Help me understand "the swarm" in the broader audiophile world

Right. If we are talking about a 2 channel high fidelity system one sub never works well for a multitude of reasons.

I must have a magic sub.

Right. If we are talking about a 2 channel high fidelity system one sub never works well for a multitude of reasons. When you get to two subs crawling around on all fours is an evolutionary step backwards and totally unnecessary. Sub placement has to consider the placement of the satellites. Whether or not you add more subs in addition and where you place them depends on what type of satellites you have, point source or line source, size of drivers, how high you intend on crossing over and how loud you want to go. Subs should always be against a wall or in corners. There is a large increase in efficiency which lowers distortion and the amount of power needed to drive the sub. It also decreases unfavorable room interactions. 

By far the most difficult problem is matching the subs to the satellites. If set up correctly you should not be able to tell there is a sub in the system.
There are three issues that have to be dealt with to get the job done right. The crossover point and slopes, the phase and time relationship between the subs and the satellites and the relative volume of the subs to the satellites. Subwoofers have a bad reputation in many quarters because getting all this right is not easy and I have not seen a single powered subwoofer that comes with the onboard flexibility to do this well. It becomes a trial and error ordeal. Passive subwoofers with outboard amplifiers and digital crossover systems have the power to do this very effectively in less than a human life span. Now I just pissed off everyone with a powered sub  🥺 Not to worry! You can use the amplifier in the subwoofer you just have to add an outboard crossover with the necessary flexibility. You have to get one anyway as very few subs come with a high pass section for the satellites and you will absolutely never get the best performance without one. 

unreceivedogma:
" A friend of mine who was the audio guy for the Untied Nations and the DJ for the Nuyorican Poets Cafe gave me a tip, which I have to try over the weekend:

Put the sub in the spot where your listening chair is. Then walk around the room. When you find the spot where the bass sounds tightest and deepest, that’s the spot to place the sub.

Assuming this theory works, I’m hoping that spot isn’t in front of the door to the room."

Hello unreceivedogma,

     Your friend's tip is a good one that I've used and recommended many times with very good success.  It's commonly referred to as the 'sub crawl' method and you're highly likely to find it to be very effective in your room as well.  
     If the result is actually in front of a door, placement immediately to the left or right side of the door will probably also result in very good bass perception at your listening seat.  This is technically a bit of a bass performance compromise but you can decide for yourself if it's a sufficiently subtle one to be acceptable. 

Tim

I manufacture bass guitar speaker cabinets and sometimes that gives the impression that I'm a bass player. But I'm not.  

" Who's you're hero, inspiration? "  

One need not be a bass player to be inspired by Geddy Lee.

Duke, your Bass cabs look nice, small and solid. Smart.
Dust collection is everything, over build it. Don't mess around.

I get stoke from most Bass players, past and present.
From Guitar / Bass player Kathy Valentine of the Go-Go's to Christian McBride, its all good.
 
In '64 with JBL's DIY plans I cobbled together two 4530 'Scoops' and drove them using a Fender Deluxe with a modified line output to a Marantz 8B for amplification. Lots of plywood on stages in those years.

Over the years I acquired a 360/361, Magnavox SVT trunk w/ Tone Tubby drivers, QSC BAG END w/ELF-M sub, Bergantino, Mesa 400+, etc. scattered around the house.
Small venue FOH gear came and went, I still have an older Tom Danley horn.

Now don't laugh, my current rig is an Acoustic Image Focus driving an old 12" drum shell fitted with a BAG END 10" Coaxial and x/over upshot.
Amp and speaker fit in a back pack, holding my Fiddle leaves me a free arm and just one trip to the car. So I began and ended up using DIY cabs. Life, eh?

I think you'd enjoy the soup-to-nuts tour of Masa Boogie operation in Petaluma California on your way to Napa valley to pick up a few bottles of Sinskie and Plump Jack.

Unreceiveddogma wrote:

" Well, if 2 are better than 1, and 4 are better than 2, then are 8 better than 4; are 16 better than 8? 32, 64, 128, 256...? (Is that a straw man argument, or, lacking other evidence, simply taking the argument to its logical conclusion?)"

My guess is that (aside from cost) practicality vs perceived utility is what sets the upper limit on the number of subs. For most people, apparently that number is either 0 or 1. For some, it is more.

Each additional sub offers LESS incremental improvement than the previous one, simply because there is less net increase in the spatial distribution (assuming the previous subs were intelligently distributed). Where the "point of diminishing returns" lies is arguably a judgment call, again with practicality probably being a major factor.

Duke

ONE:
Well, if 2 are better than 1, and 4 are better than 2, then are 8 better than 4; are 16 better than 8? 32, 64, 128, 256...? (Is that a straw man argument, or, lacking other evidence, simply taking the argument to its logical conclusion?)

TWO:
A friend of mine who was the audio guy for the Untied Nations and the DJ for the Nuyorican Poets Cafe gave me a tip, which I have to try over the weekend:

Put the sub in the spot where your listening chair is. Then walk around the room. When you find the spot where the bass sounds tightest and deepest, that’s the spot to place the sub.

Assuming this theory works, I’m hoping that spot isn’t in front of the door to the room.

dannad:
" There are two types of people, those who don't think low frequency bass is directional and accept that bass arrays must work, and those that think bass is directional and who put subs near their speakers invariably creating combing effects when there is bass leakage to higher frequencies either directly or through distortion that invariable is worse than any issues with directionality from a bass array."

     I just wanted to discuss dannard's comment above in a little more detail.
     I'm definitely in the camp that believes fundamental deep bass tones, under about 80 Hz, are not able to be localized without help from the naturally produced bass harmonics or overtones of these fundamental deep bass tones, that often extend well above 80 Hz and are able to be localized,  that are reproduced in stereo through the main speakers. 
     The key ingredient is our brain's amazingly sophisticated sound processing capabilities, developed and refined through the eons of evolution and natural selection to be currently finely honed in the vast majority of extant humans. One of the brain's extraordinary capabilities is the ability to associate the naturally produced bass harmonics or overtones of fundamental deep bass tones, that are above 80 Hz, reproduced in stereo through the main speakers and therefore localizable, with the fundamental deep bass tone itself, that are below 80 Hz, reproduced in mono through the sub(s) and therefore unlocalizable, and creates the perception of localizing the deep fundamental bass tone in space.
     This whole cerebral associative process, I believe, explains why , as dannard states:
" There are two types of people, those who don't think low frequency bass is directional and accept that bass arrays must work, and those that think bass is directional and who put subs near their speakers invariably creating combing effects when there is bass leakage to higher frequencies either directly or through distortion that invariable is worse than any issues with directionality from a bass array."

     I think there are two types of people as dannard states but I would describe them a bit differently:
1. Those that realize we all perceive deep bass tones below 80 Hz as not directional and therefore utilize bass arrays to obtain excellent bass performance.
2.  Those that believe deep bass tones below 80 Hz are directional, place a sub next to each main speaker to reproduce it and believe this configuration is responsible for their perceiving the deep bass below 80 Hz as stereo.  However, they're not realizing that their brain's ability to associate the mono fundamental deep bass tones, below 80 Hz that are actually being reproduced by their L+R  subs, with the stereo harmonics or overtones, above 80 Hz that are being reproduced by their main speakers, are the real reason they are perceiving the deep bass below 80 Hz as directional and in stereo.
     In my opinion, an understandable misunderstanding by group#2 above.  I don't think it's really a big deal, either, since both groups are ultimately perceiving the mono and nondirectional deep bass below 80 Hz as stereo.

Tim

Good bass is hard, really hard in most rooms. Bass arrays simple make good bass easier. There should be special emphasis on good. They do not magically create great bass, but then it is the rare audiophile with great bass.

There are two types of people, those who don't think low frequency bass is directional and accept that bass arrays must work, and those that think bass is directional and who put subs near their speakers invariably creating combing effects when there is bass leakage to higher frequencies either directly or through distortion that invariable is worse than any issues with directionality from a bass array.

Bass arrays by reducing peaks can even improve decay time and parasitic environmental vibration.


Audiophiles like to talk about fast bass, and then will go into great detail about damping factor, speaker design, woofer diameter and any number of other phantom impacts. Most of the perceived "speed" of bass is room decay. If you want truly fast bass, you have to address your room.  A bass array will help you get there, but can't solve all room issues. Most factory car audio systems have faster bass than high end home systems. Those windows may be reflective, but an automotive interior is filled with a lot of absorptive material by volume not to mention material specifically for sound deadening. Listen to how fast the bass is next time you are in the car.

@audiotroy

That's very nice, but what exactly does that have to do with what the OP was asking?Self promotion is tacky at best.

Things did not end well for Jaco. I love his playing early on before madness set in. He was homeless - Grace, peace compassion upon them. 
For students of the art, you might look into dual cone / dual voicecoil push pull drivers with a honeycomb core.... I listen to just such a hyper linear animal. You can almost get there in am opposed driver narrow cabinet... almost

There's something else, however, that's difficult for me to wrap my mind around. This forum insists on the importance of every detail, the importance of micromanaging every cable terminal and power source. Which is better for speaker cable elevation, cedar blocks or maple blocks? Where does one get just the right marble or granite for a speaker base? What color interconnects are the most transparent? (Blue ... no ... yellowwwwwwww!)

As me your questions OP, I am not afraid! 

You gest (I hope) but these are all serious questions. Well maybe not the color. But all the other stuff, yes it matters. Not just saying that. Actually tried and compared different wood, elevators, etc.  

And yet the discussion of multiple-sub array contains almost none of this fastidiousness. It's what academics would call a different discourse. It's by far the most casual approach to sound out here: mix and match inexpensive subs. What brand of subs? It doesn't really matter. What size? Also doesn't really matter. Should they be the same? Maybe, but it doesn't really matter. Where placed? It doesn't matter nearly as much as a single or pair. Connections, watts, power source? Doesn't really matter, relatively speaking.

My point is that, as an outsider to these technologies, the tenor of the discussion is completely different.

Good, grasshopper!

https://youtu.be/gbNCBVzPYak?t=56

There's two main reasons for this. One being the advantages of DBA are so overwhelming they tend to swamp the usual differences between subs. Things like size and power do matter. Its much better to have four really powerful high quality subs than four puny little cheap ones. Just don't be surprised if those four little ones kick butt on one big one that is much more expensive and powerful, even if it measures better. Its still just one. 

The other main reason is human beings simply do not hear very low the same as very high. Midrange and treble we localize to within a fraction of an inch. 30 Hz we have no idea whatsoever where its coming from. High frequencies we hear instantly. Low bass, less than a full wave and we don't hear anything at all. Finally there's the equal loudness thing. Really low bass doesn't even register until its much louder than the levels at which we can clearly hear midrange.  

Add all these up and it pretty well answers all your questions. It also answers the question of why its not more widely adopted. DBA shines a light on the fact our hearing is completely different with low frequencies than high. Therefore our system setup must take these two widely diverging aspects into account. Its a bit of a mental challenge. This may be the time to switch to a more modern movie metaphor and perform a Jedi mind trick.

Tim, "young grasshopper" works just fine. At nearly 60, I'm well past my meridian but always young at heart. My wife might use the word "immature," and she wouldn't be alone. 

The funny thing is that I've haunted stereo stores from New Haven to Maine since I was 16, and I've owned plenty of nice equipment (McIntosh tube amps, Maggies, Bryston, Nakamichi decks, CAL Audio, etc) but I've never taken the deep dive. I can feel myself coming over to the dark side...

northman:
" And yet the discussion of multiple-sub array contains almost none of this fastidiousness. It's what academics would call a different discourse. It's by far the most casual approach to sound out here: mix and match inexpensive subs. What brand of subs? It doesn't really matter. What size? Also doesn't really matter. Should they be the same? Maybe, but it doesn't really matter. Where placed? It doesn't matter nearly as much as a single or pair. Connections, watts, power source? Doesn't really matter, relatively speaking.

My point is that, as an outsider to these technologies, the tenor of the discussion is completely different. It's not only asking audiophiles to consider a new approach to sound reproduction but asking them to consider a completely different way of thinking about, and talking about, the hobby."

  Hello northman,
     
     Good points.  There actually is a lot of technical, fastidious, scientific and interesting reading material available on-line, supporting the effectiveness of utilizing multiple subs and distributed bass arrays (DBAs) in home audio sized room environments, if you desire to learn more on the subject.  
     I suggest googling the writings of Dr. Earl Geddes, Dr. Floyd Toole, Todd Welti of Harman International and Duke LeJeune of Audio Kinesis for a good sampling.  You could also google topics such as "the use of multiple subs for home audio", "distributed bass arrays",  " how to obtain better bass performance" along with other topics you may be interested in.
     The DBA and multiple sub concepts are not really new but the use of subs in home audio has been traditionally shunned by many 'audio purists' in this hobby ever since I started began my journey in it about 45 yrs ago.
     I've never felt the need to restrict my personal audio knowledge, experiences and adventures to the confines of audio purist approved traditional lore, tropes and dogmas.  I've continued to attempt to maintain an open mind, listen well to others' experiences and tried to gain knowledge through personal experience whenever possible.
     I suggest you attempt to do the same since we all ultimately discover our own personal truths and preferences along the way.  I've even found my personal truths and preferences to change and evolve over time utilizing the simple, honest and unfettered approach of judging things on their merits and calling them as you hear or see them
     There's no denying there'll be a lot to see, learn, experience, reject and object along your personal audio/video  journey. Enjoy the journey  and I hope you don't mind if I refer to you as 'tiger', 'sparky' or 'young grasshopper' a few times along the way.

Later,
  Tim
  
     

@northman  Excellent observation!!  Mix-and-match subs, but the orientation in the socket of the after-market fuse is absolutely crucial.

"The more things change, the more they change." William Shakespeare

I have two 15" Rel subs. One is setup at the front of the room on the right hand side and the other is facing towards the front on the left hand side of the room. I'm sure there's something better out there, but I can't imagine spending the money to try and surpass what I have.

@audiokinesis, and from a documentary I just watched, moving up the chain, it appears Geddy Lee’s inspiration is Jaco Pastorius.

I wondered if it was possible the bass traps simply didn't have the absorption (grunt) power to transform the energy from the subs, though enough to deal with the midbass??

The problem is standing waves in the room. Bass traps need to be where the standing waves are when they are reinforcing which sometimes might be near a wall but often is not, and they need to move dynamically from place to place as the frequency of the bass notes change. But they can't do anything about when the standing wave is causing a cancellation. So its an inelegant approach that simply won't solve the problem.

I hope this is not too far off topic but a quote here by bdp raised a question regarding dipole bass.  Anyone who can offer a knowledgable answer will be appreciated.

"The rear wave coming back to the woofer after it bounces off the wall behind it needs to be timed (1 ft. = approximately 1 ms.) so that the front and rear waves are in phase by the time they reach the listening location."

I've been aware of this time and distance relationship since reading about the Bell Labs experiments identifying the need to separate direct sound waves from reflected waves by at least 10 ms for clarity.  Thus a dipole speaker should be placed at least 5' our from the front wall (5+5=10 ms) for greatest clarity.

So how can it be calculated to assure rear waves are in phase for reinforcement?  I may be auditioning open baffle speakers, which includes the woofers, so how can I determine potential placement to simplify trial and error?

Concerning the swarm, I have heard a demo with that and was impressed.  But running wires and placement of four sub boxes will not be an option for me.

That sums it up nicely northman:-)

Rix, the stiffest enclosure would be a sphere. But that is difficult to produce. Next is a cylinder or tube as you suggest. This is a much easier design to deal with and perfect for a balanced force system. Just put a driver in both ends. I'm building 4 of them with 12" Morel drivers. Two in each cabinet.

For point source systems crossed over below 80 Hz it really does not matter where you place the subs as long as they are spread out always against a wall or in a corner.

For line source systems crossed over above 100 Hz you have to consider the affects on image and the increased power projection a line source has. The best way to do this is by creating  subwoofer line source along the front wall. It is still a "swarm" system of sorts just with a more specific radiation pattern. 

northman,

I've noticed this too.  Everything matters, except when it doesn't.

Renewed thanks for the lively conversation, which has been more than edifying. I don't have anything to add to the knowledgable posts but I do want to add one more reason for my original question. This thread contains some merited criticism of audiophiles who get stuck in their "snooty" ways, dealers who concentrate on the bottom line, speaker companies that are slow to update their design/marketing plans.

There's something else, however, that's difficult for me to wrap my mind around. This forum insists on the importance of every detail, the importance of micromanaging every cable terminal and power source. Which is better for speaker cable elevation, cedar blocks or maple blocks? Where does one get just the right marble or granite for a speaker base? What color interconnects are the most transparent? (Blue ... no ... yellowwwwwwww!)

And yet the discussion of multiple-sub array contains almost none of this fastidiousness. It's what academics would call a different discourse. It's by far the most casual approach to sound out here: mix and match inexpensive subs. What brand of subs? It doesn't really matter. What size? Also doesn't really matter. Should they be the same? Maybe, but it doesn't really matter. Where placed? It doesn't matter nearly as much as a single or pair. Connections, watts, power source? Doesn't really matter, relatively speaking.

My point is that, as an outsider to these technologies, the tenor of the discussion is completely different. It's not only asking audiophiles to consider a new approach to sound reproduction but asking them to consider a completely different way of thinking about, and talking about, the hobby.

Hello m-db,

     Duke is just being modest. After Earl Geddes generously bestowed the gift of his amazing DBA concept upon him many years ago, what did Duke do?
     He took the initiative to develop a 4-sub complete kit finished product that very successfully took advantage of this DBA concept at a very reasonable and affordable price, the Swarm, and has been one of the major advocates for the concept ever since. The Absolute Sound magazine has also awarded the Swarm its prestigious Golden Ear Award multiple times over the years. I believe this definitely qualifies Duke as being a world class Bassist.
     In fact, I give complete credit to Duke, along with his associate James Romeyn, and Dr. Earl Geddes for my ability to enjoy near sota bass response performance in my room and A/V system on a daily basis.

Thank you very much guys,
Tim

@millercarbon --

FIFY.

There is no "if" and, or but. Its excellent, period.

You're impervious to views countering yours - not much of a debate in that, only dictation leveled from one to the other. One thing is for sure: you love your own story. 

You're wrong about the 2 seats. The problem with fewer subs, yes you can get good bass at one or two places- but only by having too much elsewhere. The excess energy in these areas as it dissipates muddies the bass everywhere in the room. This is one reason DBA bass is so clean and articulate.

And yet, as stated earlier, we're several to prefer the presentation from 2 big subs vs. 4 smaller DBA's. In some cases this approach calls for mild PEQ and/or room treatment, but in either case it has been the preferred scenario. I'd cherish 2 more big subs like the ones I already have, but - as I've written earlier - space doesn't presently permit. 

You're wrong about the expense. DBA is actually the cheapest most cost effective solution. Yes you can spend a lot but the beauty of it is you can have truly awesome bass easily and for under $3k.

There's nothing snooty, hilarious, or sad about it. Your response, I mean. Just another failed put-down. Tiresome, is what I'd call it.

What are you rambling about? On the contrary I'm speaking in defense of DBA - read again:

"Let's be clear: what you're getting at is, essentially, spot on. The physics part of subs integration with a DBA gets annoyingly in the way of the audiophile snooty approach that loves what's more expensive is also necessarily better. It's hilarious as it is sad." 

M-db wrote: " Duke is a Bassist? "  

I manufacture bass guitar speaker cabinets and sometimes that gives the impression that I'm a bass player.  But I'm not.  

" Who's you're hero, inspiration? " 

One need not be a bass player to be inspired by Geddy Lee. 

Duke

This is actually an excellent summation

FIFY.

There is no "if" and, or but. Its excellent, period.

You're wrong about the 2 seats. The problem with fewer subs, yes you can get good bass at one or two places- but only by having too much elsewhere. The excess energy in these areas as it dissipates muddies the bass everywhere in the room. This is one reason DBA bass is so clean and articulate.

You're wrong about the expense. DBA is actually the cheapest most cost effective solution. Yes you can spend a lot but the beauty of it is you can have truly awesome bass easily and for under $3k.

There's nothing snooty, hilarious, or sad about it. Your response, I mean. Just another failed put-down. Tiresome, is what I'd call it.

Duke is a Bassist? 

Who's you're hero, inspiration?  

Mine is not likely typical. I tried to integrate subwoofers with Magnepan 0.7's and the subwoofer or pair of them always call attention to themselves without integrating into Magnepans. I wanted a more full bodied bass and I now use a pair of DWM's. My amplifier output transformers have taps at ground (for safety because the tubes run at 1 kV) 4 Ohms to which I connect the 0.7 : negative to ground and positive to the 4 Ohm tap, and the DWM "woofer" elements connected negative of one of them to the 8 Ohm tap, positive of said element to negative element of the second element of the same DWM (two 4 Ohm elements in series) and positive of the second element to the 16 Ohm tap. If you use an SET to work with Magnepans it takes an AM radio station transmitter tube such as an 833A.But I have heard subwoofers demonstrated at a high end store with dynamic element speakers and they improved the sense of image. My guess is a swarm might work with dynamic cone speakers.

@millercarbon --

...  since we all know no one or two subs can ever touch a DBA, then not only do the high-end dealers make money selling you the one sub that can’t work, they get to sell you another. And another. And another. And EQ. And more amps. And room treatments.

There’s simply way more money to be made selling audiophiles things that don’t work than things that do.

Especially if they first sell you on a good story. Which since you already know DBA works, and yet is not widely adopted, then you know how good they are at selling audiophiles on stories.

And that’s the real answer to your question. Why would anyone buy a sub? They don’t. They buy a story.

This is actually an excellent summation, if it weren't for the fact that a pair of subs can work wonders in a more limited number of seating areas. Really, why would you want smooth response most everywhere in the listening room when where you're seated is where you're seated, positioned most likely dead center in front of your main speakers and you're less than a goddamn convention of people? Yes yes, sans DSP and room treatment and what not and just close to an acoustical miracle left for you to savor relatively cheaply, but still; a pair of (not least bigger) subs can do great as well, and not only to the ears of some stubborn dumb asses that don't know any better. I have listened to DBA set-ups, not SWARM's per se but a variety of quad sub systems of greatly different sizes all from 8" DR woofers to 15"-loaded horn subs systems. By far the latter was the best, indeed some of if not the best I've ever heard/felt, but without a shred of a doubt I preferred dual sub set-ups with 2 x 18" ported DR woofers and even more so 15"-loaded tapped horns (from the pro arena), both placed symmetrically to the mains and crossed no lower than 80Hz, compared to asymmetrically placed DBA's with up to 12" DR sealed woofers and crossed somewhat lower.

I, indeed we don't know any better? Excuse me, but that would be plain arrogant, or, better yet: ignorant to presume. You're placing yourself on top of a pedestal taking a piss at what you haven't experienced, or if you have it wasn't your cup of tea (to each their own, perhaps?) - fair enough. However, this never gets through, and instead it's the same condescending diatribe again and again against anytime other or LESS (to your mind) than a DBA.

You guys love selling the DBA approach, but if bass quality and integration is anything to go by it seems I should be even more prolific with the traits of a pair of big, efficient, symmetrically placed and crossed-no-lower-than-80Hz subs. That's something to savor as well, but the same could, to a perhaps even higher degree than the audiophile resilience to DBA, be leveled: who cares?  

Let's be clear: what you're getting at is, essentially, spot on. The physics part of subs integration with a DBA gets annoyingly in the way of the audiophile snooty approach that loves what's more expensive is also necessarily better. It's hilarious as it is sad. 

@noble100 ,  Thanks for your helpful comments Tim.  In answer to your question, I have ordered a Swarm system.

Interesting comments on your experience with decay times.  In my case, REW shows the frequencies at which ringing is observed correspond to peaks in the frequency response curves, so I am pretty sure that these aberrations are due to room modes and not equipment.  I've got 3 GIK soffit traps, 3 RealTraps Mondo Traps, and 2 GIK Mega traps in the room, and these did a pretty good job of mitigating modal ringing.  What ringing remains is at a very low frequency where trapping struggles.  I've also got some speaker cabinet resonance adding to the delayed decay at the lowest frequencies. 

My thinking on removing the room treatments is that I will likely want to have one sub in a corner, and all of the corners are treated.  None of my corner treatments are permanently installed, so removal will be trivial, and doing so will allow me to select the best corner for placement of one sub.  

My room is dedicated, and I have almost complete freedom to place all 4 subs in all three dimensions. 

@noble100  
Always a +1!

+1 also to millercarbon for his advocacy in addressing the simple, inexpensive (and at times free) tweaks that most of us tend to ignore.  
I would just add for those out there attempting the sub elevation route to do the crawl method for any subs on the floor first.

In my 9' ceiling 14' x 16' room, I varied elevation of the two ceiling facing subs as a simplified "vertical crawl" method.

Latest interesting experiment has been angling the ceiling facing subs to 45 degrees relative to the ceiling.  

Not sure if this is an accurate description but it seems to have further evened out the tonal balance across the mid to lower frequency range.

There is a bit more realism as well in holographics and venue specific acoustics.  

Also apparent is an increase in sharpness (clarity?) in terms of  instrument location and soundstage height.

Lower midrange to low presence ringing that I noticed before are now significantly reduced.

Working on a ceiling mounted subwoofer isolation system that will allow horizontal and limited vertical placement in any direction.

Hanging 2 or more subs from the ceiling would likely exploit the possible sub placements in a truly 3D manner.

brownsfan:
" For those of you using DBA combined with room treatments, did you find that the DBA reduced ringing substantially without room treatments, or should I expect my Swarm to primarily rectify nulls at the MLP and expect that the traps will be required to achieve good decay times?"

 noble100:  My negative experiences with decay times in my room and system actually occurred prior to even using a DBA and concerned the opposite of ringing, which was the truncation of decay times.   I've noticed this unnatural and premature cutoff of normal note decay times on both my former pair of Magnepan 2.7QR main speakers, driven by a stereo class D amp, and a pair of 12" subs with built-in class D amps. 
     I'm fairly certain the cause in both cases was the extremely high damping factors characteristic of class D amps in general, which are typically rated in the low thousands as opposed to usually being rated in the low hundreds for class AB amps. 
     The higher the damping factor, the more firmly an amp has control over the starting and stopping of drivers, in my former case the large 623 sq.in. planar-magnetic bass section in each of my former 2.7QR speakers and the 12" dynamic cone woofer drivers in each of my former self-amplified subs.
     Since replacing my dual self amplified subs 4 yrs ago, with the AK 4-sub Debra DBA powered by a 1K watt class AB amp, I've definitely noticed the bass note decay times are somewhat longer, more accurate and more natural with a total lack of truncation or ringing.   I've never experienced boominess or ringing with my DBA, either with zero bass room treatments prior or extensive bass room treatments currently. I seriously doubt you will experience any negative bass performance issues in your room, either.
     

brownsfan:
" I guess my plan would be to remove room treatments and optimize the bass response without room treatment, then add back the bass traps judiciously to further improve frequency response and ringing.  BTW, mains are down 3 dB at 27 Hz, but I have decent response down to 20Hz or so.  Is that a reasonable approach?"

noble100:  It's an approach, but I really don't believe it's necessary.  When I installed extensive room treatments in my room, I just made sure that none of the subs were firing directly into a wall or corner bass trap, ensuring each had at least a small section of bare wall to launch their bass sound waves into and not being in very close proximity to a bass trap.  This produced very good results in my room.
     Your mains already have fairly deep rated bass extension.  I think it would be more beneficial for you to pay close attention to the volume and crossover frequency control settings on your subs, as well as the slopes of the subs' crossover filters.
     Are you planning on using an AK Swarm or Debra complete kit DBA or creating a custom 4-sub DBA using self-amplified subs?   I can better tailor my advice knowing the details.

brownsfan:
" Finally, I've read about the crawl approach to optimal placement on the Audiokinesis site, but I'm thinking of using REW to supplement what I hear.  Anyone find REW useful in Swarm sub placement? "

noble100:  I sequentially and optimally positioned each of my AK Debra subs utilizing the crawl method.  I've never used REW or any room correction software/hardware, room analysis or mics but I do recognize their usefulness. 
     My best advice would be to first locate each sub using the crawl method and then utilize REW to further fine tune and verify optimum positioning.  Ideally, they'll result in the same position but, if not, it'll be at your discretion.

Best wishes,
   Tim
      

@mijostyn -
I have full access to a cabinet making shop. I've been splitting planks on a band saw, running them through a thickness planer (before and after), joining the solid cherry wood (often with a biscuit joiner). Attempting to build four units from AcousticFields QRD 17 diffusers plans. I have only just managed to get the materials list for the diffusers, and I am going to have to let my friend program the CNC so I can get table time to cut the panels for assembly. I have some skills, always learning more.

I worked for a loudspeaker designer, my system page has photos of my current two pairs of speakers during glue up. I'm probably not going to do steel lined sub woofer enclosures though (so far the most rigid enclosure I have made is high density fiber board, 1.6 times denser than MDF, laminated to steel plate). My larger stand mounts are in the high 90lbs each. Stiffest enclosure shape might actually be a tube with baffles on the ends, not the most practical of shapes though without creating a stand of sorts.

I have a Tympnay LAT, it was controlled by a DSP, and I have to say I love the sound and without vibrations. Personal taste obviously, I was hoping a slot loaded W frame would do similar to the LAT.

The more I read, the more I want to both elevate and maybe try more subs as well.

Sorry I went off SWARM topic, but today whilst trudging through a quagmire I was considering the GIK bass traps and not affecting the SWARM sound.
I wondered if it was possible the bass traps simply didn't have the absorption (grunt) power to transform the energy from the subs, though enough to deal with the midbass??

From what I have been reading, and researching, the claims are by many that low frequency waves are very challenging and often traditional fiberglass traps simply don't have the power to deal with them as well as other frequencies.

Speculation of course.

Rix, I would forget about open baffle subwoofers. Hold on to your opposed driver balanced force design. Work on creating a very stiff, heavy enclosure design of the right size to support the two drivers. What is the stiffest enclosure shape you could use? If you have more or less advanced woodworking capabilities give me a shout and we can discuss it:)

@tyray 
Thanks!
Yes, I do have the swarm.

I have my mains placed on the long wall with a ceiling facing sub in each front wall corner.

These two subs are on the top of metal shelf units. What's nice is being able to place a monoblock lower down on each shelf.
The shelves also provide some diffusion in each corner.

One floor sub is flush against the right wall facing forward just shy of the first reflection point.
(Duke recommends facing them towards the wall with about 3" clearance.  I figured facing them forward allows them to be closer to the wall)

The other floor sub is flush against the rear wall behind me and to my left.  This sub is facing to my left.

Since the metal shelf units allow for shelf height adjustments in one inch increments, I have staggered the heights of the two ceiling facing subs.

I lowered the left front ceiling facing sub so that it is just a little closer to the ceiling that the floor. 

FWIW - I find that the ceiling facing subs need a bit more than 3" clearance.  I tried facing them away from the ceiling which helped a little.
But lowering the right another 6" and the left another 18" really made a noticeable difference.

I am now considering raising one of the two floor subs up to just under halfway to the ceiling.

Despite the different elevations, Duke's recommendation for reversing polarity on the sub farthest from the mains and removing the port plug on one of the subs in the corner works really well.

Though it is difficult to A/B test due to the time it takes to move a sub, adjust the shelf height and muscle the sub back up on the shelf,
I can hear a tighter and more even integration with the mains.

Can't really describe it other than the music sounding more "correct".
Probably because the two ceiling facing subs, due to their lower heights are closer to me and also my ear height while seated in my listening chair.  

Perhaps, like staggering drivers in some speakers for better time alignment, I am achieving similar results.

Now that I have a second Dayton, the next step will be running two subs off each at 90 degrees out of phase. 

I can tell you this ..... for years I had a surround system with Thiel 3.5s C/FL/FR and 2.2's RL and RR.  Five speakers, three flat to near 20hz and two flat to about 35hz.  The bass was incredible .... as low as any recording I had (including the St Saen's Organ Symphony) were reproduced with NO room effects whatsoever.  I vote for "Swarm".

Now in the new house, with a bigger listening room (14 x 17) I have 2 subs on the floor but still have 2 up high facing the ceiling.

@hleeid,

Sounds so cool!
I think you do have the swarm right? Where are your subs located in the new room?

Thanks for your patience and interest.....

My best to you....

Thank you mahgister. 

Duke

I called them active because they resonate in diffusing the sound....They are also many of them connected to my Shumann generators.... I use also Helmholtz resonators....But the resonators i use most were cheap brass cap or cone of different size in some grids...Connected or not... With some minerals in the center or not..... My diffusors plays a great role also... I use a grid of "strings of cheap minerals" suspended from the ceilings, some are connected some not.....Very efficient to diffuse the sound.... The main problem was for me the balance between reflective, absorbent and diffusive surface or device...

They are certainly audible because i only use my ears.... :)

I take many months to create this room.... And there is no comparison at all in nearfield or regular position with before and after....

It is why acoustic control for me exceed often upgrading electronic component in powerful transformation of S.Q.

Thank you mahgister.

What do you mean by "active resonators"? Are these Helmholtz resonators, and/or do they have moving parts? Do they operate in the audible band? 

Duke

@mahgister,

Why not start a thread with a detailed explanation of your three infamous embeddings? I think it’s long overdue :-)

Active devices controls of the room with a balance between, absorption, reflections, and diffusions, and using device (different diffusors of my creation and active resonators connected to a grid of low cost Schumann generators) to take the positive side of reverberations for example....

Active because i connect them to the S.G..... And the different resonators of different size .... I use my audio room only for music then it is possible to experiment....In a common room my device are not esthetical nor practical....

But i think it is not the thread to describe these unorthodox experiments of mine...My only point is treating the room must be made for all frequencies and in relation to timbre accuracy first and not bass....

:)

 I apologize for having disrupted this thread.....

My best to all....

Mahgister wrote:

"With acoustic ACTIVE devices controls and not only PASSIVE materials treatment, they gives me so much bass..."

"You forget Active acoustical device controls..."

"For example how do we use reverberations in a positive way to make the sound more alive with only a passive treatment? No way, it takes active acoustical control devices..."

"Active acoustic devices controls seems totally unknown"

"The easiest low cost way to improve bass is to improve the acoustical settings controls of the room not only passively but actively..."

You mention ACTIVE acoustical control devices many times, in this thread and elsewhere, and I don’t know what you are referring to.

Can you describe or explain what they are?

Duke

@tyray
 Then reading more in agon Duke did suggest to the things he told you to do with your subs, then I can't remember if it was Duke on some other reading but 'if you can raise one up towards the ceiling'. What!

Yes, that was Duke who suggested raising one or more subs up towards the ceiling here on agon.

I had decided against the Swarm for my 10 x 12 room until I read the same posting.

It was in that small room that I used a metal shelving unit in each front corner to place a ceiling facing sub with about 4" clearance.

A third ceiling facing sub was mounted on a shelf above and behind my listening chair.

After minimal placement adjustments, I had really great bass response in the small room.

No other single sub worked.  I was literally in a state of awe and shock at how the 4 subs significantly improved my listening experience across different kinds of music at most any volume.

Now in the new house, with a bigger listening room (14 x 17) I have 2 subs on the floor but still have 2 up high facing the ceiling.

I agree with you about being glad you actually tried and elevated a sub.  It really does work!

The ceiling facing subs do noticeably contribute to the vertical plane dispersion. The shelf units in each front corner provide some diffusion and are great for housing gear too!

I have a monoblock at the bottom of each shelf unit which helped streamline the crowded gear rack between my mains.

So I think most people would agree that addressing excess decay times (ringing) is as important or more important that flat frequency response.  I've added a good bit of range limited traps to my room which have helped substantially to reduce ringing.  Overall, the room is about 20% treated with the vast majority being range limited bass traps (GIK Soffit/Mega and Realtraps Mondo limp membranes) in the corners and front wall.

For those of you using DBA combined with room treatments, did you find that the DBA reduced ringing substantially without room treatments, or should I expect my Swarm to primarily rectify nulls at the MLP and expect that the traps will be required to achieve good decay times?

I guess my plan would be to remove room treatments and optimize the bass response without room treatment, then add back the bass traps judiciously to further improve frequency response and ringing.  BTW, mains are down 3 dB at 27 Hz, but I have decent response down to 20Hz or so.  Is that a reasonable approach?

Finally, I've read about the crawl approach to optimal placement on the Audiokinesis site, but I'm thinking of using REW to supplement what I hear.  Anyone find REW useful in Swarm sub placement?

veerossi:
" I'm at a point where I have the gear I want and I have setup my speakers to the best of my ability. Room treatment is my next project. I know you went the GIK route. Sounds like all went well. What do you think about Acousticfields vs GIK vs others? What made you go GIK?"

Hello veerossi,
       I checked out the Acousticfields' website and their products seem to be of very high quality.  I think I considered them when I was looking for a room treatment vendor but thought they were a bit on the expensive side and I didn't know if the premium prices were justified.  I noticed they also offer a free room analysis just like GIK.
     I went with GIK mainly because a lot of members here seemed to like their performance, I liked their variety of treatments, especially the canvas art panels my wife really liked (which was important to me since it's her living room, too.) and they seemed like high quality treatments at reasonable prices.  I knew good quality treatments wouldn't be cheap but I wasn't looking to get fleeced, either. 
     Overall, I'm very pleased with the performance, fit and finish, customer service and total costs of the GIK products.  I'm not certain but I suspect the Acousticfields treatments are a step above the GIK in quality but also in price.  
     I'd suggest you take advantage of getting a free analysis from both companies, which will include a list of recommended products along with a total price quote, which will probably help with your decision.  This process also provides info on their customer service quality levels and differences along with the interesting and fun of comparing 2 complete and independent plans and strategies for your room.

Best wishes,
    Tim

Hello millercarbon,

      I bet our room bass qualities are very close.  I was so concerned the bass traps might detract from my DBA's bass quality, I was initially going to delete all the bass traps from GIK's plan for my room.  There was a lot of them and those GIK bass traps aren't cheap.  I know the DBA concept works perfectly with no bass traps at all and the absolute last thing I wanted to do is detract from its high quality bass in any way.  
      I believe anyone who's personally experienced the DBA's performance would feel the same way.  I've never really liked the idea of bass traps and these are the first I've ever used; they've never made much sense to me.  Your system produces bass and then the bass traps reduces it?  Huh?  It's always reminded me of running the AC with the windows open. 
      I know it's more complex than that, I probably just don't completely understand the acoustic dynamics at work and they could be the reason my system's performance from the midrange on up, along with sound stage imaging, has never sounded better.  I'm trusting some experts, GIK and Duke. they haven't steered me wrong yet and overall I'm very pleased with my GIK investment.

Later,
Tim

Your room is so close to mine-  within about a foot each way- and your DBA so similar to mine, we should have virtually the same high quality bass. Anyway, I can hardly imagine how bass traps would be an improvement.

rixthetrick:
" mahgister Yeah, but did you have a swarm or an array of sub woofers?
If you did not, he was very specific in saying that he did, for many years, before applying room treatment. And it was in other areas he found the more significant performance increase with correct room treatment. The sub array had benefits all on it's own, would be my guess?"

Hello rixthetrick,
     You are correct, my AK Debra DBA performed exceptionally well in my room and system, very close to identically from my perspective, whether there were virtually zero professional room bass trap treatments or a complete GIK recommended quantity of them in my room.  I was actually expecting and hoping for at least some slight improvements but failed to notice any.
     I should note for clarity that there were no before and after room analysis measurements taken of my room to verify there were no improvements in bass performance resulting from the addition of the multiple GIK bass traps.  My comments are based only on my personal and subjective perceptions.

Enjoy,
Tim