Duel Subwoofer 1/4,3/4 placement suggestions? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 30 Old 05-18-2020, 05:59 AM - Thread Starter
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Duel Subwoofer 1/4,3/4 placement suggestions?

I am getting close to deciding on an subwoofer upgrade. I know I want duels. Due to placement limitations, I am pretty much stuck with 1/4, 3/4 placement flanking the cetner up under the 135in screen. Limited space on either side of screen is reserved for future towers (~15inches)

21inches from bottom of screen to floor....so height is the limiting factor.

-room is 21x~13x8.
-listening location is 11ft from screen.
-Hopefully <$2000.

Thus far Pair of PB2000 Pros seem to fit the bill.
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post #2 of 30 Old 05-18-2020, 09:08 AM
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What I have learned with duals is that towers confining the front wall options are a PITA if you are going to use REW and try and get the best response. If you don't have towers yet, I would strongly consider bookshelves mounted to the wall so that you can give yourself many more sub positioning options. Sometimes, you just need a move a sub over about 1' to really nail the setup and if your fronts are up off the floor that becomes a whole lot easier.
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Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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post #3 of 30 Old 05-18-2020, 09:51 AM
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I never thought that moving the subs just a little would matter until I put a couple of small towers in their place up front because I thought the towers would be too far out if placed on the outer sides of the subs. The bass was ruined and I put the subs back in their original positions. I'm working with what some would call mediocre equipment. But, even quality subs can produce mediocre bass when placed poorly.
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post #4 of 30 Old 05-18-2020, 12:16 PM - Thread Starter
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Unfortunately, it will be some time before I can get a good set of new speakers so am going to stick with my current Klipsch's which are towers. But I need a sub(s) soon since my crappy budget sub died. I figure I would start with good pair of subs then work on getting budget together for good speaker system.

What about laying subs on their side? That would let me go with bigger ones and still put them under the screen.
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post #5 of 30 Old 05-18-2020, 12:20 PM
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Quote:
Originally Posted by RafaelSmith View Post
Unfortunately, it will be some time before I can get a good set of new speakers so am going to stick with my current Klipsch's which are towers. But I need a sub(s) soon since my crappy budget sub died. I figure I would start with good pair of subs then work on getting budget together for good speaker system.

What about laying subs on their side? That would let me go with bigger ones and still put them under the screen.

Getting the best subs you can is definitely a good starting point. Laying them on the side tends to be acceptable to the ID makers who hang out on this board.


Since you are in building mode, would you consider going full budget on one moer powerful sub instead of 2?

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812

Last edited by badtlc; 05-18-2020 at 12:39 PM.
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post #6 of 30 Old 05-18-2020, 12:36 PM
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Quote:
Originally Posted by RafaelSmith
I am getting close to deciding on an subwoofer upgrade. I know I want duels. Due to placement limitations, I am pretty much stuck with 1/4, 3/4 placement flanking the cetner up under the 135in screen. Limited space on either side of screen is reserved for future towers (~15inches)

21inches from bottom of screen to floor....so height is the limiting factor.

-room is 21x~13x8.
-listening location is 11ft from screen.
-Hopefully <$2000.

Thus far Pair of PB2000 Pros seem to fit the bill.
Excellent!
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post #7 of 30 Old 05-19-2020, 05:54 AM - Thread Starter
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Originally Posted by badtlc View Post


Since you are in building mode, would you consider going full budget on one moer powerful sub instead of 2?
Well, everything I have been told and read is that its better to go with two good subs over one great sub.
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post #8 of 30 Old 05-19-2020, 06:29 AM
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Originally Posted by RafaelSmith View Post
Well, everything I have been told and read is that its better to go with two good subs over one great sub.

It is definitely better for multiple seats to have multiple subs. But it is also a good idea, IMO to start out with a large single sub when you start building up. I tried starting off with dual subs w/out really knowing what I needed in my room. The dual subs took a lot longer to get calibrated and in the end they weren't quite enough to satisfy me. I had to pay to ship both back instead of one.

If I could do it over again, and I am, I am going to try and find a single sub that will essentially get me to where I want to be SPL wise when maxed out. It is easier to integrate a single sub and get the most out of it.

Then I will at a later date get a 2nd one to increase headroom and smooth out any room mode issues I have for other seating positions. I figure that I need to get my MLP done right and make sure I am happy with that before getting another.

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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post #9 of 30 Old 05-19-2020, 07:03 AM - Thread Starter
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I have two rows of seating. I have spent quite abit of time doing what I can with the one "cheap" 12" SUB I have...played with REW, etc....actually sounded pretty good until the amp died. But never could get things decent across all seats....which is why I was thinking time to go duels and better brand.
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post #10 of 30 Old 05-19-2020, 07:13 AM
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Quote:
Originally Posted by RafaelSmith View Post
I have two rows of seating. I have spent quite abit of time doing what I can with the one "cheap" 12" SUB I have...played with REW, etc....actually sounded pretty good until the amp died. But never could get things decent across all seats....which is why I was thinking time to go duels and better brand.

If you think the level of that one was pretty good then it sounds like you are on the right path by getting not only a better sub but two of them. If you were happy before with the loudness then you will be happier after.

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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post #11 of 30 Old 05-19-2020, 07:22 AM - Thread Starter
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I need to research more into laying subs on their side. That would open up several other/bigger options. Afraid, the passive radiators and such would not allow for it.
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post #12 of 30 Old 05-19-2020, 08:51 AM - Thread Starter
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I little more info about room:

~2100 ft3

It is "enclosed"....one set of pocket doors for entry....thou the 135" screen is covering up a archway. Floor is tile with carpet tiles on it. One side wall is an outside wall/concrete with windows which are completely covered with black velvet.

Main listening row is 11ft from screen....2nd row is on a riser behind the first row.


Been mostly focused on ported subs....have not looked at sealed....which would open up some size options.

About 80/10/10 HT/gaming/music.
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post #13 of 30 Old 05-19-2020, 09:25 AM
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Quote:
Originally Posted by RafaelSmith View Post
I little more info about room:

~2100 ft3

It is "enclosed"....one set of pocket doors for entry....thou the 135" screen is covering up a archway. Floor is tile with carpet tiles on it. One side wall is an outside wall/concrete with windows which are completely covered with black velvet.

Main listening row is 11ft from screen....2nd row is on a riser behind the first row.


Been mostly focused on ported subs....have not looked at sealed....which would open up some size options.

About 80/10/10 HT/gaming/music.

For movies, you will get a vast majority of advice to go ported for increased tactile response you can feel.



I have never personally demo'd sealed vs ported in my environment so I cannot verify if I have seen a difference in "feel" between ported and sealed. There are many on here though that love their sealed subs for movies and tactile response. If you are going to look at those I would highly recommend looking at these:
  1. PSA S1512 $1200 (@bear123 tested these fairly flat down to 15Hz if I remember right)
  2. PSA S1812 $1550
  3. Dual HSU ULS-15 $1600
  4. Rythmik F15HP $1300
There are a few more sealed options. I really like the look and size of sealed subs but you definitely get more bang for the buck with ported when it comes to volume.

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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post #14 of 30 Old 05-19-2020, 11:42 AM - Thread Starter
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Pretty sure I want to stick with ported.

I think I am down to 3 choices that I know I could fit under the screen :

-Pair of SVS PB2000 Pros
-Pair of Rythmik FVX12s
-Pair of HSU VTF-2 MK5s.

SVS and Rythmik are a wash in terms of cost.

HSU about $500 less...but only 350 watt AMP.

Leaning toward either SVS or Rythmik. The APP for the SVS looks cool...I like having stuff to tinker with.
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Quote:
Originally Posted by RafaelSmith View Post
Pretty sure I want to stick with ported.

I think I am down to 3 choices that I know I could fit under the screen :

-Pair of SVS PB2000 Pros
-Pair of Rythmik FVX12s
-Pair of HSU VTF-2 MK5s.

SVS and Rythmik are a wash in terms of cost.

HSU about $500 less...but only 350 watt AMP.

Leaning toward either SVS or Rythmik. The APP for the SVS looks cool...I like having stuff to tinker with.

I have those Rhythmik subs right now. I think they are possibly the best 12" subs on the market (maybe monolith is better?). The FVX12 would be my recommendation.

However, you can try those SVS subs with no risk to get a taste of what this level gets you. You can send SVS subs back at no cost to you, I believe. Try, if you like them, keep them. If you like them but want the Rythmik or HSU subs, send them back and get the Rythmik or HSU. With the SVS you can get some trial time with calibrating dual subs. In the event, if you find calibrating two subs is too much work (that happened to me), you can send the SVS subs back and then focus on buying the biggest baddest single subwoofer you can for your budget. With the other options you will have to pay for return shipping if you need something more or you decide dual subs isn't for you.
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Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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Dual Hsu VTF-3 Mk5 HP for $1549?
600W RMS, 2000W peak

Quote:
Originally Posted by RafaelSmith View Post
I think I am down to 3 choices that I know I could fit under the screen :
-Pair of SVS PB2000 Pros
-Pair of Rythmik FVX12s
-Pair of HSU VTF-2 MK5s.
SVS and Rythmik are a wash in terms of cost.
HSU about $500 less...but only 350 watt AMP.
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post #17 of 30 Old 05-20-2020, 05:47 AM - Thread Starter
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Originally Posted by philpoe View Post
Dual Hsu VTF-3 Mk5 HP for $1549?
600W RMS, 2000W peak
Too tall to fit under my screen.
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post #18 of 30 Old 05-20-2020, 05:51 AM
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Quote:
Originally Posted by RafaelSmith View Post
Too tall to fit under my screen.

If you go to the HSU thread and verify, I am pretty sure Dr. Hsu has no issues with people putting his subs on their sides.

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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Exactly. I was following up on the sub-on-side discussions.

Quote:
Originally Posted by RafaelSmith View Post
Too tall to fit under my screen.
Quote:
Originally Posted by badtlc View Post
If you go to the HSU thread and verify, I am pretty sure Dr. Hsu has no issues with people putting his subs on their sides.
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post #20 of 30 Old Yesterday, 07:56 AM - Thread Starter
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Pretty sure I have made my decision. Spoke to the "boss" and can place my order in the next week or two.

Going to go with pair of HSU VTF-15H MK2s. Will be placing them on their side under the screen. Most likely next year will be LCR upgrade time so may end up moving them if I decide to go with bookshelves instead of towers on the sides of the screen. But for now, will use 1/4,3/4 placement and see how things go. According to my room modes...I am good in terms of where my seats/rows are.

Looking forward to setting them up. Already started prepping....MiniDSP , long cables, etc.
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Quote:
Originally Posted by RafaelSmith View Post
Pretty sure I have made my decision. Spoke to the "boss" and can place my order in the next week or two.

Going to go with pair of HSU VTF-15H MK2s. Will be placing them on their side under the screen. Most likely next year will be LCR upgrade time so may end up moving them if I decide to go with bookshelves instead of towers on the sides of the screen. But for now, will use 1/4,3/4 placement and see how things go. According to my room modes...I am good in terms of where my seats/rows are.

Looking forward to setting them up. Already started prepping....MiniDSP , long cables, etc.

Good choice! Enjoy.

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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post #22 of 30 Old Yesterday, 08:08 AM - Thread Starter
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Good choice! Enjoy.
Upgrading from a single Dayton 1200
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Quote:
Originally Posted by RafaelSmith View Post
Pretty sure I have made my decision. Spoke to the "boss" and can place my order in the next week or two.

Going to go with pair of HSU VTF-15H MK2s. Will be placing them on their side under the screen. Most likely next year will be LCR upgrade time so may end up moving them if I decide to go with bookshelves instead of towers on the sides of the screen. But for now, will use 1/4,3/4 placement and see how things go. According to my room modes...I am good in terms of where my seats/rows are.

Looking forward to setting them up. Already started prepping....MiniDSP , long cables, etc.
Please post your review and thoughts! This is helpful for those on the fence and I would certainly appreciate it. Thanks Rafael and congrats sir!
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post #24 of 30 Old Yesterday, 09:38 AM
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Quote:
Originally Posted by RafaelSmith View Post
Pretty sure I have made my decision. Spoke to the "boss" and can place my order in the next week or two.

Going to go with pair of HSU VTF-15H MK2s. Will be placing them on their side under the screen. Most likely next year will be LCR upgrade time so may end up moving them if I decide to go with bookshelves instead of towers on the sides of the screen. But for now, will use 1/4,3/4 placement and see how things go. According to my room modes...I am good in terms of where my seats/rows are.

Looking forward to setting them up. Already started prepping....MiniDSP , long cables, etc.
My suggestion... order 1. When you get it, place it on both sides of the CC and measure the response. If both responses are very similar, then adding a second will only net you more output, not smoother, more consistent frequency response across more seats. Why...


When 2 subs are placed close together, the "mutually couple." Their wavefronts couple, combine and propagate as ONE wavefront with higher SPL. In other words, you only get ONE frequency response to work with. You do get more headroom, but the FR will be only slightly impacted, if at all.



To get frequency response smoothing, you need more than one frequency response to work with. That way, where one sub has a dip, the other will likely have a peak, and vice-versa, and the two will smooth each other out. Placing the subs on either side of the CC will not get you that. If you can't spread the subs further apart, you may be better off just getting one "better" subwoofer. Then EQ it for your primary listening position, and accept whatever response you get at the other seats.



Craig

Lombardi said it:
"Perfection is not attainable, but if we chase perfection we can catch excellence.
My System (Edited Feb. 2020 to add 4K and Atmos updates)
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post #25 of 30 Old Yesterday, 11:41 AM - Thread Starter
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Quote:
Originally Posted by craig john View Post
My suggestion... order 1. When you get it, place it on both sides of the CC and measure the response. If both responses are very similar, then adding a second will only net you more output, not smoother, more consistent frequency response across more seats. Why...


When 2 subs are placed close together, the "mutually couple." Their wavefronts couple, combine and propagate as ONE wavefront with higher SPL. In other words, you only get ONE frequency response to work with. You do get more headroom, but the FR will be only slightly impacted, if at all.



To get frequency response smoothing, you need more than one frequency response to work with. That way, where one sub has a dip, the other will likely have a peak, and vice-versa, and the two will smooth each other out. Placing the subs on either side of the CC will not get you that. If you can't spread the subs further apart, you may be better off just getting one "better" subwoofer. Then EQ it for your primary listening position, and accept whatever response you get at the other seats.



Craig
That is something I had thought of....but what I did was use my existing SUB do what you suggested.....granted each individual response was not good....but they were different. Unless I am completely misunderstand how these things work...the "room" effects at a given location will be pretty much equal regardless of SUB? Better subs will be as different in those exact locations as the bad one?
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Quote:
Originally Posted by craig john View Post

When 2 subs are placed close together, the "mutually couple." Their wavefronts couple, combine and propagate as ONE wavefront with higher SPL.

Craig
Curious, any formulas,etc that detail how close subs have to be to become "mutually coupled"? If I put the pair of subs where I am planning...they would be 6-7 feet apart.
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Quote:
Originally Posted by RafaelSmith View Post
Curious, any formulas,etc that detail how close subs have to be to become "mutually coupled"? If I put the pair of subs where I am planning...they would be 6-7 feet apart.

I have not seen what you are asking for but I will say when people are attempting to do this, the subs are usually up against each other or stacked on top of each other.

Front: Polk S55
Center: Polk S30
Rear: Polk S10
Sub: P̶L̶-̶2̶0̶0̶I̶I̶ (̶2̶)̶ ̶F̶V̶X̶1̶2̶ V1812
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Quote:
Originally Posted by RafaelSmith View Post
Curious, any formulas,etc that detail how close subs have to be to become "mutually coupled"? If I put the pair of subs where I am planning...they would be 6-7 feet apart.




From Electroacoustical Reference Data edited by John Eargle.
https://www.springer.com/gp/book/9780442013974

EDIT:

Using that formula:
c = Speed of Sound = 339 m/sec.
d = 7 ft = 2.13 meters)
square root of 2 = 1.41
2.13 * 1.14 = 3.003

339/(2.13*1.41) = 339/3 = 113Hz.

So all frequencies from 113 Hz and below will mutually couple. You'll gain 6 dB of output, but you'll have ONE frequency response transfer function to your seating from 113 Hz down to the F3 of the subs. Since you state that the two subs have different frequency responses in their respective, 7' apart positions, the ONE FR that propagates to the seating will be whatever the the 2 subs combine to, which is unknowable at this point, without measurements.

Here is what happens in my room with subs placed on either side of my CC:



Cyan is one sub, purple is the addition of the 2nd sub. You can see that the FR didn't change much, but the the output increased by 6 dB from about 100 Hz down.

Lombardi said it:
"Perfection is not attainable, but if we chase perfection we can catch excellence.
My System (Edited Feb. 2020 to add 4K and Atmos updates)

Last edited by craig john; Yesterday at 02:04 PM.
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post #29 of 30 Old Yesterday, 03:53 PM - Thread Starter
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Woot...just what I needed ...more to think about =P

I have convinced the wife I need two subwoofers....not sure I want to go back on that even if it means half cost....=P Might come back to bite me in the future..."Honey, I need about 5k for new speakers..... ...."

Does beg the question about all the articles ive read about 1/4 and 3/4 being good choice for placement....unless they are dealing with really wide rooms.

Also....does not two subs create a "virtual" sub between them that helps with room modes?
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post #30 of 30 Old Yesterday, 05:17 PM
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Quote:
Originally Posted by RafaelSmith View Post
Woot...just what I needed ...more to think about =P

I have convinced the wife I need two subwoofers....not sure I want to go back on that even if it means half cost....=P Might come back to bite me in the future..."Honey, I need about 5k for new speakers..... ...."

Does beg the question about all the articles ive read about 1/4 and 3/4 being good choice for placement....unless they are dealing with really wide rooms.

Also....does not two subs create a "virtual" sub between them that helps with room modes?
The 1/4 - 3/4 placements should address the width modes. If those were the only modes in a room, that would be all you need. But there are two other axial modes, length and height, as well as tangential and oblique modes. All the modes impact the modal response.


It is the sum total of all the modes that represents the steady state response in a room. By having two subs displaced around the room, you provide the opportunity to have differing and offsetting frequency responses that smooth and flatten the response. The primary goal is null elimination. Nulls can't be fixed with EQ. Peaks can be cut and so a response with no nulls and a few remaining peaks can easily be corrected with EQ. Plus, that EQ will apply over more seats because the pre-EQ response was more consistent over a wider listening area. People always say multiple subs are better, but that's only true if they can be set up properly. From my experience and from what I've learned, placing subs on either side of the CC is generally not the best use of dual subwoofers if frequency response smoothing is the primary goal.

https://www.harman.com/documents/multsubs_0.pdf

Conclusion:
One subwoofer at each wall midpoint is the best in terms of Std, Max-ave and Max-min but does not support low frequencies particularly well. Two subwoofers, at opposing wall midpoints, performs very nearly as well as four at the midpoints and gives a much better LF factor. One subwoofer in each corner also has good low frequency support, but does not perform quite as well as one subwoofer at each wall midpoint, in terms of Std, Max-ave and Max-min. If cost and aesthetics are considered, subwoofers at 2 wall midpoints is preferred.

Lombardi said it:
"Perfection is not attainable, but if we chase perfection we can catch excellence.
My System (Edited Feb. 2020 to add 4K and Atmos updates)
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