Anybody else using a distributed array sub system?


     I was just about to respond to zardozmike's forum post titled 'subwoofers' about suggestions for subs for Magnepan MGIII speakers but decided a new post might be more useful for him and others.  I have Magnepan 2.7QR speakers and posted a similar question about a year ago.  After reading his thread, I realized he was getting about the same responses I had received.  All were very good responses but I thought a new thread detailing my effective solution may be more relevant and attract responses from other users of a distributed array sub system.    


     About a year ago I purchased the Audio Kinesis DEBRA (Distributed-Eq Bass Reflex Array) sub system from James Romeyn Music and Audio in Utah. Here's a link describing the system:


http://jamesromeyn.com/old-pages/home-audio-gear/dsa-1-0-distributed-subwoofer-array-5-pieces-4k-usd...

 

       This system is expensive at $2,990 but well worth the investment.  I rationalized the price by noting it's about the same as a pair of very good regular subs.


     The performance of this system in my 23' x 14' living room is excellent.  The bass can be fast, tight and tuneful for music or loud and impactful for music and home theater.  The subs seem to disappear since there are no audible clues to their locations; the bass is very well integrated into the music and movies. From my personal experience, I'm not convinced of the reality of stereo bass but was willing to give it a try.    I was originally thinking of buying 2 high quality subs such as Rhythmik, SVS, JL, Martin/Logan, Vandersteen or REL.  I was skeptical of the DEBRA system at first but, after reading a lot of research about multiple sub systems on the internet, I decided to give it a try and I'm now very thankful that I did. 


     Because it is such an ideal system for me, and because I think it would work well in almost any room or system, I want to go into more detail about the system, its setup and the theory behind it. I have no affiliation with the company but will admit, after considerable phone and email time with the dealer, that I now consider James Romeyn a friend of mine but don't know if he feels likewise.

     The system consists of the following:

A dedicated Dayton Audio mono class A/B amp rated at 950 watts @ 4 ohms with dual A&B spkr output terminals.

4 67lb. bass-reflex  subs that measure a relatively small 23.75" H x 14.5" W x 10.375" D.

Each sub is ported on the bottom, supported by 3 spiked cones and contains a single 10" 4 ohm driver. The subs are designed to be facing, and within 2" of, the room walls.

     The setup procedure is:

Sub#1 is hooked up and placed on its back  (driver facing the ceiling) at the normal listening position.  Music is played that has good and repetitive bass.

Walk around the edges of the room and determine exactly where the bass sounds best to you.

Attach the 3 spiked footers to Sub#1 and position it upright facing the nearest wall to the spot you determined the bass sounded best.

Sub#2 is hooked up and placed on its back at the primary listening position. With sub 1 & 2 playing, continue walking around the edges of your room and determine again where the bass sounds best to you.

Attach the 3 spiked footers to Sub#2 and position it upright facing the nearest wall to the spot you determined the bass sounded best.

Repeat this procedure for sub 3 & 4.

Small positioning adjustments may need to be made for each sub due to avoiding furniture and the WAF. 

Once completed, final sub hook up is done in parallel:

Attach a single wire from the amp's speaker A's pos. output terminal and to Sub#1's pos. input terminal.

Attach a single wire from the amp's speaker A's neg. output terminal and to Sub#2's neg. input terminal.

Attach a single wire from Sub#1's neg. input terminal to Sub#2's pos. input terminal.

Attach Sub 3 & 4 using this parallel method on the amp's speaker B's output terminals.

I ordered single, high quality and low gauge speaker wire along with the sub system for a very reasonable price. Once the ideal locations for the subs was determined, I drilled holes in my room's floor to the crawl space below, and was able to hide the connecting wires. 

     I'm definitely not an expert on subs or room acoustics but, from my reading, here is how I understand the theory behind the distributed array sub systems:


The lower the frequency the longer the sound wave produced, or launched,  into a room. 

Since these waves can be even longer than the actual dimensions in many rooms, these low frequency waves bounce off room surfaces and the music may dictate subsequent bass waves being launched into this acoustic environment. These initial waves, their reflections and subsequent bass waves inevitably collide and cause 'standing waves'.

Areas in the room where sound waves meet can make the bass sound under emphasized, over emphasized or even totally missing (nulls caused by wave cancelation).

When one sub is launching low frequency waves from 1 specific location, areas in a specific room where bass response is not accurate will be numerous and predictable based on sub location and room dimensions.

Adding a 2nd sub to the room will decrease standing waves and increase bass accuracy and bass dispersion.

According to scientific studies I read, standing waves are reduced, and bass accuracy and dispersion increased, as more subs are used in a given room.  Their experiments utilized more subs than anyone would even consider for home use. They basically concluded that the more subs in a room, the fewer standing waves are perceived and the better the bass quality and bass dispersion results.

However, they determined that most of the benefits are gained with the use of 4 subs, with only minimal and incremental gains in performance attained through additional subs.  Due to practical room considerations, the researchers recommended 4 subs for an effective distributed array bass system.


     So that's the equipment, set-up and the theory behind the DEBRA system and I can personally attest to its effectiveness in my room.  I have 6 listening/viewing positions in my combination music and ht system in my living room.  Bass response is equally good at all 6 positions without the use of acoustic devices (no absorbing or diffusing panels or bass traps) and without any electronic  equalization (room analysis/correction equipment, software or eq).  I should mention I've never had my system/room analyzed using a mike and software.  From my purely subjective perspective, however, I'm confident the results would be good since I spent hours on the setup and critical listening from all six listening positions in my room.  I would suggest this type of sub system as a viable alternative for anyone considering investing in one or more quality subs.  The system is rated clean at 113 decibels at 20 hz.  I've often heard and felt it go much lower.  It feels and sounds clean and right but I can't verify the decibels or lack of distortion.


Sorry this turned out so long and windy,

  Tim

Also, my system photos are old but I'll try to update them showing my current system (with the subs and new electronics) soon.



     


  

noble100
Noble,

I've always liked the idea and briefly screwed around with a four sub home-brew version.  It worked well, but just took up too much floor space.  Your set-up makes a ton of sense to me.  Enjoy.

BTW, I thought that James Romeyn used to carry guitars (Thorell) as well as HiFi gear.  Solvency was the main reason I had to avoid that web site.  I didn't see any on your link.  If the store is local for you, do you know if they simply moved on from the instrument business?
Hi Marty,

     James still sells musical instruments as well as audio gear out of his home, I believe.  His company is called James Romeyn Audio & Music, LLC and his website is www.jamesromeyn.com


       The 4 sub distributed array has far exceeded my expectations and works perfectly in my room.  But I understand your concern if 4 larger subs are used.  All 4 of my smaller subs are not very noticeable (front 2 mostly concealed by my front 6' x2' panel speakers, the rear left behind a large leather chair and the rear right between the side wall and a large end table.  I'll try to update tmy system photos soon.

     Sounds like finding 4 smaller powerful subs @ 4ohms along with a good amp that can handle 4 ohm loads may be able to work for you.  Not familiar with your system but I think this works well in any system.

Later.
Tim

















ZI forgot to answer your question on whether I'm local to James; I'm in Indiana.

Tim
In my main rig I have the speakers/listening position setup on an angle with a REL Stadium lll cabinet/driver in the front corner and a REL Strata lll cabinet/driver in the opposite rear corner. The Stadium lll amp/controller has been removed from the Stadium lll cabinet and mounted on the equipment rack and wired with MIT speaker cabling from amp/controller to both subs. The Strata lll amp/controller has been removed from the Strata lll cabinet and put in storage. 

This arrangement really smoothed out the low end response along with an utter seamless integration with the main speakers with the added bonus of removing the physical vibrations from the Stadium lll driver impinging on the Stadium lll amp/controller.
Noble

I don't have time to offer a link but remember reading Harmon/Revel white paper by Sean Olive which researched performance of using multiple subs. At the end Sean described improvements and the associated # of subs and placements in the room. He also discussed the sound quality and kind of improvement. If I remember correctly one comment Sean made was with 4 subs the the overall room response was more even through out all listening positions, not just sweet spot. The drawback was that when listening to 2 channel  stereo imaging was effected. The bass was even and was coming from all around but not from a front soundstage. So It seemed that for theater 4 sub is great for effects but for 2 channel listening where stereo imaging is valued 2 subs worked out better. 

Have you noticed anything like this with your setup?
mcloughlin,

     Very interesting.  I can verify that this array works very well for ht.  Watching a movie, it doesn't seem like they're even on but the impact ,when a scene calls for significant bass, is startling.and makes the video content more life-like and tactile.  This effect definitely adds to viewers' enjoyment and involvement in the movie.  I wouldn't describe it as overblown but more natural and real.  I usually set the sub system crossover to 40hz.

     Maybe I should do some more critical listening to the sound stage on music, but I usually  perceive the sound as coming from in front of me even though I intellectually understand bass is emanating from 4 small boxes near the corners of the room.  That is the exact reason I like this bass system so much; I only perceive the bass being augmented as part of the large video content on ht or as part of the sound stage seemingly emanating from the proper instruments.  I can honestly state that I never perceive sound coming from any of the individual subs, even though the rear subs are located only a few feet away ( the left/rear sub is located about 8' from my left ear and the right/rear is about 4' from my right ear.)    Stereo subs may work for some but, from my own subjective experience, I know I can't discern left and right bass. There is only one exception I can think of: ht explosions and some other effects I tend to perceive as more enveloping and coming from all directions.
 
    Otherwise, it seems almost magical to me how such well articulated bass can be produced in my room that is so well integrated into both the on-screen image for video  and the sound stage illusion for music.
   
  I can only disagree with Sean Olive's white paper conclusions, with only subjective but no scientific evidence of my own,  and invite him over for a listen.  
Tim
musicman,

   That's a unique setup.  I was initially planning on buying 2 very good quality subs like your RELs  and place them in the front corners behind my panel speakers.  I was also thinking of experimenting by putting 1 in a front corner and 1 in a rear corner before deciding to go with the 4 subs.

     Good to know it's working out for you.  Have you noticed any issues with your 2--ch music sound stage that musicman mentions in his post?

Thanks,
 Tm 
Noble
Thanks for response on your impressions of your sub system. I have been reading about multiple subs in a room and am glad to get your impressions with your setup.
Here is that link to the white paper. 
http://www.harman.com/innovation?CategoryID=White%20papers
It may be Floyd Toole not Sean Olive anyway It is kind of lengthy but I found it interesting.
I started with one velodyne dd 12 sub. I liked them mostly because they have a remote which, depending on the music, I can use to boost or flatten the output. I lived with this not totally satisfied for a few years then a friend lent me one of her dd12 and instantly, not even optimally placed or eq-ed, I noticed a more complete image. It was mostly noticeable with male vocals, that lower register joined the rest of the range and became a part of the central vocal image. Needless to say I recently purchased a DD 12 plus, considerably better than the dd 12, and have used them both in stereo. Like your description I placed them in the room where the null in the room was reduced the most, within reason, then did a little eq and wow I have been very impressed since.

Mark
Post removed 
Or, for $2800 you can let the Audiokinesis Swarm 4-sub system do the heavy lifting.
Absolute Sound review.
http://www.audiokinesis.com/the-swarm-subwoofer-system-1.html.
noble1K, thanks for posting about the DEBRA.  I'd not known of this approach to subs or sub systems.  The whole concept appeals to me and makes too much sense IMHO.
'Distributed bass' in your case  reads as being more 'seamless' with the balance of the freq range, something I find attractive.  I've been playing about with 'staging' with diy Walsh omnis purposely throttled back from the lowest registers.  A single sub, well placed, almost works...  A 'distributed' bass line would blend better, esp. with flat response (my personal grail...).
So, thanks for this thread. *S*
Hi Tim,

I'm a bit confused.  Is the DEBRA designed by/built for Romeyn and is similar to the Audiokinesis Swarm, or is it an additional Audiokinesis product sold by Romeyn?

Your first link from Romeyn's site does not identify the author so I assume it relates his perspective.

Thanks

Johnnyb53,

      You wrote:
" Or, for $2800 you can let the Audiokinesis Swarm 4-sub system do the heavy lifting".
Absolute Sound review.
http://www.audiokinesis.com/the-swarm-subwoofer-system-1.html.


     I read the entire Absolute Sound review on the Swarm sub system you referenced and that is almost exactly like my James Romeyn Audio Debra system.  The sub modules look identical except mine are in birch.  The only differences I could discern are  the weight of each sub and the system price.   The Swarm lists theirs as 45 lbs/each but my Debra subs are listed as 67 lbs/each.  I paid $2,990 for the Debra and the Swarm is listed at $2,800.  There were no pictures of the Swarm's amp but the description matches the Debra's amp exactly.

     The setup procedure described in the review is also identical, even down to the option to invert the phase on 1 sub module ( mine are all currently in phase since I haven't  tried  inverting 1 sub's phase yet to see if it improves performance)..

     The reviewer's description of the sound is also the same: very smooth, tuneful and natural bass throughout the room with an absence of peaks and nulls.  

     I know James Romeyn  and Duke Lejeune, of Audio Kinesis, have been collaborating together for some time, with a distributed array bass system being one of the results.  I'm actually not sure why they each have their own versions of a distributed array bass system,especially since they're so similar.

      I'm going to call James and try to get some more information.  I'll post again after I know more.

Tim  

     
pryso,

     You wrote:

" Hi Tim,

I'm a bit confused.  Is the DEBRA designed by/built for Romeyn and is similar to the Audiokinesis Swarm, or is it an additional Audiokinesis product sold by Romeyn?

Your first link from Romeyn's site does not identify the author so I assume it relates his perspective."

     I'm a bit confused, myself.  Hopefully James Romeyn can clarify and I'll post again after he replies.  I prefer not to speculate for accuracy's sake.

Thanks,
  Tim
My intention in posting in this thread is to clarify, answer questions, and to avoid, as much as possible, soliciting kind members and any obvious sales pitch. If I fail, please let me know and if possible I'll delete and/or append  offensive text.


To my best knowledge, it's appropriate to credit three persons for inventing the multiple or distributed sub array: Dr. Floyd Toole, Dr. Earl Geddes, and Todd Welti. Duke LeJeune is an early adopter, studied w/patent holder Dr. Earl Geddes, and Duke introduced me to Distributed Sub Array. 

Duke adds a unique feature to his DSA (called Swarm): "Small" or "Domestic" size rooms (as opposed to commercial size rooms), naturally boost bass about 3 dB per octave <100 Hz. To counter or neutralize this effect, Duke naturally tuned his subs for a mirror image of this curve, w/acoustic roll off of about 3 dB per octave <100 Hz, or about -7 dB @ 20 Hz.

All comments Re. performance apply to a properly designed and well-setup distributed array.

DSA has no perceived nor mathematical disadvantage for 2-ch music. I've read much though not all of Toole's writings on the subject. AFAIK Toole has written nothing suggesting a weakness for DSA in 2-ch application. Properly designed and installed, transition to any main speakers, regardless the architecture, is absolutely seamless and transparent. DSA improves spatial performance in every way, and has no downside except cost, hookup wire, and possibly larger foot print (only about 11-3/4” x 14-3/4”).  

Single amp crossover pole should be 80-90 Hz maximum. If a second amp is used, crossover pole may increase to about 150 Hz. In this case, the two subs closest to the front wall cross higher, while the two subs closest to the rear wall cross in the range of 70-80 Hz maximum.

I typed a text document about 1.3 pages, comparing DSA to four spinning propellers in a fish tank aquarium. Upon request I'll post it at my DEBRA web page.

Re. the “solvency” issue mentioned above relative to my one time selling Thorell guitars and not selling them now. I enjoyed selling the few Thorell guitars I did, and by mutual agreement with Ryan, decided to concentrate on my professional “wheel house,” being music and audio.  (Downbeat Magazine reviewed my personal Thorell Sweet E guitar, which I latter sold.  Some time latter, another client offered to buy the exact same guitar for a lot more than what he paid.  When I asked the first buyer if he was interested in splitting the profit margin, he refused.)


Duke licenses me to sell DEBRA, which functions identical to Swarm. Differences: DEBRA cabinets are about 1.75” wider and 1.75” less deep. Also, for $2990/five pieces (four subs + kilowatt amp), DEBRA cabinets include a 3/4” solid wood top panel w/round over on all four corners (under the solid wood crown is 3/4” MDF veneered both sides).  Also, my prices include maple, cherry, walnut, or satin black, whereas I believe Swarm costs extra for black (images to be posted soon of current production cabinets).


For $2800/set, subtract the solid wood crown w/round over, and all corners are square 90 degree.


Another difference is that all four DEBRA subs have only one pair of binding posts, while two of the Swarm subs have two pairs of binding posts and the remaining two subs have one pair of posts.


I credit Bob Carver w/giving me the idea for my setup advice, which has proven to work very well in a large variety of rooms. Without EQ of any kind, the worst case I have seen in any room is +/- 2 dB <100 Hz throughout the room, w/only minor “build up” in the most extreme corners. When one sub is ideally located in my current room, the FR window is 13 dB at the sweet spot, and extreme “hot spots” throughout the room.


Circa 2015, prices increased for the 10” ultra low bass driver. For the increased cost, cutoff now extends to 18 Hz.


Changes in cabinet construction circa 2015: Noble100's enclosures are 5/8” old growth Russian Baltic Birch ply laminated over 5/8” particle board for damping quality via its random shapes and sizes of wood chips. We switched to Duke's old cabinet maker (Duke moved from just north of me in ID to TX). Current cabinets are 3/4” MDF veneered both sides, with double thick baffle (1.5”) under the 10” driver, with a full “picture frame” brace just above the 10” driver. Recently we auditioned with 115+ dB peaks and no one including myself noticed any audible distress of any kind, in my 3300cf room.


Classic setup advice for one or two subs: distance between two subs and/or from any sub to the farthest main speaker should not exceed one quarter wavelength of the crossover pole. Conversely, with DSA, there is no “proximity effect” crossed @ 80 Hz, even with about 25 feet between two subs close to diagonal corners.


Strangely enough, as much as bass modes distort pitch, non-linear time distortion may be even worse and more audible. Bass modes can cause a particular bass note to linger or continue bouncing between boundaries long after the bass player on the program muted the note and played the next note of a different pitch. Listeners can and often do hear the two disharmonious notes playing simultaneously, where should be only one proper note.


Once listeners hear the difference of a system lacking this type of distortion, it's hard if not impossible to go back.


My last sound room had the equivalent of about $7k in acoustic upgrades and structural modifications, including a 3-sided acoustic ceiling soffit, w/mixed results at best. I paid $750 for the acoustic design alone. By huge margin the DSA outperformed the mods in that room.


       I talked to James Romeyn this afternoon and here's how he described the differences between his Debra and the Audio Kinesis Swarm bass systems:

They're basically the same systems and perform about the same.  James' company sells the Debra system under a licensing agreement with Audio Kinesis.

The Debra subs are a little wider and a little less deep than the Swarm subs.  His cabinets are made at a different facility than the Swarm's cabinets.  Both are constructed using braced MDF particle boards but the Debra's cabinets use a solid piece of wood  for the tops.

He didn't think the sub weight difference between the two (67lbs vs 45lbs) is accurate He thinks the Debra subs weigh less than 67 lbs. and the Swarm subs weigh more; he wasn't certain of the exact figures.

He thinks the difference in system price (Debra at $2,990 and Swarm at $2,800) is due to the differences in the cost of sub construction.. He said he'd probably price match if requested.

He also told me some interesting related information:

He said each room has a unique modal response, similar to a fingerprint, that is based on the configuration and dimensions of each room. It is further complicated by the fact that a room's bass modal response is different than the same room's mid-range/treble modal response.  The very long sound waves produced by bass frequencies result in peaks and nulls in different physical room locations than the much shorter sound waves produced by mid-range and treble frequencies.  Because of this, he thinks it's best to treat them as separate systems; a multi-sub bass system that eliminates bass frequency peaks and nulls in the entire room that establishes a solid foundation along with a  mid-range/treble system that consists of a pair of speakers positioned for optimum  performance at the 'sweet spot'.  A distributed array sub system will provide very good bass for all listening positions in a room but providing very good mid-range/treble beyond a single optimum listening position 'sweet spot' is much more difficult.  He also stated that both the Debra and Swarm systems provide good bass for ht and 2-ch music with no detrimental affect on the sound stage. I can verify this is true in my system/room.  In my opinion and if anything, the Debra has improved my 2-ch sound stage illusion for music by making it seem more like live music in my room. 

     He said he'll read this thread and join in if he has something to add to the discussion or wants to clarify.

Tim 
.  




     I wanted to clarify the descriptions of the Debra and Swarm bass systems by adding a couple of quotes from the James Romeyn Audio & Music website  (jamesromeyn.com ):

" Dr. Robert E. Greene is Senior Editor at The Absolute Sound Magazine and Math Professor at UCLA. He also tutored Russell Crowe in the violin for “Master And Commander” and Russell’s Appalachian accent for “A Beautiful Mind”. AudioKinesis Swarm Sub Woofer Array was reviewed by Dr. Greene in TAS Issue 252, April 2015. Swarm won TAS Editor’s Choice Award, their second major journalism award. DEBRA is similar to Swarm, with different cabinet materials, different construction, and different cabinet dimensions (wider and less deep)."

"DEBRA employs four subwoofers each with a high-output reflex-loaded 10″ driver. Duke LeJeune of AudioKinesis specified the drivers, distributed array concept, and special “Room Gain Complementary” tuning. We specified original “Progressive Null Point” siting instructions and cabinet architecture (cosmetics, fasteners, unique bracing, special laminate, and three panel materials to minimize and distribute resonant qualities).

Thanks,
 Tim.


I can attest to the advantage of adding in some out-of-phase bass to smooth the bass curve. One thing I discovered when I set up my Maggie 1.7s is how the out-of-phase backwave took away that typical (and annoying) 100-200Hz in-room bass hump. Detractors often complain about Magneplanars’ "weak bass", and while lower reach is not a strong suit, the smoothness and quality of the bass beats most box speakers and also makes subwoofer integration easier.

My biggest objection to the distributed array idea is that you have to be willing to give up everything for the sake of the subwoofer locations, and of course you have more subwoofers and more wiring.

From a practical standpoint, I'd much rather have 1 or 2 subwoofers reasonably well placed along with high quality bass traps and DSP. 

It's been shown that properly done, this combination does in fact minimize ringing, which is the very source of uneven response in a room.  With that problem solved, the distributed array seems like jumping through hoops when a simpler solution is at hand.

Best,


Erik


johnnyb53,

     Yes, the Magnepans do have an advantage over box spkrs in terms of quality of bass.  I have much older 2,7 Magnepans than you but, when I switched amps fro an older Aragon class A/B amp (200 watts@4ohms) to a new pair of class D monoblock amps (1,200 watts @4ohms), I was quite impressed with the amount and quality of the bass produced.  

     My main intention of adding a separate bass system was for more impact on ht.  It definitely added impact to ht but it also increased the impact of all my familiar music.  With the added bass system, I cannot identify any flaws in my system's musical reproduction; the smooth mids/treble and great sound staging are still there but an effortless quality to the bass has been added in a seamless, well-integrated manner that enables the bass to go as deep as the content calls for.  This may be something someone needs to hear to completely understand but it has transformed my system performance and musical enjoyment tremendously.  

     Ever since I've been an Audiogon member, it seems like magneplanar and electrostatic spkr owners have been searching for subs that will keep up and integrate well with their quick spkrs.  My main motivation for starting this thread was to let members know of the distributed sub array concept and that it actually works amazingly wel, probably in any system.

I'm glad you're enjoying your very nice 1.7 Magnepans,

Tim 
erik squires,

     I understand your reluctance to adopting a distributed array sub system. I was initially concerned that I'd need to move furniture and seating to properly install it.  Perhaps I was lucky since the first 2 subs sounded best, as dictated by the setup procedure mentioned earlier, located along my front wall with each mostly hidden behind a left + right panel spkr. The final 2 subs sounded best along each side wall near the back wall, which were easily accommodated in my room.
       I was also fortunate with the wiring since I was able to run them in the crawl space below my living room ( this required drilling four 1.5" holes in my floor at the final sub positions and spending some time crawling in the limited space below routing the wires, which was a pain).

      From what I've read, however, a 2 sub array may get you most of the benefits of a 4 sub array with less hassle and expense.  I cannot verify this since I never tried my initial thought of adding just 2 subs.  I think sub positioning may be even more critical in a 2 sub vs 4 sub array but I'm not certain.

     I have no experience with bass traps or DSP since neither is needed in a 4  sub array.   

I wish you the best and am interested in the results of your experiments with a 2 sub array.  

Tim
I've said this before, and I'll say it again.  The problem with subwoofer integration isn't the speakers, it's the room.  Solve that and you can seamlessly match with any speaker.

The notion that planar speakers (of any kind) are difficult to integrate with subwoofers is a little misguided.  The problem is that the planar speakers never excite the room modes which a subwoofer will. Deal with that correctly and it's like butter. The experience that users have x brand speaker, which sounds great, then they brought in a sub, and the subwoofer itself wasn't as good as the speaker is also misguided the same way.  I mean, the experience is real, but the attribution to it being caused by the difference between a dynamic and planar speaker, or that the large dynamic speaker has too high moving mass is incorrect. The problem is the minefield that is most rooms below 40 Hz. 

The distributed woofer array seems to be addressing the same problems, but, to me, in a much more difficult manner.

Best,


Erik
I added a REL 10" sub a few years ago and in my largish hifi room it works well without digital eq…furniture, large rug, high sloping ceiling…lucky me as this obviates the need for bass traps or hiring fat people to sit around (no offense to fat people, but my experience in decades of live sound mixing has proven they make great sound absorption pods, although you do have to feed them from time to time). My perfect Q150e cost 200 bucks from Ebay a few years ago, and last year I scored a clean Q108 II, also 200 bucks. YAY…I have a large outside deck next to my listening room and sometimes stick a couple of small speakers in the windows to play to that deck (a dedicated amp drives those), and the 108 was bought to put in one of those windows for outdoor bass, which works swimmingly…however, when at its non window spot it provides a standing wave canceling (or at least reducing) extra mojo in concert with my Q150 so I’m in the multiple sub boat indoors at least…both subs take their signal from the tube main amp but the amp doesn’t seem to mind (50,000 ohms instead of 1000,000?). Note that as a professional Knob Turner I’m not averse to adjusting the output of the subs here and there (not often) as recorded bass levels can differ wildly…but you knew that...
Spkrplus,

To clarify my solvency remarks from an earlier post to this thread, I certainly wasn't talking about any issue I had with the solvency of your business.  I was talking about my own!  

The distributed array subwoofer is mighty tempting and I've had a longstanding desire to add one of Ryan's flat tops to the Thorell arch top I already own.  When visiting your site, I was always itchy fingered and a couple of clicks away from an expenditure with bad personal ramifications (certainly marital if not purely financial).

Sorry if I stated that poorly.
wolf garcia,

     I'm definitely not an expert on bass systems or acoustics but I have a few thoughts on your situation based only on personal experience and sub research:

1. I think your outdoor deck setup may work well since there are no standing waves created on your deck since there are no room boundaries that create them.  You're listening likely to only the direct sound waves from both your speakers and sub.

2. Your indoor setup may not work as well because there are standing waves created in your listening room since there are room boundaries that create them.  

I suggest you try the following to see if it improves the sound in your in-doors listening system:

Place your Q150 sub at your normal listening position and play some music with good and repetitive bass at a medium volume.

Starting near the front right corner of your room, walk around the perimeter of your room completely and determine exactly where the bass sounds best to you.  For best results, you may need to crouch down to approximate your ear height when seated at your normal listening position.

Move your Q150 to the spot you determined the bass sounded the best to you.

 Place your Q108 at your normal listening position.and continue playing the music with repetitive bass

Starting  at the newly sited Q150, continue walking the perimeter of the room and determine again where the bass sounds best to you.

Move the Q108 to the spot the bass sounded best to you.

Done.  

 I think the above process will allow for the best bass in your room  using both your subs.  I think it'll reduce standing waves (bass peaks and nulls) and give you good, smooth bass response at your normal listening position and possibly throughout most of your room.

Hope this helps,
 Tim
.
 
Harumph! (heh) I actually AM an expert in bass and acoustics (pro musician and live sound mixer for 5 decades or so), although my opinions on sound aren't necessarily driven by anything beyond personal taste. I wasn't complaining about my indoor setup, just describing it. There are no standing waves at the sweet spot I listen from as I set up the first (Q150e) REL carefully initially…I also highly recommend spending the time to do that. Bass intensity is of course more powerful in the corners (normal), and I was merely noting the fact that REL #2 does mitigate the standing waves near it by providing an in phase sound wave to eat the bass that crawls along to the corner it's near. I think that's why "swarm" subs are a great idea and work so well. A note on my outdoor sound…the little 8" woofer in the Q108 II when locked into its spot (the window and a rubber foot hold it in place) does use the rest of the window and outside walls to provide an interesting gigantic baffle…the design of this speaker is floor firing normally, but firing out to the deck works really well when combined with the coincident tweeted KEFs also stuck in the windows for deck duty. Plus I think the plants like my choice of music…I could be imagining that…jazz plants…
I'm using Duke's Swarm system with five subwoofers and two Vandersteen Quatro Woods which have built in subs of their own.  In my previous set-up I used a single Vandersteen V2W sub with the Quatros.  I use a Meridian G68XXD with MRC room correction below 250 hz.  The previous system required 16 filters between the Vandersteen speakers, the V2W sub and the Vandersteen center and surround speakers (ITU spec. 5.1 set-up).  The Swarm setup required only 2 filters, and only for the two Vandersteen surround speakers (VSM-1s), which are close to the rear ceiling / wall corners.  The room, wherever you set the calibration mic, is very flat and uniform.  

The sound, particularly with large-scale symphony music, is utterly realistic, with the acoustics of the hall the recording comes from.  (I regularly attend the St. Louis Symphony Orchestra classical series, so I know what it should sound like.). My previous set-up (single sub) sounded like a very good hi-fi system in my medium size room.

Anyone who dismisses these multi-sub systems doesn't understand the acoustics of small rooms, and is really missing something special.  As added bonus, the power response of the swarm and similar systems is uncanny.  You really haven't heard "bass slam" until you experience one of thes set-ups.

Noble100 wrote:
johnnyb53,

    Yes, the Magnepans do have an advantage over box spkrs in terms of quality of bass. I have much older 2,7 Magnepans than you but, when I switched amps fro an older Aragon class A/B amp (200 watts@4ohms) to a new pair of class D monoblock amps (1,200 watts @4ohms), I was quite impressed with the amount and quality of the bass produced.
I didn't mention it in this thread before, but actually I also have a pair of small subwoofers to add some depth and slam to the Maggie 1.7s. The self-canceling nature of the 1.7s minimizes the upper bass hump that's so pervasive in room matching, and why many audiophiles have bass traps. 

Another advantage, however, is that it also makes it *easier* to match  subs with Maggies. I have a pair of Mirage MM8s. These now-discontinued mini-subs were little gems--long-throw 8" drivers with twin passive radiators. The active driver occupied the entire sub enclosure except for the plate amp, which packed 1400 watts peak (340 rms) power. Controls were granular--continuous knobs for crossover (50-200 Hz), phase (0-180deg.) and volume. 

To dial in the phase, I put on "With a Little Help from My Friends" from the recent Beatles Mono reissue. I know the bass line from this song note for note and it dances frequently across that 50Hz crossover line. I played it one channel at a time and twisted the phase knob until it sounded right. Then I did the same thing with the other channel. At that point I had excellent-to-perfect (sounds perfect to me) integration between Maggie panels and subwoofers. 

You might say I dialed in perfect subwoofer integration with "A Little Help from My Friends."



wolf garcia,

 My mistake, I thought you were looking for assistance.  With your experience, I now realize you don't need it.

Tim
noble100…wait…I still might need assistance…don't abandon me!
I forgot to mention that I was playing the recently released (Sept. 2014) Mono LP of Sergeant Pepper. Hearing the exact same bass line in each subwoofer was essential for this to work. One channel at a time, I turned the phase knob until the bass synced up between the 1.7 and the sub. Having a bass line that frequently crossed the 50Hz crossover point ensured that the quality and volume of bass would be seamless between the sub and panel.
johnnyb53,

You stated:
"I didn't mention it in this thread before, but actually I also have a pair of small subwoofers to add some depth and slam to the Maggie 1.7s. The self-canceling nature of the 1.7s minimizes the upper bass hump that's so pervasive in room matching, and why many audiophiles have bass traps."

I agree that Magnepans avoid the upper bass hump more common with box speakers.

     Bass traps always seemed like a wasteful and awkward solution to me; bass waves are launched into a room then big and ugly devices are strewn about to modify and put the brakes on these waves to avoid bass peaks and nulls.  Comparatively,  the distributed bass array system is a much more efficient and elegant solution; bass waves are launched into a room at strategic points, uniquely tailored to each specific room,  in order to avoid bass peaks and nulls.  Both the Debra and Swarm systems, as well as similar systems, obviate the need for all bass traps, equalization,  signal processing and filtering.  


     In your case, I think the main advantages of using a distributed sub array instead of your dual MM8 subs would be even more consistent bass throughout your room and  perhaps deeper bass extension that is more impactful and visceral.

Tim.

  
johnnyb53,

Forgot you said 'I dialed in my subs With a Little Help From My Friends'(Sgt. Pepper album track).  Informative, witty and funny.... excellent.

Tim 
dcbingaman,

     Are you stating that you're using a 5-sub Swarm system along with your pair of Vandersteen Quatro Woods that each have their own built-in sub?

First, that means you have a total of 7 subs in your room.
Second, I didn't know the Swarm was available with an extra 5th sub.

Very interesting, please clarify,
  
Thanks,
 Tim
Tim, the basic Swarm system comes with four subwoofer speakers, ported 10" drivers in a 1.6 cu. ft. box.  I had a cut out in the front wall that my V2W fit in that was too short for Duke's subs, so he made a 5th one for me to fit that space.  Same driver and Thiele-Small alignment but with a fatter and shorter box.  I use the Swarm Dayton rack amp in series/parallel for the four 4 ohm subs in the room, and a 300W BASH plate amp for the 5th one.  They are all driven from the LFE output from the Meridian which is split between the processor and the amps.

The Quatros are run full range and uses two 8" drivers and an internal 250W amp.  I run the Quatro analog EQ flat.  The center channel, a VCC-5, is crossed over at 60 Hz and the VSM-1 surrounds are crossed over at 80 Hz.  I usually use Meridian's Trifield DSP which uses the L, R, C and LFE for stereo recordings, and discrete for 5.1 recordings.

dcbingaman,

     Thanks for clarifying.  So, in effect, your system does consist of 7 subs; the 2 in your main Vandersteens, the normal 4 Swarm subs driven by the supplied amp and an extra 5th Swarm sub located in-wall that's driven by a dedicated BASH plate amp.  As you described, I now understand how it produces extraordinary bass response in your room; the 7 subs not only supplying great bass quantity but also great bass dispersion and smoothness. 

   Now that I better understand your bass system setup, I have 2 questions concerning the extra 5th sub located in your custom wall cut-out section and driven by a BASH plate amp:

1.  Is the 5th sub's  driver pointed at the back wall of the cut-out section like other Swarm subs are pointed at your regular room walls?

2.  Do you think driving all the Swarm subs with  class D amps, like your Bash amp for the extra 5th sub, would offer any sonic improvements when compared to the standard Swarm class A/B amp?  


   I'm not considering adding a 5th sub because I don't view it as a need in my room, just curious.      

   I have considered swapping out my subs' class A/B amp for a powerful class D amp just to see if the switch would be as noticeable on my subs as it was on my Magnepan 2.7s when I switched from 200 watts class A/B  to 1,200 watts class D driving them.   I know for my 2.7s the increase in bass performance was due mostly to the increase in wattage and not  the change in class, but I welcome all improvements and class D watts are relatively inexpensive.  I really have no complaints with the supplied 950 watt A/B amp for the Debra; I don't want to give the impression that it's not a good amp because it has been working very well. 

Thanks,
 Tim
Noble100 said:
   
In your case, I think the main advantages of using a distributed sub array instead of your dual MM8 subs would be even more consistent bass throughout your room and perhaps deeper bass extension that is more impactful and visceral.
No argument here. If I had the space and funds I'd probably have a Swarm. However, these Mirage MM8s were a stone cold bargain for me. They retailed at $799 each and it showed--diecast frame long throw drivers and 1400 W peak each. I got them on closeout--when Klipsch or Audiovox started selling off and ransacking Mirage and its patents--for $250 ea. They are 9" cubes, sealed enclosures, with long throw 8" aluminum drivers that are flanked on the sides by same-size and materials (minus the motor) passive radiators. I have them turned backwards so the active drivers face the wall behind the Maggies with about 2" space to pressure-load the bass waves like a downfiring sub would. As it is, with the Maggies' dipole aspect canceling the 100-200 Hz in-room hump and the Mirage's 0-180 deg. continuous phase dial, I can get excellent and uniform integration, and together the pair is capable of adding a lot of thump. However, it doesn't go all that deep--probably around 36 Hz--and I'd love some subs that would take me cleanly and strongly into the 20's, but I have to stand pat and enjoy what I have for awhile.



Hi, Tim.  To be honest with you, I can't tell the difference.  In my opinion, a Class D plate amp is as good as a decent Class A/B amp for this application.  TIM and all the other issues Class D amps have been associated with are really not that audible at 100 Hz and lower.  As you point out, the newer Class D amps are pretty good across the whole audio band.  BTW, Duke's subwoofers are also pretty efficient, especially when you use 4 or more of them in parallel.

The Vandersteen Quatros, 5CT's and 7's all use Class B amps for their bass drivers for efficiency. Crossover distortion is really not an issue at the frequencies they are used.  

The 300W BASH plate amp has worked well, but I found I couldn't just put it in the cabinet - the pressure from the driver rattled all the components around !  I had to put it in a separate vented enclosure which I mounted on the outside of Duke's cabinet.

The driver faces outward into the room, and the port faces the floor.

johnnyb53,

     I understand your situation because I've been in the same one many times; your wants are just a bit beyond your available funds.  But you bought some good subs at bargain prices and have made it work well in your room.

      I never intended to imply that a 4+ sub distributed bass array was required for good bass.  As you've proven, there's more than 1 way to skin that cat.  It seems you have a custom Debra/Swarm bass array that is effective with only 2 subs.  Well done and congrats.

Enjoy,
Tim
dcbingaman,

     I agree that both class A/B and class D amps can work very well as sub amps.  You've convinced me that the only way to know which I prefer is to buy a high powered class D amp, that can handle 4 ohm loads,  and compare.  I think 'I'll start researching the class D mono amps that are 1,000 plus watts @  4 ohms, have 2 pairs of spkr output terminals
 
Hi,Bingaman,

     Sorry, fell asleep in the middle of my last post.  I'll continue from where I left off below: 

....have 2 pairs of spkr output terminals and have some sort of in-home free trial period.  I'll probably post my results on this thread if I decide to do this.

   I'm assuming that you position your 5th sub as you do (the driver pointing out into the room as opposed to the driver facing the rear wall of the cut-out section)  because the bass sounds best that way. I would think that, with the driver facing the rear wall of the cut-out section, the launched bass waves would bounce off most of the cut-out's surfaces before escaping the small enclosure and launched into your room. This may result in bass waves being launched into your room at varying times dependent on their wavelength/frequency. This would likely detract from the total bass smoothness and accuracy in your room so you chose the more direct route of launching the bass waves.  Okay, I'm now going to stop pretending that I fully understand how all this bass stuff actually shakes out and leave it to the experts for explanations.

     Unless we hear from other users, it seems like you and I may be the only members using  full Debra or Swarm bass systems.  That either makes us wise and brave pioneers/ early adopters that were rewarded with 'state of the art'  in-home bass systems or dim witted and gullible  knuckle-heads who deserve the snake oil they bought.  

     I definitely realize we both know which ones we are,

Congratulations,
  Tim     

Tim,

"consist of 7 subs; the 2 in your main Vandersteens, the normal 4 Swarm subs driven by the supplied amp and an extra 5th Swarm "

This may sound picky but it is a matter of definition.  Most often I've seen subwoofer defined as producing the lowest octave of sound, 20-40 Hz.  So a standard woofer may cover bass as far down as 40 Hz.  The crossover for the Quatro passes over to the lowest range at 100 Hz so that would seem to be primarily a bass driver(s).

However I see that Vandersteen refers to the lowest range drivers in the Quatro as subwoofers, so what do I know? ;^)

Aside from that I do find the Swarm system interesting.

pryso,

I'm not sure if you know, or have heard, how good Vandersteen speakers are.  The Quatro Woods that dcbingaman owns are one of their top models.  They are full-range speakers that are expensive (about $11k) and have been very well reviewed.  Here's a link to one of the reviews I've read:

 http://www.positive-feedback.com/Issue65/vandersteen.htm


     While I agree that price does not always equate to quality performance, in the specific case of the Quatro Woods I suggest it does.  

     You stated:
" This may sound picky but it is a matter of definition.  Most often I've seen subwoofer defined as producing the lowest octave of sound, 20-40 Hz.  So a standard woofer may cover bass as far down as 40 Hz.  The crossover for the Quatro passes over to the lowest range at 100 Hz so that would seem to be primarily a bass driver(s)."

     I don't think you're being picky and I'll define excatly how the Quatro Woods function and let you decide what to call the drivers:

Each tower has a 4.5" midrange driver.

Each tower has a 6.5" mid-bass and lower midrange driver, that Vandersteen describes as a 'woofer', that are limited to a frequency range of 100-900 hz.

Each speakeralso have dual 8" deep bass drivers, that Vandersteen describes as 'subwoofers', that operate from 20-100hz.   Room compensation controls, along with bass level contour controls, allow the speakers to be placed where they image best and the bass to be optimized in that position.  The dual 8" drivers in each cabinet are driven by a dedicated 250 watt class B amp.

I consider any driver that is near flat at 20hz, and utilized for frequencies between 20-100hz,  to be a 'subwoofer'. Both the Vandersteen and Swarm deep bass drivers meet this criteria.  Any differences beyond this,  I would suggest get into the area of definitions, semantics and perhaps nit-picking.

Tim .





Thanks Tim.  My comment was intended for anyone else reading this discussion as much as for you.

I've been in the audio hobby for decades so am likely considered "old school", if not just an old fart.  That's why I adhere to the traditional definitions -- bass = 20-160 Hz, mids = 160-2K Hz (approx.), and highs = 2K-20K Hz.

The range for woofers certainly varies, sometimes extending as high as 500 Hz, so well into the lower-midrange.  But in my experience the lowest octave, 20-40 Hz, is always considered sub-bass or subwoofer range.

I only "nit pick" because I find it helpful to define terms, particularly when any one of them may be considered vague.  I define subwoofer differently than you or Richard Vandersteen, and that is fine so long as each of us is clear about our intent.

Lastly, I've owned three different pairs of Vandersteen speakers and still admire them, but that was some time ago.  I've heard the first generation Quatro but not the current iteration.  By the way, do you know why it is named "Quatro"?

Happy listening. 

Hi pryso,

      It seems like we've both been involved in this hobby a similar amount of time, myself for over 4 decades.  

     I also generally agree with the traditional definitions you listed: bass=20-160 hz, midrange=160-2k hz and treble=2k-20k+ hz. However, I think bass needs to be further defined between mid/upper bass ( ranging from about 30-40 hz to about 160 hz) and deep bass (I would suggest anything below about 30-40 hz).  I'm not knowledgeable enough to stipulate an exact frequency that divides mid/upper bass and deep bass best reproduced by 'subwoofers'.

     My current opinion, on both ht and music reproduction in home sound systems, is that best results are achieved by utilizing 2 separate systems: one for midrange and treble frequencies (using a pair of stereo speakers optimized for best sound stage imaging) and the other exclusively for bass frequencies (using 1 or more subwoofers and dedicated amp(s) and optimized for best bass reproduction through proper positioning that is tailored to each specific room.  I prefer running the main speakers full range and having the bass system's upper frequency cut-off set at just above the main speakers' deepest clean bass capability.  This cutoff frequency will differ based on the main speakers and the room they're set up in.  There is fine tuning and experimentation required when determining the proper upper cut-off frequency of the sub(s) to seamlessly integrate them with the main speakers.  Some may prefer to limit the bass their main speakers reproduce since this considerably reduces the power required from their main amp and eases the demands on their main speakers.  

     I believe the above works best for me in my particular room.  This dual system approach also makes sense to me since it is has been proven that midrange /treble frequencies interact differently to a room than bass frequencies do to the same room.  This is due to the great differences between the lengths of the sound waves each produces.  The lower the frequency, the longer the sound waves become with bass sound waves often being longer than a room's boundaries.

     Toole, Geddes and Welti, among others, have shown that multiple well positioned subs are able to produce accurate and well dispersed bass in any room smaller than a theater or auditorium.  This creates a solid bass foundation or base (a base for bass?) in the room without the need for bass traps or any corrective digital room processing systems.

     Fortunately, the much shorter mid-range /treble frequencies are more easily accomodated than the much longer bass frequencies in most rooms.  Main speaker positioning, along with the possible need for  acoustic panels to control first sound wave reflections,.are all that's needed to create a solid, well integrated sound stage illusion.  The mono bass system integrates seamlessly with the mid-range /treble system without one detracting from the other.   It is highly unlikely that 2 full-range speakers could be positioned in a particular room and be capable of producing such excellent results.  Either the bass or the mid-range / treble performance will typically need to be compromised. I think getting optimum performance of both at specific locations in a room may not even be possible.

Just my thoughts,
  Tim

    

 

     
pryso,

     I forgot to respond to your question on why Vandersteen calls hiis speakers 'Quatro".

     I don't know for certain, but it may have something to do with the speaker being a 4-way design: treble, mid-range, bass and sub bass.  Quatro is spanish  for four and they probably thought 'Quatro Woods'  sounded a bit better than 'Four Woods'.

Tim

     
Tim, if curious you might verify this with Richard.  This is my understanding.

The first four models of Vandersteen speakers were identified One through Four.  The Four was the top of the line and similar in appearance to the others with a wood cap and bottom and stretched grill cloth covering the boxes and drivers, except it was much larger.  Then after just a few years the Four was the first model to be discontinued.

The next top of the line model was the Five, leaving a gap in the numbering system.  So when a new intermediate size between the Five and Three was introduced Richard identified it as the Quatro because it was significantly different from the old Four, thus hopefully avoiding confusion.

Just don't ask me whatever happened to his Model Six! ;^)

pryso,

     Thanks for the info.  But why did you ask me about the Quatro name if you already knew the answer? Wiseguy,  I was just guessing.

     Whatever happened to his model Six?

Tim
Quatro question was just for fun.  But also chance to offer my understanding to be corrected if necessary.

Oh ya, no idea about the Model Six.