Searching for matching(?) Subwoofer solution


Hi folks,

I have a relatively new setup in my home office (12' x 14' with hardwood floor) and am seeking recommendations for a subwoofer solution.

Speakers: Ologe 5
Preamp:    Bryston P26 
Amp:         Forte 1A
Budget:     Flexible but just want something to provide a good match for the above components.
Music:       Mostly Classical and Jazz.  Some rock, some fusion.
Source:     Well, that's something else I am seeking advice on too and will post under the appropriate discussion topic

Problem is none of the local Hi Fi shops here in the Boston area have any experience with, let alone heard of Ologe speakers.  Couldn't get any recommendations there.

Has anyone owned or at least listened to these speakers? Or any of the other Ologe speakers?
The Ologe site (http://www.ologe-acoustic.com/) features a subwoofer called Ologe 20 at USD $8550.  
Just wanted to look into alternatives before dropping over 8 grand on the Ologe 20.
 I am open to but don't know much about subwoofer swarms.

I am not looking for anything overkill.  Just a subwoofer solution to nicely complement my somewhat modest home office system.

Thanks,
H
hleeid
Hello Mike,

     If you're intuitive, you can probably guess what this word means just by looking at it. No? Maybe you're not so intuitive, after all. Intuitive means having the ability to know or understand something without any direct evidence or reasoning process. Your statement that "Now that I know what is going on it makes perfect sense and is indeed intuitive"   defies logic; the very fact you required more information to fully understand the DBA concept proves it is NOT intuitive. I don't understand why you felt the need to rebut my statement that the DBA concept is counterintuitive, when it obviously is, but I suggest we just drop the whole subject and move on.

    Thanks for explaining what you meant by having no rear wall, I get it now.

    You stated: "I firmly believe that with any dipole speaker, Planar magnetic, ribbon or ESL you have to cross up higher at least at 100 Hz. This disqualifies a DBA. On the other hand my way of doing things may not work well with regular dynamic speakers. Pick your poison:)"
    We seem to have different audio experiences and opinions but I think that's healthy since we both can benefit by discussing our differences. Even though you utilize a line source bass array system (LSBA) and I use a distributed bass array system (DBA), I believe it's a win-win scenario because we've both attained exceptionally good bass response performance in our rooms/systems along with also learning more about an alternative bass system solution.
     In the spirit of benefiting from discussing our differences, I disagree with your statement that planar-magnetic dipole speakers need to use crossover frequencies of at least 100 Hz.   I have planar-magnetic, dipole, 3-way Magnepan 2.7QR mains but they have decent bass extension, rated at 35 Hz +/- 3db. I run them full-range and usually cross them over to the 4 Swarm subs in the DBA at 40 Hz. This works very well in my system/room with the bass seamlessly integrated with my main speakers without any downside I'm aware of.
     I think I understand your reasoning for suggesting using higher crossover frequencies on planar-magnetic, ribbon and electrostatic speakers.  These speaker types don't typically have very deep bass extension and freeing both the speakers and the amp(s) driving them from the demanding requirements of reproducing deep bass are logically reasoned to improve the performance quality of both as a result.
    This theory makes so much sense to me that I experimented with using crossover frequencies at various settings as high as 100 Hz,  both with filtering out the low frequencies below the crossover setting and running the mains full-range.  I stopped experimenting with higher crossover settings once I began perceiving the location of the subs at around 100 Hz and it began to have a negative affect on the normally very good stereo imaging of my mains.
     I believe my system didn't gain the expected sound quality benefits of reducing the low frequency demands placed on my amps and speakers due to a couple of reasons.   The first reason is the Magnepan 2.7QR mains I use are a 3-way design with rather large 625 square inch dipole bass sections that reproduce frequencies from their lower limit of 35 Hz to  650 Hz.  But relieving these bass sections of reproducing the deepest bass frequencies in this range had no significant affect on the midrange and treble sections of these speakers. Also, any significant sound quality improvements in the bass sections' performance would be masked by the high quality bass reproduced by the Swarm bass system.
     The second reason is that the D-Sonic class D mono-block amps I use for the mains deliver 1,200 watts into the Magnepans' fairly consistent 4 ohm loads.  However, I still believe that systems using less powerful amps and speakers with simpler. less than 3-way, designs could realize  significant overall sound quality improvements.
     After extensive experimentation, I actually arrived at the opposite conclusion than you recommend, at least for my system.  I thought my system sounded the best overall with the main speakers running full-range and the Swarm subs only becoming active on frequencies at or below a relatively deep 40 Hz and when the source content called for it.
     I believe my system may perform even better overall with an even lower crossover frequency setting but 40 Hz is the lower limit on my sub amp/control unit.
     My current thinking is that there are a number of good bass system solutions available, beginning with a pair of good quality subs, and that the choice of the optimum bass system, as well as its optimum configuration, is best determined on an individual basis.

Later,
Tim

  
     
      
If my 2 RELs (run in mono) seemed to be lacking anything at the 58hz or so point where they match the bass rolloff of my main speakers, I'd consider the "swarm" system, although 4 boxes and the wires are somewhat off-putting. Also, my RELs cost about 200 bucks each used and are perfect, providing a 250 total watt low bass enhancement to the 12wpc SEP main amp, and it all works extremely well with no DSP needed. Big-ish room with very tall sloping ceiling (that helps keep bass sounding right).
Post removed 
Ok. So after researching the wonderful resources about subwoofers, I think I am beginning to understand nodes, evenness, cancellation, etc. and leaning towards going with the Swarm again.

But Swarm or DEBRA?  Not finding much info about the differences.

Anyone have experience comparing them?

Thanks,
Hans
Tim, Once I read Gedde's explanation of how DBAs work it makes absolute sense. My problem was that Duke was using terms that I was not familiar with that were not self explanatory. He was talking in a language I did not understand. Now that I know what is going on it makes perfect sense and is indeed intuitive. However it has limitations the biggest one is that you have to keep the crossover under 60 Hz or it will start messing up your image. This may work well for people with regular point source speakers that get down to 40 Hz ok. I firmly believe that with any dipole speaker, Planar magnetic, ribbon or ESL you have to cross up higher at least at 100 Hz. This disqualifies a DBA. On the other hand my way of doing things may not work well with regular dynamic speakers. Pick your poison:)

My media room is 16 X 25 feet. The back wall is 75% open to the kitchen and then 30% open to the dinning room the back wall of which is 75 feet away. So, the back wall reflection is broken up all over the place. I designed it that way. Between my speakers is a 113" diagonal Stewart screen the idea being that I can either listen to music or watch TV while cooking and having dinner. The projector hangs from the ceiling.  

Mike
mijostyn: "Tim, in this case I don't think psycho-acoustics is the reason."   "when a concept is counter intuitive it usually means it was not explained well."

  Hello mijostyn/Mike,

    I think we have different ideas concerning what qualifies as psychoacoustics.  Psychoacoustics is the scientific study of sound perception and audiology—how humans perceive various sounds. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound (including noise, speech and music).  I think you're right, masking and volume could be construed as part of that definition, they're just not the primary examples that I usually think of.
    I also believe my explanation of the DBA concept and the psychoacoustic dynamics involved was sufficient. 
 
    When I stated the DBA concept is counterintuitive I was referring to the method of creating more bass peaks, dips and nulls in the room to eliminate the perception of all of them in the room, with our brains being used as a sort of natural room correction software and hardware.  
     Do you think the DBA concept is intuitive?  
     Don't you think the cognitive dynamics involved with the DBA concept fall within the definition and realm of psychoacoustics? 

     You're correct, Geddes has stated that good in-room bass response can be attained over a wider area using as few as three subs and good at a single listening position using just two.

     Hopefully, Duke will respond to the bass phase issues.  

    You have no rear wall in your room for bass soundwaves to reflect off of? You must have very good bass performance along with very high heating and cooling costs.


Tim
Tim, in this case I don't think psycho-acoustics is the reason. An example of psycho-acoustics is masking. MP3 compression strategies operate on this principle. The normal undistorted music masks the distortion because or brains can only pay attention to the loudest noise. If you don't want to hear your car rattle, turn on the radio.
Nodes form in rooms below what is called the Schroeder Frequency which depending on the size of the room is somewhere around 130 Hz.
Where the nodes are depend on the frequency, room size and the position of the woofer. By  positioning the woofers at different places in the room you create nodes in different places which overlap at different phases creating what I think Duke is referring to as a minimum phase system. This is a bit of a tough one to explain but I will give it a shot. Draw a sine wave on paper now draw another one 10 degrees out of phase with the first. Keep drawing sine waves 10 degree off from the last one until you come around a full 360 degrees. Now lets say these sine waves represent volume. The very bottom is zero dB and the very top is 20 dB. If you average all of these sine waves what you get is a flat line at 10 db. Or as Duke implies a minimum phase system. Geddes seems to think that just three sine waves is enough to create reasonably flat response and you can do this at any frequency below 80 Hz because below 80 Hz you can not locate the source. I personally think that should be below 60 as I know for a fact me and my audiophile friends can locate a 60 Hz test tone. The problem with this approach is what about the frequency band up to the Schroeder Frequency? By absolute coincidence I cross over at 125 Hz just below the Schroeder point. So my subs have to deal with all the room nodes from 125 Hz down. Above the Schroeder Frequency nodes do not form. My way of dealing with the node problem is to limit the dispersion below 125 Hz by forming a line source that is right up against the front wall. Now there are only reflections off the ceiling and rear wall. In my case the rear wall is broken up or there really is not a rear wall. The nodes that do form are easily managed by room control. I am not sure this approach would work well with point source speakers. Such an array may overwhelm them. 
When a concept is counter intuitive it usually means it was not explained well.
Hello Mike,

    You stated: "Simplifying the situation, what Duke is saying is that placing subs randomly throughout the room creates a situation that smooths out the frequency response throughout the room. I am trying to understand how that happens. "

    Hopefully, Duke will respond, too. But as I understand it, the key to understanding how and why a distributed bass array (DBA) smooths out the bass frequency response is psychoacoustics, how the brain processes bass information in the room delivered through the ears, as well as through other body senses, and creates our perceptions of the bass.  
    The purpose of four independent, well distributed subs launching bass soundwaves into the room, with the full knowledge that these soundwaves can be relied upon to reflect off room boundaries and collide into themselves and one another until they run out of energy, is to create an abundance of bass room modes (bass peaks, dips and nulls) and then depend upon our brains to process, sort and make sense of the abundance of room modes in order to create an overall perception of the bass in the room. In other words and simpler terminology, psychoacoustic principles, which explains how the brain will sum the bass by frequency and average it out which results in our perception of the bass as smoothed out and natural.
    I believe psychoacoustics are the key to understanding why and how the DBA concept works so well. It seems to me that explaining how and why a line source bass array (LSBA?) concept works so well can be done more easily with just physics than the DBA concept can and the LSBA concept seems to rely much less on psychoacoustic dynamics than the DBA concept does.  I think psychoacoustic principles and dynamics are a bit esoteric and counterintuitive.
    I've never experienced the bass response performance of an LSBA system in any room. I know the first time I experienced the bass response performance of a DBA system in my room it was a revelation and uncanny how well it performed.  I'd love to experience a LSBA system some day soon since I believe it could also be a revelation.
     I share your curiosity about whether I would detect any difference in bass performance with my DBA by limiting the distance between subs to under 14 feet.  However, in 2008 I had a stroke and still don't have full mobility of my left arm and leg.  I also had custom length speaker wires made for all four subs and the wiring is all run and hidden in the crawl space below my room.  Due to these factors,unfortunately, I don't think it's practical for me to experiment anytime soon.  Perhaps I could recruit a fellow audio enthusiast friend as an experimental lab assistant and mover but no promises.


Tim  
Here is Earl Geddes explaining subwoofers
https://mehlau.net/audio/multisub_geddes/
Smoothing the bass frequency response in a room with multiple subs is a simple matter of overlapping nodes. He thinks that three subs is optimal the 4th adding little to the solution. He also wants the subs as far apart as possible. He would cross over somewhere below 80 Hz where he thinks bass becomes non directional. So his approach is radically different than mine. I cross over higher but still below the Schroeder frequency and create a line source. Funny thing is that he greatly favors directional speakers over omni directional speakers because they reduce room interactions in a way superior to room treatments. He does not say that in this paper but relates this strongly in other papers. My array does exactly this. Again, I have a sophisticated room correction system which is to some extent cheating. If I bypass it my speakers sound like crap because of the rising response of the transformers I am using. I can not separate the subs from the satellites in this regard. It is either all on or all off.
This paper was written for lay people so he does not use terms like minimal phase system. He may well use terms such as this in more scientific papers aimed at people who understand what he is talking about. I got as far as the Fourier wave equations and gave up.
So Tim, According to Earl Geddes I am wrong. You want to keep your subs as far apart as possible and throw the fourth one away. It is just taking up space. Or, you could try making a line array using all 4 subs and see what happens. Couldn’t hurt to try:)


Mike
Ok Tim, first of all this is not my method. It a rule of acoustics and speaker design. I started applying it to subwoofers because I was having difficulty matching subwoofers to my Line source ESLs. So I created a horizontal line source subwoofer array which has the added benefits of being very efficient and greatly reducing reflected sound in the room because of the way a Line Source radiates. 
Now I have no experience doing Swarm systems around point source satellites. But I find it an interesting concept as I too have great performance using four subwoofers. Your numbers are about right. So, if you are crossing at 40 Hz you would want 14 or less feet from one sub to the next. Theoretically the drivers are now acting as one acoustically and are phase coherent. But, then you have to add the room into the equation which I think is Duke's message and I would like to understand what he is trying to describe better. With subs at various distances from walls and each other you have a very random pattern of reflections at different times (phase) and with dimensions in and around the wavelengths of the frequencies you are producing certain frequencies are going to resonate longer. Simplifying the situation, what Duke is saying is that placing subs randomly throughout the room creates a situation that smooths out the frequency response throughout the room. I am trying to understand how that happens. 
I would not say that the line array is better bass in all situations. It is better in my situation because I cross over much higher and I have line source satellites. If I put my subs around the room it would really screw up the image. In your case crossing over at 40 Hz  you can not tell where the bass is coming from. The question I have Tim is if you arrange your subs so that any gap is not longer than 14 feet can you detect any difference in the bass. 40 Hz is way down there. What you might try is playing a 30 Hz test tone. Many test records have test tones. You can even download them digitally. Play the tone and some music with deep bass before and after you rearrange things. It may not make any difference at all. 
Tim, I just read your full post. I will comment on it when I have a chance.

Mike
Thanks Tim, Subs oriented in a line array are going to project more power because the volume drops off slower as you move away from the speaker than a point source. I can up with this approach because it is the best way to integrate subs with line source loudspeakers. I also cross over to my subs at 125 Hz which may be why Duke and I have somewhat opposing views.
Duke I need you to define what you mean by a minimum phase system.
Yes, I understand if the decay is slower at a certain frequency that frequency will be emphasized. Your ears register everything immediately just like any good microphone. It is your brain that takes time to register just about anything. I think you missed my point about impact. It is the visceral component that adds excitement to the music and why live performances can be so exciting. You not only hear sound but at lower frequencies you feel it. When you confuse phase like that the impact goes missing. When said individual reconfigured his system he described it as having more impact without my prompting him. The result I would have expected. 
I have to admit I also cheat because I am using very elaborate room control. Anyway there is more but my wife is pressing me to go out for a bike ride. Time to go out and assault the motoring public. Back later:)

Mike
Hello Mike,

     I usually crossover my four Swarm subs at 40 Hz for music and HT but sometimes as high as 50 Hz.  According to your method of 1/2 the length of the crossover frequency, this would mean my subs should be no more than 14 feet apart at 40 Hz and no more than 11 feet at 50 Hz.
    My room is 23'x16'x8' with my main speakers (with bass extension rated at 35 Hz +/- 3db) along the 16' wall and run full-range. Two of my subs are along this 16' front wall with each about 2' away from the nearest corner and about 6' apart from each other.  The other two subs are located, one each, along the left and right 23' walls and each about 3' away from the corners along the rear 16' wall.  This results in my rear subs being about 16'apart from each other and about 20' apart from the nearest sub along the front 16' wall.  So, since some of my subs are more than 14' apart and exceed your rule of thumb, you're suggesting I should have bass phase issues in my room.
     The Swarm amp/control unit does have a continuous phase control adjustment.  I set this by inverting the phase on both of my main speakers and setting the phase control to the position at which the bass sounded the weakest at my listening seat.  I then reattached the speaker wires to in-phase and the bass sounded equally very good throughout my entire room and at the 6 seating positions in my room.  Do you think this is why I don't detect any obvious bass phase sound quality issues in my room?
    Although I've never heard one, I do understand from what I've read and from your comments that subs configured in a line array are capable of even better bass performance than subs configured in a distributed bass array.  However,  my music listening and HT room also doubles as my living room and devoting the entire 16' wall of my living room to a line of subs is not practical. I'm not stating I disagree with the high quality bass capability of a line array bass system.  I'm just stating that I'm willing to sacrifice optimum bass response performance in my room for the extremely good bass response performance of a distributed bass array that blends much more inconspicuously in my living room.  

Tim

Mijostyn wrote: "The statement that the ear (which should be ears) have very poor time domain response is 180 degrees wrong."

You are correct! I did not proofread carefully. Here is what I should have said:

"Because the ear has very poor time domain response AT LOW FREQUNCIES..."

The ear is indeed quite sensitive in the time domain at higher frequencies.

Mijostyn again: "Speakers + Room do not equal a minimum phase system."

Yes they do at low frequencies, which is what I said. This according to Floyd Toole and Earl Geddes. The in-room frequency response tracks the time domain response. The phase behaviors of individual reflections don’t matter when viewed in isolation, but their sum is relevant as it shows up simultaneously in both the in-room frequency response and in-room time domain response. It is the sum that we hear.

Mijostyn: "With the drivers acting as one the bass drum impact will strike the listener in phase with the greatest force resulting in the largest smile. The decay afterwards is of no great significance."

This is what our intuition tells us, and our intuition is wrong.

We literally cannot detect the presence of bass energy from less than one wavelength, which is 22.5 feet at 50 Hz (ballpark resonant frequency of a bass drum). A study was done in which less than one full wavelength of low frequency energy was played over headphones, so there were no room reflections, and it was UNDETECTABLE. And it took MANY cycles before the ear began to register the pitch. By the time your ears BEGINS to hear the impact of that bass drum played over your system, so much time has passed that any minor arrival time differences are inconsequential.

The decay is of enormous consequence because it shows up as a frequency response peak. And this is because speakers + room = a minimum-phase system at low frequencies. If the decay is slow at some frequency then the bass sounds fat because there is a response peak at that frequency.

Mijostyn:  "I know of one person who set up his four subs as I suggested and he thought it made an improvement."

The improvement may not have been for the reasons you suggest.   I strongly suspect that what happened is, the frequency response improved.  The in-room frequency response is what dominates our perception at low frequencies (though the in-room frequency response is merely a manifestation of the in-room time domain response, and vice versa).

Duke



Hi Duke,
You will have to give me some time to think about it. Humans are extremely sensitive to phase. It is why we have two ears 8 inches apart. In nature it is how we locate danger and why a listener can put himself perfectly in phase with two speakers just by moving his head side to side a little. So the statement that the ear (which should be ears) have very poor time domain response is 180 degrees wrong. Now most of us can accurately locate a test tone at 60 Hz. Anyone can prove this to themselves by unplugging all the subs but one.
Blindfold the listener and in the middle of the room spin them around a few times, play the tone and ask them to point to it. Below 60 Hz and it gets progressively more difficult. Now this is a test tone, not music which is more complicated. If you put two subs in front of you and reverse the wires on one putting it 180 degrees out of phase the bass output decreases dramatically everywhere in the room. With more subs out of phase at various angles things get more complicated. Next in regards to very low bass, sensory input is not just coming from your ears it is also coming from visceral sensation. If I set off an M80 50 yards away from you you will hear it and feel it at the same time. All frequencies travel at the same speed. Regardless of what your ears are hearing if your woofers are out of phase with each other you may hear bass but you will not feel it. Speakers + Room do not equal a minimum phase system. They equal a confused phase system as you have the primary signal from all the drivers and their reflections bouncing all over the place. With the drivers acting as one the bass drum impact will strike the listener in phase with the greatest force resulting in the largest smile. The decay afterwards is of no great significance. 
So I suggest to those interested in this thread who have SWARM systems to play around with positioning and see what happens. This is a group experiment. I only know what happens in my room with my system which is different acoustically than most of yours. I know of one person who set up his four subs as I suggested and he thought it made an improvement. But, others indifferent situations may not feel this way. Or maybe not:)

Mike

Mijostyn wrote:

"For the drivers to act as one they can be no farther apart than 1/2 the wavelength of the crossover point."

You do an excellent job of explaining your suggestion, but imo the issue it addresses is not one that a distributed multisub system is concerned with.

With a distributed multisub system, "the drivers acting as one" is definitely NOT the goal. We want each sub to interact with the room very differently from the others, and that is accomplished by spreading them far apart. So not only are there subs more than a half wavelength apart, they will also (almost always) have different path lengths to the listener(s).

Because the ear has very poor time domain response, such that it cannot even detect the presence of bass energy from less than one wavelength, a bit of smearing in the initial arrival times of the different subs is inconsequential. What DOES matter a great deal from a perceptual standpoint is how the notes decay. Since speakers + room = a minimum-phase system at low frequencies, when we have fixed the frequency response we have simultaneously fixed the time-domain response. Imo this is something that a good distributed multisub system does well.

(The ear hears low-frequency ringing quite well, but such ringing is always accompanied by a frequency response peak, and vice-versa. Anywhere in the bass region where there is a peak, whether it originates from a speaker anomaly or a room anomaly, the energy in that region takes longer to decay. It is actually the frequency response peak that we hear, not the ringing - the slow decay - itself. But when we have fixed the one, we have simultaneously fixed the other.)

Duke

Wow this topic has legs. I like to simplify things. First of all it is not a sweet spot. It is a sweet line 90 degrees from the center of the speaker axis.
On this line the speakers are in perfect phase with each other and will cast an image of the recording to the degree that the system is capable. 
Now because of standing waves and interference patterns the frequency response below about 100 Hz on this line can vary up to 10 db. It depends on room dimensions and the way the subwoofers are used. 
You can hear this easily in your system. Just play a test tone at say 60 Hz and walk back and forth across the room and you will be flabbergasted at how the volume changes within just a few feet. When I was using two woofers I dealt with this by moving my listening position along the "sweet line" until I felt the bass sounded right. Doing this even with room control is a benefit because it will cost you much less amplifier power to correct the response at your listening position. With a point source system and one favored listening position 2 subs can do the job fine and as Raul suggests I think two good woofers is better than 4 bad ones. 
But, when it comes to other situations like having multiple listening positions along that line or having line source or linear array speakers you run into trouble. It is difficult to compensate for two positions and two point source subs will not project as well as line array speakers so the sound gets thinner as you move away from the system. This is where multiple subwoofers come into play. It seems that the SWARM group wants to place their subs anywhere in the room. This will smooth out the frequency response throughout the room but depending on the distance between to subs may cause phase issues. Here is a rule of thumb. For the drivers to act as one they can be no farther apart than 1/2 the wavelength of the crossover point. So say you are crossing over at 100 Hz. That is about 10 feet at sea level. If your subs are less than 5 feet apart they are acting as one and no matter where you are in the room they will always be in phase and as long as additional subs are closer than 5 feet to the last one in line they will always be in phase no matter where you are in the room. If you make the array longer than the lowest frequency you want to reproduce you have created a line source subwoofer. At lower cross over frequencies say 80 Hz the distance would increase to 7 feet between subs. 
Now in my case I need a subwoofer linear array to match the output of my ESL linear arrays and the woofers are arranged across the front wall with the outside subs in the corners. I am doing this to make the array function to below 20 Hz but a point source system does not have to worry about this. So, what I am suggesting to the SWARM people is to place their woofers in configurations so that one is no farther than 7 feet from the next assuming you cross at 80 Hz, 5 feet if you cross at 100 Hz. This will make all of them in phase no matter where you are in the room and should increase the dynamic response of the bass. Try it and let us know what happens. This rule is used by designers that use multi driver arrays. If you study various designs you will always notice that tweeters are always closer together than midranges which are always closer together than woofers. We are just extending the same principle to subwoofers and the much longer wavelengths involve. Pheyew that was tiring.

Mike
raulruegas:
"Fortunately I already made my choices on room/system choosing what for my MUSIC/sound priorities, still today, gave and give me the best trade-offs for a high quality overall level performance. Truly satisfied, not " perfect " but always perfectible."


Hello rauliruegas,
     
      You're obviously very fortunate.   You made an informed choice and picked the set of tradeoffs that makes you happy.  
     Congratulations, you only have one thing left to do; enjoy the heck out of your high quality system with your music of choice.

Enjoy,
Tim
Dear @audiokinesis  : Fortunatelly I already made my choices on room/system choosing what for my MUSIC/sound priorities, still today, gave and give me the best trade-offs for a high quality overall level performance. Truly satisfied, not " perfect " but always perfectible.

R.

Audiorusty wrote: "With as good as a DBA system is, there still will be only one sweet spot in the room."

Imaging will of course be best in the sweet spot.

But it is possible for the imaging to hold up fairly well across a fairly wide listening area, and for the tonal balance to hold up well just about throughout the room. This all depends on the directional characteristics of the main speakers and how they are set up, and the details are somewhat counter-intuitive.

* * * *

Raulirugas wrote: "I’m just talking about the myth that we can’t detect the direction for frequencies 80hz down ( two channel with two subs. ) and this is not true."

Detectable under specific conditions that are not representative of listening to music reproduced in a home listening room, yes.

Worth trading off the advantages of a good distributed multisub system for, well I guess that depends on your priorities. Just about everything in audio involves tradeoffs. Make an informed choice and pick the set of tradeoffs that makes you happy. Fortunately in audio if a particular choice doesn’t make you happy, you can choose again.

Duke

Dear @audiokinesis : "" in which a distrubuted multisub system falls short..."

I’m just talking about the myth that we can’t detect the direction for frequencies 80hz down ( two channel with two subs. ) and this is not true. Our brain/body can, @tyray explained twice .

What is true is that some people can’t detect it but other can do it.

Even with frequencies/instruments that speakers puts at the center of the imaging/soundstage is difficult to detect if the sound comes from the left or rigth speaker.

Knowledge/experience to know what to look for is what tell each one of us the true not that myth per se.

Inclusive other gentleman posted that not playing music but test tones proved that our ears can detect 50hz.

No one knows the whole body/brain abilities on that myth subject when even the scientifics say the human been knows how the brain works only at around 18% of its overall capacity ! !

Audio is surrounded of to many myths many of them by our self ignorance levels or just for not know what to look for.

Some times is more problematic due that we own different kind of room/systems and obviously different ears/body/brain sensitivity to different frequencies and to different SPLs.

Noble 100 is spreading " everywhere " that low bass non detectable myth and that says he can't do it but that he can't do it does not means no one else can.

Audio is complex issue, especially on what we are perceiving and a home system behavior is different of what happens in a MUSIC hall or a small club.

R.


Thanks Tim,

You did answer my question. With as good as a DBA system is, there still will be only one sweet spot in the room. This is what I figured but I wanted to make sure that I wasn't missing something. 
Hello audiorusty,

The use of a distributed bass array (DBA) system is a very good solution for distributing low bass evenly throughout the entire room. Unfortunately, there’s not currently an equally effective solution that will distribute the mids and highs throughout the entire room, at least not while maintaining good stereo imaging throughout the entire room.
Since using and understanding the exceptionally high quality bass performance of a DBA system, I now view my system as two systems, a bass system and an ’everything else’ system, with ’everything else’ meaning the mids, highs and stereo imaging.
I recommend installing the bass system and getting that performing optimally first since it has traditionally been the hardest system aspect to get sounding right in most home systems, due mainly to the extreme length of bass soundwaves and how this results in audible bass issues in domestic sized rooms, and because high quality bass is the solid foundation that most music and high quality home audio systems are built upon.
Once the bass is performing optimally in the room, the next priority is to position the main speakers, in relation to the dedicated listening seat, to optimize the midrange, treble and imaging performance. This has traditionally been a much easier system aspect to get sounding right in most home systems, due mainly to the much shorter length of these midrange and treble soundwaves and their resultant highly directional nature. All that’s normally required is precise positioning, including toe-in angles, along with room treatments to control the first reflection points and perhaps some room treatment along the front and back walls.
All soundwaves of all frequencies reflect or bounce off of room boundaries (floor, walls and ceiling) until they run out of energy and collide with themselves and other soundwaves along their reflected paths within any given room. However, when bass soundwaves collide it’s perceived as a bass peak, dip or null, while when midrange and treble soundwaves collide it’s usually perceived as an airy quality except when they have a negative effect on imaging at the designated listening seat.
The final steps are directed at integrating or blending the bass system’s sound with the ’everything else’ system’s sound as seamlessly as possible. This is accomplished through precisely adjusting the volume, crossover frequency and phase control settings collectively for all four subs on the amp/control unit for an AK Swarm or Debra DBA system or individually for each of the four subs on a custom DBA system.


Tim

Audiorusty asked: "Since a DBA system can evenly distribute low bass evenly to all parts of a room are you also able to distribute the mids and highs evenly to all parts of the room or are you still relegated to a single listening sweet spot in the room due to the directionality of the mids and highs?"

Are you asking about speakers in general, or about my speaker designs in particular? 

Duke

Duke, Thanks for the reply.

I need to re-ask my first question since I wasn't clear. Since a DBA system can evenly distribute low bass evenly to all parts of a room are you also able to distribute the mids and highs evenly to all parts of the room or are you still relegated to a single listening sweet spot in the room due to the directionality of the mids and highs?

Thanks
Post removed 
H

   Your primary concerns seem to be a subwoofer that will match your speakers presentation, its just a modest office system but your open to the idea of swarm system.
  You should be looking for a DSP sub that uses a calibrated mic (not a smart phone) to make auto and manual adjustments to multi band EQ, variable phase, crossover slop and freq, adjustable Q, etc.. A sub that has the connectivity to daisy chain its equalized signal to non DSP powered subs for your own swarm if desired.
   Check out JL Audio F series and their CR-1 crossover $$$ read the CR-1 manual. SVS has a new DSP line, Syzygy, Martin Logan, Velodyne Plus did it all but they're no longer available.
   

@bdp24 wrote:

"would you expand on your recommendation of introducing a 90 degree phase difference between left and right subs?"

This is an idea I learned from a paper written by David Griesinger many years ago.

David recommended two subs, one directly to the left and one directly to the right of the listening area, up against the side walls. With the phase 90 degrees apart (in "phase quadrature"), this would approximate at the left and right ears the somewhat out-of-phase low frequency waves one would experience in a large hall. The result is a greater sense of being immersed in a large acoustic space, which means the ear is not perceiving as much "small room signature" super-imposed on top of the recording. As you hear less of your room’s signature, you correspondingly hear more of the ambient space on the recording.

Wouldn’t say it’s a huge difference, but as long as it doesn't bust the budget I think it’s arguably a worthwhile improvement. 

Duke

Excellent, thanks Duke. If you care to, would you expand on your recommendation of introducing a 90 degree phase difference between left and right subs? That's a new one on me!---Eric.
@bdp24 asked:
"Is for the subs to be wired/operated in mono mandatory in a swarm sub system?"

Not at all.

"In other words, does the swarm not "work" (reduce/minimize bass peaks and nulls in the room) if the subs are run stereo?"

Works just fine in stereo. The only reason my commercial Swarm system is normally mono is, I can hit a more attractive price point by driving all four units with a single amplifier. As an option the Swarm can be supplied with a second amplifier.

"Or is it just a matter of that with a steep enough filter (say 4th-order, 24dB/octave), there is nothing to be gained by running the subs stereo?"  

If the bass is summed to mono on the recording anyway, which I believe to almost always be the case, then imo there is nothing to be gained by running the subs in stereo. But imo there is something to be gained (greater sense of envelopment) by using introducing a roughly 90 degree phase difference between the subs on the left-hand side of the room and the subs on the right-hand side of the room, and doing so requires two amplifiers, in which case you might as well do stereo. That way if you know you have a recording with true stereo separation all the way down, you can quickly dial back in normal phase using the phase controls on the amps.

"Is running two subs at the front of the room (in the neighborhood of the loudspeakers) in stereo, and the third and fourth in mono, a viable option? THAT would make using a shallower low-pass x/o filter on the subs (for whatever reason) possible." 

You can do that, but imo it doesn’t really make a shallower low-pass filter more feasible. Imo the main reason for using a steep low-pass filter is to prevent the subs from passing upper bass and lower midrange energy loud enough to betray their locations.   

If your subs have fairly shallow (12 dB/octave) built-in lowpass filters, you might try this: Use a lower low-pass filter frequency for the subs that are closer to the listening area, since these are the ones most likely to be heard as separate sound sources in the upper bass/lower midrange region. 

Duke

Duke, here's a simple question for ya: is for the subs to be wired/operated in mono mandatory in a swarm sub system? In other words, does the swarm not "work" (reduce/minimize bass peaks and nulls in the room) if the subs are run stereo? Or is it just a matter of that with a steep enough filter (say 4th-order, 24dB/octave), there is nothing to be gained by running the subs stereo?

Is running two subs at the front of the room (in the neighborhood of the loudspeakers) in stereo, and the third and fourth in mono, a viable option? THAT would make using a shallower low-pass x/o filter on the subs (for whatever reason) possible. 

audiokinesis:
"The point is not whether there is an unrealistic test condition in which a distrubuted multisub system falls short. The point is, how does it perform when used under normal conditions?

Duke"
Hello Duke,

     Yes, I believe that's the goal of most of us if not all of us: 
"How does it perform when used under normal conditions?"

Rauliruegas,

     As I've stated, the AK Swarm/Debra 4-sub DBA system performs exceptionally well in my 23'x16'x8' room and seamlessly integrates with my fast and detailed Magnepan main speakers (which for years have been infamous for being difficult to integrate well with conventional subs) for both 2-ch music and HT.  
     My main concern is music and I don't think I can overstate how well it performs on all of my CDs and it performs even better on my high-resolution 24bit/96KHz direct to digital FLAC music files.  
     This combination transports me to a fairly wide and deep 3D soundstage in my living room of the musicians and the recording venue, usually jazz or blues in a small club or Sound Liason's larger European direct to digital recording studio,  that's ultra-realist sound quality, I believe, can be largely attributed to the bass quality, impact and dynamics that's normally only experienced with music heard live and in person.  Thank you, Duke.
     I consider this state of the art bass performance but I understand that similar results can be achieved at a single dedicated listening position utilizing two high quality subs that are properly positioned and configured, like the approach you chose.  Here's a link to a Todd Welti, of Harman International, that confirms this:

https://www.harman.com/sites/default/files/multsubs_0.pdf

Later,
Tim  
@rauliruegas wrote:
"Position at a normal one seat position and play music ( digital or analog ) with very low bass recorded information and then through several tests/evaluations lest us know if you can or can’t detect from where comes the sound you are listening... Main speakers off(no sound.)."  

Well of course under those conditions (playing music through the subs with the main speakers OFF) you can hear where the subs are! This is because the lowpass filter on the subs are not brick walls.

But with the main speakers on, the output of the mains will be so much louder than the output of the subs that it will effectively mask the location of the subs, even if the subs are letting a little bit of upper bass/lower energy leak through.

The point is not whether there is an unrealistic test condition in which a distrubuted multisub system falls short. The point is, how does it perform when used under normal conditions?

Duke



Dear @audiokinesis : " I agree ".

I don’t know from where you take that " I agree ". I think that you can make some tests with two of your subwoofers crossed at 30hz and with different SPL on each test. Position at a normal one seat position and play music ( digital or analog ) with very low bass recorded information and then through several tests/evaluations lest us know if you can or can’t detect from where comes the sound you are listening.

Tests using first one subs at a time and then the same with the other and you can follow with both at the same time. Main speakers off(no sound.).

I already dit it and I think that only true personal tests we can have an answer. Every one with subs can do it. Please don’t ask my conclusions, we have to make our work/job.

R.

Btw, this is what I posted here about mono/stereo:


"""   Atmasphere that has first hand experiences on the overall recording proccess posted in other thread what oput true ligth on that mono/stereo subs issue:

""" Its not so much the limitations of the format as it costs a lot of money to pay an engineer to work a way around "out of phase bass". If you spend the time with the recording, you can usually find a way to master it without having to process it. But that takes time and at $500/hour most often bass processing is used. This is a simple circuit that senses when bass is out of phase and makes it mono below about 80Hz for a few milliseconds until the event has passed. This makes mastering LPs less expensive!
But CDs do exist where out of phase bass exists. This can happen because a microphone is out of phase with the rest of the recording when a bass guitar or bass drum is recorded. For this reason, the recording engineer has a phase inversion switch on every channel of his mixer but he may not have thought to use them.

If the recording is done in its entirety with only two mics, out of phase bass will not exist. """

@noble100 wrote:

"Are you making a distinction between the perceived true stereo bass that I'm currently experiencing and your mention of "a second amp can be added to give you true stereo bass"?" 

IF the recording has true stereo bass, adding the second amp would allow you to reproduce left and right channel bass separately, instead of summed.   That's a big IF. 


"On several other threads no one, including myself, was able to name a single recording on any format containing true stereo bass. Are you aware of any?"

I don't own any, but my understanding is that Ralph Karsten has said the vinyl recordings he makes have stereo separation all the way down.  And I believe him!  

Duke

Audiorusty asked:

"A question for the DBA folks; How do you get the mids and highs to spread out evenly through the room to match up with the bass at all locations in the room? Also does a DBA affect impact?"

The bass doesn’t sound like it’s coming from everywhere. The bass sounds like it’s coming from wherever the bass instruments are in the soundstage. We get our localization cues from the higher frequencies that the main speakers produce.

In my experience impact is improved with a good distributed multi-sub system. This is because smooth bass is "fast" bass. We hear peaks as "slow bass" or "boomy bass", and we hear dips as "weak bass" or "lack of impact". (Dips are usually less objectionable than peaks.)

Our natural instinct is to think that having multiple arrival times from the various subs degrades the bass impact, but that’s not what happens. The ear DOES NOT EVEN DETECT the presence of bass energy from less than one full wavelength, and bass wavelengths are many feet long. So by the time we even begin to detect the presence of bass energy, the bass has already reflected off of room surfaces multiple times. We do not hear a "first arrival sound" in the low bass region because by the time we hear the bass, we are already hearing the room’s effects. But what happens to the trailing edge of the notes (how quickly and smoothly they decay) is very important to the sense of impact, and this is where a good distributed multisub system excels.

To put it another way, we cannot hear bass apart from the room’s (detrimental) effects, so we might as well take the room into account. By spreading multiple bass sources around the room, one might say that we get the room to work "with us" somewhat instead of "against us".

Last year at the Rocky Mountain Audio Fest we got a nice compliment from an extremely competent cable manufacturer with decades of audio show experience. He asked us to play his reference recording of "Fanfare for the Common Man". He said ours was the most natural reproduction of that recording he had heard at a show, and in particular he said "THAT is what a tympani sounds like - THAT is what I hear at the symphony".

Duke

Duke,

    Thanks for taking the time to review my thoughts on multiple subs. I'm glad you validated my understanding, with the 80 Hz revision, since my thoughts are all reflections of my personal experiences using your 4-sub DBA system.  
    You stated:
"I wouldn’t say "all", but I would say "almost all". (If we’re talking about a Swarm/DEBRA system, a second amp can be added to give you true stereo bass)."

    Is there such a thing as true stereo bass? I'm still a little fuzzy on this issue. I run all my subs in mono and perceive true stereo bass on all recordings regardless of format. This is due to the process I mentioned in my summary, of our brain's ability to associate the fundamental deep bass frequencies reproduced by the 4 subs in mono, that are below 80Hz and not able to be localized, with the deep bass’s higher harmonic frequencies, that extend well beyond 80 Hz, which are reproduced by the main speakers that are able to be localized. This is what I'm currently experiencing on my system that I would describe as true stereo bass.

Are you making a distinction between the perceived true stereo bass that I'm currently experiencing and your mention of "a second amp can be added to give you true stereo bass"?

Also, when I asked you whether the bass is summed to mono on frequencies below 100 Hz on all vinyl and cd recordings?   

You said you wouldn’t say all, but almost all.   On several other threads  no one, including myself, was able to name a single recording on any format containing true stereo bass.  Are you aware of any?


Thanks again Duke,
     Tim
Hleeid,

Before you do anything I would suggest reading http://www.soundoctor.com/whitepapers/subs.htm I think you will find them very informative.

A question for the DBA folks; How do you get the mids and highs to spread out evenly through the room to match up with the bass at all locations in the room? Also does a DBA affect impact?

Thanks
@noble100 wrote: "Duke... I was hoping to get your honest opinion on my thoughts on how I understand multiple sub systems function in general as well as my understanding of how bass is recorded on CDs and vinyl."  

In general I agree with what you wrote, so let me just toss out a few comments.
" We all are unable to localize deep bass frequency soundwaves..."  

My understanding is that’s generally true in a room. The figure I use is 80 Hz, rather than 100 Hz. I think Floyd Toole uses 80 Hz. This doesn’t necessarily mean that one cannot detect the location of a sub which is crossed over significantly lower, say at 40 Hz, because crossovers are not brick walls, so upper bass/lower midrange energy can give away a sub’s location if it comes through loud enough. Therefore in my opinion a steep lowpass filter on the sub helps to hide its location.  

"the bass is summed to mono on frequencies below 100 Hz on all vinyl and cd recordings."  

I wouldn’t say "all", but I would say "almost all". (If we’re talking about a Swarm/DEBRA system, a second amp can be added to give you true stereo bass).

"Our brains are able to associate the fundamental deep bass frequencies reproduced by the subs, that are not able to be localized, with the deep bass’s higher harmonic frequencies, that extend well beyond 100 Hz, which are reproduced by the main speakers that are able to be localized. This psychoacoustic association allows us to localize the deep bass in the soundstage, for example the kick drum is located in the rear center and the upright bass is located in the front to the left, which would not be otherwise possible without this psychoacoustic association our brain’s are capable of."

I agree.  

Duke
Btw, first step/tread on that music quality learning ladders is to attend as many live music events we can, second can be to listen as many other home systems as we can and other truly revelatory thread/step is to listen live music seated at near source position that’s where normaly " seated " the recording microphones ( 1m to 3m. ) and we have to do it not one time but several times.

All those steps are a learning lessons to understand the true meaning of quality in the MUSIC/sound reproduction on each one of us room/systems and at the same time we will use those lessons to through the time be up-dating/grading our system., fine tunning the system.
Again, I’m talking of systems dedicated to listen only MUSIC not along HT option.

R.
Hello rauliruegas,

       Did you read the responding post I directed to you yesterday 8/15/19?  If not, here is a direct quote addressed to you from my earlier post:
"I agree with you that using better quality subs will only improve the quality of bass reproduced. I think this is true whether one uses a single sub or multiple subs."

     I appreciate, respect and understand the importance of good quality in almost everything, especially in things I decide to purchase or am considering purchasing.  What I don't appreciate, respect or understand is why you believe you made it clear to me, with my own facts and statements, that my system is of poor quality.  I must have missed that deftly executed revelation you so kindly presented to me, using my own words no less.  Well played, mi amigo, well played.

Later,
Tim
Maybe problem is that each one of us usually can think that what we own is the " best of the best ". That does not exist quality levels where belongs each room/system

There are low/poor quality, lower quality, medium or so so quality, top quality and the like. Quality is a ladder that where we need to learn how to go up step by step.

I already left clear with his own facts/statement why noble100  system  is a poor quality level  and he needs to learn about that ladder quality steps/treads because many of us just do not want that low qualityn levls.

Knowledge levels through first hand experiences helps a lot to learn about.. 

R.
Dear @audiokinesis  : What you posted was exactly this that I pasted from other thread:

"""  """ You can get good bass in one sweet spot with two equalized subs """

the words: not 3-4 but 2 were only to emphasis that you talks of two subs. In the same way the word " enough " that for the 99% of good low bass range at one seat position with high quality levels is enough.

I don't care about HT needs.

For two channels systems dedicated to listen only MUSIC the name of the game is QUALITY all over the room/system frequency range.

To other gentleman I posted in this thread:

"""  Example: https://systems.audiogon.com/systems/615 

do you think that the owner of this two channels room/system could " live " with 2-4 or what ever number of subs you name it of Rythmik subwoofers/DBs instead those self powered/active subwoofers towers that can go down to 3hz with almost no distortion levels at full power? """

that's top quality level in a dream dedicated MUSIC room/system. Obviously that only a few gentlemans ca own and enjoyb that quality levels but other audiophiles can do it some steps down with optimal quality levels that gentlemans like noble can't even imagine what really means quality. I already posted here that his attituted is a " robotic " one because he has a tatoos of number 4 and one model by SVS that even is not a true subwoofer.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.



Hello millercarbon,

     Very good post, well worded, sincere and I definitely know it's honest and accurate.  I think Duke helping you with advise even though he knew you were building a DIY clone of his 4-sub Audio Kinesis Swarm system was unexpected, unselfish,says a lot about his priorities and was just very cool.

Enjoy,
Tim   
There is more than one way to implement a multi-sub system. For a long time the idea of using any sub in my system wasn't an option. Didn't see the need for them and systems I heard that had a sub(s) in them were not to my liking.

The idea of the distributed bass array made sense to me. It certainly had some science and research behind it. Whether one agrees with it or not is another matter. Since I work with someone who also makes speakers I ran the idea past him. He agreed in principle and actually read Geddes work and supported it. So I figured at that point what did I have to lose. With his help I was able to put together my own array and it has made a significant difference in my room and my system. I should also note that while I do use 4 speakers in my array, my friend just uses 2.

Since this topic has been popular around here of late I have learned even more. I have tweaked my array with the assistance of another member here, mijostyn, to leverage the specific type of speaker I use. Again, a marked improvement. It's good to have options and I would also agree with Raul that quality trumps quantity. It is unfortunate that around here we sometimes have to sift through some unpleasant minutiae to get value from what is posted, but that's what filters are for.

@millercarbon


I completely understand you and appreciate everything you have to say.

But I have to respond to someone who actually has the swarm system and understands it and has a working knowledge of it and basically calls my a lier - without himself doing his own research - I’m going to take up for myself whether you or no one else does. He does the op, this thread and even Duke a disservice. Let me remind you of the lie Tim posted about me:

’I seriously doubt someone as knowledgeable and experienced as Mr. Vandersteen would make the numerous obviously false statements contained in your supposed quote of him you cited above in your last post.

Please verify this quote as valid by referencing your source for this quote. I’m almost certain you’ll be unable to do so, however, and you’ll likely just fail to ever provide any reference, never admitting to your deliberate false quote ...’

What am I supposed to do? I thought we are here to share ideas from one another? In a respectful courteous manner? Am I missing something here? Not make up vicious lies.

This is a small snippet of what I’m calling psycho bass bable bullshit:

’Hello cleeds,

Very interesting that you responded before tyray and that the supposed direct quote from Mr. Vandersteen is actually from his website’s promotional information for the 2W subwoofers.

I read the linked website info and it reads more like the work of a professional advertising copy writer promoting a client’s product that he doesn’t completely understand, which is actually the case, than a knowledgeable and experienced speaker designer sharing his expertise on how his subs are able to take advantage of his knowledge of speaker design and how bass soundwaves behave in a typical home room environment to provide high quality bass reproduction.

The quote from the Vandersteen website referred to by tyray and yourself, listed below, contains too many errors for me to believe that Mr. Vandersteen would vouch for its accuracy. It seems much more likely the numerous errors are the result of an advertising copy writer plying his trade on a subject and product he has a general lack of knowledge about. I seriously doubt Mr. Vandersteen even scrutinized the content of this promotional quote since I doubt he would approve this much misinformation. I’ll explain the errors and my reasoning below after the advertising quote.’ And he goes on and on and on... And you quoted Stevie Wonder?

-Not the science behind the swarm.

And apparently I guess this type of interaction with someone on this thread is okay - if you have the swarm and have read the studies of Earl Geddes. Well I’m here to tell you it’s not.

I did look up this term though:

Psychoacoustic Phenomenon Psuedo Stereo Deep Bass

Apparently it does not exist. Especially when Pseudo is spelled wrong.

I really wanted to ask is this psychoacoustic phenomenon only in playback and the recording studio environment? But I guess I can’t cause I don’t have the Swarm and haven’t fully read the studies of Earl Geddes. 











Hello Duke,

     I'm glad you chimed in and shared your knowledge. 
     If you don't mind and have the time, I was hoping to get your honest opinion on my thoughts on how I understand multiple sub systems function in general as well as my understanding of how bass is recorded on CDs and vinyl.  Basically, I'm asking if you agree with my summary below?    
     
       We all are unable to localize deep bass frequency soundwaves, that is determine where the sound is coming from, that are below about 100 Hz but we're very good at localizing higher frequency soundwaves in the remainder of the audible spectrum, from about 100 to 20,000 Hz.
    This is the reason there's no such thing as 'true stereo' deep bass and why the bass is summed to mono on frequencies below 100 Hz on all vinyl and cd recordings. If you doubt this, try to find a single vinyl or cd recording that is not summed to mono. This means it's pointless to configure subs in a stereo configuration with one located by the left main speaker and one by the right.
    However, thanks to psychoacoustics and our remarkable brains, it is possible to create the perception of stereo bass in our systems. Here's how it works:
    Whether you use 2, 3 or 4 subs, run them in mono and optimize the bass at your listening seat. The bass below 100 Hz won't be able to be localized but there are bass harmonics or overtones of the deep bass fundamental frequencies that extend into higher frequencies that are reproduced by the main stereo speakers and can be localized. Our brains are able to associate the fundamental deep bass frequencies reproduced by the subs, that are not able to be localized, with the deep bass's higher harmonic frequencies, that extend well beyond 100 Hz, which are reproduced by the main speakers that are able to be localized. This psychoacoustic association allows us to localize the deep bass in the soundstage, for example the kick drum is located in the rear center and the upright bass is located in the front to the left, which would not be otherwise possible without this psychoacoustic association our brain's are capable of.  


Thanks,
Tim
Up until some time nearly a year ago I had never heard of using more than one or two subs. All my personal experience was based on one sub, plus maybe once or twice hearing two somewhere. Based on all that it seemed getting really good smooth articulate bass, by which I mean bass every bit as good as the midrange and treble, was for whatever reason impossible.

I still think this is the case. My current understanding is the reason this is impossible is, briefly, what Duke stated above. Its a natural physical consequence of the physical character of house-sized rooms. 

The DBA idea seemed at first unlikely to work. But a lot of the threads I came across were like this one, where if you could somehow wade through the BS and sniping there were mentioned real research articles and work by guys like Geddes, which anyone interested can scroll up and see yes indeed once again he's mentioned. The question is will you dear reader take time out of your busy day opining and parroting and go and look it up and read it and actually try and understand what its all about.

Which I did. Which whatever it is, it sure ain't religion. 

Duke at one point when I said I was going to do this he thanked me for having faith. My reply was I had read enough and understood enough to know for certain and without doubt its going to work. This really is no different than someone teaches you math. You can then determine how many oranges each of 6 people can get if you have 24 oranges. Its not faith and it sure ain't religion. Its physics.

And psycho-acoustics. Humans do not perceive sounds anything like the meters so many wanna-be audiophiles put so much faith in. Which yes that is exactly the correct use of the term. Or maybe like Stevie Wonder said its superstition- when you believe in things you don't understand.

We don't perceive volume equally flat, go look up Fletcher-Munson curve. We don't perceive location equally with frequency either. We are really good at localizing midrange and treble. We can hear even just a millisecond snippet. At low bass frequencies we can't even hear them AT ALL until and unless its a full wavelength. At 20 Hz that means 1/20th of a second. 

The full range of sounds we are trying to create is so different in physics and perception it simply cannot be faithfully recreated with just the one approach. No two speakers can do it. No two speakers with any sub however good can do it. Two good speakers with four or more subs? No problem!

I've been using mine for a good six months now. One of the most amazing things I am still getting used to is the way really low powerful bass can present so many different ways. Sometimes its the low acoustic of the recording venue. In that case its so diffuse as to be completely unlocalizable. It is enveloping. It is what people mean when they talk about good bass expanding the sound stage to completely envelope you. Other times it is so precisely localized within the sound stage its every bit as palpably solidly there as the singer or drum or whatever. 

Never, ever, does it sound like the bass is coming from any of the five subs in my room. Often times early on I would walk right up to one and not believe it was even working until I put my finger on the driver.

There's a lot going on here that is very new and very different. Its a lot to get your head around. People interested will be well served to avoid the silly comments from people who haven't tried it and therefore haven't a clue, and instead read those who have and those who did the very impressive pioneering research that made this most revolutionary discovery in audio in many years.

Tyray wrote:

"When your Swarm first came out I and bunch of others were impressed at such a brilliant thinking out of the box idea. I completely believed and understood the science behind it."

Thank you very much. If there was any "brilliant" thinking on my part, it was in quickly recognizing the merit of the distributed multi-sub concept when Earl Geddes described it to me, and in immediately asking him if I could license his idea (he replied, "No, you can just use it," so I try to give him credit when the opportunity arises).

I also appreciate the Richard Vandersteen quote you posted above:

"... multiple subs automatically give a linier response in the room. This should be amazing as we have always been a supporter of multiple subs."

Indeed, I recall Richard recommending stereo subs long before I heard about using four distributed subs from Earl. Was Richard the first to propose that two subs are significantly better than one? I think he was.

I have always liked Richard’s speakers very much, and feel honored that a few of his customers have chosen my somewhat unorthodox little subwoofer system to go with them.

Duke

@hleeid'

'Should I take advantage of the temporarily empty office to lay down carpeting?'

My buddies that have man caves and and not only use their system for playing music but watching movies too - swear by adding carpet.