at 1 kHz.

This is what I was talking about, and once you understand that, it will be clear why a small change in gain on the subwoofer amp typically results in a larger than expected change in perceived loudness. Or, to put it another way, why it takes a while to dial in the gain setting on a subwoofer amp.

Duke

golfnutz- You’re twisting it around MC, the whole purpose of level matching is to prevent you from trying to figure out what the volume on the subs should be. That’s why its called level matching.

If you say so. I prefer to say it is to achieve a seamless and pleasing presentation. Please read Duke’s posts above.

I find in practice extremely minor adjustments to my sub level are needed to get it tuned in exactly to my ears, which is consistent with what Duke is saying. Very minor....

Yes, Duke agreed with me suggesting level matching as a good starting point. Thanks for pointing that out.

Sorry MC, you're a dart thrower, here's what you said. Guaranteed your system would sound better if you learned to install it correctly with the right tools. You're the one adjusting the bass whenever the next 'more bass on this song, better turn those subs down again'. If you learned how to use the tools you wouldn't need to do that.

" What I did, once the initial phase is done, was listen to a lot of different music at my normal levels. I abhor meters. Most of the time I listen at a nice satisfying volume level. Sometimes not that loud. Occasionally I listen Supertramp Loud. Gradually, over time, I make really small level adjustments. Really small. Like I turn the knob but about half the time not really sure it did anything. This works because the meaning of the equal loudness contours is we go from being relatively insensitive to bass at low volume to hyper sensitive to bass at high volume".

Question:   
When using the crawl method and picking the best spot for Sub #1
are you supposed to then power up Sub #1 while crawling for Sub #2`s best spot and so on with each sub thereafter....??

Duke- This is what I was talking about, and once you understand that, it will be clear why a small change in gain on the subwoofer amp typically results in a larger than expected change in perceived loudness. Or, to put it another way, why it takes a while to dial in the gain setting on a subwoofer amp.

MC- Gradually, over time, I make really small level adjustments. Really small. Like I turn the knob but about half the time not really sure it did anything. This works because the meaning of the equal loudness contours is we go from being relatively insensitive to bass at low volume to hyper sensitive to bass at high volume".

golfnutz- The difference between the two is: MDS.

@scm asked, " When using the crawl method and picking the best spot for Sub #1 are you supposed to then power up Sub #1 while crawling for Sub #2`s best spot and so on with each sub thereafter....??"

Yes.

When doing the Crawl to set up a Swarm or DEBRA system, which uses a separate amplifier, connect the additional subs in series, such that the overall subwoofer volume level stays the same. If doing your own distributed multisub system with conventional self-powered subs, I think you’d want to adjust the volume of the pre-existing subs before adding yet another, and measurements would probably help a lot with this.

Duke

Thanks Duke.
 I did that with self powered subs and what I found was that the best spots that where candidates for Sub # 1`s position ended up being where Sub # 2 went and the third best spot s where Sub # 3 ended up.
So in this room, there didn`t seem to be a need to go through the Sub in the listening spot routine after all. 

I have been enjoying my custom swarm( it’s on AK main page). Looks a lot better than the pic. Dual amps in a stereo config

I basically set it up in my 27x16x10 room just as recommended. So many adjustments and I am not versed in computer calibrations.  My mains are Persona 5f’s which are pretty flat to 43 hz per Paradigm. Last night I upped the crossover on the amps to what I think would be around 50. The amps have lines with no values so really not sure if it’s exact. Everything seem to snap into  place a little betterIf there is anybody in the NE metro Detroit area that would like to tweak these fro me I would gladly pay. Heck I will take ya for a boat ride and grill you a great steak and pour you some fine Tequila. 

I want accurate music, what is on the program. To me that means accurate frequency response (I know some do not seem to feel this way for their own reasons).  Even though my ear might prefer this or that ‘type’ of sound, I want it to first hear what’s intended on the music program (I can screw up the artist’s intended sound later if I want to).

This means first fixing the room’s acoustical problems (most always the bass errors). Since mine cannot be obliterated like a man music cave I use a bass room correction DSP device and an SPL meter to work towards a flat response, and a bit of very judicious digital equalization. Unless the recording is crap, my main speakers always ‘disappear’. They could be run sans subs for most music.

The room correction DSP is very effective. The REL B1 ‘disappeared sonically in my listening position, low crossed at 25Hz or so with low volume to supplement the D2s deep low response (w/limited dynamics, for some). I also enjoyed the spaciousness a good REL sub-bass system can provide (even one), even on non-bass material.

BUT, based on the above posts, I lugged subwoofers upstairs and downstairs this week and reset the main audio listening/living room (20w x17 x10, three SVS subs), the basement home theater (12x22x8:  REL B1 & Def Tech PF-1500, old 15”), and the upstairs TV room (13x16 x9 using singe REL Storm III very successfully with Elac Debut 5.2 system).

The SVS SB-3000 went into the old REL B1 spot (right front corner) as it was demonstrably the ‘invisible spot’. The two SB-2000 units (all 3 are sealed) went onto left side wall and the rear wall, semi-asymmetrically (as much as this room would allow with two large openings). SB-2000s only low pass to 50Hz so that’s where they stayed. Also set SB-3000 to 50Hz and at low volume (half the time testing I had fingers on cones to be sure the subs were on; they were…).

From 100Hz to 31.5Hz the 1/3 octave frequency measurements (80dB volume baseline at 200Hz) were between 81.5dB and 80 (at 31.5Hz). I was pleased and initial thoughts were increased solidity at the extreme bottom end along with more oomph when required. I heard no bass where it was not before. I want to do more listening with subs off and on as the difference in apparent openness is a bit subtle at the modest volumes.

I suspect perhaps better physical positioning, phase setting, and general integrating will help even more. The SB-3000 offers a cut-off down to 30Hz as well as some additional parametric equalization for the single sub only. Perhaps working with all of these variables would dial it in better. Like others I do not see myself going back to one sub (probably more like looking for my 4th SVS and making a 10ft high real-wall mount for one of them…).   Thanks to all. I’m a DBA believer.

p.s. Thanks to Duke for bringing up the Fletcher Munson curves. For those of you that still don’t quite get it; it seems to be the reason the “Loudness” button was invented.

 

After a 10 minute read I believed the hype of the DBA and purchased four of the 10''Morrel titaniums and two sa-1000 amps, only needed one amp I found out later. Built some plywood boxes and these things have transformed my system into something I never dreamed possible. These b&w 802 series 3 were garbage speakers for anything just about, not so now. I don't even have the subs completely dialed in,  it doesn't matter. 
 

The only thing you need to know is how soon can you get yours started! You don't need fancy mics and other crap like that to measure anything, has anyone tried a swarm and not like it and removed it?

@brunomarcs which model Morel drivers did you get?

@clio09 I have the Morel Ticw 1058ft Titanium series 10'' subwoofer 8 ohm. You have experience with them?

@brunomarcs no I do not but have been intrigued by Morel and want to try out a set. I built my own DBA as well using Dayton Audio drivers in sealed enclosures. I do not use the Dayton Audio amps, but rather a pair of Bel Canto mono blocks to power the low end. I have an Accuphase F-25 for the active crossover with low and high pass filters.

Does the DBA/Swarm system work equally well for home theater?