Single vs. Dual Subs

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. 

You can't recreate the sound field of a live event in your room with a stereo system. It can't even be recorded. The best you get is a good facsimile. 

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.