Upgrading sub to get a live feel.

thewatcher101,

     You may be able to improve the bass response at your listening seat just by repositioning them.  I'd suggest using the crawl positioning method sequentially for each.
     If this doesn't work and you have the room space, using three SVS-SB1000s, sequentially positioned using the crawl method, is virtually guaranteed to provide bass response at your listening seat approaching state of the art.  This is called a distributed bass array (DBA) system and it works amazingly well in virtually any room and with any pair of main speakers, even with faster and very detailed speakers like electrostatics and Magepans.
      The bass perceived is very smooth, detailed, as powerful and dynamic as the music requires, seamless integration with any pair of main speakers and an overall quality of effortless bass on music and HT.
      I use a 4-sub DBA system called the AudioKinesis Swarm in my 23'x16' room with large Magnepan panel speakers and it works like a charm.  The DBA concept usually requires four subs to function properly but works almost as well with three.  
     Here's an Absolute Sound review of the AK Swarm that gives a good explanation of how it works and what to expect.  The SB-1000 subs are ideal to use in custom DBA systems because they're very good subs and are relatively small.

https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/ 

Tim 

Hello the watcher101,

     Man, you've received a lot of conflicting advice on how to best improve bass response performance in your system and room.  I believe they're all sincere and well-meaning in the advice they've given.
    However, they all seem to have a complete lack of knowledge and experience of the most effective method of achieving excellent bass performance, in any room and with any pair of main speakers as well as without any room treatments and room correction, that I'm currently aware of: the 3 to 4 sub distributed bass array (DBA) system. 
     I recall having a very similar need for good bass advice as you have about 30 years ago but mine concerned how to get better system bass performance with Magnepan main speakers.  
     Well, it took me a lot of research and experimenting with subs, but about 29 years later I finally stumbled upon the ideal solution of the DBA. I'd like to save you some time and frustrations by relating  what I learned over the last three decades of searching for detailed, smooth, powerful, dynamic, seemingly effortless and seamlessly blended with the main speakers bass in my system and room.
     Through experience, I've discovered that one sub is able to provide good bass performance at a single designated listening seat if located properly utilizing the 'crawl' method but you may find it difficult, depending on the main speakers utilized, to configure it so that the bass seamlessly blends with the sound performance of your main speakers' reproducing the mid-bass or midrange on up to the treble. The bass may sound as if it's lagging behind and/or disconnected from your main speakers, especially on fast, smooth and detailed speakers such as electrostatic and planar-magnetic panels. I know the JBL 4319 and 4367 are very good bookshelf speakers but I'm not certain if they're fast, smooth and detailed enough to cause integrating seamlessly with a single sub an issue.
    I understand most individuals would prefer to buy a single top-notch sub and be done with it but, unfortunately, the truth is that attaining good in-room bass response is not that simple no matter the price or quality of the single sub. The reason this is true really has more to do with the quantity of subs in a given room and how they're positioned, than the quality of the subs utilized. Better quality of subs never degrades from good bass performance, it's just not as important as most would assume. I'll try to explain why.
      Two properly positioned and configured subs in a given room typically provides bass response at a designated listening seat that's approximately twice the quality level of utilizing a single sub. Two subs provide increased bass output capacity and impact as well as increased bass dynamics due to the sharing of total bass requirements between two subs operating well within their limits and stress free with ample power reserves for sudden bass output dynamic demands.
    Psychoacoustic principles also begin to be applied beginning with the use of two subs in any given room that results in the bass being perceived as smoother, more detailed and better integrated with the main speakers.  
    To understand how this psychoacoustic process works, it's important to understand how bass soundwaves behave in a room with a single sub. Soundwaves increase in length as the frequency decreases and deep bass tone soundwaves are very long. A full cycle soundwave of a 20 Hz deep bass tone is 56' long, a 30 Hz is 36', a 40 Hz is 28' and a 50 Hz is 23'. For reference, a full cycle soundwave of a 20,000 Hz high treble tone is a fraction of an inch long. This mainly explains why humans are easily able to determine the originating source location (localization) of the shorter soundwave and higher frequency tones above 100 Hz and are unable to do so on the longer soundwave and lower frequency tones below about 100 Hz.
    It's also important to know three facts:
1. Our brains can't even process the presence of a deep bass tone until the full cycle soundwave exists in the room and our ears have inputted this information into the brain.
2. Our brains require the input of at least three full cycle bass tone soundwaves before we're able to recognize a change in bass volume and pitch.
3. Our brains cannot localize deep bass tones (detect where the sounds are coming from) with frequencies below 100 Hz.
    With the deep bass soundwaves being longer than any room dimension in many individuals' rooms, this means the soundwave will leave the single sub and need to travel as far as it can in the room and then reflect off the first room boundary (floor, ceiling or wall) it meets then keep traveling in the reflected direction until it meets the next room boundary. This process continues until the soundwave runs out of energy and with each subsequent bass tone launched into the room by the single sub.
    These numerous bass soundwaves of various frequencies launched into the room by the single sub, and reflecting off room boundaries, inevitably run into each other at various angles causing what are called a Bass Room Mode at each specific room location at which they meet or collide. Depending on the specific angle at which the soundwaves meet, we perceive these bass room modes at specific spots in the room as either a bass overemphasis (bass peak), a bass attenuation (bass dip) or even a bass cancelation (bass null). The result is an overall perception of the bass from a single sub as uneven, not detailed, somewhat disconnected and not natural.
    However, when a second sub is properly deployed and positioned in the room, the very interesting and useful principles of psychoacoustics (how our brains process sound and our perceptions of it) begin to come into play, which results in a perception that the bass is smoother, more detailed, better integrated with the main speakers and more natural or realistic.
      Unexpectedly, this is accomplished through the second sub actually significantly increasing the number of bass room modes (bass peaks, dips and nulls) in the room. Our brains naturally and fortunately process the presence of multiple bass soundwaves below 100 Hz, by adding them together by frequency and averaging them out. This results in fewer bass modes being perceived in the room and a perception overall that the bass is smoother, more detailed, better blended with the main speakers and more natural.  
    Acoustical experts, such as Dr. Earl Geddes, Dr. Floyd Toole and others, have proven scientifically that in-room bass performance perception improves as more subs are added to virtually any given room, beginning with two subs and with improvements continuing up to the theoretical limits. Of course, there's a practical limit to the acceptable number of subs in a domestic room.
    I'm fairly certain the exact number of subs considered acceptable in a domestic room is higher for most men than most women but, interestingly, the scientists found significant bass performance perception gains were attained with each additional sub up to four but smaller more marginal gains were attained with each additional sub beyond four.

    Three properly positioned and configured subs in a given room typically provides bass response at a designated listening seat that's approaching the optimum quality level attainable at a single listening position. Three subs provide even further increased bass output capacity and impact as well as further increased bass dynamics due to the sharing of total bass requirements between three subs operating well within their limits and stress free with very large power reserves for sudden bass output dynamic demands.
     Psychoacoustic principles are more strongly applied with the use of three subs, as opposed to two subs, in any given room that results in the bass being perceived as even smoother, more detailed and better integrated with the main speakers.  
    My opinion is that the SVS SB-1000 (a small sealed sub with bass extension down to 24 Hz) and the PB-1000 (a slightly larger ported sub with bass extension down to 19 Hz) subs are ideal for utilizing in two and three sub bass systems because they're both very good quality, are relatively small, have all the necessary features/controls and are currently great bargains at about $500/each (slightly more for gloss black or white finishes). 
     The larger and more expensive Seaton, Rhythmik, HSU  and JL Audio subs may be better subs with more features but, remember, the critical factor for in-room bass performance is the quantity of subs used in the room and the quality and features of each is much less important. Besides, the reality is they're all high quality subs and room correction is not required for optimum performance on bass systems utilizing two or more subs.  
      However, if you prefer the best in-room bass performance, the Audio Kinesis 4-sub Swarm distributed bass array (DBA) system is definitely the ultimate bass system that I'm aware of. This is a complete $2,800 kit that includes four 4 ohm unamplified subs that are each 1' x 1' x 28", weigh 44lbs and have a 10" aluminum long-throw driver and a 1,000 watt class AB amplifier/controller that powers all four subs and controls the volume, crossover frequency and phase of all as a group.  
      The use of a 4-sub DBA system will provide near state of the art bass performance not only at a single listening position but throughout the entire room. This is very useful if you have multiple seating positions in your room and prefer having very good audio at each position for both music and HT.
    Of course, only the designated listening position will be optimized for bass, midrange and treble response along with stereo imaging but very good full-range audio will still be provided at each seating position.
    They're also other benefits of the 4-sub Swarm DBA system. Absolutely no bass room treatments are necessary. You'd just need to incorporate room treatments for the midrange and treble response on your main speakers (first reflection points on each side wall and possibly some treatment on the front and rear walls). And these subs look very stylish in the room, kind of like hi-end wooden art gallery pedestals, since the 10" drivers face towards the nearest wall and have connections hidden on the bottom so all that's visible is three wood sides and the top in the wood of your choice. My wife usually has a small vase with fresh flowers sitting on one of the two that are visible in my room. They also make good end tables since they're an ideal height of 28 inches.  
    You also have the option of creating your own custom 3 or 4-sub DBA system, rather than using the complete Swarm system, by utilizing three to four SVS SB-1000 subs, you already have two so you would just need one or two more at $499 each, or any three to four subs you'd like.  I also believe adding one or two PB-1000 subs (that extend down a bit further than the SB-1000's 24 Hz to about 20 Hz) to your system would extend the perceived bass in your room down to about 20 Hz.
     The only down side of using a custom 3-4 sub DBA system is that you need to configure the volume, crossover frequency and phase settings individually for each of any self-amplified subs used rather than once for all four subs as a group on the Swarm system. 
     As I've stated, I use the 4-sub A K Swarm system in a 23'x16'x8' room with Magnepan main speakers and it works like a charm.  But, while I haven't personally tried it to verify, I believe three subs would perform nearly as well, especially at a single designated listening seat.

Hope this helped you a bit,
                Tim

Hello Erik,

     I understand your points but think they’re only partially valid:

"Sure, swarms are nice, but not everyone can afford or has the space for them."

     Thewatcher101 currently has the $4K/pair JBL 4319s and was looking for a sub or subs that would perform and integrate so well and "live" with them that he wouldn’t need to spend $15K/pair for the JBL 4367s for a significant bass performance upgrade.
     I suggested he could significantly improve the bass performance of his system by any of the following methods:
A. Create a custom 3-sub distributed bass array (DBA) system by either adding one SB-1000 or one PB-1000 sub, both currently on sale for half price at $500. I know this would produce exceptionally good in-room bass response and integration with his current or any future pair of speakers he may own for a total expenditure of $500.
B. Create a 4-sub custom DBA by adding two of the $500 SVS subs. I’ve learned this would produce virtually state of the art in-room bass response and integration with his current, or any future pair of speakers he may own, for a total expenditure of $1,000.

C. Buy the AK Swarm 4-sub DBA kit that not only will produce state of art in-room bass response and integration in any room and with any pair of speakers, but also has the advantages of using relatively small subs and being much easier to configure. The ease of configuration results from the volume, crossover frequency and phase controls only being required to be set once for all four subs as a group rather than individually for each sub. Total expenditure equals $2,800.

     Compared to the OP attaining better bass by upgrading to a pair of the $15K JBL 4367s, this means that thewatcher101 would realize savings between $12,200 and $14,500 by adopting one of my suggested solutions as well as guaranteed better in-room bass response and integration than any pair of speakers by themselves, including the JBL 4319s and 4367s. I thought he would appreciate being aware of this and is also why I don’t believe your point on affordability is valid.
     To quote the owner of Audio Kinesis, Duke Lejeune, "two subs will sound twice as good as one, four subs will sound twice as good as two and eight subs are likely good grounds for divorce".
     However, I believe your point about individuals having the space for up to four subs has more validity but it’s not insurmountable. I also had concerns about accommodating four subs in my 23’x16’x8’ combination living/music/HT room. I decided up front that excellent bass performance and integration were my top priorities and not room decor. So my plan was to just position the subs according to the procedures so the bass was optimized and rearrange the room furnishings afterward as best my wife and I could manage. As it worked out, my total room furnishings rearrangements consisted of moving an 8’ couch along a 23’ side wall about 2’ closer to my front 16’ wall. You can view my system photos on my profile and decide for yourself how well they blend and are inconspicuous in my room.

"Also, most people have never heard a great single sub integrated well."

     I have and definitely have learned that two subs properly positioned and configured will significantly outperform a single sub, no matter the single sub’s size or quality, in bass impact, dynamics, detail, realism and ability to seamlessly integrate with the main speakers.

"The difference in sound quality between a poor sub set up and a great set up is astounding."

     Whadda ya know? I completely agree with you.
     Based on my experience, I would rank the effectiveness of the various general sub set up formats in order of in-room bass performance effectiveness from least to most effective, with the stipulation that any set up format has the potential to be further improved through the use of room correction software/hardware, parametric equalization and higher quality subs, as:
1. A single sub
2. Dual subs
3. A three sub DBA
4. A four sub DBA
5. Live music in a small venue heard in person
     No matter which general sub set up is utilized, of course, proper positioning as well as the proper setting of the volume, crossover frequency and phase controls of each sub is critical for optimizing performance and the integration with the main speakers.
     I’ve read many of your posts over the years here on Audiogon and mainly tend to agree with your statements. I’m somewhat surprised we disagree a bit on the subject of subs.

Thanks,
Tim

   
Hello Erik,

     The truth is that any audio and music lover, who even briefly experiences the state of the art bass from a DBA, would obviously do whatever it legally or illegally takes to get the money and find the space. 
     The concept works that well and I'm just trying to spread the word.

 Tim

mijostyn:
"I would rather two high quality subs than four cheap ones. Room control is a must for thewatcher with two subs as his room is very square. Make yourself a plan and stick to it. Messing around for the sake of messing around is a waste of money. "

Hello miijostyn,

Even though I’ve learned it is true that 4 cheap subs if properly positioned and configured will typically deliver better in-room bass performance than two subs regardless of their quality, I believe you’ve confused the current $500 half-off sale price of thewatcher101’s subs he’s already using, two high quality SVS SB-1000s, and assumed they are cheap, low quality subs which they definitely are not..

It’s also becoming more apparent that you have a lack of knowledge and experience concerning the distributed bass array (DBA) concept in general. I’m basing this on your comment that the OP would need to use larger and more powerful JL F212 subs on a previous post and your comment that room control is required on your last post, neither of which are true.
My previously proposed plan for the OP to use a 3-4 sub DBA system is based on my belief that home audio systems are best optimized in performance by considering them as two systems, a bass system and a system for everything else, due to the very different manner that the very long bass and much shorter midrange/treble soundwaves behave in any given room.
I recommend first getting the bass sounding good (powerful, dynamic, smooth, detailed, with a seemingly effortless and unlimited quality and seamlessly blended with the main speakers) because it’s typically the most difficult to achieve in most rooms. The best method I’m currently aware of to get the bass sounding good in virtually any sized and shaped room, even in an acoustically challenging square one like the OP’s room, is a 3-4 sub DBA system.
The lowest octave on music is about 16-32 Hz with the audible range extending down to 20 Hz and anything lower only felt and not heard. The ability of a bass system to accurately reproduce deep bass tones down to at least 20 Hz creates a solid bass foundation that a lot of music is built upon and on which the OP can build the remainder of the audible frequency spectrum, reproduced by his main speakers, upon.
Utilizing a 3-4 sub DBA system also allows the OP to extend the deep bass response performance by adding one or two PB-1000s subs (with a rated bass extension limit of 19 Hz) to his two existing SB-1000s (with a rated bass extension limit of 24 Hz).
Just to be clear to you and the OP about 3-4 sub DBA systems:
-There’s no lack of bass output or dynamics since bass duties will be shared between 3 or 4 subs and you can adjust to your preferences using the volume and crossover frequency controls on each. You definitely do not need to purchase higher quality and more expensive subs.
-There’s absolutely no mics, room correction, parametric equalization, bass room treatments or anything else required.
- The main reason the DBA concept works so well is the psychoacoustic principles involved which take advantage of how our brains naturally process bass soundwaves below about 100 Hz.
-The quality, agility, smoothness and speed of the bass produced by 3-4 sub DBA systems allows them to be seamlessly integrated with virtually any pair of main speakers you currently own or will own in the future.

Hopefully, the OP will check back in soon and let us know his thoughts and impressions.

Tim

Hello watcher,

     Congratulations on your decision to give the 4-sub DBA concept a try.  Prepare to be amazed! 
      Pay no attention to critics claiming there'll be a lack of output, poor integration with your JBL 4319s, the 4367s or literally any other imagined shortcoming of the DBA concept because it works like a charm in virtually any room as well as with any pair of speakers. The only criticism of a 3-4 sub DBA system I consider even faintly valid is having the room space to accommodate  3-4 subs, but this is easily solved by using smaller subs and a little redecoration imagination.  I'm sure they mean well, it's just that they have a complete lack of knowledge and experience with DBA systems.  They just don't know what they don't know.
      But you made a very wise choice and I know you're going to gain the knowledge and experience of what a good DBA is capable of soon enough.
      Choosing to add two PB-1000s to your existing two SB-1000s will extend your system's bass response down to the audible limit of 20 Hz.  It shouldn't matter whether you alternate between sealed and ported or use the two taller ported subs as end tables.  The reason is that your brain is going to just sum and average all the bass present in your room by frequency; your perception of the bass will reflect the average by frequency.  Psychoacoustics in action.
      If you'd like, I can offer specific further advice on sub positioning and the setting of the volume, crossover frequency and phase controls on each sub.  I can also answer any questions you might have, you won't find a DBA advisor charging lower fees.


Enjoy,

 Tim 
     
   
  
     

jetter:
"Hey Tim, its great to read you love your four subwoofers. I may be wrong but it kind of seems like I read it before."

Hello jetter,

     Okay wiseguy, I get the sarcasm.  Yes, I may have previously mentioned a few thousand times on various threads just how amazingly well 4-sub DBAs actually work.  
     Sorry, but I felt the overwhelming responsibility to spread the word to the humans, kind of like that long-haired bearded guy a few thousand years ago spreading the word about his father.  
     What can I say?  I am a true believer.  The only difference being I'd likely cut it out if threatened with crucifixion.  I'm a true believer but have my limits.

Tim

Hello mcreyn,

     I agree with you that a pair of higher output subs such as the Seatons, JL Audios and larger SVS subs, properly positioned and configured, are capable of providing good bass response performance at a single designated listening position sweet spot at a higher volume level than a pair of SB or PB 1000s subs are capable of. 
     I'm not certain, however, whether a pair of SB-1000s and a pair of PB-1000s setup as a 4-sub DBA system, would provide a sufficiently high bass volume level to meet the OP's requirement or even exceed the bass volume level of a pair of larger and more expensive subs are capable of at his listening position sweet spot.
    Just as we're unsure of the exact size of the OP's room, we're unsure of the OP's actual desired bass volume level requirements, "live sounding bass" is not very specific.  I can only rely on my own perception of loud bass but the four relatively small Swarm subs in my room are capable of providing very good bass performance almost flat down to 20 Hz and at extremely high wall- shaking volume levels, much higher than I prefer.
     Of course, it's the OP's preference on bass volume levels that matter.  Hopefully, he'll respond again soon and let us know.

Tim

mcreyn:
"We do have a pretty good idea on the OP’s preference for bass levels, he has a pair of SB1000s and is not satisfied. To get a significant feeling of increased volume, he needs to pick up 10db. Adding two more SB1000s will only net him about 6db (again, because we are not co-locating). The PB-1000 a little more. Two Seaton Submerssive HPs are capable of 115+ db at 20hz without room gain. By 30 hz, we are well over 120db. We do know this will keep up with his current speakers as well as his future speakers."

Hello mcreyn,

You stated " To get a significant feeling of increased volume, he needs to pick up 10db. Adding two more SB1000s will only net him about 6db (again, because we are not co-locating). The PB-1000 a little more."

      If 4db more volume gain could be attained by using two additional PB-1000 subs rather than the net 6db more using two additional SB-1000 subs, wouldn’t that provide the net 10db increase in bass volume to perceive a significant feeling of increased volume?
     Without specifically knowing or measuring, I’d suggest we can’t know with any certainty and it’s best to just wait and let the OP decide based on his perception of the bass. Do you agree?

     Also, I don’t believe it’s reasonable to assume the OP wants to listen to music or HT with deep bass at a 115 db volume level. Doctors claim exposure to 115 db sound levels for more than 30 seconds can cause permanent hearing loss. I’m just stating the OP needs to verify he listens regularly for extended periods at this high of a volume level.


Thanks,
  Tim

Hello mcreyn,

       Between you arguing for the ability for mega-bass at arena rock volume levels in his living room and me arguing for very high quality bass at less masochistic volume levels, I believe thewatcher101 will understand his options and decide for himself.  
     To be fair, I wanted to point out that running subs well within their limits is definitely beneficial, mainly lower distortion, a sense of ease to the bass and ample power reserves  for powerful bass dynamics.  
     For balance, I wanted to also point out that my Swarm system, with four 4 ohm passive (not self amplified) subs each consisting of a single 10" long-throw driver in a 1'x1'x28" cabinet that are all driven by a single 1K watt class AB amp connected in a series-parallel configuration, operates well within its limits, provides low distortion bass with a sense of ease and ample power reserves for powerful dynamics with the volume control set at the 11:00 o'clock position, a bit less than halfway.  In the four years I've used the Swarm, I've honestly never perceived the bass as being not loud or powerful enough on either music or H T. I perceive the bass output as consistently high quality, powerful, dynamic, with not only a sense of ease and naturalness but also a sense of unlimited capacity no matter what volume level is chosen on the Oppo's remote. 
     I could be wrong, but I currently believe a 4-sub DBA consisting of a pair of PB-1000 and a pair of SB-1000 self amplified subs is likely capable of performing just as well, provided the OP wasn't referring to hearing loss inducing volume levels when he mentioned "upgrading sub to get a live feel". 
     You are now welcome to the last word as we await watcher's verdict.




  

Hello watcher,

     I think you meant to say "I’m going for a live feel, not actual live music dbs."
     If so, I’m very glad to hear that since you’ll likely be more inclined to really enjoy the bass performance of your new custom 4-sub DBA system consisting of your two existing SB-1000s and the two new PB-1000s.
Mcreyn was right about the bigger and more expensive Seaton and JL Audio subs producing even deeper, louder and more powerful bass than the SVS-1000 series subs are capable of.
    However, I believe mcreyn’s knowledge and experience on subs is more slanted toward HT usage like many of the members on the AVS website that put more value on the size, bass extension, room shaking capacity and maximum deep bass db level ability as signs of a sub’s quality. In general, Audiogon members knowledge and experience on subs is more slanted toward music usage and they put more value on the sound quality and seamless integration with the main speakers as signs of a sub’s quality.
     Mcreyn’s suggestion that you need subs with a capacity to output deep bass down to 20 Hz at a volume level of 115 dbs to match the max output of your JBL main speakers was ridiculous and an obvious clue that his priority is not high quality music reproduction, which I believe your main priority is.
    I’ll continue to monitor this thread just in case you need assistance but I realize it may take a month until you have your new custom 4-sub DBA up and running.

Later,
Tim

mcreyn:
"At the end of the day, it is not about hitting huge SPL levels, it is about getting the best sound, which requires using subs that can stay clean and not run into dynamic compression. 4 10" subs can't do this in a reasonably sized room. It is why my progression of home subs has taken me from Velodyne F series, through ULD's, to HGS, and finally Rythmik. At each step, it has seemed to be amazing (and better than anything I ever heard at a dealer), but the next step revealed more."


Hello mcreyn,
     I'm glad to read your comment that "at the end of the day, it is not about hitting huge SPL levels, it is about getting the best sound, which requires using subs that can stay clean and not run into dynamic compression".  This makes complete sense and I agree with this statement.
     I was questioning whether you had the knowledge and experience to realize the truth in your statement because you were mentioning earlier the ability of larger subs being able to reproduce deep bass at 115 db which is not necessary and can literally cause permanent hearing loss after about 30 seconds.  I wish you had made this statement earlier. 
     Your statement, "it is about getting the best sound, which requires using subs that can stay clean and not run into dynamic compression. 4 10" subs can't do this in a reasonably sized room", I believe also indicates that you have a lack of knowledge and experience of how well the 4-sub DBA concept actually works in any room and with any main speakers.  
     It's definitely true that the four subs in the AK Swarm DBA system are each relatively small (1'x1'x28"), weigh only 44 lbs, contain only a single 10" aluminum long-throw driver and are used in a room considered by most to be reasonably sized (my room is 23'x16'x8').  After using this bass system for almost 5 years now, I know with certainty this system is an excellent performer in the limited 20-50 Hz range that I require supplemental deep bass, my main Magnepan 2.7QR planar-magnetic dipole speakers provide excellent bass performance but only down to about 35Hz but it blends seamlessly with the deeper bass produced by the four Swarm subs that extends bass response of my system down to 20 Hz.
     I completely understand the skepticism from you and other individuals accustomed to utilizing fewer but larger traditional self-amplified subs in their systems.  I understand the lack of comprehension and justified skepticism because I initially lacked the comprehension of how this was possible and was very skeptical myself.  It took me a lot of research on the science behind the DBA concept, reading numerous extremely positive reviews on the AK Swarm and custom DBAs from professional reviewers as well as users and a lot of email and phone conversations with AK's James Romeyn to convince me to give it a try in my room and system.  
     I'm  so glad I did because I consider the bass the 4-sub Swarm DBA system provides in my system/room to be state of the art for both music and HT.  It honestly seems to me like I've learned about an audio secret and I now feel a responsibility to spread the word and let my audio brothers and sisters in on this almost magical secret.
     Of course, I realize the Swarm does not provide the optimum bass response performance that the DBA concept is capable of.  I believe the optimum bass response performance that the DBA concept is capable of would most likely be realized by a combination of our viewpoints, four very large subs with even greater bass extension and output capacity positioned in the room as a distributed bass array system. It's also possible that room correction, either of each sub individually or as a 4-sub group, could further optimize the performance of such a system.   
    I'm currently more than satisfied with the Swarm in my system/room, even though it's performance is a bit less than optimum for a DBA system, due to its combination of extremely good bass performance and its inconspicuousness in my living room.
    In my experience, I can definitely state with validity that the extremely high quality of the Swarm's or a good custom DBA system's bass performance exceeds the sum of its parts.  I'm convinced the factor that's responsible for this is the DBA concept's utilization of psychoacoustic principles that I've explained in detail on an earlier post on this thread. 
     How our brains process the existence of the abundance of bass room modes (many bass peaks and dips) produced by the 3-4 subs in a DBA system by summing and averaging the bass by frequency which results in the perception of the bass as being very accurate,detailed, smooth and natural while also being very flexible to reproduce whatever bass the source content calls for; fast, rhythmic and tight on music or sudden, deep,dynamic,powerful and impactful for music and HT.  

Tim
    

mcreyn:"You can also continue to believe that your 2.7s extend with any authority to 35 hz, they start to roll off in the 50hz range and will quickly slap the panels when trying to reproduce any type of deep bass. If you would high pass the 2.7s they will sound less dark and sound cleaner after being relieved of trying to handle the deep bass. Did I mention I owned a pair of 2.7s for more than a decade which were run both full range and with an active crossover?
Those that get so myopically focused as to believe there is only, or decide they already know it all, never learn and never develop further."

Hello mcreyn,

      You're likely not aware of how well your 2.7QRs reproduced bass because of the amp or amps you used to drive them. In my experience, they performed better over their entire frequency range with more powerful amps that have high damping factors. 
    The 2.7s are 3-way speakers and actually have a rather large planar-magnetic dipole bass section in each panel (625 sq. inches). I was previously driving mine with an Aragon stereo class AB amp that was rated at 400 watts into the 2.7's 4 ohm load and the bass was decent. Their bass performance noticeably improved when I switched amps to a Class D Audio stereo amp that was rated at 440 watts at 4 ohms and with a damping factor >1,000 and later they produced the best bass I'd ever heard from them when I switched amps again to a pair of D-Sonic class D mono-blocks rated at 1,200 watts each at 4 oms and the same very high damping factors.
    Your statement that "You can also continue to believe that your 2.7s extend with any authority to 35 hz, they start to roll off in the 50hz range and will quickly slap the panels when trying to reproduce any type of deep bass." is definitely and categorically false when the 2.7s are driven by sufficiently powerful amps with very high damping factors. I didn't measure the exact in-room bass extension but, by ear, the 2.7's rated bass extension of 35 Hz seems accurate and there was absolutely zero panel slapping occurring at anytime. I've had that occur on previous Magnepans I've owned and know what that sounds like.
    I think the 2.7's bass by themselves would more than meet the needs and expectations of most, including myself, but it lacked a bit of the visceral bass you feel as well as hear that gives the perception you're listening to live music unless I cranked the volume up to halfway. I don't always like to listen to music that loud so I continued to use the two 12" subs. This worked well but I thought the bass detail, impact, dynamics and blending with the 2.7s could be improved upon.
    I began thinking a pair of more expensive and higher quality subs might improve the performance in these areas but stumbled on the Audio Kinesis Swarm 4-sub DBA concept during my search for a very high quality pair of subs for about $5K or less.  I decided to give the Swarm an in-home free tryout first at $2,800. I think I may have previously mentioned how well the Swarm 4-sub DBA system performed in all the important bass areas in my system.
    You stated: " Those that get so myopically focused as to believe there is only, or decide they already know it all, never learn and never develop further."
    I think my path described above disproves the accusations that I'm myopic, believe there's only one solution, know it all and never develop further. The truth is I was willing to try two different amps of a type I'd never used before, gained practical bass system knowledge and experience by utilizing several different supplemental bass methods in my system such as a single sub, dual subs and even a sophisticated and advanced method using four subs strategically positioned and configured. Now that I've thought and written about some of my audio journey,  I know that none of your descriptions apply and the more fitting description would be open-minded, willing and daring enough to try various methods and gear to gain knowledge and experience. Perhaps I should change my user name to audioadventurer.
     Finally, you stated " If you would high pass the 2.7s they will sound less dark and sound cleaner after being relieved of trying to handle the deep bass. Did I mention I owned a pair of 2.7s for more than a decade which were run both full range and with an active crossover?"
    Were they black and did you sell them to a guy from Indiana that met you in a parking lot in Dayton, Ohio for the $1,200 transaction?  If so, that was me.  Hah!, that would be unbelievable.   Maybe you'd have kept them if you had a better matched amp or amps to drive them.
     I did try running the 2.7s high pass filtered through the Swarm's amp/control unit, trying various crossover settings between 100 and 230 Hz and was expecting the 2.7's to benefit.  I believe I didn't get the typical sound quality gains from high passing the mains because my D-Sonic mono-block amps, at 1,200 watts each, were not overtaxed driving the 2.7s full-range. 


Later,
Tim

Hello ihor,

     I would suggest running all three subs in mono and adding a larger 10 or 12 inch sub for your third sub would be the best choices.  
     There are virtually no current or past music recordings in any format (vinyl, cd or hi-rez files) that contain stereo deep bass, all of the bass below about 80-100 Hz is summed to mono on the recordings since humans are unable to localize (tell exactly where the bass is coming from) on bass tones below about 80-100 Hz.
     Even though all three subs are outputting mono bass, you'll perceive the bass as a form of stereo bass, with the sound seeming to come from the proper bass instruments within the soundstage illusion ( for example, the drums are located in the center rear of the soundstage and the upright acoustic bass is located in front of the drums and off to the left.). 

      This is because, even though the fundamental deep bass tones below about 80-100 Hz coming from the subs will not be able to be localized, the related bass harmonics or overtones of the fundamental bass tones coming from the main speakers are able to be localized (since they extend above the 80-100 Hz limit).  Our brains are able to associate the higher frequency bass harmonics/overtones with the much lower frequency bass fundamental tones and thereby determine where the much deeper fundamental bass tones are originating from. This process is one of the principles of he science of psychoacoustics (how our brains process sounds and form perceptions).
      Having a larger 10 or 12 inch sub as the third sub also relies on psychoacoustics and will give the perception that the overall in-room deep bass response has been extended a bit deeper.  
     Proper positioning within your room and the proper setting of the volume, crossover frequency and phase control of each sub are very important for optimizing bass output in your room and integration with your main speakers.

Tim

Hello ihor,

     Cool, it's a bit difficult to put into words and I'm glad you understood.  I can help you with the positioning and proper setting of the volume, crossover frequencies and phase controls when you get your third sub. Just send me a personal message or post again on this thread when you're ready.

Tim

Hello Watcher,

     Sorry about mcreyn and phusis having a discussion on the benefits of horn tapped subs in the middle of your thread.  I just found out they're both longtime members of the Church of Latter Day Bass. A little rude but no big deal.
     I'm going to give you a step by step procedure for how to position each of the four subs and set the controls on each very soon but I need to know a few things before we get started to make sure we have everything we'll need:

1. What are the brand and model numbers of your other components?  I need to know whether you're using an AV receiver, integrated amp or preamp and power amp setup.

2. How do you currently have both of your SB-1000s connected? I need to know what method, line level or speaker level connections, you currently use and how you planned to connect all four subs.  If you don't already have a plan, I'll figure it out but it may require you buying a few things before we can begin.

3.  Are your JBL 4319 main speakers positioned on the floor, on stands or a different method?

    Depending on your other components, mainly your amp, we need to determine whether you should limit the bass reproduced or run them full range. W'll pick backup once you give me your answers to my 


Tim

phusis: "Truth be told I’m not on a mission to willfully oppose your views, but simply to recommend what I feel would be one heck of subwoofer pairing with a future main speaker acquisition the OP appears to have in mind. But you don’t want to hear that, right? You’re all over the place with your "my (sub-)way or the highway," and when a couple of guys have a few challenging thoughts on the matter you’re choking on your morning smoothie."

Hello phusis,
If I recall correctly, I stated that the interjection between you and mcreyn was no big deal and I meant it. I welcome new ideas, new information and actually found your discussion of horn tapping subs very interesting, thank you. My intent was not to dismiss or reject the idea of a different solution for watcher, I just thought, since he already committed to trying the 4-sub DBA concept by buying two more SVS subs, he should first give that concept a fair try before being asked to consider a solution that would be much more expensive and require utilizing much larger subs.
You are correct, I am an advocate of 4-sub DBA systems and I understand many likely prefer I’d just stop already. I think it’s an excellent solution for anyone who has the funds and room space. However, I’m not naïve or ignorant enough to think it’s the only or even the best solution. I understand each individual situation deserves an individual and unique solution based on the specific circumstances and preferences. I believe the best solution for a given individual system and room can span from a single sub or dual sub setup to a 3+ sub linear or distributed bass array setup to more elaborate and larger sub bass systems utilizing horn tapping or even larger horn based subs to something new or that I’ve never even heard of.
You stated "But you don’t want to hear that, right? You’re all over the place with your "my (sub-)way or the highway," and when a couple of guys have a few challenging thoughts on the matter you’re choking on your morning smoothie."
Wrong, I want to hear your discussion with mcreyn and all sorts of opinions, information and ideas from you guys or anyone else willing to share them. Who knows, I may even feel the urge to share some, too.


Later,
Tim

watcher,

Okay, speaker level connections should work well and daisy-chaining from one sub to the next is convenient, too.
When I positioned my four subs, I decided to just follow the suggested procedure and locate the subs to optimize the bass performance in my 23x16x8 foot room that serves as a living/music/HT room. My audio equipment, tv and main speakers are along a 16’ wall with my listening chair about 12’ back from the center of this 16’ wall. I decided my wife and I could then do any necessary furniture rearrangement afterward. Here’s the procedure, based on the ’crawl’ method, that I used to position each of my four subs:

1. Power down system, disconnect speaker wires from main speakers and remove them from the room.

2. Connect Sub#1, power up system, set sub#1’s volume to 50%, crossover frequency to 65 Hz with the phase set at in-phase (’0’) and place it on its back (driver facing the ceiling) at the normal listening position. Play music that has good and repetitive bass.

3. Walk slowly along the perimeter walls of the room, starting at the front right corner of the room and moving in a counter-clockwise direction, listening for the exact spot that the bass sounds best to you; not exaggerated, attenuated or missing bass but detailed, solid, smooth accurate and natural bass. Walk slowly enough and you’ll definitely notice the exact spot it sounds best.

4. Place Sub#1 at the exact position you determined the bass sounded best to you.

5. Connect Sub#2, set sub#2’s volume to 50%, crossover frequency to 65 Hz with the phase set at in-phase (’0’) and place it on its back (driver facing the ceiling) at the normal listening position. Play music again that has good and repetitive bass.

6. Continue to walk slowly along the perimeter walls of the room, starting now at Sub#1 and continue moving in a counter-clockwise direction, listening for the next exact spot that the bass sounds best to you.

7. Place Sub#2 at the exact position you determined the bass sounded best to you.

8. Repeat this procedure for Sub# 3 & 4.

9. Replay the same music with good and repetitive bass, sit in the designated listening seat and verify the bass does not sound exaggerated, attenuated or missing and that the bass does sound detailed, solid, smooth, accurate and natural.

10. If it does not, repeat steps 1-9. If it does, reinstall your JBL speakers, ideally on the floor or on custom stands and about 3-4’ away from the front 16’ wall. Obtain an assistant and proceed to the 4-sub Custom DBA Configuration and Seamless Main Speakers Integration Procedures.

Following this procedure in my room with the Swarm subs, it resulted in two subs located along the front 16’ wall, with sub#1 located 2’ away from the right corner and sub#2 located 2’ away from the left corner. The other two subs sounded best toward the rear of my room with sub#3 along the left 23’ wall and sub#4 along the right 23’ wall, both about 2’ away from the nearest rear corners formed by the 16’ rear wall.

I’m not suggesting you save some time by just positioning yours like mine. I’m suggesting that you follow the same subs positioning procedure and that your subs are likely to sound best in a similar distribution pattern. Your room is the same 16’ width and rectangular shape as mine but it’s 7’ longer and I’m uncertain if your ceiling height is similar to my 8’ ceiling. In any case, there are enough differences that your subs may sound best in somewhat different positions; perhaps with only one sub along the front 16’ wall and the remaining subs in different positions along your 30’ side walls and even one or more along your rear 16’ wall.

I’m just not sure where they’ll ultimately be positioned for best performance. I suggest you just trust and follow the procedure, position each in sequence exactly where it sounds best and everything will probably work out fine.

I was also mentioning the overall distribution pattern of my four subs to give you an example to plan how you’d be wiring and connecting your four subs. I think the speaker level connections and daisy-chaining capability will work well. You just need to determine exactly how you’d prefer to distribute the two shorter SB subs and two taller PB subs. Unfortunately, I have a lack of knowledge and experience concerning how best to deploy two sealed subs (with rated bass extension down to 24 Hz) and two ported subs (with rated bass extension down to 19 Hz) for best overall performance. Theoretically, I believe it should not make a significant difference but you’re the only scientist among us that’s currently capable of carrying out the required scientific experiments to obtain the empirical but very personal and subjective results. If you have a preference doctor, even if it’s based on the trivial idea of having the taller PB subs being located in certain areas near the seating and doubling as end tables, I’d suggest that’s a good layout variable to begin your experimentation with.

I also strongly suggest you invest in a good pair of speaker stands for your JBL 4319 main speakers and positioning them at least 2-4 feet away from the 16’ wall behind them. You can thank me later and I saw several suitable pairs starting at $85 by searching for "speaker stands" on eBay.

I’ll post the 4-sub Custom DBA Configuration and Seamless Main Speakers Integration Procedures once you complete the subs positioning phase of this project.

Later,

Tim

wspohn:
"I have run the subs with the audio front end on occasion and they are very good indeed, not just for bass reinforcement with video. Note that they were installed using proper analytic instrumentation for location, configuration and tuning and not everyone has that available - if you just stick them wherever they fit in your room, YMMV."

Hello wspohn,

    Just to clarify for thread readers and prevent them from being discouraged or misled about incorporating one or two subs in their systems, I thought it was important to let them know the following about your post:

    While you're absolutely correct in stating that you can't expect to just stick one or two subs in your room wherever they fit in the room and expect to obtain good bass response, it's absolutely not true that they need to be installed using proper analytic instrumentation for location, configuration and tuning and not everyone has that available.
    Everybody has what's required, two ears and what's in between, and knowledge of the 'crawl method of sub positioning' to incorporate one or two subs in their system. Thread readers can refer to my previous posts on this thread or google "the crawl method of sub positioning" to learn more on the specifics of using this method.
    Your use of the abbreviation YMMV can also be misleading since their mileage will not vary. The science of Acoustics has established how the longer bass soundwaves behave in any room and this knowledge is baked into the concept and effectiveness of the 'crawl method'.
  The single most significant rationale for utilizing the 'crawl method', as an alternative to the more expensive and complicated method using analytic instrumentation, is precisely because your mileage will not vary and it can be relied upon to be just as effective in any room or system.
  I'm not claiming any of the above possibly misleading or discouraging language in your post was your intent, I just wanted to make sure a few points were clearly understood by thread readers and potential sub users.


Tim  
 

millercarbon:
"Especially with bass. A lot of the problems people have getting this concept seem to have their roots in some really fundamental misunderstandings about how human beings hear and perceive different frequencies. We simply do not register timing with bass, for example, anywhere near the way we do higher midrange and treble frequencies."


Hello millercarbon,

     Yes, very good points about how we perceive bass sounds differently than higher frequency sounds.  
     We don't even perceive the existence of a deep bass tone sound in a room until the full cycle bass soundwave(a 20 Hz bass tone has a soundwave that's about 56' long) has been reproduced in the room, our ears have inputted the presence of a detected full cycle bass soundwave to the brain and our brain has processed this information as a perceived bass tone.  Any partial soundwave (less than a full cycle bass soundwave) presence detected and inputted to the brain is not processed as a perceived bass tone or any sound at all.
     Our brains also require the detection of multiple full cycle deep bass (below 80 Hz) soundwaves in the room to perceive a change in volume or pitch.  
     Another poorly understood aspect about how our brains process deep bass soundwaves below 80 Hz is the whole subject of psychoacoustics that come into play beginning with use of two subs and the main reason the 3-4 sub DBA concept works so incredibly well.


Later,


  


  
     

  

    

Hello Watcher,

Sorry about the side-tracks. Back to your system.

I'm glad you used the crawl method and discovered your system sounds good with the PB subs located along your back wall. I believe you’ll notice significant overall system performance by addressing the front of your system and the positioning of your two SB subs.
I suggest you try abandoning using the SBs as speaker stands for your 4319s. For best results, I think you need to treat your system as two systems, a bass system and an everything else system.
The bass system you set up first by properly positioning your 4 subs for optimum bass performance in your room. This provides the solid bass foundation for your system and most music. Its ultimate effect, after your 4319s are seamlessly added as part of your everything else system, will be to make the 4319s sound like much bigger and higher quality speakers.
You need to temporarily move your 4319s out of the room. Set all subs at 50% volume, crossovers at 50 Hz and phases at zero ’0’ for this step. Then utilize the crawl method I described earlier for optimally positioning both of your SB subs in your room, which will probably be along your front 16’ wall but not necessarily. Just locate each where the bass sounds best and trust the procedure. The goal is solely to optimize the bass in your room at this stage, so take your time and get the bass sounding the best you can to you.
Your four subs now form a completely separate and independent bass system that serves as the solid foundation for the rest of your overall system. The everything else system, consisting of your 4319s properly positioned in relation to your listening seat, is also a completely separate and independent midrange and treble system that’s going to be laid on top of your solid bass foundation.
The goal in this phase is to optimize the midrange, treble and the stereo soundstage illusion created by your 4319s at your listening seat. I strongly recommend you invest in a good pair of speaker stands for your 4319s to get the midrange and treble drivers up to the height of your ears when you’re seated at your designated listening seat and to position the 4319s on stands at least 2’ away from the 16’ wall behind them. You’ll notice that, the more you move them away from the front wall, the deeper and more 3 dimensional the stereo soundstage illusion will become. 2’ out will be good but further will be increasingly better.

I think it best we pause here until you’re able to receive a good pair of speaker stands that I believe are very important for best results. In the meantime, you could just position your 4319s on the floor, not ideal but better than nothing.
Also in this meantime, I’ll write up a procedure for the final stage of properly positioning of your 4319s and how to best adjust the volume, crossover frequency and phase controls on your subs for the seamless blending or integration of your two systems.

Is this all acceptable to you? Let me know.

Later,
Tim

Hello Watcher,

     Great, just so we're on the same page you need to:
1. Complete your bass system by positioning your two SBs using the crawl system.

2. Order a pair of speaker stands for your JBL 4319s. I think the best place to search is eBay and google, just search for "speaker stands for  JBL 4319 speakers" on either.  You'll probably get even better deals on them if you'll accept used ones in good condition.  
     The exact height of the stands is very important.  You should measure A. the distance from the floor to the middle of your ears when seated at your listening seat. Then measure B. the distance from the bottom of one of your 4319s to the middle of the tweeter.  Take measurement A and subtract measurement B and you'll have the exact height required for the height of your speaker stands.  
     My assignment is writing a procedure for you on how to properly position your 4319s in relation to your listening seat and how to best adjust the volume, crossover frequency and phase controls on your subs for the seamless blending or integration of your two systems. 
     Just a heads-up, when you receive the speaker stands and it's time to follow the procedures, things will be easier if you can recruit an assistant to help you out.  Without an assistant, you'll be going back and forth way too many times between your listening seat and each sub and you'll probably wind up exhausted by the time you're done. 
     Send me a pm or post again when you order the speaker stands.

Thanks,
  Tim
    

Hello Watcher,

     Excellent, I'll try to complete the procedures today.  

Later,
Tim

Hello watcher,

      You stated your room size is 16x30. The speakers are placed on the 16' side, and you sit about 11 feet away from the speakers. The SB are located right under the main, 6" from the wall.
    Instead of specific procedures on steps to take, I decided to just generally discuss the important areas of concern and the variables you're able to control. I'll provide specific procedures only when the areas of concern allow such specificity.

1. The Optimum Positioning of your 4319s:
    I went to the Cardas website linked below and read their suggestions for positioning a pair of stereo speakers in a rectangular room. I'm less confident on these suggestions than I am on the remaining areas of concern and my suggestions of steps you can take to address them.
          www.cardas.com/room_setup_main.php

    I just wanted you to realize this from the beginning and attached their link for your reference. I'd suggest you just follow their suggestions, determine for yourself how it performs in your system and room both sound performance wise and aesthetically and then experiment after with speaker placement adjustments that may perform better in your determination.
    According to Cardas, the optimum positioning of your 4319s would be with them positioned 7.5' apart from each other, 7.5' out or away from your front 16' wall, each speaker 4.4' away from the nearest side wall and with your listening seat exactly between the speakers and 7.5' away. They state that this is the recommended starting positioning and that making a series of small speaker position and toe-in angle adjustments are required to fine tune the stereo imaging, with the presence of a realistic, solid and stable soundstage illusion of vocals and the vocalist between the speakers being a good measure of positioning success.    

2. Procedure for optimizing the phase control settings on all four subs for improved subs and speaker integration:

A. Invert the polarity on both speakers by reversing the positive and negative speaker wire connections on the 4319's terminals only (NOTE: do not reverse the speaker wire connections on the amplifier, just reverse the speaker wire connections on the speakers). IOW, instead of the proper connections on the 4319 speaker terminals and speaker wires being pos. to pos. and neg. to neg., reverse them to pos. to neg. and neg. to pos.
B. Play some music with good and repetitive bass and sit in your listening chair.
C. With only Sub#1 powered on/active and both 4319s playing, have an assistant very slowly rotate the Continuously Variable Phase Control on Sub#1 until the bass sounds the weakest and worst to you.

D. Leave Sub#1's Phase control at this setting since the sub and 4319s will be both precisely in-phase once the 4319's polarities are not inverted and returned to normal.

E. Repeat steps A-D for Sub#2-4

F. When all 4 subs have had their Phase control set in this manner, return the speaker wire connections on both of the 4319's speaker terminals to the normal, pos. to pos. and neg. to neg., positions.

    This polarity inversion method works well because it's easier to
determine when the bass sounds the weakest and worst than the strongest and best.  
    The remaining two sub controls useful for optimizing the blending, or seamless integration, of the very good bass produced by your new 4-sub DBA system and the very good midrange and treble produced by your pair of JBL 4319s are the Volume and Crossover Frequency control settings on all four subs. Unfortunately, I'm unaware of a simple and effective procedure, like the one described above for optimally setting the Phase control, for optimally setting the Volume and Crossover Frequency
controls.  
    Based on my experience using a 4-sub DBA system, I consider the specific actual positions of the Volume and Crossover Frequency controls as the most important determinants of how well the bass produced by a 4-sub DBA system will blend, or seamlessly integrate, with the main speakers, as separate controls that are actually very interdependent in terms of their ability to influence the overall sound and performance quality of the combined system and as controls that are likely to be readjusted periodically over time as experience is gained and personal overall system preferences develop. Hopefully, you understand why I'm unable to offer simple procedures on how to set these controls and you quickly become proficient at setting them yourself on your new 4-sub DBA system.
     
    However, I can offer some advice and guidance.  The Volume control setting was probably the simplest for me to set since I don't want the bass to be overemphasized in my system. If you feel the same, then it's just a matter of matching and setting the Volume level on each of your four subs to the relative volume of the midrange and treble frequencies played back by your main speakers. The Swarm system requires only the setting of a single volume level on the amp/control unit, which I have set at 11:00 which is about 45%, but your custom DBA requires the desired relative volume to be set on each sub individually.
    The Crossover Frequency requires a bit more planning and experimentation. First you need to determine the bass extension limit of your main speakers, a good indication is the published rated frequency response figure usually stated as a specific frequency range capacity listed in hertz which indicates the upper and lower frequency limits along with a decibel deviation in output over the entire specified frequency range. For example, my Magnepans are rated at  34Hz-26kHz +/- 3dB, 34 Hz -3dB being the important figure for the bass extension limit.  Your JBL 4319s are rated at 38Hz-40kHz -6dB, 38Hz -6dB being the important figure for the bass extension limit. Since 3dB is the smallest change in loudness humans typically can notice, -6dB at 38Hz indicates that the bass will output at that frequency will be noticeably lower.
       Second, you need to decide whether you'll run your main speakers full-range or limit their bass output to a certain limit, I believe the built in filters on your SB and PB subs only allow limiting your main speakers bass output to a fixed 80 Hz and below.
     I did not perceive any sound quality benefit on my system by restricting the bass frequencies my amps and main speakers were responsible for reproducing so I run my mains full-range and usually have my Crossover Frequency set at 40 Hz, which means my Swarm DBA is reproducing the bass from 20-40 Hz.  
     However, I suggest you try both options and decide for yourself whether running your 4319s full-range or with restricting their output to 80 Hz sounds best to you.  If you prefer them running full-range, I'd recommend initially setting the Crossover Frequency on each of your subs to  45 Hz and then experiment by progressively decreasing the Crossover Frequency on each sub as low as possible while still liking the overall system sound quality.  If you prefer them running with the bass restricted to 80 Hz, I'd recommend initially setting the Crossover Frequency on each of your subs to 85 Hz and then experiment by progressively decreasing the Crossover Frequency on each sub as low as possible while still liking the overall system sound quality.  
     For best overall results, I'd also recommend initially setting the Volume level on each of your subs to your best estimate level and then experiment by progressively decreasing the volume on each sub as low as possible while still liking the overall system sound quality. 
     Remember, the goal is not to constantly be aware of your upgraded bass performance, the goal is for your overall system to effortlessly reproduce whatever bass the music, or any HT content, calls for whether it's accurate, detailed, quick,taut and rhythmic bass or accurate, detailed, sudden, deep, dynamic and powerful bass.


Enjoy,
Tim

Hello Watcher,

     Okay, I'll keep monitoring the thread. I you have any questions, you can always pm me, too.


Good luck and take your time,
 Tim

Hello watcher,

    Excellent!  It sounds like you're very pleased and are gaining some good knowledge and experience with your custom 4-sub DBA.   

You stated:
"Volume is fun to play with, if you set them all the same you get a better sense of space, but if you set the front higher than the rear, you get stage imaging. I'll play with this setting and see what comes from it."

     This is very interesting to me.  I've never used a custom DBA where you can control the volume and crossover on each individual sub. I've only used the AK Swarm DBA system were you control all 4 subs volume and crossover as a group.  
     I have all 4 set at 45% volume and a crossover usually at 40-50 Hz and I'd characterize it in your terms as improving my system's soundstage and its sense of space or airiness. But I'd like to be able to control the degree of these qualities like you're able to. 



Enjoy,
Tim