New Magnepan "Concept Speaker" introduced at Audio Connection

Just saw a Youtube clip by the Audiophiliac Steve Guttenberg on this new design by Magnepan. He raved about these speakers on the realism that they created. Anyone else heard these???
We were asked how seamless the mid/lower base integrated with the ribbon speaker.  From my listening I thought the concept speaker system did a very good job.  I could not hear a disconnect that one would hear with other speakers.  As always the maggies had a sense of realism.
I was there, and it was just like Steve said -- they’re the best speakers I’ve ever heard. Stunningly realistic.

I didn’t have a real idea of what they could do until they played the last track, after most of the guys had left. Someone asked them to play Stravinsky’s Firebird Suite and Jesus, they did everything, from the most delicate detail to orchestra hits that made you jump. They seemed to combine the detail and imaging of panels with the slam of dynamics.

I told Wendell Diller that he should have played that cut first, and he said he puts on classical music when he wants to get people to leave the room. :-)
Does anyone know what amp and how much power was driving these? When I went to the 30.7 demo they sounded very good as they were powered by Mark Levinson No. 53 Monoblocks (500w into 8 ohms 1000w into 4).
I attended Mr. Diller’s Magnepan 30.7 demo in Indy a few months ago and those speakers are excellent but are priced at about $30K. I asked Wendell if he ever thought about combining and offering a 4-sub distributed bass array system (DBA) with a high quality pair of Magnepan panels for the mids and treble for a more reasonable price.
Unfortunately based on his reaction, I don’t believe he has ever heard of the DBA concept and how effective it has been proven to work in virtually any room both scientifically and anecdotally.
I knew at the time that I didn’t need to wait for Wendell to become enlightened to the DBA concept with Magnepans because I’d already been using an Audio Kinesis Debra 4-sub complete DBA system kit with an older pair of Magnepan 2.7QR speakers for about 4 years with excellent results; providing bass that is powerful, dynamic, smooth, fast, seemingly effortless that seamlessly integrates with the main speakers.
The $3K Swarm or Debra kit consists of four relatively small 4 ohm subs (14"w x 12"d x 24"h and 44 lbs that each contain a 10" aluminum long-throw driver and four port plugs for the choice of either ported or sealed sub operation) and a 1K watt class AB amp/control unit for powering all four subs in mono and setting the volume, crossover frequency and phase of all four subs as a group.
Knowing a mini Magnepan 30.7 system was a very good concept and for anyone else who thinks they may want to approximate this type of overall sound quality in their home, I believe I’ve discovered a method to achieve this; I replaced my older pair of 2.7QR with a preowned pair of Magnepan 3.7i speakers and combined it with my AK 4-sub DBA system. I’m using a Synology 20 TB NAS feeding a Lumin D2 dac/streamer a combination of FLAC, WAV and DSD music files with the output sent via balanced cables to the balanced inputs on a Levinson 326S preamp and on to the balanced inputs of a pair of D-Sonic M3-600-M class D mono-blocks. The D-Sonic amps provide 1,200 watts to the 4 ohm 3.7is which drive them very well.
The 3.7i have more midrange and treble energy than my former 2.7QR, with a much newer and improved quasi-ribbon mid-range section and a true ribbon treble section that allows for a very smooth, detailed, neutral and natural midrange/treble presentation that’s never harsh or bright and has a very high quality sound. Combined with the near state of the art bass performance provided by the AK’s 4-sub DBA system that seamlessly integrates, the result is an overall high quality sound from top to bottom that I perceive as very similar to a mini version of the Magnepan 30.7’s traditional open, natural Magnepan sound but with significantly better bass quality and a more dynamic quality overall.

But hey, we all know how subjective this whole home audio hobby can be. My main point is that the combo of a pair of 3.7i with high quality mid/treble and imaging performance paired with a 4-sub DBA system with high quality bass performance, in my opinion, already represents a legitimate mini 30.7 system at a fraction of the price. I paid less than $7,500 for a preowned pair of 3.7is and a new AK 4-sub DBA system.
I can certainly confirm that my custom mini 30.7 system combo sounds spectacular and definitely exceeded my expectations.

The open question is how much will they cost?

The 30.7 sounded poor in 3/4ths of the road trip demos, and 2 years later how many dealers have sold even one pair?

The top Magnepans (30.7 and 20.7) are not even on demo at most all the dealers.

If Magnepan is to compete with Magico and Wilson, the dealers need demos in the stores!

Also the new swarm milti-subwoofer type of arrangement with a 3.7i or 20,7 may be as good, and much cheaper.

More appealing to frugal Magnepan buyers.

Magnepan does not have the "snob appeal" that the real big buck high end buyer desires.

@don_c55 Your last sentence says a lot! It is so very true. I had a long discussion with Wendell about this very issue when I was at his 30.7 demo. Wendell stated something that I think is very much on point...he does not want to make speakers for the rich and the entitled.
Instead, he is trying to bring speakers to the market that have a wide appeal to the music lover, without having to require that they have ’deep pockets’.
As such, I mentioned to him that perhaps from a marketing perspective he is actually hurting himself!! The ’cachet’ attached to the price is what appeals to so many ’neophyte’ audiophiles. Pathetic in the extreme IMO, but still a major factor.
The new ’concept speaker’ will still suffer from the same issue...too inexpensive to be good.
BTW, I guess I was one of the few folks who heard the new 30.7’s ( and after some minor room acoustic mods and placement changes that we ’convinced’ Wendell to do) thought it was a superb sounding speaker.
Kudos to Wendell for doing what he is attempting to do...
Thanks for all the informative responses to this thread. I have listened to several setups at various HiFi shops with the Magnepan 3.7i and have always liked the sound. One system had a REL sub connected to it and it sounded really punchy with the 3.7i's. Steve Guttenberg didn't say much about the build of the speaker other than it was a ribbon design. Does it have conventional cone woofers like a hybrid, or no???
Cheers to all, and Merry Christmas!
     I agree that the 30.7 is a great sounding pair of speakers but I'm really not looking to impress anyone except myself and my wife with my audio/video system and they're friggin'  $30K a pair.  Did I mention that I'm a frugal guy?
     I think a frugal music lover is a good description of myself.  I really enjoyed the 30.7 but never seriously considered buying a pair.  I'm frugal but willing to spend money on high quality audio equipment if I believe it's going to make my music sound better and I consider the equipment somewhat of a bargain.  I think that's what attracted me to the idea of a mini 30.7 system, although I didn't think of my system as a mini anything until I read this thread.
      I was just very interested in upgrading my almost 25 year old 2.7QRs to a pair of 3.7is and already was well acquainted with the high quality 4-sub DBA system that would be an ideal pairing with them.  In fact, I'm so frugal I was originally considering pairing my 4-sub DBA system with a pair of LRS or 1.7i until I auditioned a pair of 3.7i.  To satisfy my frugal and bargain hunting nature, I bought a pre-owned pair of 3.7i for about $2K less than a new pair.
     But I really do believe that combining a pair of 3.7i with a 4-sub AK DBA is one of the rare true bargains in high-end audio after experiencing the extremely high sound quality obtained through this bargain combination for a total of exactly 5 days thus far.  I live in a suburb just north of Indy if anyone lives in the vicinity and would care for an audition, just send me a pm.

janmnov, the panels were being driven by the Maggie 300, a 300 WPC amp that will be manufactured by the Minnesota Amplifier Company and that Wendell has been showing at some of his demos. The woofers had a large Bryston on them -- a commercial version would come with a dedicated woofer amp.
mr_m:"Does it have conventional cone woofers like a hybrid, or no???"

     The 3.7i are dipole 3-way planar-magnetic panel speakers with a true ribbon treble section, a quasi-ribbon midrange section and a quasi-ribbon bass section.  The true-ribbon is very delicate and light weight foil transducer which results in it being very fast, accurate and detailed.  The quasi-ribbon transducers consist of a slightly heavier polymer material which are also quite fast, accurate and detailed but just not to the same extreme degree as the true-ribbon. Both ribbon types utilize precisely placed small magnets for controlling movement and sonic output.
     I was a bit concerned that the 3.7i's true ribbon treble might sound overly bright or harsh in my room currently lacking acoustic room treatments (soon to be remedied via several GIK products), thinking I likely would install the provided resistor to attenuate its output.  But I've been experiencing nothing but very high quality and detailed treble response thus far with no sense of brightness or harshness playing them unrestricted.

Josh358,  Thanks for that. Let’s hope a commercial version might give us a choice to use amps of our choice, if possible.  Time will tell.
If you get a chance a must audition of a planar magnetic speaker is the GT Audio Works.
TheyDo not use a crossover on the main 6 foot planar magnetic panel and rely upon a sophisticated open baffle servo woofer system.
Herb Reichert from Stereophile said they sounded fantastic at Capital Audiofest and said they could go toe to toe with any speaker cost no object.
I’m proof that a DBA can work with Maggie’s, I built my system around the concept. It’s all active with a mini DSP, 8 channels (4 subs) with 12 biquad filters on each. The filters were generated with an Earthworks Mic that measures +-30k using Room EQ Wizard, results plugged into Multi Sub Optimizer without any restrictions.  The results are breathless, total seamless integration. I had a friend over who notes that the 20.1’s were full range speakers and asked me to turn off the subs as he couldn’t hear them. I muted them and played the same piece and he couldn’t believe the difference. I just wanted to affirm the statements above that DBA’s work wonders and is the only real way to tame low end room distortion and seamless integration in my opinion. 
I wish I had known about this demo at Audio Connection.
I definitely would have stopped by.
So what's the deal with this concept speaker ?
A departure from planar bass to OB dynamic bass drivers ?
Sounds very interesting.
Can anyone elaborate ??

"The bass unit was about 3 feet tall and about 1 foot wide. The cabinet or structure consisted of a V shaped open baffle with 8 total drivers—4 vertically mounted dynamic cone woofers on each side of the V. These woofers were approximately 6.5 inches in diameter. Though there has been several dynamic cone dipolar designs attempted before, Wendell commented that this was a unique design that utilizes DSP and would eventually be patented. Yes, I said DSP! "
To what gnjtack said, I'd add that the planar panels are only 12" wide and use technology adapted from the 30.7. So you could think of it as a 30.7 with compact dynamic dipole woofers. Also that the DSP is used only on the woofers -- if Magnepan commercializes the concept, it will come with DSP and a high-powered woofer amp (the panels will be powered by your own amplifier).

The open baffle servo-feedback bass system used in the GT Audio Works magnetic-planar loudspeaker mentioned by faxer above is the GR Research/Rythmik sub. It is available separately from both GR Research and Rythmik, and can be used with any loudspeaker. It is THE ultimate sub for all planar loudspeakers, as it’s dipole characteristics make it possible to blend seamlessly with them as no monopole woofer can (even in swarm fashion). It also features the Rythmik servo-feedback system, which when combined with the virtues of ob bass, creates the best bass reproduction you’re ever likely to hear. It has found favour with owners of Maggies, Quads, Eminent Technology LFT’s, Acoustats, and of course GR Research speaker owners.

But the Magnepan "Project" loudspeaker is a complete package, including the "midbass coupler" used in the 30.7, as well as the fantastic Maggie ribbon tweeter used in the 3.7i/20.71/30.7. It will be interesting to compare the Magnepan OB woofer system with that of GR Research/Rythmik. The GRR/R uses 2 or 3 (or more!) 12" woofers per side, the Magnepan eight 6.5" per. The GRR/R uses servo-feedback woofers, the Magnepan DSP. Should be interesting!

That would be interesting. Though they have different purposes, in that the Magenpan woofer is designed to be small and easy to hide. When it comes to output and bottom-octave performance, I've no doubt that the GR Research/Rhythmik comes out ahead -- but you can't hide those big H frames behind the couch!

     It makes a lot of sense that the true-ribbon and quasi-ribbon dipole plana-magnetic transducers, for the midrange and treble output, are positioned next to each other in the same panel.  This is because soundwaves in these frequency ranges have a very directional radiation pattern that need to be precisely positioned in relation to the listener's ear positions when seated at the designated listening position in the room for optimum midrange, treble and imaging results.  
     Conversely, it makes very little sense for bass transducers, in any form (dipole, open baffle or dynamic), to be positioned in the same panels with or even in close proximity to the panels containing the midrange and treble transducers.  This is mainly due to the fact that bass frequency complete cycle soundwaves are physically much longer than midrange and treble frequency complete cycle soundwaves.  The lower the frequency, the longer its complete cycle soundwave and the higher the frequency, the shorter its complete cycle soundwave.
     This results in a continuum of all audible frequencies having complete cycle soundwave lengths that are directly proportional; from the deepest audible frequency of 20 Hz having a complete cycle soundwave length of about 56 feet  to the highest audible frequency of 20,000 Hz having a complete cycle soundwave length of a fraction of an inch. 
      Greater understanding of how we all perceive sound is gained by the fact that we are unable to localize sounds (determine exactly where the sound is originating from) at frequencies of about 80 Hz or less but increasingly more adept at localizing sounds at frequencies of about 80 Hz and above. 
      Some deep bass soundwaves have actual lengths that exceed the physical room dimensions in many typical domestic listening rooms and humans require at least one complete full cycle bass soundwave to be present in the room before our ears can detect it, send the information to our brains and have the brain create the perception of the corresponding bass tone. The brain also requires the input of multiple complete full cycle bass soundwaves to create the perception of a change in bass pitch.  By contrast, our brains have a relatively easy task of creating midrange and treble tone and pitch perceptions due to their much shorter soundwaves.
     Given the above, my main concern is the bass response performance of the Magnepan "Concept Speaker".  Would I consider its bass performance, utilizing DSP but only 2 bass cabinets of unknown design with 6.5" woofers and seemingly positioned haphazardly, as fast, smooth, powerful, dynamic, effortless and detailed as the Audio Kinesis Swarm/Debra distributed bass array system (DBA), utilizing no DSP but 4 bass cabinets of sealed or ported design with 10" woofers and each sub positioned strategically and sequentially?  
     I think it's only fair that I reserve judgement until I actually listen to it.  I attended a Wendell led demo of the $30K 30.7 speakers at a local high-end shop here in Indy a few months ago and was highly impressed. 
     When I asked him whether he ever considered combining the 30.7 or 3.7i speakers with a AK or custom 4-sub DBA system at a significantly reduced price, however, he seemed to be completely unaware of the scientifically proven and very effective 4-sub DBA concept.  
     This was not very confidence instilling but I decided to buy a pre-owned pair of 3.7i anyway and create my own "concept speakers".  I'm certain that this combination represents a smaller version of most of the 30.7's very impressive attributes at a significantly reduced price of less than $10K, even with both purchased brand new.


Tim, Duke of Audio Kinesis was asked by the owner of a planar loudspeaker if his Swarm or an OB/Dipole woofer system would meld better with the planar loudspeaker. Duke recommended the OB/Dipole. The monopole characteristics of sealed and ported subs is a major factor in making the seamless integration of planars and subs as unsuccessful as so many have found it to be. Magnepan chose to go with an OB/Dipole woofer system in the proposed new model for exactly that reason.

The distributed array bass system addresses the problem of bass/room interaction, but does nothing to address the issue of the difference between monopole and dipole propagation. OB/Dipole woofers eliminate that difference. 

What BDP24 said -- four monopoles are as smooth as two dipoles, but the backwave of a dipole will cancel with the backwave of a monopole, so the crossover will always be somewhat problematic.

Another consideration here is that the 30.7FC is intended to address the needs of the "conflicted couple." The ability to hide the woofers was an important consideration in the design. 
Hello bdp24 and josh358,

     Have you two gentlemen ever listened to a pair of the Magnepan DWM dipole woofer panels? I intentionally described them as woofer panels, as opposed to subwoofer panels, because they only have rated bass output extension down to 40 Hz. I’ve listened to all the latest Magnepan speakers, all 3 top models from the 3.7i on up to the 30.7, combined with a pair of DWM dipole woofer panels and the bass they contribute is very well integrated with all 3 pairs of main speakers but their bass contributions always sounded to me as no deeper or impactful than mid-bass
     Heck, each of my Magnepan 3.7i speakers basically have a large built-in dipole woofer section that are rated to have bass output extension deeper than the DWMs, down to 35 Hz. I run the 3.7i pair full-range and utilize the 4-sub AK Debra DBA system, with all 4 subs powered by the included 1,200 watt class AB amp/control unit and the crossover control set at 40 Hz, to supplement the bass in my system from 20 to 40 Hz.
     From first hand experience using the monopole 4-sub AK Debra system with large 6’x2’ 3-way Magnepan dipole planar-magnetic panel speakers (initially the 2.7QR and now with the 3.7i) for the past 4 years, I can state with certainty that the bass produced by the AK 4-sub DBA system is just as fast, smooth, effortless, natural, detailed and seamlessly integrated with my main panels as the dual DWM bass panels I’ve heard, but with significantly better bass impact, dynamics and extension. It’s the difference between hearing some additional mid-bass emphasis and hearing as well as feeling the bass as experienced when music is heard and felt played live in person.
     I’ve always respected Duke’s knowledge and experience and am aware he has made very positive statements in the past about the general bass quality produced by open baffle, line source and dipole speakers and subs. If he ever made the statement bdp24 has claimed, however, I seriously doubt Duke was referring specifically to comparing the bass performance of a pair of Magnepan dipole DWM panels to the bass performance of his AK Swarm or Debra monopole 4-sub DBA system. The differences in their bass performance quality are just too obvious and stark.
     Jdp24 made the following 2 related statements:
#1: "The monopole characteristics of sealed and ported subs is a major factor in making the seamless integration of planars and subs as unsuccessful as so many have found it to be. Magnepan chose to go with an OB/Dipole woofer system in the proposed new model for exactly that reason.?"

#2: "The distributed array bass system addresses the problem of bass/room interaction, but does nothing to address the issue of the difference between monopole and dipole propagation. OB/Dipole woofers eliminate that difference. "

     Both of these statements are demonstrably false and just serve to acknowledge your obvious lack of knowledge of, and experience with, the 4-monopole sub DBA concept that’s been scientifically proven to be remarkably effective in virtually any room and with any pair of main speakers by 2 separate PHD acoustical scientists, Dr. Earl Geddes and Dr. Floyd Toole,
     You and any thread readers interested in research on the acoustics of attaining exceptionally good in-room bass response in domestic sized rooms can google both of these names and find an abundance of factual information on how and why the 4-sub DBA concept was developed based on these men’s research, along with the related contributions of Duke Lejeune and Todd Welti.


Yup, I’ve heard the DWM panels. They were never offered as a subwoofer, but rather as additional woofers, to help bring up the level of the Magnepan speaker’s bottom end as it dropped off (due to a couple reasons, including dipole cancellation). I’ve always considered them over-priced for the little bass reinforcement they afford.

It was here on an Audiogon post that I read of Duke telling an interested party that he recommended a dipole sub for use with dipole loudspeakers over a distributed bass array. I wouldn’t know how to find it now, but perhaps someone remembers it.

Tim, if you hear no discontinuity between your Maggies and your subs, congratulations, your search has ended successfully! Since there are far more monopole loudspeakers out there than dipoles, there is a huge market for the distributed bass array sub systems now available. We agree that everyone should check them out. When I hear live electronically-created music (as opposed to purely acoustic), one of the main things I am aware of is the weight of the sound. I will never forget the sound Of John Entwistle’s electric bass/amp! The most massive thing I've ever heard, and I've been on a stage with a Hammond B-3 with a Leslie!

Most hi-fi systems sound bass-shy to me: all upper bass, midrange, and highs, lacking the heft, the weight of the live experience. Some of that is of course a result of live SPL, not all of it. Most speakers can’t play the bottom octave (16-32Hz, or 20-40Hz) AT ALL. Everything down there is doubling and distortion. You don’t have to put up with that, people!

I don't think anyone was questioning the quality of a four-woofer array. The research demonstrating that is well known, and as I said, a speaker designer I know (who played a role in the development of the new Maggie) compared four sealed woofers with two planar woofers and found their quality comparable.

I'd point out, though, that the new woofer is *not* a DWM, or a planar woofer at all. It's a dynamic dipole woofer that has response similar to the response of the 30.7's bass panels. Which is to say it isn't a sub, but neither is it a DWM, which is designed to reinforce the midbass and has limited output. It's designed to be small and easy to hide, though the woofers can be stacked in a large room.

(I wonder what happens when you use four dipole woofers in an array? It could potentially be smoother than either four monopoles or two dipoles!)

Josh, what Danny Richie (GR Research) uses at shows is a pair of OB/Dipole subs at the front of the room (phase aligned with the loudspeakers), and a pair of sealed monopoles (his F12G model) at the rear, which their phase opposite the fronts. That system won him the "Best Bass At The Show " award at a number of RMAF.

The challenge in creating a swarm using all OB/Dipoles, is that the H-frame, like all dipoles, must be at least 3’ from all walls, and face the listening position. On each side of the sub there is of course the dipole null, so while the sub will pump bass energy into the room, it will do so only out of it’s front and rear, not it’s sides. Could be tricky!

Another way to go, is to use a pair of OB/Dipoles as woofers/subs for the speakers, and augment them, as does Danny Richie, with a pair of sealed subs, positioned in the room ala a swarm, to deal with room modes, etc.

Hello bdp24,
     I completely agree with you that most systems sound bass shy.  
I believe almost all music sounds its best when there's a solid bass foundation down to at least 20 Hz.  I don't expect or want high SPL bass like an arena rock concert.  My bass goal has been more the bass impact and quality one experiences when listening live to rock or jazz music 
at a smaller club venue. I enjoy the perception that the musicians are playing in my room or I've been transported to the recording venue. 
     I know from experience that good bass performance is much more difficult to get sounding right than the midrange, treble and imaging in most rooms.  This is mainly due to the bass soundwaves being much longer and behaving very differently in typical rooms than the much shorter and directional midrange and treble soundwaves.
     Because of this, I prefer to treat my system as 2 systems: a bass system and an everything else system.  Once I get the bass sounding optimum, it's relatively easy positioning the main speakers optimally in relation to my head and ears at the designated listening seat for very good midrange and treble performance along with a wide, deep and 3 dimensional soundstage illusion with solid, stable and natural images. 
    I've been able to attain what I consider near state of the art bass performance in my room utilizing the AK 4-sub DBA system without any room treatments or room correction software and hardware.  I've also been able to attain very good midrange, treble and imaging results in my room without any room treatments and room correction.  However, I do realize that an accurate room acoustics analysis along with the appropriate selection and positioning of various room treatments would likely result in even further improvements in my system's performance.
     As a result, I've had GIK give me a free room analysis and I'm about to order a few thousand dollars of room treatments, including stacked bass traps in all 4 room corners and a roughly 5/50 balance of absorption and diffusion treatments for selected room surfaces throughout my room.  I almost declined the recommended bass room treatments, since I was concerned about degrading the already exceptionally good bass performance in my room, but have been assured that these bass treatments will only further increase bass performance quality.  I've decided to trust their knowledge and experience.
      On another subject, you state:"It was here on an Audiogon post that I read of Duke telling an interested party that he recommended a dipole sub for use with dipole loudspeakers over a distributed bass array. I wouldn’t know how to find it now, but perhaps someone remembers it."

     I've been thinking about this and I do recall Duke stating on another thread that he thought that a 4-sub line source bass array system would probably outperform his 4-sub distributed bass array system.  This member did have a pair of Eminent Technology dipole planar-magnetic speakers.
      This member had an odd room, where there wasn't a typical rear wall that bass soundwaves would normally reflect off of causing bass issues.  Instead of a wall existing behind his designated listening seat, there was another room with the far wall in that room being a large distance away.
      This member had 4 large subs aligned along his front 16' wall in a line or row, with all the subs less than 4' apart.  He and Duke seemed to agree that, because there was no traditional rear wall and the 4 subs were aligned in a row with all being less than 4' apart, this constituted what's called a 4-sub bass line array. 
      Basically in this 4-sub bass line array, all 4 subs act as one giant sub and big bass soundwaves that are as wide as the room are effectively created that travel directly to the listening seat.  If there's no wall directly behind the listening seat to reflect off of , the bass is perceived as very powerful, accurate, detailed and dynamic.  
     So, I believe Duke was stating that a 4-sub bass line array can outperform his 4-sub DBA if your room effectively has no rear wall for bass soundwaves to reflect off of, which I think you agree is highly unlikely for most individuals' rooms.
     Duke definitely knows that the bass produced by his AK Swarm/Debra 4-sub DBA systems is sufficiently fast, smooth, accurate and detailed to seamlessly integrate with any pair of main speakers, even very fast and detailed planar-magnetic and electrostatic panel speakers.  I think you would immediately recognize this obvious quality if you auditioned a 4-sub DBA in person.


Interesting, I'd never thought of running sealed subs and dipoles over the same frequency range. I had considered it, but only using the sealed sub in the bottom octave to boost output and extension there (my IVA's go to about 25 Hz in my room). (As I recall, Wendell tried using a sub with the Mini 30.7's and found it unnecessary. But AFAIK, he wasn't playing pipe organ!)

I think that if you wanted an open baffle swarm you'd use the along-the-sidewall arrangement (two woofers on each sidewall). IIRC from the multiple sub paper, it's one of the most effective arrangements.
     For those thread readers interested in trying out the 4-sub DBA concept in their rooms, I think it's simplest just to buy a complete DBA kit like the Audio Kinesis Swarm or Debra systems for about $3K.  These systems consist of 4 relatively small subs(the Debra subs are each 12"dx14.5"wx18"h, weigh 44 lbs, have a 10" aluminum long-throw 4 ohm driver), a set of 4 sub port plugs for either ported or sealed sub operation and a 1,000 watt @ 4 ohm class AB sub amp/control unit with a volume, crossover frequency and continuously variable phase controls. This amp/control unit also has a limited band equalizer, left/right and LFE unbalanced rca inputs as well as 2 sets of speaker terminal outputs.
     The AK Swarm and Debra 4-sub DBAs are both high quality systems.  However, it's also possible for individuals to build a high quality custom 4-sub DBA system either as a DIY project, with the sub amp and all sub component parts sourced from retailers like Parts Express, or purchasing 4 self-amplified subs of one's own choice of quality and expense. 

     Just like everything else in home audio/video, quality matters, obviously varies between specific products and is very important in determining performance results.  Millercarbon took the DIY route option, buying the exact same Dayton SA-1000 sub amp/control unit that the Swarm/Debra DBA systems use for less than $400 from Parts Express, sourcing his own sub cabinets and drivers and building his own custom subs.  He and Duke agreed the drivers he purchased and used were more expensive but also even higher quality drivers than those used in the Swarm/Debra subs.  
      A second custom 4-sub DBA option is to buy the sub amp and 4 passive (unamplified) subs of one's personal quality/expense choice and then follow the sub positioning and amp configuration instructions detailed on my prior thread post.  It's important with this option to ensure the sub amp has the required volume, crossover frequency and continuously variable phase controls.
      Finally, a third custom 4-sub DBA option is to just buy 4 traditional self-amplified subs of one's personal quality/expense choice and then follow the sub positioning and amp configuration instructions detailed on my prior thread post.  It's important with this option to ensure all 4 of the self-amplified subs have the required volume, crossover frequency and continuously variable phase controls; as well as realize that this option requires the user to set these 3 controls individually for each of the 4 subs rather than once, for all 4 subs as a group, like on the prior options.
    The good news, however, is that some newer self-amplified sub brands even have the very useful added feature of being able to be configured to work together in a group in what is unfortunately termed a Master-Slave relationship, which functionally means the control settings made on the Master unit are able to be mirrored on each Slave sub able to be attached to the Master in a daisy-chain method.  This is a very useful feature if one's attempting to create a multi-sub DBA system.

     Sorry, I need to make a correction and add a comment from my last post:

The 4 AK Debra subs are actually each 12"Dx14.5"Wx28"H, not 18"H as I mistakenly stated.
I also should have added that, no matter which option chosen, the utilization of bass room treatments, room correction software/hardware and DSP will not have negative effects and it's possible they may even have positive effects.