Dual Subwoofer Placement


Rule of thumb question, do you prefer placing dual subs inside or outside the front speakers?
Assume all distances are equal for both fronts and subs regardless of placement. 
jimmy225
I prefer placing where they sound best.

One is a little to the left and in front. Another almost directly behind. Another to the right and a little behind. The other two are way out off to the left and right behind me.

You do know sub placement is all about frequency response and has almost nothing to do with the stereo pair, right?

(And how do you get by with only 2?)
jimmy225,

I agree with millercarbon, a pair of good quality subs are very capable of providing very good bass, that’s well integrated with your main speakers, if you’re only or mainly concerned with the bass quality at a single designated listening seat.
However, you’ll need to completely abandon the ineffective method of positioning one sub by each main speaker. The much longer and omnidirectional bass soundwaves launched by your subs behave completely differently in your room than the much shorter and highly directional midrange and treble soundwaves launched by your main speakers.
For best results, use the crawl method (google it) to sequentially and optimally position each of your subs in your room, which will typically be completely independent from the positions of your main speakers. In my experience, the likely best bass, at your listening seat, will be achieved with one sub positioned somewhere along your front wall and the other positioned along a completely different wall, which could be the back wall or one of your side walls depending on your listening seat position within your room.
I also suggest running your main speakers full range and setting the volume and crossover frequencies as low as possible on each sub as you can with the bass still sounding powerful, dynamic, detailed, smooth, fast and natural to you, as well as seamlessly integrated with your main speakers.

Best wishes,
Tim
Actually, no.

there are three variables you are solving for with placement

image
frequency response with room
integration with the mains.

where you are crossed over and at what slope is critical for image. Much energy at 150 HZ and you want them near the mains.
So, OP where are you crossed over ? Are the mains full range or hi passed? What settings available on your subs? What is your room dimensions and setup ?


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Its not a matter of belief. Its a matter of physics.
The more sub locations the more bass modes and the smoother the bass response.

The more subs the less volume each one has to put out and so again the smaller the modes and the smoother the bass response.
This is all due to the fact low frequency waves are very long. None of this changes when the room gets smaller.
The problem is people don't understand what's going on. They buy a sub to hear low bass. So they turn it up enough to hear low bass. This excites room modes making boomy bass. They conclude its the room. Or the sub. Or anything but what it is, the universal physics of long waves in small rooms. The solution is many small subs.
Its not that 2 or 4 is best. Its that more is better.
Asymetrical placement of the subs helps control the very worst room modes.

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jt35:
"agree there is no rule of thumb on this one...I'm getting great results with one sub, inside and slightly behind right speaker...friend with similar system gets best results with 2 slightly smaller subs, on outside...many believe 2 or 4 subs are best, but not in every room or every system..."

jt35,
     I don't agree, there is a rule of thumb on this subject of in-room bass response in smaller domestic rooms that's been researched scientifically by acoustical experts, Dr. Earl Geddes and Dr. Floyd Toole.  Both have documented their research, methods, results and conclusions in published White Papers that you can google and read completely on-line.     Numerous other acoustic scientists have independently repeated their experiments and verified their results.  I've read both of their White Papers and, if their conclusions were to be summarized in a rule of thumb guideline for in-room bass response in smaller domestic rooms, it would be: In virtually any given room and any pair of main speakers,two subs perform twice as well as one sub and four subs perform twice as well as two subs.  
     As millercarbon stated, these conclusions are not based on opinion or belief.  They are based on standardized scientific experimental research, under controlled conditions, with results measured and recorded by accurate and reliable equipment.  
     You've stated that you believe one sub is best, that many believe 2 or 4 are best but not in every room or every system.  My point is that this defies the scientific research results that specifically were found to apply in virtually any given room and with virtually any pair of main speakers.
     In my personal experience with my own systems and assisting to construct other systems, I've invariably found that 2 subs actually do perform twice as well as 1 sub and 3-4 subs perform at least twice as well as 2 subs.  Why you would prefer 1 sub over 2 or more subs in your room and system is hard to understand.  It makes no sense to me not only because it defies the scientific findings and my personal experiences, it defies the laws of physics.  
     Well, it's really your big loss since you're the one who's definitely missing out on significantly improved bass performance with your system and in your room.  Of course, it's your choice if you're satisfied with the bass quality attainable by only using a single sub in your room.  If you do get the urge to improve your system's bass performance, however, I'm willing to assist if you'd like.

Tim
Apology in advance for getting all mathy, but its V/N where V is the variance and N is the number of subs. So if one sub measures +/- 6dB then 2 subs will be 6/2=3dB and 3 subs will be 6/3=2dB and so on. Main point being, once again, its demonstrably proven with measurements that more is smoother, ie, better.

http://www.gedlee.com/Papers/multiple%20subs.pdf

Its a bit nerdy but good solid facts like this together with informed impressions from users like Tim that convinced me to build my DBA. Finally in one fell swoop my system went from bass being the weakest aspect to probably the strongest. And for only $3k! Yeah, science!
To those asking about my setup, I will be setting up two Martin Logan 1100X subwoofers with a pair of Martin Logan ESL 9’s. I’m estimating my crossover will be around 60-80Hz. I have about 10’ from where the speakers and subwoofers will be placed to the listening position (longer if I measured at the actual angle from the placement to the seats). The room is approximately 30’ wide
Tim & millercarbon,

I envision adding another pair of Velodyne HGS-10s to the room.  To review, the stereo setup is comprised of a pair of KEF Reference 1s and a pair of HGS-15s crossed at 40 Hz 4th order by a SMS-1 bass manager that provides acoustic room correction.  The HT setup uses six KEF LS50s and a pair of HGS-10s crossed at 80 Hz 4th order by Bryston SP3 processor with correction by a second SMS-1.  Would it be preferable to use the subs 3 & 3 or 4 & 2?

db
Hello DB,

     Back at it again?  Good.  I'd suggest that as long as you have 4 subs active in your room (the 2 HGS-15 and 2  HGS-10), and they are properly positioned in a distributed bass array configuration, then you will certainly attain excellent bass performance for both music and HT throughout your entire room.  
     For best results, you should position each sub sequentially around the perimeter of your room using either mics and frequency spectrum analysis software tools or using the crawl method.  Both are very effective and you can always run your room correction processing afterward, to see if the bass, in your opinion, is even further improved or sounds better without it.  It's completely your choice how you distribute the 2 larger and 2 smaller subs throughout your room.  The essential factor is that  4 subs are launching bass soundwaves into the room from independent, and typically asymmetric, positions in the room.  This 4-sub distributed bass array (DBA) concept has been both scientifically and anecdotally proven to be tremendously effective in virtually any room and with any pair of main speakers.   
     If you utilize the crawl method of sub positioning, begin the search for the optimum position of sub#1 in the right front corner of your room, begin by positioning the 2 HGS-15s as sub#1 and #2 and continue to progress counter-clockwise around the perimeter of your room for positioning the 2 HGS-10s as sub#3 and #4, I believe this will result in both larger HGS-15s being optimally positioned along your front wall and the 2 smaller HGS-10s being optimally positioned elsewhere, likely in a well separated and distributed configuration.
     I located my 4 identical subs sequentially around my 23'x16'x8' room using the crawl method.  The optimum positioning turned out to be 2 along my front 16' wall, about 2' away from each corner, and 1 along each 23' side wall, toward the rear of the room and also with each about 2' away from each rear corner.  I'm thinking your 4 subs may be optimally positioned similarly, but likely not identically, in your room.
     I'm willing to continue to assist you, pm me if you'd like.

Later,
 Tim

Would it be preferable to use the subs 3 & 3 or 4 & 2?

You lost me. Do not understand why different setups. Sound is sound, and the best is the best, movies or music. What is 3&3? What is 4 & 2? Besides 6 I mean.

jimmy225: "To those asking about my setup, I will be setting up two Martin Logan 1100X subwoofers with a pair of Martin Logan ESL 9’s. I’m estimating my crossover will be around 60-80Hz. I have about 10’ from where the speakers and subwoofers will be placed to the listening position (longer if I measured at the actual angle from the placement to the seats). The room is approximately 30’ wide."

Hello jimmy,

     Sorry, dbphd kind of sidetracked the thread temporarily.

     You seem to have a rather large room, based on your prior statement that it’s 30’ wide. If your room’s length is even half its width and you’re goal is to attain near state of the art bass response not only at your listening seat but throughout your entire room, I am certain that a custom 4-sub DBA system would be your best option/solution. If you’re goal is only or mainly to attain very good bass response at your listening seat, I’m fairly certain that your current two ML 1100X subs will be adequate if both are properly positioned in your room in relation to your listening seat.
     Before you decide whether to use dual or quad subs in your room and system, however, I think it’s important you understand that quad subs will definitely provide significantly higher bass quality performance than dual subs are capable of providing. Yes, this is my opinion based on my own results of using both dual and quad subs in my 23’x16’x8’ room and large Magnepan 2.7QR and 3.7i main speakers.
     But my opinion is also based on many hours of research on the subject of attaining very good bass performance in domestic sized rooms, which include scientific White Papers as well as professional reviews on quad sub systems such as this review by The Absolute Sound on the Audio Kinesis Swarm 4-sub DBA system linked to below:

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

     I actually purchased the very similar and identically priced Audio Kinesis Debra 4-sub DBA system about 4 years ago on a 30-day free in-home trial basis. The above review served as another major impetus for me to give the 4-sub DBA concept an in-home audition.
     With the help of a buddy, we were able to set the entire bass system up, including running all connecting wiring under my room in a crawl space, by about 4pm on a Saturday afternoon. Within an hour of listening to music and HT, there was absolutely no doubt in my mind I was going to keep it. I also discovered the Absolute Sound review, that I linked to above, is an extremely accurate description of what to expect from a 4-sub DBA system.
Based on my experience beginning with upgrading from a single sub to the use of 2 optimally positioned subs, the bass will become more powerful, more dynamic and have a seemingly effortless quality due mainly to the fact that there are 2 subs sharing bass duties with neither operating anywhere near its limits.
     Upgrading from a single sub to the use of 2 optimally positioned subs, the bass will also noticeably become smoother, faster, more detailed. better integrated with the main speakers and the soundstage will become wider, deeper and more open. This is mainly due to physics and the fact that there are 2 separate, independent and optimally positioned subs, in relation to the listening seat, launching bass soundwaves into the room. This is true even if both subs are operated in mono configuration for reasons I explained in a previous post.
     Upgrading from dual subs to a 4-sub DBA system provides even further improvements in all the bass performance qualities I already described in upgrading from a single to dual subs but with the added benefit of providing near state of the art bass performance quality throughout your entire room, not just at your listening seat.
     I suggest you take your time, learn more about the physics and psychoacoustics involved with utilizing multiple subs in a domestic home audio/video room and seek out a local audition of a 4-sub DBA system if possible. I don’t know where you live but I live in a suburb just north of Indianapolis. You’re more than welcome, if you live nearby or are ever in the area, to stop by my home for a demonstration.
     Whether you ultimately decide to utilize dual or quad subs in your system, however, I’m willing to assist you in optimizing either configuration.

Best wishes,
     Tim
WOW! I really appreciate the detailed response. Unfortunately, I live in an apartment and don't have the space to go with four subs, my neighbors will already hate me having two. I was in the process of getting a house, and then setting up my equipment, but that has since gone out the window and now I'm trying to make the best out of a bad situation. Not having the correct spacing for everything definitely makes it a little difficult but, if done correctly, I think I can still turn the space I do have into a solid listening stage, thus why I am asking for experienced feedback while trying to plan out my own layout. Again, thank you for taking the time to offer your advice.
Hello jimmy225,

     Okay, you want to keep it at 2 subs for now.  That's fine, the most important thing to do is position each sub sequentially in the optimum spot, in relation to your listening position,  along the perimeter walls of your room.  Please don't expect these positions to be just one next to each main speaker with the drivers pointed directly at your listening seat.
     I can describe exactly how to do this but, before I do, I need the width, length and ceiling height of your room along with a description of what's currently  along the room's perimeter (couch, chair, windows, system equipment rack, speakers, subs, tv, doors, openings and their approximate dimensions). 

Thanks,
  Tim
millercarbon, I assumed it was obvious that I have two setups, one stereo, the other HT.  I choose to keep these setup separate for energy efficiency -- the three HT amps are Class D.  Question was whether to use three subs for stereo and three for HT or four for stereo and two for HT.  I know Tim favors a four sub array.

Tim, the manual for the SMS-1 suggests a variation on the crawl method in which the sub is placed in the listening position and the crawl is with the microphone while watching the video display.

db
dbphd:"Tim, the manual for the SMS-1 suggests a variation on the crawl method in which the sub is placed in the listening position and the crawl is with the microphone while watching the video display."

Hello DB,

    I think the SMS-1 approach is a good one and you could use either that method or the crawl. The SMS-1 approach is definitely more objective, scientific and sophisticated than the crawl method. However, if one has a good ear for the sound of high quality bass, has no hearing deficiencies and doesn't have an excess of ear wax, I'd suggest both methods will result in identical optimum sub positioning. The choice is yours.


Later,

Tim
Tim,

The idea behind the SMS-1 method is that it's easier to crawl with a microphone in hand than move a sub.

db
Hello DB,

     Makes perfect sense to me.


Best wishes,
     Tim
Years ago I took a cue from Pierre Spray (Mapleshade) regarding sub placement. I've experimented lots since. In (my room) I love them inside of the main speakers. I can actually tell a big difference positioning them as little as 1/4".

I need to get a life.

No I don't, I love my life!
Tim,

I'm thinking about using the pair of Velodyne HGS-15s to supplement the six KEF LS50s I use for HT -- the big subs are great for LFE, and add another pair of HGS-10s to supplement the KEF Reference 1s with a distributed bass array for stereo.  Both setups will use SMS-1 bass managers.  What do you think?

db   
Hello dbphd,

     I think you should try it and find out what you think.  I'm completely certain that a single setup of 4 subs in a distributed bass array configuration will perform equally extremely well for both stereo music and HT because I've been doing it for years now. 
     It's also very convenient having them combined but it takes a bit of noodling and planning.  For some reason, you seem to have always wanted to treat them separately but I think that's a mistake.
      But regardless, I always wish you the best and I'm always willing to help you out as much as I can.

Later,
 Tim
Tim,

We use the HT setup mostly for Cox Cable.  The Bryston SP3 processor, NAD M22 amp, KEF LS50 speakers, and Velodyne HGS-15 subs are used for energy efficiency. The Ayre KX-5/20 preamp and KV-5/20 amp are used with the QX-5/20 for Roon and DX-5 DSD for discs where audio quality is paramount.  The KEF Reference 1s are supplemented by two Velodyne HGS-10s, (likely to be expanded to four).  They are separate setups with separate goals: energy efficient v audio quality.

db
Hello DB,
     Okay, now I understand much better.  Several months ago, I  bought an LG C9 77" OLED 4K hdtv to replace my Panasonic V60 series 65" plasma 1080p hdtv (which is still functioning perfectly)for the same reason, energy efficiency. 
     The local electric utility consistently sends a quarterly report stating how my household electricity usage and cost compares to the neighborhood household average.  For the years I used the plasma, my electricity usage/cost was always a bit above the average.  I just received the first quarterly report since switching to the much more efficient OLED technology and, for the first time in at least 6 years, my usage/cost was a bit below the neighborhood average.  Bigger screen, better picture, greener and I save money every month? I'm with you on energy efficiency.
 
Never mind,
     Tim
Tim,

A bit off-topic, but I hadn't realized OLED technology was energy efficient.  I'll keep that in mind when we move to an apartment in a local retirement community.  The apartments have so much glass a projector seems impractical, yet we enjoy the immersive experience of a large screen.  (The retirement community is celebrating Julia Child who lived there in her final years.)

db