It's common wisdom that dual or multiple subs help smooth out bass response in different spots in the room, but what about for a dedicated listening room with a fixed single listening position? What do two subs add to the music presentation that a single dialed in sub is missing provided that single sub is dialed in perfectly for the listening position? Caveat: not interested in the SWARM method or multiple subs at the moment, strictly comparing single to dual subs
Strictly interested in confining the discussion to your pre-determined conclusion. Wonderful. But you get the answer you weren't looking for anyway. Each additional sub, by being in a different location adds to the number and location of bass modes. The result is that for each additional sub the bass becomes smoother, and smoother bass is faster cleaner more articulate bass. It also improves extension, slam, and dynamic headroom. The man who wrote the paper discovering the distributed bass array approach you are so intent on not talking about even reduced it to a mathematical formula expressing the improvement of each addition sub.
The single greatest development in high end audio in a generation, but you don't want to talk about it. What a shame. Oh well too late now.
Your single sub by the way never can be "dialed in perfectly" but in order to understand why you will have to first permit talking about that to which your mind is currently closed to considering.
Wouldn't it be wonderful if we could just dictate to the world how things are? Maybe. But it would not be the world we live in now, would it?
You can obtain satisfactory results with one sub, but to achieve really great integration you also you need; lots of time, and a way to equalize and tailor the bass frequency response to correlate to your listening position. I have found great results by using an old Velodyne SMS 1 Sub equalizer. It allows you to hook up a monitor and has a long enough microphone cable to setup at your listening position to achieve exceptional results. By adjusting EQ parameters on the Velodyne EQ, you can see in real time what effect your settings will have at the listening position displayed on the monitor. It is easy to use if you under stand crossover settings, slope, phase, -+20db settings for frequencies of 20-120hz, and a few other settings that I forget. It does allow up to two subs to be hooked up.
One Sub does not have the power to load most rooms down to 20 Hz at least up to 15 inches. An single 18" sub might get you there. Two 12's is the minimum. Two 15's even better.
Speaker frequency response is taken near field usually at one meter from the speaker. 4 meters back in a 16 X 30 foot room is a much different story. In order to get the right "feel" you need a rising response from 100 Hz down to 18 Hz. That takes big drivers and a lot of power. Two subs will also smooth out the nodal behavior in the room. Without proper low end you will never feel as if you are at a live performance.
“What do two subs add to the music presentation that a single dialed in sub is missing provided that single sub is dialed in perfectly for the listening position?”
When you add a second subwoofer, most of the peaks and dips get canceled out by the second sub. Two or more subwoofers also help in reducing low-frequency distortion and offer improved dynamics over a single subwoofer. This is a simple function of having more radiating area, plus more power on tap.
The realism and imaging you experience from two subs over one is unmistakable.
OP, I appreciated your question because my room cannot accommodate a SWARM. When I move into a new room, I will be able to try it. Your question is a logical one for someone like me, and there's no reason you should be berated for limiting the question. After all, you said "at the moment" and "caveat" to try to forestall the kind of denigration you (alas, inevitably) received.
I like the answer from @lalitk for it's directness and simplicity.
I have two JL audio E112s both are high-passed at 60hz but no dsp. Over the last few months both broke (bad volume pots) and needed repaired so I had one sub at a time as I rotated then out for repair. During this time I optimized the placement with one sub (large dedicated room). After a lot of messing around I got one sub to sound fine but the volume level adjustment was picky and it never felt just right. I assumed this is because there were some lumps in the bass. Some songs seemed light and some seemed heavy. After a few months I got both subs fixed. Dropped them into their normal spot and boom everything locked into place and sounds much better. No more chasing sub volume adjustments. With two subs placement is much more flexible too.
I've run a few simulations and honestly with an untreated room the benefits of filling in nulls aren't something I can replicate.
If anyone puts together an REQ simulation that shows 2 subs vastly better please point me to it online, I'd love to learn that this is better than I think it is.
You may have a single, fixed listening position, but the sound that you are hearing is coming from the whole room. And a single sub, no matter how well placed, will tackle all the acoustic anomalies that the room has.
I have a small dedicated listening room with a single chair in it. I had a single REL sub and thought my setup sounded pretty darn good (Anthem STR, Merlin TSM’s), I decided to try adding a second subwoofer, the improvement was well worth the investment.
What do two subs add to the music presentation that a single dialed in sub is missing provided that single sub is dialed in perfectly for the listening position?
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You answered your own question. If ONE sub was dialed in perfectly, the second sub will add ZERO.
The first one is dialed in PERFECT. STOP!! :-)
Second who said the first sub can’t have 6 active drivers and 12 passive radiators, BUT all in the same SINGLE 50 cubic foot box. :-)
One box fits all in some cases.. At one time I built 500 lb enclosures that were 22 cubic feet. You only needs two in a 50 x 100 x 12 room. 2 18" 2 15" and 4 passive 15" radiators.. 500 watts was plenty.. BTW they were Bins not subs, they were CUT on purpose at 28 hz and below.. 28-80 hz. The room still had 4 72" Narrow baffle bass columns 80-280hz. 6 8" MB drivers per enclosure
It’s about pressure in a room for BASS. 60-80hz and below not so much. WRONG kind of pressure.. High sub pressure can wear you out.. I don’t like it when I have to open my mouth to EQ the pressure fast enough to get clarity in the mids...
I've built single driver slot loaded bass bins.. ONE would fill a hole two car unfinished garage to 110+ db.. with 200 watts MAX. Boom Boom in the room room.. Modified Jensen Imperial Subs.. I've seen them look like an upright pianos, they were so big..
When you see SUBs working well into the BASS region, that’s when it get messy and bloated..
The technical theory behind multiple subs stacks up and there’s a lot of support for it. The only caveat I can see is that to make the most of it you need to be pretty flexible about where those subs go, if they just go right behind the L/R speakers then it may be an imperceptible improvement. Also it’s worth remembering that your room is a 3d space so different height placements should be considered as well. Basically symmetry is most pleasing to the eye but probably the worst way to lay out your two subs. If you have the freedom to put them wherever you want then there’s a good chance you’ll hear the benefits. You’ll also want to do a bit of research into how to systematically set them up either by ear or using a mic.
The technical theory behind multiple subs stacks up and there’s a lot of support for it.
People I respect a lot like Toole propose this, but they often are talking about large rooms.
Conceptually this practice makes perfect sense to me. However in simulation, I just can’t get it to do much. So I’m unable to recommend it as much as I used to. If only I had the time energy and money to buy another 15" sub and shlepp it around my room. :)
I defer to those with more hands on experience than I.
Of course, you all know, the middle course here is bass traps plus EQ. The traps reduce the nulls and peaks, and the EQ takes care of what’s left. Unlike multiple subs in a room, this is an approach which I have enough experience personally to recommend. Of course, I'd never deny anyone the right to spend money, and I acknowledge my limitations in experience.
I agree with @mijostyn - my experience is that adding a second sub resulted in significantly better sound compared to using a single sub. The designer of my speakers (Michael Kelly with Aerial) has commented about the benefit of multiple subs in the Aerial literature, in addition to saying more than two subs is even better. As full disclosure, at the time I added the second sub I also switched from larger, (almost) full-range, bass reflex floor standing speakers to moderate sized, acoustic suspension, stand-mounted speakers. The stand-mounted speakers are solid to about 40Hz and the subs roll in at that frequency. The result is a vastly superior ability to tune the bass to the room, lessening of nodes, absence of boominess, more power/drive in the low frequencies, and greater clarity up through the midrange. Both sets of main speakers utilize the same midrange and high frequency drivers so the only difference is in how they handle the bass. It is a bonus that the subs have their own remote control, making it easy to dial the bass volume up or down to sound best with specific musical content.
For two channel stereo the best to the worse is: A pair of woofer towers, a pair of front firing subs, a pair of down firing subs, a single front facing sub, one down firing sub.
I would say that with dual subs you can have stereo bass if you mount them in the same plane as the main speakers if you use a single sub you need one with a blend circuit and again mount it in the same plane as the speakers both types work well for music but finding a good single sub with a proper musical sound is more difficult. Same plane is no more than two feet forward or back from the main speaker baffles.
Thank you all for sharing your experiences, seems like a majority of people have seen great benefits going with two instead of one. I will go for two for my 16x23 room and report back.
carlsbad, I have been using ESLs for over 40 years and am very familiar with the CLS. When you get the second subwoofer get a two way crossover. Rolling the bass off in the CLS's will result in a very large improvement in distortion and headroom. You will easily get another 10 dB out of the system. Cross up between 100 and 120 Hz. I would use a Mini DSP to do this. That way you can use steep slopes and you can time align the subs to the CLS's which is very important. You will soon realize that the crossover is the single most important piece of equipment you have. Also, do not put the subs behind the CLS's put them outside the CLS's preferably in corners right up against the walls. They are an easy 6-9 dB more efficient in this location, the sub does not have to work as hard and this lowers distortion.
Hi, I have a similar question relating to 2 vs 1 subs. I currently have a single REL sub sitting right next to my right speaker. If I were to add a second sub. Does it need to be placed symmetrically to the first sub? i.e. right next to my left speaker.
The reason I ask is I simply don't have the room to accommodate a 2nd sub on the same side of the wall where my speakers are. So is it ok to place the 2nd sub somewhere else, like on the opposite wall diagonally from the first sub. Will that ruin my stereo imaging?
xcool - Our ears aren't good at locating low frequencies so subwoofers don't contribute to the stereo image. In fact you will probably find that the best locations are not near your speakers or symmetrical. What you're looking for is for each sub to excite different room modes so that they balance one another out to some degree. If you're not familiar it might be worth looking up 'room modes' and 'standing waves'. There are also some neat tricks for finding good locations although the whole process is a lot easier with a measurement mic and some software. You need to also make sure that the speakers are 'time aligned' which you can do by measuring and with some simple maths.
I use a pair of Velodyne HGS-15s in the corners of a 14’ X 19’ room with acoustic room correction by an SMS-1 to supplement KEF Reference 1s below 80 Hz @ 24 dB/octave. The result is excellent. I’ve tried a couple of high-pass filters, but they seem to take a bit of air out of the sound, perhaps a peculiarity of the sticking them between an Ayre preamp and amp with the zero feedback.
I’m not a real sub person for stereo, only for my AV system, which I have two. I started with one and noticed a vast improvement with two in terms of balance.
xcool - Our ears aren't good at locating low frequencies so subwoofers don't contribute to the stereo image. In fact you will probably find that the best locations are not near your speakers or symmetrical. What you're looking for is for each sub to excite different room modes so that they balance one another out to some degree. If you're not familiar it might be worth looking up 'room modes' and 'standing waves'.
Excellent answer. My system is a great example. There are 5 subs asymmetrically placed around the room with each one a slightly different distance from a corner than the others. With music playing, even with plenty of bass, you can walk right up to any of them and think it is disconnected. In fact I wasted a lot of time in the beginning doing exactly that!
HOWEVER in spite of this when listening to music it is incredible how the bass always has some sort of definite location or character. What makes it so incredible is this happens even with bass notes that seem to have no sharp transient or leading edge. Like a big drum whack, it makes sense your ears are cued to a location by the initial whack on the skin of the drum. Or pluck string bass, same thing, the initial string plucking off the fingertip. But all kinds of bass does this too. It SEEMS to be localized BUT it is NOT and the proof is I can run the amps mono and STILL hear the exact same localized bass!
None of this makes any sense other than our hearing does not localize very low frequency bass but does localize higher bass AND THEN combines the one with the other to form a clear image of where the whole thing is coming from.
In other words, a great example of psycho-acoustics.
Everyone needs to go to another live concert and ask this question (assuming the sound system is a good one) Why does this sound better to me. Why does this feel better to me. Jazz in a smaller venue is perfect. The idea is to recreate that sound and that feel in your room. Having a room longer than 30 feet is a big help but not mandatory. A lot of systems have the capability of doing this. What is usually missing is the bass. It requires a lot more than people realize, a lot more speaker and a lot more power. I just get there using 7000 watts and four 12" subwoofers. It requires a 2 way crossover with steep slopes and the ability to delay speakers to get them aligned correctly. Just adding bass is not the point, it is getting to realistic bass. No speaker that I have ever heard had realistic bass down to 20 Hz, not a Wilson, Magico, Magniplanar, or Apogee. It takes a specialized driver in a very heavy stiff enclosure and a lot of power. You could use one really big one but IMHO it is easier to live with multiple smaller ones than one huge one. In my case it is absolutely necessary. IMHO if you are going to add subwoofers wait until you can do it right. It can be very frustrating if you don't and waste a lot of your time. @erik_squires , forget about simulations. Measure actual setups and see what they do in reality. A simulation can not possible cover all the variables involve like what frequency the walls resonate at. Are the subs well matched or are they 90 degrees out of phase with the main speakers. Why do some people think their subwoofers sound better 180 degrees out of phase? One sub may do fine in an 8 X 10 foot room or as fine as you can get in a room that small which is not very. Do not make up your mind on someone's idea of what a simulation should be like.
My system is a great example. There are 5 subs asymmetrically placed
around the room with each one a slightly different distance from a
corner than the others. With music playing, even with plenty of bass,
you can walk right up to any of them and think it is disconnected. In
fact I wasted a lot of time in the beginning doing exactly that!
Just for the record, I do this regularly with a single sub, traps and careful use of an EQ.
Just for the record, I do this regularly with a single sub, traps and careful use of an EQ.
I guess the advantage to doing it this way is that there is less trial and error involved. If we ignore the EQ for a minute then room treatment only attenuates reflections but it happens over a wide range of frequencies. The only limit is how much space you're willing to give up to absorbers e.g. to treat a problem at 80Hz you're looking for 1m depth of treatment... 1.5m at 60Hz etc. With EQ I think the only compromise is that you are getting a flatter response at the listening position but probably making other places in the room worse.
Theoretically with multiple subs you should be able to cover multiple frequencies but it could easily turn into a game of 'whack a mole' where you treat one node only to reinforce another one. I guess some of you EQ each sub individually to get around this.
Personally low frequency room response is somewhere I'm willing to compromise... treat the worst modes and live with the rest. Each room has imperfections which are part of its character if you're willing to think of it that way.
Don't forget that ours ears are not the only way we experience the music we're listening to. There are pressure sensing structures called Pacinian corpuscules distributed over the entire surface of our skin that contribute to our perception of lower frequencies.
I'm not sure whether these sensors are wired to our brains in a manner that allows source localization, but it would make sense if they were.
It's a fact that having appropriately distributed multiple subs (more than 2) improves the bass. I wonder if anyone has looked into whether it makes a perceptual difference if you try to keep the channels separated from left to right when you place them.
Recently blew a sub in the living room where I run a two sub system for video. Decided to move the matching sub from my listening room there and replace the listening room sub with something newer. New Martin Logan 800 X (10" sub) to augment the 8" woofers in my classic Acoustats is working beautifully. Everything adjusts from a phone app at your listening position and it has Anthem Room Correction built in as well. Sub is tucked away behind the couch wood arm at the far right. It's gets lots of reinforcement coming out of that couch "baffled" corner. https://www.martindareff.com/Other/HDR-Treated-Images/i-3ZfL6Gq/A
Using a Dual Rel T7i subs make my soundstage become wider and deeper, comparing to one subs only. Also, the bass goes deeper and smoother. I am not a scientist, so I don't know how to explain it, I can only report what I observe. Also, placing the dual subs right next to the speakers closer to the side wall makes the soundstage wider, comparing to closer toward the center .
I ran a single powered sub (15" driver) for awhile in my main listening room and then added a second. The second made a considerable difference to the sound.
Save yourself a lot of time and effort and go directly to a Swarm. I just set mine up two days ago and it was an epiphany. All my bass issues were resolved immediately. Smooth, balanced, realistic low end. Now it's time to tweak things. Very simple. I used a MiniDSP 2x4 connected to the pre outs on my integrated, set the parameters in the software, then connected the outputs to 4 subs (two REL, one SVS and an older Sunfire). Only downside is more wires running everywhere and five more power cables.
As of this moment. Musical Fidelity M6si integrated amp. Vienna Acoustics Mozart Grand SE Audioquest Black Lab sub cables Room 9"6" high x 12' wide x 16' long Speakers 4' from front (12') wall Rel T5 (2) located behind main speakers 24" from front corners SVS SB-2000 rear left corner Sunfire True Architectural Signature Sub behind couch. Midway along right wall. The MinDSP has just a basic setup of all crossover points at 70hz. I have downloaded Room EQ Wizard, purchased a MiniDSP Umik-1 microphone and will be doing an analysis when I am feeling motivated. This allows me to create a parametric EQ file to import and do a final tweak. REW will also provide me with a roadmap for adding room treatment as required.
Indeed, the multiple sub solution outlined by Toole and on which the Distributed Bass Array approach is based is a game-changer. Multiple subs distributed asymmetrically around the room effectively minimizes the problem of bass modes. Then when the subs and everything else are isolated on Townshend Podiums and Pods this virtually eliminates another major source of room mode excitation. The combination of the two is stunning. It takes a huge amount of bass traps and other room treatments to match what isolation and DBA can achieve.
Then if on top of all that you go to Townshend F1 cables, these eliminate yet another source of harmonic resonance.
The old-school approach of EQ and room treatment really is old school. There are much better solutions available. People are catching on. Good to see.
My subs have been supported on foam padded dollies with extra soft rubber wheels for many years now. After a move and before a permanent system setup we had our single 18" sub sitting on some folded moving blankets. We noticed how much less the low frequency excited the structure while still providing deep bass.
When we purchased our current 12" subs ten years ago I connected the 12s and the 18" with RS-232 cable and the home theaters 15" Super Nova with L/R interconnects. Effectively creating what's now called a swarm which did indeed eliminate all the rooms bass modes.
We noticed little if any sonic advantage between Cardas Golden Reference XLR to Canare XLR. On the other hand when I applied the four subwoofers with fourteen parameters of the subwoofers Room Optimization the improvement was stunning while adding the flexibility of remote controlled preset equalization.
I'm very interested in the "much better solutions available" you mentioned?
@m-db, The much better solution is using digital bass management which includes room control and digital crossovers which are far better than analog crossovers. From less to more expensive you have MiniDSP, DEQX, Anthem and Trinnov. Check them out. If you are a person who is stuck on analog only just forget about it, my mistake.
I'm running a pair of Tekton 4-10 bass towers & am very pleased. Prior to this, I was using a single REL sub. The bass towers improved not only bass (as expected) but also soundstage width, depth, instrument separation, & top end clarity. A very nice improvement top to bottom. I have these in a dedicated room that is around 15' square.
@ieales I am driving the mains as full range because I have no choice. "What type of XO [BW,LR, BE & order] are you using?" I would answer your question, but I have no idea what you are talking about. I assume XO is a crossover, but what is everything else?
BW Butterworth, LR Linkwitz-Riley, BE Bessel which are types of crossovers. Each type has a different phase and group delay which impact how well the subs integrate with the mains.
Order is dB/octave and controls the slope.
The
Vienna Acoustics Mozart Grand SE claim 30Hz bottom end. It's a ported design. The subs are unported and thus the bottom end characteristics are radically different.
It's a good move to use the miniDSP. Turn the sub's XO frequency all the way up and set Phase to 0.
You should use something other an integrated so you are not driving the main speakers full range. With a 70Hz corner in the miniDSP, I surmise there is a LOT of incoherent bottom and mid-bass in the room. 70Hz is easily localizable.
Having used full range monitors in recording studios and subs at home, it my experience that maximum musical impact occurs with coherent low end.
Caveat: not interested in the SWARM method or multiple subs at the moment, strictly comparing single to dual subs - divertiti
Second who said the first sub can’t have 6 active drivers and 12 passive radiators, BUT all in the same SINGLE 50 cubic foot box. :-) - oldhvymec
I’ve got dual opposing drivers in the same enclosure (internal vibration cancellation), both dual voice coil 10". It’s been on springs since the day it was dragged into my system, abused for being so heavy and awkward. I cannot get another class D amp module to match the one I have, so I’m thinking of making two more dual opposing driver subs (they will be on springs also) and using four drivers in two enclosures. Taking my 2 x 400 watt AB power amp to drive just the subs, and go valve for the stand mounts.
May toy with using the dual driver sub I currently have somewhere in the mix as well??
As I’m strictly digital at the moment, a DSP isn’t a bad idea, I’ve only used one in the car, with excellent results. The DSP was used on a single sub. So I have experience with single subs, however, I do believe it's an upgrade to use more.
mijostyn, I appreciate your suggestions and yes I'm pathetically stuck on analog but our low frequency system is master and slave digitally processor controlled.
At shows I'm regularly impressed by total bandwidth room correction demonstrations and then I walk into an analog demo and am often quickly reminded.
divertiti, after many 18" single subwoofers when some dedicated subwoofer manufactures began designing ten and twelve inch top line models I liked the idea of at least two smaller units. After experimenting with four subs I found my room loaded nicely with just two 12"s running summed L/R located asymmetrically in the rooms largest bass modes. Good luck with it.
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