My experience adding subwoofers to 2 channel

Sub integration for proper bass is not the way...
Note the word proper.

Change your speakers or accept them for what they are.

Jmac:

I have been using a HSU ULS -15 MK2 , doing double duty for music and HT, for about a year. I find it very well built and performs very well. With all the talk of multiple subs I am tempted to get another one to see how much better it could be, but so far every time I think it out loud, the wife gives a bad reaction. But you know what they say, its easier to get forgiveness than permission, so one day it might just apare.

Hello mijostyn,

    Thanks for the clarifications on your system. I know 'ESL' is usually an acronym for electrostatic loudspeaker but mistakenly thought the Acoustat 2 + 2 were planar-magnetic speakers. I now understand they're ESLs with the '2 + 2' designating there are two 94" tall panels utilized for each channel, meaning they're technically not a pair of speakers but a quartet of speakers. My mistake.
     Ever since I bought my 2.7QRs used about 2001 I've been experimenting with single and dual subs in an attempt to incorporate good bass response and impact in the 20-35 Hz range I knew they were lacking.  After a lot of research and some luck, this led to my learning of the 4-sub distributed bass array (DBA) concept and buying the Audio Kinesis Debra 4-sub DBA system on a trial basis about 4 yrs ago.        
      My current thinking is that this DBA system has provided such accurate, detailed, smooth, natural, dynamic and extended bass down to being flat at 20 Hz while also seamlessly integrating with the quality and speed of my planar speakers in my room, that I honestly feel very fortunate to have this high a level of bass quality in my system.
      I realize, however, that a linear bass array sub configuration could provide even better bass performance in my system and room than my distributed bass array.  
      I'm hesitant to find out, though, for several reasons. I have a much better comfort level with the distributed array concept due to a better understanding of the physics and psycho acoustics involved than I do with the linear array concept, the distributed array is already completely hooked up and working extremely well and my wife and I are also very pleased that the 4 subs in my room are currently so physically inconspicuous and well integrated into our combination living, music and ht room.  In addition, it would likely take a large room rearrangement just to give the linear bass array a try and there's no guarantee I would prefer it either.
     I wanted to respond to your questions and suggestions from your last post, too.  My listening chair is backed up to and centered along my room's 16' rear wall.  But I move it about 3 feet out into the room for serious and prolonged listening sessions for better soundstage imaging. My panels are always a minimum of 3 feet and sometimes more away from the pair of subs behind them.  Both sub 10" drivers are also facing the front wall and not directly into the back of these panels.  I notice no detrimental effect in any frequency range from this positioning.
     You also stated: "You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time."  
     It's my understanding that the time-domain on frequencies under 100 Hz are not as critical as some believe.  I also read an article on an experiment proving we don't even detect deep bass sounds until the entire frequency soundwave cycle exists in the room.  The experiment consisted of subjects wearing headphones.  A series of computer generated  partial and full cycle deep bass tone soundwaves were played and the subjects only were able to detect the bass tones in which the full cycle was played and no sound at all when the partial cycles were played.  As you know, it takes some time and distance for a full 56 foot long 20 Hz soundwave to develop in a 23 x16 foot room.

Tim 
      

I have used a tri-amped electronically crossed three way line array system that I built myself.  This worked seamlessly.  The 12 inch woofers worked well as subs essentially running 32- 250 hz.

I am currently building a new system to go downstairs(sine my wife commandeered the other one for watching movies upstairs).

This one will be a Quad amped electronically crossed  line array: per side:  15 ribbon tweeters, 25- 2 inch midranges, one 8 inch mid woofer, and one 12 inch sub woofer.  

Electronic crossovers(digital or analog) are the key to making this work, IMO.

I recently purchased some transmission line (like) ported towers and was unable to successfully integrate my single sub- so I sold it.  
I have had no problems in the past with typical ported monitor speakers- and am quite good at integration using RTA, phase control for time delay, etc.  
I could not get the bass to sound good- often hard sounding despite my efforts.

I had no peaks in the response either so EQ will not help.  

I'm guessing that transmission line ports are somehow more difficult to integrate.
I miss the impact my sub provided and any advise would be appreciated.  

zarathu,
     
    I wasn't implying speaker and sub line array configurations don't work well, I know they do.  I was just stating these arrays are best for a dedicated room or stage, using them in a living room requires serious rearrangement of the décor.

Tim    

The idea mijostyn has (and others, he is far from alone in this) of bass timing being smeared is of course based on the false assumption that human hearing responds to all frequencies equally.

That this is false is proven by a simple experiment in which subjects wearing headphones are played test tones of short duration. This test demonstrates conclusively that less than one full wavelength of low frequency bass is not heard AT ALL. Say again, human hearing does not even register very low bass less than one full wave duration.

Understand what this means? A single 20 Hz wave lasts 0.05 seconds. Anything 20 Hz lasting less than 0.05 seconds will not be heard at all. Sound travels roughly one foot per millisecond. Ballpark. So think about it. Bass can travel FIFTY FEET before we are even capable of hearing it.

So I ask, from the point of view of timing- not frequency response, just timing- how in the world is it possibly going to matter where you put the subs? Any normal size room the bass is going to leave the speaker, bounce off half a dozen surfaces, probably more than once, all before you even hear it.

Yes timing is super important - at high frequencies. I take heat on here all the time for saying speaker placement being off as little as 1/8" matters. But that’s high frequencies. Low bass is completely different.

Just one of several deeply ingrained yet totally false concepts hampering our ability to understand the beauty of the distributed bass array.

avanti1960,

     You may want to try the 'room crawl method'.  Place your sub at your listening position, play some music with good and repetitive bass and walk around the perimeter of your room counter-clockwise starting at the front right corner.  Walk slowly listening for an exact spot where the bass sounds best to you (accurate, detailed and natural).  When you find this spot in your room, just move the sub to that position and verify the bass sounds good from your listening seat. You can use your RTA at this point for fine tuning if you'd like.
      If you prefer good bass response throughout your entire room, and not just at your listening seat, the only solution I'm aware of is a 4-sub DBA system.

Tim

Tim,

Thanks.  I'm going to start a thread on this topic.  

Cool.

I have recently added 2 more 21 inches subs to the existing 2 12 inches subs to my main speakers. I find that the system sound more engaging with just the 21 inches subs. Maybe the subs are out of phase with each other. I do not know how to integrate them.

"I have recently added 2 more 21 inches subs to the existing 2 12 inches subs to my main speakers. I find that the system sound more engaging with just the 21 inches subs. Maybe the subs are out of phase with each other. I do not know how to integrate them."

khiak,

     I think you're saying you have four total subs (two 21" subs and two 12" subs) and like the sound with just the two 21" subs and no 12" subs in your system.  Is this correct?

Tim

Yes

I have the 12 inches subs for 6 years. The 21 inches subs added this month of May. Room is small so limited choice of placement.

Thanks, Tim for your help 

Hello khiak,

     What are the dimensions of your room (length x width x ceiling height)?  What are the brands and model numbers of your subs? 

     You can definitely achieve very good bass response at a single dedicated listening seat with 2 subs. Using the 'room crawl method', described to avanti1960 earlier, in a sequential manner (first sub#1 and then sub#2) is probably the best way to position them.
      In my experience, 2 subs will provide much better bass performance than 1 but in my opinion 4 subs will provide the best bass performance since line array sub configurations are not well suited for small rooms like distributed array sub configurations are. 
     The 4-sub DBA system concept works incredibly well in virtually any room and actually is perceived as making a small room seem like a larger room.
     The key to a DBA system being such an exceptionally high quality bass solution is the use of 4 subs; the brand/model, size, power, price and type (self amplified or passive) are much less important than the fact that there are 4 of them active in the room.  There are also no requirements that all subs are identical and subs of varying driver sizes, power, prices, types and bass extension are viable.
     If you have a smaller room, however, I'm curious why you chose to add 2 subs with large 21" drivers when adding 2 more subs with 12" drivers is more logical and physically suitable?

Tim

Hi Tim,
The room length 18 ft, width 12 ft and height 9 ft. The subs are JL212v1 and 21.0LX Funk Audio.

The main speakers are 7 ft apart and the JL212 sit about 1.5 feet behind the main speakers inner side. The main speakers is 5 ft from the back wall.

The main listening chair is 7ft from both speakers and 12 ft from the front wall.

Three feet behind the main chair are a row of 3 chairs.

A 21.0LX sit on the left wall 3 feet from left main speaker with the driver facing the right wall.

Another 21.0LX sit near the corner of the right wall 9 feet from the right main speaker with the driver facing the left main speaker.

The acoustic of the room is designed by ASC of Seattle.

So much discussion on 4 subs in the room, so I want to hear how 4 subs sounded in my dedicated room which is for 2 channel and home theatre. Why 21 inch driver, I never hear how 21 inch driver sound.

The rest of the wall space are occupy with racks and equipments and tube traps.

There are no other location available for the 2 21.0LX.


I have no idea how to go about to setup/calibrate  the 4 subs optimally.

Any help appreciated. Thanks.

khiak

Hello khiak,

     Those Funk Audio 21.0LX are beautiful subs but they're really meant for a larger room.  If you live in an apartment, your neighbors are going to hate you if you start using those in your room.  If you really want to use those in your room, you'll need to keep them turned to a low volume to work well in a 4-sub DBA.  I currently think the best solution for your room size would be 4 subs with single 12" drivers.  A few more questions:

I'm having trouble looking up the JL 212 V1, is the model# F212 V1?
Do they have single 12" drivers or dual 12" drivers?

Would you be able and willing to return the big Funk Audio subs to achieve better overall bass in your room?

It sounds like your main speakers and rack are along the long 18 ft wall with your listening chair, with 3 seats behind, along the opposite 18 ft wall.  Is this correct?

Are you planning on moving to a bigger place or home soon?

Thanks,
  Tim

Hello Tim,
i have the dual 12” F212v1. I just got the 21.0LX the early this month after waiting 6 months for them. Comparing to the F212v1 which I have for the last 6 years, I like the 21.0LX better as it makes the overall sound more engaging. Big doesn’t have to be loud, the output level gain have to be lowered so they just disappeared into the room like the F212v1.
Unlike the F212v1 which have the variable 360 phase adjustment, the 21.0LX have delay adjustment in ms by the software DSP. My system sound best with only the 21.0LX. With the 4 subs, I think there is a timing issue between them which smear the sound. I have no ideal how to set them to be in phase with each other and the main speakers.
All available space on the left and right wall are racks with the hifi equipments. The back wall are tube traps from floor to ceiling and blue ray cabinets. On the front wall I have the fix screen for the projector, and half tube traps below the screen. Also floor to ceiling tube traps on the corners of the front wall and a cradle mounted center speaker.
I am not planning to move as I am over the 70s, my last hangout. Hahaha.

Hello khiak,

      Well, you have four very high quality subs which you should be able to position and configure into a very high quality 4-sub distributed bass array system for music and ht.  
     I'm willing to assist you in this process but I want to warn you it's going to take some work and trial and error experimenting to properly position and configure the settings. 
     If you'd like me to assist you, I just need to know a few more things before we get started.  It sounds like you have a screen and projector for video setup on the opposite 18 ft walls. So, I need you to confirm this and describe the rest of your audio/video equipment:

1.  All your receivers, amps, preamps,surround sound processors, turntables, cd players, video players and any other hardware you use.
2.  All equipment and storage racks.
3.  The main speakers, center channel and surround speakers you use. 
4.  Any room treatments you currently use such as carpets,bass traps and absorption or diffusor panels.

Tim

noble1001,287 posts05-23-2019 4:00amHello khiak,    
    I'm willing to assist you in this process but I want to warn you it's going to take some work and trial and error experimenting to properly position and configure the settings.

Very nice offer.

Researching khiak's Canadian Funk Audio 21.0LX subwoofer's their enclosure seems to be well crafted and similar to another successful subwoofer design. 

Tim, I'd suggest obtaining more information on the parameters of their DSP process. Specifically, if they're able to line out their DSP'd signal into the F212s. I was able to do this with an F113v1 from my Velodyne DD and the F113s integration and output improved in my room. 

The F113 is a very fine subwoofer but its crossover and manual adjustability seemed to be a shortcoming in my experience. JL Audio currently markets version 2 processing and a separate CR-1 Crossover component which I have no experience with. 

I would definitely NOT sell your F212 v1s. Good luck with it.

Hello m-db,
     Thanks for your information.  I'll look at the manual on Funk Audio's website to learn more. 
     He has four very high quality and expensive subs.  The 4-sub DBA concept works exceptionally well even without room control. Do you use 4 subs in your system and room control?
     If so, I'm interested in learning what specific additional bass performance improvements you noticed beyond the typical bass quality improvements gained from using the 4-sub DBA system.  In other words, what specific bass quality improvements did you notice after applying the room control?

Thanks,
  Tim
   

Hello Tim,
Many thanks for your kind offer to help me in the setup of the 4 subs in my music room. 😃😃😃

After viewing Audiogon forum on getting better bass performance with 4 subwoofers in a room, I decided to give it a try. So I added two 21.0LX to my existing two F212.v1 early this month. Instead of adding another two F212v2, I decided to go for 21 inches woofers as I have never heard the bass from such woofers in my life. I have owned the F212v1 for 6 years but I have to say the bass of 21.0LX is awesome.

I have a fix Stewart movie screen frame 94” X 55” at the front wall about 5 ft behind the tweeter of main speakers. The bottom edge of the screen frame is 27” from the floor. From the left edge of the screen frame to the left wall, there is a ASC full round tube trap from floor to ceiling, similarly on the right edge. From the bottom of the screen frame to the floor, I have half round ASC tube trap horizontally. I have 2 half round ASC tube trap mounted on the ceiling between the 2 corners full round tube trap. There is a set of 3 half round tube traps mounted on the ceiling across the width of the room above the main speakers.
A Revel voice 2 center speaker with mounting pedestal sit in front of the movie screen with the F212v1 at each side. The subs are about 2 ft from the edge of the Center speaker.
The Kharma Exquisite Reference 1E Signature main speakers are 7ft apart and the F212v1 is about 1.5ft behind the main speakers inner side. Between the main speakers are 3 rows of 5 mono amps and preamp power supply. Left row is Goldmund Telos 600 stack on top of each other for left main speaker bi-amps, middle row is Goldmund Telos 600 mounted on the bottom of 2 deck rack for the center speaker. The power supply of the Goldmund Mimesis 22S sit on the top deck of the rack, right most row is Goldmund Telos 600 stack on top of each other for the right main speaker bi-amp.
The Goldmund Mimesis 22S Signature preamp sit on a rack in front of the Rack for the center  speaker power amp. 
On the right wall 1.5 ft away from the right main speaker are 3 rows of 3 deck racks where two Mark Levinson N332 for Revel Embrace surround and Vienna acoustics back speakers, Marantz MM8077 for  four Beale Street ICA6-BB height speakers and two Bose wide speakers. Marantz AV8802A processor, Pioneer DVL-919, Dream Vision Sealer 3, Lexicon RT-10, Phillips BDP9600 and Panasonic DMP-UB900 are located.
On the left wall 1.9 ft from left main speaker, sit the 21.0LX follow by a rack with 2 deck for the Reimyo CDP-777 and DAP-999EX and finally the door to the room.
On the corners of the back wall are full round ASC tube traps from floor to ceiling with a 70”X16” wall mounted Blueray cabinets on their side and 3 columns floor to ceiling full round ASC tube traps between them.
The right and left walls above the rack height are space with ASC sound planks. At the wall just beside the main speakers are custom wall mounted reflective towers.
The main listening chair is 7ft from the main speaker and 12ft from the front wall.
The JVC RS-65U projector is mounted to the ceiling directly above the main listening chair.
Hope all these info are helpful. I wish I can send you photos which are much better.

😃 Thanks 
khiak

Hello khiak,

     Well, you certainly have some excellent and expensive audio equipment in your system.  My system is a starter system in comparison to yours but I still believe my knowledge and experience with 4-sub distributed bass array (DBA) systems can be of benefit to you.
      I'm running into a few issues while determining the best bass solution given your current room and equipment.  My concern is you may be hesitant to adopt some of my suggestions because you've obviously invested a lot of money in a few of these areas and some may require room rearrangements. 
      I thought it would be best if I just described these issues in a straightforward manner with the assurance I'm not criticizing you by doing so.   My intention is just to learn more about your system's development, better understand your room requirements, get your thoughts and discuss as necessary before proceeding.  I'll assume you agree with this approach and begin describing these issues:    

1.  Why do you have so many bass traps in your room?  
     
     I fail to see the reasoning of having 4 high quality subs producing high quality bass energy in your room only to have much of this bass energy absorbed by numerous large and expensive bass traps positioned around your room.
     One of the major benefits of using a 4-sub DBA system is that it eliminates the need for all bass room treatments.  I currently use the Audio Kinesis Debra (identical to the AK Swarm but with slightly narrower subs) 4-sub DBA system in my room and the only bass room treatment I have is wall to wall carpeting.  Do you have hard surface or carpeted floors in your room?
    The above is the description of the 1st issue I wanted to address with you.  My initial suggestion is to remove all of the bass traps currently in your room.  They're not only not necessary, this would also free up a lot of floor space for optimum positioning of your 4 subs.
     I know these bass traps are expensive but I really don't think they're doing anything to improve the perceived bass response in your room, although I'm sure an ASC sales rep would disagree.  Are you okay with removing all your bass traps?
     It sounds like your 21.0LX subs are on the left wall in front of your equipment deck and near your left Kharma main speaker. Both of them?  Are they currently hooked up and running or just stored there for now?

2.  My current thinking is you place both 21.0LX subs on the front wall, replacing your JL subs.  Set each sub's delay and phase setting to zero  and adjust the volume and xover frequency identically for both until the bass sounds the best to you at your listening seat. 
     Then place a JL sub on each left and right wall, about 1-3 feet away from the rear corners and, with both front subs running, set each sub's room control to "off" and phase setting to zero and adjust the volume and xover frequency identically for both until the bass sounds best to you at your listening seat. 
     Of course, having an assistant make the adjustments as you evaluate the sound will be very helpful.  Once the bass sounds very good to you at your listening seat, adjust the phase control on each sub, in sequence one at a time, to check if altering the phase on any single sub improves the overall bass even further. If not, just leave them all set to zero which is in-phase.       
     A 2nd option could be using what  M-db also mentioned about JL Audio currently marketing a version 2 room processing and a separate CR-1 Crossover component which could be useful just in case the above configuration and sub positioning doesn't provide excellent bass response performance in your room.  I'm going to check this out and see if it'd be useful for your scenario.
     A 3rd option could be the method I used for positioning each sub, which involves a sequential positioning I can explain later if needed.
     Please let me know your thoughts, comments and questions.

Tim

Hello Tim,
In 2000, I bought a pair of MBL101D Radialstrahier speakers. I enjoy listening to my music very loud around 85dB to 90dB, so you can imagine in a room 18’X12’X9’ without acoustic treatment, everything sound bad especially the bass. So I got ASC Mr Art Noxon from Seattle to design the acoustic for the room.

The floor is concrete overlay with 3” wide 0.75” thick 48” Long teakwood of various length

Hello Tim, 
Is there a way I can send you a video clip of the room? 

Tim, sorry I did not get back earlier. I can not believe people are so far off on the subject of time and phase. Time and phase are intimately related. wire two of your subs backwards and see what you get. That is 180 degrees out of phase. You get exactly the same effect when the distance between speakers is different. The wave length of a 100 Hz tone is about 10 feet. If you put one sub 5 feet closer to you than another you get exactly the same effect as if you wired one speaker backwards. Music is not one tone so you get every frequency altered by a different phase angle. Then you have a range of frequencies to deal with at the cross over which depending on slope may be as high as 250 Hz. It is also not only about what you hear but about what you feel. In phase you feel the thud of that bass drum strike. Out of phase and you feel nothing. You can easily demonstrate this to yourself by reversing wires. A system that is aligned in phase and time is a wonderful thing to hear and feel. It is much more realistic. If I blind folded you, drove you around and brought you into the room you would think you were in a jazz bar. I'm afraid millercarbon is spouting off with excuses to support his infatuation with SWARM systems, all of which are entirely unsupported assumptions which in reality are entirely wrong. Humans are marvelous creatures. When they don't know what is going on they make stuff up. They mythologize. Zeus, great explanation for lightening don't you think?

Oh, and Tim. I am not saying that in certain situations a DBA system may not be the easiest way to reasonable bass performance. It may work reasonable well for many people. What I am saying is that in the end it will not produce the most accurate and realistic results but do to do so usually requires advanced digital speaker control that at this time costs at least $6K. If however you have a tape measure, some savvy and some luck, you might be able to get there without the computer. An important part of this hobby is being able to screw around with your system to see if you can get it to sound better and in doing so you learn. So, start screwing around! 

mijostyn writes:

I’m afraid millercarbon is spouting off with excuses to support his infatuation with SWARM systems, all of which are entirely unsupported assumptions which in reality are entirely wrong.

This is what psychologists call projection. Whatever you are doing you project onto someone else. Instead of actually listening to what they are saying.

Which if you did mijostyn, what you will read if you can be bothered is pretty much everything I have written is based on my actual experience. There is posted among the many threads my actual experience of actually reversing phase, adjusting phase, and trying different locations.

What actually happens- actually not in your imaginary theory world but a real live room- is when you reverse the phase the drum does not disappear. You still hear it. In fact it sounds almost exactly the same. Not quite. You can’t ever change anything and yet have everything be the same. But you said, "Out of phase and you feel nothing." That could hardly be further from the truth.

Now at this point I have to be clear. I’m talking about the lowest bass component only. Of course if you reverse phase on the main speakers the drum is going to go from being focused and located to the opposite, coming from everywhere. At very low frequencies though, and with four subs- which is what we are talking about- its a completely different story. The kick drum does not disappear to "nothing". Talk about unsupported assumptions!

So much for your projecting your own faults onto me. What about your projecting your own misunderstandings onto the Swarm?

You say everything about the SWARM is entirely unsupported assumptions. In fact the distributed bass array concept is based on extensive real world measurement and experimentation. In sharp contrast to your fantasy of it being all "unsupported assumptions" it is in fact only there because of the measurements. In other words it was not a case of a theory in search of evidence. It was the exact opposite of that. It was a case of testing and measurement and then eventually figuring out how to explain why we get those measurements. And only then what to do about it.

Its Audiogon. Someone is always getting something worse than backwards, then posting authoritatively about it. So nothing new here. But just because others do it doesn’t mean you have to follow them over the cliff.

Hello khiak,

  I just sent you a personal message.  You should see a 'dialogue bubble' icon on the upper-right side of your screen, next to the 'shopping cart' icon.  Just click on that and my pm should show. Click on my pm and I think you can hit reply and attach your video clip before sending. 
 I'll re-post on this thread once I receive it.

Tim

Hi Tim, sorry about the delay in answering your question. I hope this helps somewhat.

  Currently subwoofer digital signal processing (DSP) varies a great deal and so too do thier results. My only in home comparrison with a JL Audio F series Automatic Room Optimization ARO v1 was with my old Velodyne DD-18 (v1). 

   Instructions and methods for both differed greatly and can be reviewed and compared on line. For example:
  The JL F v1 uses a limited amount of manual adjustment (at the sub) before and after the internally generated test tone ARO program. Aside from two channel connection instructions there seemed to be little mention of integration with main speakers other than the basic crossover adjustment. 
  The DD (v1) setup procedures include a test tone disc played via CD player were the in room bass roll off of the main speakers and the sub can be viewed from 200Hz on down. Auto-EQ adjusts the level of the eight preset parametric filters from 100Hz on down. Only Manual-EQ allows adjustment of the frequency, bandwidth, and level of these filters and to further tailor the output desired by the user. The sub is not bound by the Auto-EQ or its limits. All DD adjustments can be performed at the listening position using a laptop or by the supplied remote and a TV.   

  The initial equalization results from JLs ARO were different than the DD. After processing the F113 via the DD Auto then Manual-EQ the equalization graph was only slightly different between the two subs. The JL now had better integration and overall presentation. Surprisingly, its 13" driver was every bit as formidable as the DD-18. The JL Audio F series is a great subwoofer.

  Both manufacturers are now using second versions, JLs DARO v2 with an optional CR-1 Crossover and DD Plus. There is a possibility the Funk Farm software could be applied to khiak's 212s which offer a similar amount of cone surface and twice the motor control than the 21.0LXs. 

mijostyn:
" I can not believe people are so far off on the subject of time and phase. Time and phase are intimately related. wire two of your subs backwards and see what you get. That is 180 degrees out of phase."

Hello mijostyn,
     It seems we still have a misunderstanding about time and phase on deep bass sound waves. I believe, at the core of this misunderstanding, is that you're referring to arrival times of deep bass tone frequency soundwaves at the listening position and assuming that the effects of these deep bass soundwave arrival timing are just as critical as they are with midrange and treble tone frequency soundwaves.  
      The owner and speaker designer at Audio Kinesis, Duke Lejeune, has stated that the arrival timing of deep bass tone frequency soundwaves at the listening position are much less critical than the arrival timing at the listening position of midrange and treble frequency soundwaves.  He stated the reason is the extreme differences in the physical length of these sound waves: a 20 Hz bass soundwave is about 56 ft long, a 2,000 Hz midrange sound wave is about 6.75 inches long and a 20,000 Hz soundwave is a fraction of an inch long.  
     I wanted to include a prior post in which I responded to another question from you concerning the time-domain of bass soundwaves that contains similar and some additional relevant info: 

 mijostyn: "You have two subs back there with you and you hear those fractionally before you hear the ones on the front wall. This will smear transients. You want to hear all your subs at exactly the same time."  
    It's my understanding that the time-domain on frequencies under 100 Hz are not as critical as some believe. I also read an article on an experiment proving we don't even detect deep bass sounds until the entire frequency soundwave cycle exists in the room. The experiment consisted of subjects wearing headphones. A series of computer generated partial and full cycle deep bass tone soundwaves were played and the subjects only were able to detect the bass tones in which the full cycle was played and no sound at all when the partial cycles were played. As you know, it takes some time and distance for a full 56 foot long 20 Hz soundwave to develop in a 23 x16 foot room.

     I realize the importance of correct phase in audio reproduction but admit only having a basic understanding.  All 4 of my Audio Kinesis Debra DBA subs are operating in mono and in-phase configurations.  Once all 4 of my subs were optimally positioned, however, I followed the procedures by reversing phase on each sub sequentially, one at a time, to verify whether or not the overall bass response improved with one specific sub's phase reversed. I noticed no improvement with any single sub's phase reversed and, therefore, maintained operating them all configured as in-phase.
     The above is what I learned from scientific research results conducted by acoustical experts Dr. Earl Geddes and Dr. Floyd Toole and Duke Lejeune's posts and writings.  I believe everything I've stated is accurate but you could always refer to their writings if you'd like to verify or learn more.


Tim

millercarbon the radiologists when doing a barium GI study call it FOS.
Blaming me for not knowing what you are talking about will not change the reality of the issue. All of you reverse the wiring of one of your sub woofers and tell us what you hear. millercarbon you are way out of your league. In my estimation filling other people full of your mythology is not an ethical way of dealing with your compatriots. 
Tim, never trust anyone who is trying to sell you something. Arrival times (phase) are even more critical in the bass. I wish I could demonstrate that to you directly but that is not possible. Again, wire your subs out of phase and tell us what happens. Regardless of what anyone says, a phase (time) coherent system is more accurate and realistic than one that is not, particularly in the bass. I have nothing to lose because I am not trying to sell you a darn thing. Beware of Greeks bearing gifts. Go to a local club and have a listen. If your Hi Fi does not approach that sound quality playing similar and well recorded music you have problems you might want to conquer if you even care. Music is not something you just  hear. You also feel it which is critical to the experience. millercarbon obviously does not understand this and is destined to wallow in mediocrity unless he changes his approach to life. It is not easy to achieve this with analog equipment but it can be done and there in lay the challenge. millercarbon would rather make excuses than except that challenge. Will you do the same?  I hope not. It is a wonderful thing to be able to get home at night, go to the concert and feel as if you are really there. If not it is something to strive for which I did for 45 years.

Hello m-db,

     Thanks for the additional info.  I do understand your point about subwoofer DSP room correction differing among manufacturers as well as differing by version from the same manufacturers.
     I only have limited sub DSP room correction knowledge and experience, mainly gained from helping install and configure subs in the systems of friends and family.  My 4-sub Audio Kinesis Debra DBA system has provided exceptional bass results in my room without utilizing any DSP room correction or room treatments and I believe this can be accomplished in any room and with any pair of main speakers. 
     Khiak has 4 exceptionally good subs, two JL Audio F112s and two Funk Audio 21.0LXs, that utilize relatively basic DSP room correction (with the Funk Audio subs only using DSP to adjust signal delay times and not the more specific adjustments possible via parametric equalization) and my current thinking is that these subs could be used to form a very high quality custom 4-sub DBA system either with or without  running their DSP room correction.  
      The main adjustments for good integration would be the manual settings on each sub for volume, xover frequency and phase.  I used these exact same controls, although on my sub amp for all 4 subs running in mono mode simultaneously, to achieve excellent bass response and seamless integration.  I'm unaware of any reason khiak couldn't get the same or even better results in his system and room. 
     Once all 4 subs are positioned and configured, he could always run room control, for a pair of subs at a time, to see if it improved the overall bass performance and just use the configuration he liked best.
     But I think khiak was a bit shocked by my suggestion he should remove all the numerous and expensive bass traps he currently has installed around his room.  I understand since they were likely a big investment but they actually are unnecessary and it would free up a lot of room space.

Tim
       

     
 

My experiences tuning subwoofers with main speakers is that the phase timing is critically important at crossover blend region where the subwoofers and main speakers transition between each other.
An 80Hz wavelength is ~ 14 feet long and is small enough that room dimensions, distance between subwoofer and main speakers as well as distance to listening position can affect the quality of bass response.
Even with a 40Hz crossover frequency there is still significant energy at critical mid bass frequencies (e.g. 80-120Hz) being broadcast by the subwoofers and main speakers. If the timing of the subwoofers is not adjusted accordingly so that the mid bass frequencies aren’t optimized then the listener will hear weak midbass from phase / timing cancellations.  The deep bass will be OK but there will be a gap in the response such that the impactful midbass frequencies are relatively weak.  
The only way I have found to get this right is to use tracks with powerful bass beats and adjust the phase of each subwoofer until it sounds the best- (by ear). With experience you’ll know it when you hear it.  The impact frequencies in the midbass will sound effortless even at low volume levels.  The key is in the midbass.     
DSP, room correction etc. fall short of achieving this automatically.

mijostyn:
"Oh, and Tim. I am not saying that in certain situations a DBA system may not be the easiest way to reasonable bass performance. It may work reasonable well for many people. What I am saying is that in the end it will not produce the most accurate and realistic results but do to do so usually requires advanced digital speaker control that at this time costs at least $6K. If however you have a tape measure, some savvy and some luck, you might be able to get there without the computer. An important part of this hobby is being able to screw around with your system to see if you can get it to sound better and in doing so you learn. So, start screwing around!"


Hello mijostyn,

     Incorrect, wrong and you're mistaken.  Millercarbon absolutely knows you're wrong because he had the intelligence and cajones to give it a try.  There's no need for expensive advanced digital speaker control gear, any other DSP or PEQ equipment, tape measures, meters, bass room treatments, voodoo, chants, snake oil, savvy or even luck. 
    The key ingredients are just a minimum of 4 subs , proper positioning of all 4 subs and some precise and time consuming listening, calibration  and repeating of the volume, xover frequency and phase settings until it sounds just right.
     I believe the root cause of our disagreement over the effectiveness of 4-sub distributed bass array systems is your lack of experience and familiarity with them.

Tim 

Avanti I agree with you almost entirely. You do have to with your rooms acoustics physically but particularly when it comes to bass there are limits as to what you can achieve. You can not achieve SOTA bass without digital bass management and subwoofer control. First you have much more control over x-over frequencies and slopes. In the digital realm there is no phase shift. Then you can adjust the frequency response of the sub woofers so that they are up 3 db at 20 Hz. Tolerably sized sub woofers start rolling off at around 60 Hz and are down 6 to 9 db at 20 Hz especially if they are not closely coupled to a wall or corner.
With enough power this can be corrected with startling results. Putting on a 20 Hz tone is a riot. It sounds and feels as if it is coming from the whole house and everything buzzes and rattles. Dishes, silver ware, picture frames, the toilet and my teeth. At 60 Hz I can definitively localize the sound and the symphony of rattles stops around 40 Hz. 
Tim, the best speaker control (room control) measure each speaker independently and adjusts each speaker independently. The problem with sub woofer systems is that they ignore the satellites.     

Oh and Tim I have used subs in every configuration you care to think about and have been using 4 subwoofers for......25 years anyway.
I am glad you like your system and that it works for you. Unless you are extremely lucky your bass below 40 Hz is for certain a mess. Lord knows what it is doing up to the x-over. If you send me pictures of your room and system I would be happy to fix it for you. I am working with another forum member who has Acoustats and was unhappy with his DBA system. Of course he is use to a level of detail and imaging that you can't get out of dynamic drivers so the muddiness of a DBA system would be more offensive to him. I have not heard back from him yet but I think we have finished adjusting his system.
I don't have to use a tape measure myself. All I do is set up a microphone and tap the measure button which is displayed on my PC. If I am happy with it I tap the enable button and all the volume, delay and frequency adjustment are made in a few seconds. Then I overlay my own response curves and we are good to go. No guessing and I am not relying on anybodies hearing not even my own. There is no way I could get bass this good by playing around and depending on hearing. You can't either especially with sub woofers thrown all over the room.

noble100 says of mijostyn:

Incorrect, wrong and you're mistaken. Millercarbon absolutely knows you're wrong because he had the intelligence and cajones to give it a try.

Yup. And thanks. Finally got the Rosewood veneer on and finished. 

I believe the root cause of our disagreement over the effectiveness of 4-sub distributed bass array systems is your lack of experience and familiarity with them.

For sure. Demonstrably so. Thanks again.

Ok, DBA SWARM subs are absolutely the only way to go I wish I had the cojones to take my 200 lb subwoofers and their 2000 watt amplifiers and toss them up in the air to let them play wherever they land happily ever after. But I am an old man and to stupid and weak to lift these things never mind throwing them up in the air.
I'm sure you guys are on gluten free diets. You need to switch to now to Keto!

Hello mijostyn,

     I’m running all 4 subs in mono with a xover frequency between 40-50 Hz and a filter slope of 12 db/octave, usually configured for a 40 Hz xover for music and 50 Hz for ht. My main speakers are Magnepan 2.7QRs that each have a 620 square inch planar-magnetic dipole bass section but they only extend down to 35 Hz. I run these full range with a pair of D-Sonic M3-600-M mono-blocks rated at 1,200 watts each at 4 ohms. This combo produces very accurate and high quality bass on their own but I added the AK Debra 4-sub DBA system for added bass impact and increased dynamics.
     Since the 2 bass sections only extend down to 35 Hz, I don’t consider them extra subs in the room but I do think they help on the overall bass quantity and quality in my room; for example, hearing the initial pluck of an upright bass’s string followed by hearing the deeper bass produced by the body of the instrument and finally the natural decay.
     Subjectively, I perceive the bass as very accurate in tone, detailed, extended, dynamic, smooth and natural with an impact that is felt as well as heard. I don’t detect any bass muddiness or have the sense that the bass is too slow, lagging behind or disconnected from the rest of the reproduced spectrum. 
     However, I’ve never had the in-room frequency response measured but I would be very surprised if it didn’t measure well.  I do have pictures of my room and system on my profile if you’d care to look and my room is 23 x 16 feet with 8 foot ceilings.


Thanks,
Tim

I have known Duke LeJeune for quite some time now, even owning his Jazz Module speakers for several years and using his speakers in my exhibit rooms at audio shows. Earl Geddes was his mentor and while Duke manufactures box speakers, he has a pretty good understanding of ESLs having used the original Quad ESL in his research (the speaker that replaced my Jazz Modules) and being one of the more prominent Sound Lab dealers. I think he has a good grasp on sound dispersion and how to maximize it. In addition, I should mention I had never been keen on using subs in my system even though I was well aware of Duke's initial work developing the Swarm.

The last show I exhibited at with Roger Modjeski we used his ESL speakers which by default had to have subs since they only went down to 100 Hz. Roger designed a sub with an 8" driver in a 0.3 cu. ft. sealed box (air resistance) and used two to compliment his panels in a bi-amp set up with the Beveridge RM-3 crossover he designed for the 2SW speakers long ago. After hearing this I followed suit but decided I would expand to 4 subs to replicate the DBA of the Swarm. For the last few years I have enjoyed this set up with both the Quad ESL and now my modified Acoustat Model 2 speakers.

However, I was intrigued enough by mijostyn's set up that I contacted him and he sent me a photo so I could visualize it. I would like to add that I was not unhappy with my DBA set up, but since he was also using Acoustats (they are essentially a bigger version of my Model 2s) I felt this was worth a try. Over the past few days we have been communicating and he has helped me tweak things to get the set up just right. I have been listening on and off since last evening and have to say I am impressed by what I hear, the primary difference being what I feel in the low end. So I would like to thank mijostyn for his contributions to this topic and help getting me there. I will try to post more on this as I continue my listening.

Hello clio09,

     I'm very impressed with mijostyn's linear/line array sub system and I've never even heard one in a home system, although I'd love to.  
     I'm also very interested in in your bass system build with your Acoustats that mijostyn is very kindly assisting you with.  I'm also very happy with my DBA system but would be tempted to try it if I had the clean slate of a dedicated room.  My combo music and ht room is also my living room.  My 4 subs are currently very inconspicuous in the room which I think is very cool, because you only hear and feel them when there's prominent bass content on music and ht being played, and my wife can live with.
     As I understand line array bass systems, the subs would be aligned across the front wall of the room and my 6x2 foot Magnepans would also be positioned about 4-5 feet out from this front wall.  I'd be okay with it but my wife's opinion of this in our living room would likely be expressed by a sturdy frying pan smacking my skull. 
    But I wish you only the best on your build clio09 and hope you and mijostyn enjoy your linear array bass systems very much.

Please do post updates.
Thanks,
  Tim

My subs were built a while back, mijostyn helped me set them up for optimal performance in the line array. His subs have quite a large footprint, as do his speakers which are probably the best Acoustat model in my opinion. They line array per mijostyn is actually a semi circle as opposed to all of the subs being against the front wall of the room. A very interesting set up and one that does require some attention to detail. I appreciate mijostyn’s patient with me.

In my room the DBA did work well for my needs, and it wasn’t a difficult system to set up. My only nit was that my room constraints didn’t allow me complete freedom to place the subs anywhere I wanted. The sound was quite good though. I am embarking on building 4 new subs using a 10" driver and look forward to going to the audio show in Long Beach to hear Duke’s Swarm in person.

Hello Tim,
 “ I just sent you a personal message. You should see a 'dialogue bubble' icon on the upper-right side of your screen, next to the 'shopping cart' icon. Just click on that and my pm should show. Click on my pm and I think you can hit reply and attach your video clip before sending.
 I'll re-post on this thread once I receive it.”

i do do not know where to locate ‘dialogue bubble ‘ icon.
khiak

Thank you clio. You said something that is very important (to me at least)
Bass is not just about hearing. It is about feeling. Part of the rush of a live performance is the visceral sensation you get from accurately projected lower frequencies. This is not easy to do in the home environment. Very few systems do this well but it is vital if you want to feel as if you are at a live performance. Even with string quartets the cellos go low enough to feel to to mention the transients caused by banging and thumping on this that and the other. The "visceral" range is (I'm guessing) from 150 Hz down.
Tim, Magnepans are great speakers. If you remove enough bass from them you can get them as close as 28" to the front wall. Just put some acoustic foam directly behind them. There is this thinking that you have to keep the cross over as low as you can to prevent the woofers from getting up into your mid range. It is easier to blend in with the satellites at higher frequencies and this is particularly true with dipoles which you have just like clio. He crosses over at 100 Hz, not sure about the slope.
Many cross low because they are trying to avoid a high pass filter on the satellites which is also mistaken. Removing the low end from the satellites cleans up the midrange and increases your power handling. You can put a simple 6 db/oct high pass filter on your Maggies simply by putting a cap across the input of your amps the value depending on your input impedance. The equations are on line. 
The reason clio is now feeling his bass is because his subs are now functioning as one driver and the arrival time (phase) is the same across the entire room. His Acoustats are now part of that linear array in the crossover zone. He is now getting his bass as one unified whole not the random output of various drivers around the room. Placing speakers around the room will smooth out response variations but because the speakers are more than likely 1/2 wavelength of the highest frequency you want them to carry apart, they are acting as individual drivers and transients are being smeared. This may be another reason DBA people want to stick with lower x-over frequencies. You can put the subs farther apart and get away with it. A SWARM system can work under certain circumstances. Low x-over points in smaller rooms. Once you pull your cross over up and get into a larger room say 15 X 20 you get into trouble.
What you hear is important. But with bass what you feel is more important.

I forgot to mention that clio has also eliminated 4 of the 5 primary reflections that cause comb filtering in the bass. 
Another way to look at this is that the bass linear array is just a more specific DBA system. It will always require 4 or more drivers unless you listen in a closet.

Hello clio09,
     Wait a minute.  What's your plan?
I thought your plan was switching to a line array with larger subs. Four new subs using 10" drivers sounds like your planning a dba.

Tim
  

I use low pass and high pass filters in my active crossover, Linkwitz-Riley 4th order 24 dB slope. One reason this was chosen is that we wanted to keep deep male vocals out of the subs. The other reason had to do with the resonance of the 8" drivers which we wanted to keep above 100 Hz. This is the reason for a 0.3 cu. ft. box which is stuffed tightly with cotton batting. The last reason has more to do with Roger Modjeski’s ESL design which only goes down to 100 Hz but that is irrelevant to me as I use the Acoustats which he modified to create greater dispersion, but left the rest alone, sort of ;)

I should also mention that the speakers are 4 ft. from the wall behind them, 18" from the side walls, and about 94" apart, which is the same distance to my listening position.

clio09:
"My subs were built a while back, mijostyn helped me set them up for optimal performance in the line array. His subs have quite a large footprint, as do his speakers which are probably the best Acoustat model in my opinion. They line array per mijostyn is actually a semi circle as opposed to all of the subs being against the front wall of the room. A very interesting set up and one that does require some attention to detail. I appreciate mijostyn’s patient with me.

In my room the DBA did work well for my needs, and it wasn’t a difficult system to set up. My only nit was that my room constraints didn’t allow me complete freedom to place the subs anywhere I wanted. The sound was quite good though. I am embarking on building 4 new subs using a 10" driver and look forward to going to the audio show in Long Beach to hear Duke’s Swarm in person."


Hello clio09,
     
     I'm having difficulty following along with your posts.  From your post quoted above, it seems you're switching from using a distributed bass array (DBA) to a line bass array system for your Acoustats and with mijostyn's help.
     Then, in the very next paragraph, you state you're starting to build four new subs with 10" drivers and you're looking forward to hearing Duke's Swarm DBA system, which happens to utilize four subs with 10" drivers just like the four new subs you're about to start to building, at an audio show in Long Beach.       
     Don't you agree this might be a bit confusing to a reader, especially when you just stated you're in the process of switching from a distributed to a line array bass system?
    But the confusion continues with your latest post from5/27/19:
"I use low pass and high pass filters in my active crossover, Linkwitz-Riley 4th order 24 dB slope. One reason this was chosen is that we wanted to keep deep male vocals out of the subs. The other reason had to do with the resonance of the 8" drivers which we wanted to keep above 100 Hz. This is the reason for a 0.3 cu. ft. box which is stuffed tightly with cotton batting. The last reason has more to do with Roger Modjeski’s ESL design which only goes down to 100 Hz but that is irrelevant to me as I use the Acoustats which he modified to create greater dispersion, but left the rest alone, sort of ;)"

     Now you're discussing 8" drivers in 0.3 cu. ft. boxes stuffed with cotton batting that only extend down to 100 Hz?  Would this even be considered a sub and how are these 'mid-bass woofers' even relevant to either the DBA or the line-array bass system you're using?

     Can you please clarify?

Tim