Lots of bass at walls, lack of bass in center of room/listening position


I guess this is relatively common in listening system. Is there any way to smooth this out so I get more bass energy at my listening position? This happens with our without my 2x 18 inch subs. Room is 12 x 16 x 8 ft, speakers 4.5 ft apart on long axis and I am sitting 4.5 feet away. I tried moving back and forward but the entire middle center of the room except near the walls has decreased bass.
Is this a boundary effect or could it be due to bass cancellation effects?
smodtactical
@millercarbon: Ya I am not against a bass array. I would have to get probably 2 more subs and they would have to be smaller, maybe 12s or 14s because I am really running out of space. It would be great though if I could solve this without subs. I wonder if bass traps would allow me to turn my subs up more while still retaining cleaner bass.
@erik_squires : Ya moving the speakers around, forward, back, side to side seems something worth while and free! You mentioned dispersion, do you think dispersion panels behind the speakers would do anything  or be of any value ? My friend is selling two really nice 2 foot x 3 foot wood panels that look extremely well made for $400 usd for the pair.
Hi OP:

Use the tools you have. Move the speakers back to see if you can find a better bass balance. Next, see the tooth like ridges in the high frequency? That’s evidence of regular reflections, possibly even slap echoes.

Yes, diffusion is a great idea, but at $400, I suggest you call GIK Acoustics and see what they could do in your budget. I mean, I am sure these are find diffusors, but for maybe a little more you might be able to get a lot more room treatment from GIK. They have an online service where you can send them pictures and room measurements. I strongly suggest you take advantage of it.

So, this is the order I recommend you work:

  1. Main speaker placement
  2. Room treatment
  3. EQ
  4. Subwoofer

For 3, the Schiit Loki ($149) may be just perfect. Only after you have sorted this out should you spend too much time attempting to integrate your sub.  I can't tell you how much more important 2 is going to be though. 

Again, what speakers are you using though?  This may provide clues.

Best,

E
It would be great though if I could solve this without subs. I wonder if bass traps would allow me to turn my subs up more while still retaining cleaner bass.


So here's how that works. In order to get even bass the conventional way you have to turn the subs up loud enough to bring the drop-offs up to where they sound good. This means having way too much energy at other frequencies. So you try and damp that out with traps.  

But the traps and loud spots are only in certain places, while the excess energy is everywhere in the room. This physical energy excites the walls, the whole room, and physically dissipates over time. Its the dissipation of this energy that smears and muddies bass response. There really is nothing you can do about it. More and more traps leads to more and more EQ and you just never get enough. 

What's funny is everyone knows the last thing you want is to have an overdamped room. A certain amount of acoustic reverb is nice and helps create a sense of spaciousness. Too dead and the room sounds... dead. Yet that is exactly what a lot of these bass trap people are having you do, only with bass instead of midrange and treble. So you don't notice it when you walk in the room the way you would with panels all over the walls that kill the sound. But its the same thing, only lower in frequency. 

You don't need 12" or 14" subs. Those are for when you haven't figured out the answer is more subs and still think its more sub. That "s" makes all the difference in the world. You can easily use 10" subs. I have four of em. Its not how big. Its how many. And where. Dispersed asymmetrically around the room. 

This will cost less, take up less space, and work better than all other options. I really cannot think of a single objection, other than the mental effort required of any new idea.