room setup suggesion needed

@ssg308, bass boom does not come from speakers or subwoofers. Bass boom is a product of room distortion see here.

Mike

Anyone who thinks they know anything about how their speakers sound in a room because of the specs is probably mistaken.  The room changes everything and measurements are key.

The ability to limit the bass in main speakers and move subs to ideal locations can be life changing, as are bass traps and sub EQ.

@ssg308 What you have is too much mid bass and not much really low bass. Very few speakers do much below 40 Hz particularly ported designs. You have a more complicated problem because your 15" driver is really a mid woofer. It crosses to the horn at 700 Hz which means it carries a significant portion of the midrange. You really do not want it doing very low bass because that would distort everything else it is doing. JBL needed to use a big efficient 15" midrange driver to keep up with the horn. It was not designed to do really low bass and the specs are very misleading. Ideally you would cross over to subwoofers at around 80 Hz which would clean up your midrange and pass the signal to drivers specifically designed to run down to 20 Hz flat. In my case I used 12" drivers for packaging reasons. I would have used 15" drivers but the size of the enclosures needed to house them would have been prohibitive. I use 8 drivers not to blow everyone away or impress the neighbors, but to form a linear array to match the radiation pattern of my main speakers. For people with point source systems like yours two subs, in your case at least 15", will suffice. You have to hear a system that is capable play low C on a pipe organ. It is a religious experience. 20 Hz is barely audible but boy can you feel it. 

I assume you have been to a large concert or two. The game is recreating that visceral experience in your home. Large venues breath at low frequencies. You know you are in a large space even with eyes closed. A good live recording of a stadium concert should feel the same way. 

I agree with everything @erik_squires says except I am not so impressed with bass traps, digital EQ is way more effective. 

@mijostyn 

all great points and I agree with most of it as long as we talking about that low C on the pipe and not about death metal or grind core that also have to sound great!

the way I see it, is that there are variable in whole equation and rather you have too big room too small speakers too weak amp or any other not correct for conditions of the room combinations of above elements you won't be satisfied.

Now if system works great as is, sounds fantastic and than you take away subwoofers and its all dramatic, guess what you don't have speakers, if my issue is the fact that some frequencies are overlapping and I have to sit and pay attention when they overlapping because my ears are not the freshest, o well so be it.

Ive been listen stereo way before subwoofers were invented and I'm sure they have application somewhere, but not in my system, even at the price of not having 100% sonically correct sound.

and yes I agree manipulation of digital signal by software before decoding is far more superior than any other filters.

I am the lowest budget member here and I too benefit from subs, the cheapest you can buy. The depth of the soundstage just isn't there without the low end, the low end from a separate driver.