How large is your room? Speakers, Amp, etc.?
You will have much better results adding than subtracting. The problem is none of the conventional approaches addresses the fundamental problem of resonance nodes at low bass frequencies. Two subs are better than one, but three is even better and four is better still. Beyond four continues to improve but the benefit in terms of smooth response falls off rapidly so that four is the sweet spot so to speak.
You're right about it being covered elsewhere. Unfortunately few seem to have bothered to read, or if they've read then to understand. The place to start if you're interested this review explains the what and the why better than most http://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/
Then if you want more technical http://www.gedlee.com/Papers/multiple%20subs.pdf
Then of course there are useful threads right here, although with the usual caveat of having to sift through mounds of dirt to mine the occasional gold nugget https://forum.audiogon.com/discussions/will-a-subwoofer-add-depth-and-clarity-to-my-system-or-just-b...
Or you could go straight to the gold itself
What’s your purpose in uograding, SPL, bass extension, or sound quality?
Also, I know SVS has an upgrade program, but their higher end loses bang for buck due to the digital screen, remote mobile app control, room correction, etc. I mean, if you want those things, it’s great, but from raw performance, a Rythmik F18 smokes the SVS SB-16 Ultra.
Dual subs give a more even response, better seat-to-seat consistency, and lowers localizability.
I agree with millercarbon that you'll have much better results adding 3 to have the magic 4 subs in any given room that almost magically provides state of the art perceived bass response in virtually any room.
Of course, it only seems like magic once you actually experience the amazing transformation in bass performance in your room when you utilize 4 subs properly positioned in your room rather than 1,2 or 3 subs. It is actually the opposite of magic since it is all based on the rigors of scientific experimentation, documented results, peer review and the experimental results have been verified independently numerous times by other scientists.
This proven concept is called a Distributed Bass Array (DBA) system and it consists of 4 subs strategically positioned in any given room that scientifically (not magically) provides state of the art perceived bass response throughout the entire room and not just at a specific sweet spot.
I don't know the size of your room, bryantdrew, so I'm not suggesting you deploy 4 large SVS 3000 subs in a DBA system unless your room is huge and you're OK with weakening the structure of your home. You could attain all the benefits of a custom DBA system in your room by just adding 2 smaller subs of your choice to the 2 larger subs you already have.
This concept works so well due to there being at least 4 distributed points (subs) in the room launching bass sound waves into the room. These 4 subs are actually creating more bass modes in the room (spots where the bass is perceived as exaggerated, attenuated or even absent) but, due to the way our brain processes multiple deep bass sound waves, we perceive the bass in total as smooth and articulate.
When I setup and listened to my Audio Kinesis Debra 4 sub DBA system in my 23x16 ft. room and initially heard the excellent bass produced, my first thoughts were that it actually did seem like magic how the bass performance in my room/system had been transformed so dramatically. I know it's all scientifically based but experiencing what I consider sota bass in my room, on my system and on my music still seems magical to me.
I'd suggest you state a few more details for best responses:
What's the size of your room?
Are there any irregularities or restrictions in your room?
Carpet or hard floor?
Is your system used just for music, ht or for both?
What does your current system, besides the 2 SVS subs, consist of?
What's your budget?
Big single. Providing its better of course ie faster, more responsive, gets under 30Hz comfortably etc. Always liked this quote found on the REL website,
The great race car designer, Colin Chapman of Lotus was once quoted as saying “To go faster, first add lightness.” Words to live by.
I hope I did not make any comments that broke rules that hurt anyone, that was not my intent. Oh maybe profanity?
I think my purpose is SPL but as a result better sound. I don't know if anyone has ever heard Phil Lesh hit these certain bombs, when that happens I want to feel it. During regular listening I want it to sound better than good, but never overpowering. Listen, I'm not in search of bass that somehow overpowers the music but if the walls shake when something goes down to 35hz, thats kind of cool to me, whatever, but saying that I need the fullness. It does not fill the room as it is right now. I know the power should be there. They are placed right next to the open baffles. I need to experiment more. Anyway I do not want to really shake anything I just want good bass. My system is moving upstairs above the garage that will be a designated listening room. (in two months?) I want it to sound good where it is now though. I know there are fans of different sub companies, I went with SVS for 65 days or something. I think I might add one more and if I still have a girlfriend I can go from there. Thanks for all the help. Im in the process of reading millercarbons suggested links.
Homemade open baffle audio nirvana 10" drivers (backups)
2 SVS 3000
ATA Phono Pre
VPI with a good cartridge
These sound different and I switch them out sometimes
Lumnous audio passive pre
Tannoy Glenair 10" speakers in process of repair
I have (4) JL Audio F-113 subs with my 2 channel. You can never have too much subs. The problem is that you don't want to have so much bass that it drowns the mids. That being stated, I have a DEQX unit that can dial in the subs to work well with the mains.
BTW, when I use my Hometheater equipment there are 4 more subs added to the 2 channel set up.
You almost never get stereo bass unless your room is very dead and you crossover high. I have a single sub crossed at 80Hz that’s decently far from my speakers, and in my wooden-floor open floorplan with no treatment other than a rug, I almost never hear where it’s coming from.
I would say dual Rythmik F15HP, dual bundle brings it to <$2400, they are very “musical” and are +/-3dB down to 10Hz! I mean, if you have money to blow there is also their F18 :).
I think Noble is on the right path here. Look at the difference between the radiation patterns of point source and linear arrays. The trick is in creating a linear array woofer. If two drivers are closer than 1/2 the wavelength of the highest frequency they are to reproduce they will act acoustically as one driver. The wavelength of 100 Hz is around 10 feet. So, if you space subwoofer drivers 5 feet apart they they will act as one driver up to 100 Hz. Say you have a 15 foot wall. Space 4 subwoofers at 5 foot intervals along that wall the outside two being right in the corners. The other two in the center should be pointed at each other with the drivers as close to the wall as you can get them. What you have created is a horizontal linear array subwoofer which minimizes room modes and reflections and takes full advantage of intersection gain. 12" drivers are way more than enough. Many will do fine with 10" drivers.
mijostyn wrote: "I think Noble is on the right path here..."
And I think you’re on the right path too. Your idea for spacing four subwoofers along the front wall will greatly improve their interaction with that end of the room.
But here’s the thing: The rest of the room matters just as much. Here’s why:
Unless you have a very large room, by the time you even BEGIN to hear the bass energy, reflections off the rest of the room’s boundaries are fully in play. So Noble’s approach of modal smoothing throughout the room is imo better aligned with known psychoacoustic principles.
That being said, once you have four subs, there are a LOT of different things you can try. See the writings of Earl Geddes and Todd Welti.
You haven't stated whether you have two of the larger,ported SVS PB3000 or the smaller, sealed SVSSB3000 subs. It'd also be useful to know whether you're going to use these just for music, just for ht or a combination.
I'm very confident that either the Audio Kinesis Swarm or Debra distributed bass array system will outperform any pair of subs of almost any size and price for music and ht. Both are priced at $2,800 for the complete system which includes 4 subs(each sub is 4 ohms, 1'x1'x23",44 lbs, has a 10" long-throw aluminum driver and have removable port plugs so they can be run as ported or sealed.) and a 1,000 watt class AB amp/controller that powers all 4 subs and controls the volume, phase, crossover frequency and has limited e.q.
All 4 of my AK Debra subs are configured as ported and operate in mono mode with a flat frequency response from 20-100 Hz. I have a combination 2-ch music and 5.1 surround sound ht system using Magnepan planar magnetic speakers across the front (a pair of 6'x2' 2.7QR panels that have a deep bass limit of about 35 Hz as mains and a CC3 center channel that has a deep bass limit of about 50 Hz. I run all these speakers full-range with the cutoff freq.usually at 40 Hz for music and 50 Hz for ht.
The Debra or Swarm system provides natural, pitch-perfect, taut, articulate and dynamic bass that seems to effortlessly go as deep as the content requires and integrates seamlessly with the mid-bass to treble response from my main speakers on music. But the system also provides these same bass qualities along with the ability to provide deep, powerful, dynamic and accurate bass at high volumes that will shake the room when the content requires it on ht.
I think one of these DBA systems would perform equally well in virtually any room and with any speakers. I really don't believe it's possible for me to overstate how well this concept works and just an audition would convince almost anyone. I'm certain that an AK Swarm, Debra or even a custom DBA using a sub amp and 4 subs of your choice will significantly outperform any system using less than 4 traditional amplified subs of any size or price; definitely in bass quality and probably in bass quantity and impact. It truly does provide sota bass response that I've never been able to equal with 1 or 2 subs of various brands in my room and system.
It's also relatively inexpensive at $2,800 for everything but the rca interconnects and speaker cables, about the same price as 2 SVS PB3000 subs or a pair of many other high quality subs.
I'm not a retailer and have no association with Audio Kinesis. I'm just a very pleased customer trying to spread the word about how exceptionally well these DBA based systems actually perform.
The idea of 4 subs is the correct one. In case its not clear, the problem is standing waves and this is not easily corrected by room treatment if it can be treated at all.
But its easy to treat with 4 subs. Just do what Duke mentions above. He's a modest individual and didn't mention that he makes some of the best subs out there- the Swarm, which comes in sets of 4. Two of them are placed asymmetrically in the room and it is this placement that breaks up standing waves, allowing you to hear all the bass notes at the listening chair.
"One question concerning 4 subs - How are they connected to the amp?"
The amp I supply with the Swarm is the Dayton Audio SA-1000, part number 300-811 at Parts Express.
It has a single channel of amplification but two sets of output binding posts wired in parallel.
The subs are connected in series-parallel, such that the four 4-ohm subs present the amp with a 4 ohm load.
Two subs are connected in series (via binding posts on the bottom), forming a two-sub "series string". Then the other two are also connectged in series, forming a second two-sub "series string". Then the two "series strings" are each connected to one of the sets of binding posts on the back of the amp, which puts them in parallel with one another.
Going into a bit more detail, the first sub in each "series string" has two sets of binding posts. One set is connected to the amp, and the other set is connected to the second sub in the "string", which only has one set of binding posts.
So you’d need four sets of speaker wire: Two sets go between the amp and each "first" sub of a "series string", and the other two sets of speaker wire go between the "first" and "second" subs of each "series string".
Some people use two amplifiers, typically one for each series-wired string, for a bit more flexibility.
"Stacked spades/bananas? Seems like a lot of hardware to me."
No stacked spades or stacked bananas.
I guess it’s a lot of speaker wire. Unless the runs are really long, sixteen gauge wire works just fine. You end up with the equivalent of thirteen gauge wire because of the series-parallel topology.
I have my 4 subs connected to a single amp just as Duke described. It's all fairly basic but I would suggest having a plan for running the wiring.
In my case, my living room is directly above a crawl space and I drilled 1/2" holes through my living room carpet and sub floor for access. I have a hole in back of my rack that holds the Dayton sub amp and a hole underneath each of the 4 subs. Remember, the spkr terminals are on the bottom of each sub and there's the option of using spiked or flat footers. I ran thickly coated 16 gauge wire suitable for outdoor use which wouldn't be needed indoors.
There are a lot of methods you or a ht installer could use to run the 4 sets of wiring inconspicuously. I'd definitely recommend hiding the wiring, however, since the finished look is so clean and even stylish. All that's visible just looks like a wooden pedestal.
In my 23x16 ft room, each of the 2 subs positioned along my front 16 ft. wall are actually hidden from view by each of my 6x2 ft. panel speakers. The 2 other subs, one along each of the 23 ft. side walls are visible but look good to my wife and I.
Oh yeah, and the whole system sounds awesome.
Audiokinesis, If you create a linear array very little energy disperses off the top and bottom or in this case to the side walls minimizing that interaction. Because the woofers are up against the front wall there is only the primary wave and no separate primary reflection off the front wall. So, you have eliminated three primary reflections. The reflections from the floor and ceiling are scattered in time. The reflection that will cause the most trouble is the one from the rear wall. The only thing that really works here is just get rid of the back wall. I am fortunate in that I designed my media room without a back wall. It just opens up into the rest of the house scattering the rear primary reflection. The end result is that the bass intensity is even throughout the room and much less equalization is required. If you can't get rid of the back wall you will be stuck with a degree of "comb filtering." I am not sure if spreading other sub woofers around the room would minimize this or just create more complex patterns. In reality it only really matters at the listening position.
The best bass is bass you can feel.
"If you create a linear array very little energy disperses off the top and bottom or in this case to the side walls minimizing that interaction."
The array you described only tries to provide significant smoothing in one dimension, and it primarily does so at one end of the room (your four subs only approximate a line . The same number of subs arrayed differently can result in significant smoothing in two or even three dimensions (if you elevate one of the subs so that it’s closer to the ceiling than to the floor), and this smoothing will extend throughout the room.
"The only thing that really works here is just get rid of the back wall. I am fortunate in that I designed my media room without a back wall."
Relatively few people have that option. I have a hard enough time selling four subs without also requiring customers to remove their back wall! In other words, regardless of how well what you are doing works for you, it is not a generally-applicable solution.
"I am not sure if spreading other sub woofers around the room would minimize this or just create more complex patterns."
More complex patterns of modal behavior is how modal smoothing naturally occurs in a large room. The reason a large room has smoother (faster, better, more natural-sounding) bass than a small room is that the larger dimensions result in greater de-correlation of the in-room bass energy. Greater decorrelation = smaller and more numerous peaks and dips. A distributed multisub system mimics large-room modal behavior in a small room.
Editing timed out before I could fix one sentence; here’s how it should read:
"The array you described only tries to provide significant smoothing in one dimension, and it primarily does so at one end of the room (your four subs only approximate a line source; each sub still behaves as an omnidirectional point source).
The one sub I have now was a nightmare to place. Because: one! With one you can move it around forever and never find the right place. I know. I tried. With four though....
From what I read they seem to work best distributed asymmetrically around the room. I'm thinking one front wall near the left corner, one right wall near the front corner but further from the front than the left one is from the side. Asymmetrical. Then one along the left wall further back than the sweet spot but not far enough back to be the same distance from the back corner as the front right is from the front corner. More asymmetry. Finally the right back one same deal, maybe a little further back than the one on the left. More asymmetry, more modes, more better.
As cool as it would be to play 3D asymmetry I think putting one up on a stand near the ceiling is aesthetically speaking a bridge too far.
I don't mind wire on the floor which is good because drilling holes is for me a tunnel too far.
From what I’ve read about DBA systems, I believe your asymmetrical sub positioning/distribution plan will create more complex patterns of modal behavior in your room, resulting in decorrelation due to the smaller and more numerous bass peaks and dips present, which will be perceived as smooth, natural and seemingly effortless in-room bass response that is capable of reproducing fast, solid and taut bass just as accurately as deeper, more sudden and more powerful bass.
While I think you should get good results from your planned asymmetrical approach, I think it’s important you know that I’ve never actually tried this configuration with my subs in my room.
Just in case you’d like an alternative positioning plan that I know works, here’s how I positioned mine:
I removed my main speakers from the room, hooked up sub#1 and placed it at my normal listening seat position on its back, with the driver faced upwards.
I played some music with good and repetitive bass at a moderate volume and, beginning at the front right corner of my 23’x16’ room, I walked slowly across my front 16’ wall listening for the exact spot where the bass sounded best to me (the most natural and pitch accurate without being exaggerated or attenuated). I took my time and walked from right to left numerous times to verify the best spot. Once verified, I placed sub#1 at this exact spot with the driver facing, and less than 2 inches away from, the front 16’ wall.
I hooked up sub#2 in-series to sub#1 and placed sub#2 at my normal listening seat position on its back, with the driver again faced upwards. At this point, sub#1 and #2 are both active.
I played some music with good and repetitive bass again at a moderate volume and, beginning at sub#1 (now located about 2’ away from the front-right corner of my room along the 16’ front wall), I walked slowly across the remaining space along the front 16’ wall to the left front corner then turned left and continued walking from front to back along the left 23’ side wall of my room, listening again for the exact spot where the bass sounded best to me. Once verified, I placed sub#2 at this exact spot with the driver facing, and less than 2 inches away from, the front 16’ wall.
This completed the placement of both subs connected in-series to the first of the Dayton amp’s two sets of speaker outputs.
I continued this sequential sub positioning procedure for sub#3 and sub#4, with first sub#3 placed face up at my normal listening position and finally sub#4 just positioned at the exact spot I determined the bass sounded best with the first 3 subs playing the same musical content that had good and repetitive bass. This resulted in sub#3 sounding best along my left 23’ wall about 2’ away from the rear-left corner and sub#4 sounding best along my right 23’ wall also about 2’ away from the rear-right corner. So, subs #3 and #4 are located directly across from each other along opposite and parallel 23’ walls.
The results of this procedure in my room were so good that I never bothered to do the final procedure step of checking if the system sounded better with the phase reversed on one of the 4 subs as Duke and James Romeyn suggest.
I’ve been enjoying the excellent bass of the Debra bass system for almost 4 years now and I still haven’t felt the need to complete this step. The reasons are that I really have a difficult time imagining how the bass this system reproduces could be improved upon for music or ht and I really don’t want to jinx anything. If it’s not broken, don’t try to fix it, right?
Hopefully, Duke or James will chime in on their recommended DBA system setup methods and tips, too.
I’m looking forward to hearing your thoughts on your new custom DBA system.
Audiokinesis, It always helps to know what ideal is to make the best compromise in any given situation. 4 subs at 4 foot intervals with the outer two in corners does not approximate a linear array. It is most definitely a linear array up to 125 Hz or so. If you review the acoustical properties of linear arrays you will note that they throw very little acoustic energy off their ends almost totally killing any refection off the side walls of the room. No other array does this in any dimension. The best you can hope to do in any enclosed space approximating a livable room is to control primary reflections and since they have the most energy that represents 90% of the battle. Of course most people are stuck with a rear wall. My point is that all the room treatment in the world will not stop that reflection in the subwoofer region. The wavelengths are simply too long. Putting subs all over the room simply creates more primary reflections. For most people with normal rooms digital room control is the only way they stand a chance of getting flat bass at their listening position. The horizontal linear array minimizes the problem to a degree no other set up can and it increases efficiency at least 6 db requiring 1/4th the amplifier power which is critical with room control that frequently has to correct troughs of up to 10 db and more. This is why we need so much power when room correction is used particularly with small sealed woofers that have to force response below 40 Hz. The only other ways to achieve flat response at the listening position are to move the listening position to a point in the room where the bass is satisfactory or move the subwoofers around in the room in a trial and error way to accomplish same. Good luck.
"The best you can hope to do in any enclosed space approximating a livable room is to control primary reflections and since they have the most energy that represents 90% of the battle."
I disagree with this statement as far as the bass region goes.
From a perceptual standpoint, speakers + room = a minimum phase system at low frequencies (according to Toole and Geddes and Welti, among others), which means that the ungated in-room frequency response is what matters. Focusing on the first reflections is at least paying attention to room interaction, but imo it’s not focusing on solving the problem that matters the most to the ears in the bass region.
"Putting subs all over the room simply creates more primary reflections."
Primary reflections in the bass region are not the primary problem that needs solving. But having many primary reflections contributes to solving the primary problem.
"... room control [EQ?] frequently has to correct troughs of up to 10 db and more..."
With a decent distributed bass array, you will not begin to have troughs of 10 dB or more. If your technique results in troughs of 10 dB or more then it is not solving the problems that matter. I don’t claim my customers will necessarily get plus or minus 3 dB in-room in the bass region, but many of them have reported that.
"Oh, by the way Duke, I am not trying to sell anything."
Okay. Maybe I’m missing something. How is that relevant? Please clarify because I don’t want to jump to conclusions.
Several posts above I wrote: "your four subs only approximate a line source; each sub still behaves as an omnidirectional point source."
Presumably in response, mijostyn wrote: "4 subs at 4 foot intervals with the outer two in corners does not approximate a linear array. It is most definitely a linear array up to 125 Hz or so."
Okay, but a line array is not a line source. A line array *approximates* a line source, which is what I said.
"If you review the acoustical properties of linear arrays you will note that they throw very little acoustic energy off their ends almost totally killing any refection off the side walls of the room
Imo their behavior at their ends isn't a potential issue; their behavior out in front of their ends (along the sidewalls, in this case) is a potential issue.
I know how to model line arrays. The spacing you used is not optimal. I can explain why if you are interested. Because its propagation is not perfectly perpendicular to the line, your array will have increasing sidewall interaction with distance. I’m not saying that’s a fatal flaw, only that it happens.
"No other array does this in any dimension."
A planar array does this in two dimensions. In fact, I think a planar array would make more sense than a line array for your situation, given that your room doesn’t have a back wall (which imo offers you a unique opportunity). Again, I can explain if you are interested.
I have been provided conclusive evidence of Duke's (audiokinesis) integrity. Due to my postings on the subject of OB/Dipole subs (particularly the one by GR Research/Rythmik Audio), I was contacted by an Audiogon member concerning their use with planar loudspeakers. I answered his questions, and a few days later received another email from the member, telling me Duke had told him OB/Dipole subs would be a better choice for use with his loudspeakers. How rare is THAT?!
I'm not surprised at all that Duke displayed his knowledge and integrity when asked about open baffle dipole subs. He's displayed to me the exact same vast knowledge of in-room bass sound wave behavior and the explanations of why/how 4-sub distributed bass arrays are such an effective solution with the exact same integrity.
As far as my understanding of psychoacoustical bass principles and DBAs are concerned, I think of Duke as Mr. Miogi and he's showing me how to wax his car.
"Duke had told him OB/Dipole subs would be a better choice for use with his loudspeakers."
"when I told Duke what drivers I was going to use he said mine will kill his."
Okay that’s it. I’m firing my marketing department!!
Seriously thank you both, and thank you too Tim. I try to promote the distributed multisub concept when I post here rather than my specific product, but that distinction probably doesn’t always come across. My product is really just one possibly way of doing it. I would rather spread a good idea (which Earl Geddes developed and freely shared with me) than sell a lot of subs. (This isn’t as altruistic as it might sound - I have enough orders on the prosound side of my business to keep me busy full time.)
Nor is a distributed multisub system necessarily the most sensible approach for every situation.
If mijostyn takes my posts with a grain of salt, that’s fine. He has every right to be skeptical; I would be if our positions were reversed.
I am probably gonna get a Rythmik F15HP after I get my Preamp situation squared away. Although I would love to buy 2 subs, alas, I cannot. I think I would rather buy one very big, powerful, tuneful sub than 2 smaller, weaker subs for the same amount of money. I assume I could get great sounding music from my 2-channel with 1 sub. Especially since I would only be using high level inputs and running the mains full range and only using the sub to fill in right around 40hz and below. I know that placement would be more important here, so I might do a sub crawl, but I am a bit nervous about it since I really only have 1 place it could fit while still having acceptable WAF - in the corner of the room just to the right of the right main. Hopefully, that position will suffice.
I have made dipole subs using 6 drivers aside. They do not work. Even with huge amounts of power and room control you can not get 20 Hz out of them effectively. IMH experience the best performance comes from sealed, enclosed 12" subs Q @ 7 with Room control and a high powered class AB amp damping > 500, the higher the better. The only difficult variable is the enclosure itself which ideally should be infinitely stiff and heavy.
Stereo bass? Vinyl mixes bass to a single channel for practical reasons. Moreover, localization of low bass is a non issue as you can't really tell where its coming from, only the higher harmonics is a clue, AND most music only have one bass instrument.
More subs is for other reasons, but stereophony it is not.
Room aucoustics really need to be covered. Buy a measurement mike.
Use REW program, its free.
Your best bet to archive deep clean bass is missing subs together from 2-4 brand
im using SVS PC13 ultra with two klipsch SW-115
way better than using only one brand
also use both red and white outputs with Y adaptor don’t use only LFE
You want two. Most subs have to cover a range from low bass, which is 'locatable' by a listener, to very low bass which isn't and the power needed to produce a given spl is only 1/4 as much with a pair than it is with one.
Best test is to play a CD of organ music with low notes with no sub, then with one, and finally with two - makes a big difference and moves you, the room walls and anything in between.
You need pretty decent quality subs to integrate well with hi fi audio. The best bang for the buck I could find was the VTF-15H MK2 DualDrive
110 lbs each, 600 watt on board amps and they look pretty decent, not like something that got drop kicked off the back of the band's bus.
Stereo bass? Vinyl mixes bass to a single channel for practical reasons. Moreover, localization of low bass is a non issue as you can't really tell where its coming from, only the higher harmonics is a clue, AND most music only have one bass instrument.While most of this is true, the comment about vinyl is not. We don't mix bass at all when mastering. That is a technique used to reduce the time and cost of mastering time but its not something cast in concrete.