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

@atmasphere  Does subwoofer direction make a difference since the waves are omnidirectional below a certain frequency?

@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.

That is so fascinating using all different kinds of subwoofers. Is there any downsides to this? Do they have different speed or timbre?

@golfnutz Ya I think making them myself makes sense, can save a ton of cash. I wonder if I can order the wood pieces cut to precise size via home depot and have them delivered or something with the rockwool. And just order the fabric as you said, awesome plan. So then I just nail everything together and staple?
Just curious I heard some people using this special denim material that is a bit safer? Any thoughts on that?

@erik_squires Appreciate it man but ya I think NS5K is a totally different speaker.

Thanks guys. Will look into treatment and DSP.
I do plan to move to a bigger space in 2-3 years so thats why I have the NS5000. But I agree totally a smaller speaker might be better. Although not sure it would be better for bass impact?

Hey just made a discovery.

Just played around with the roon dsp, i hit invert on my left channel, and all of a sudden the bass came out of nowhere, was focused, intense and powerful and evenly distributed as I lean left and right. When you turn invert off on the left it weakens and becomes much more diffuse. So maybe i have something wired incorrectly? Only thing is if i leave invert on, i sometimes get some popping and crackling so sounds on the inverted channel.

Guys thanks for all the feedback!
I forgot to mention my speakers are Yamaha NS5000 and they are about 1 foot off the wall. As for the separation I know its not ideal but i just don't have much space because I have a door to the left of my left channel and my sub to the right of the right channel.

My right sub is at the front right corner. My left is at the back left corner. Both firing down the long axis. I guess if I had 4 smaller subs I might get a better response than 2 subs. I don't have a ton of space to move my subs around because of other items in the room.

Would changing the firing direction of the subs make a difference since bass waves below 80 as you said are non-directional. I might be able to move one of my subs to a position where it is to the right of the listening position firing at the center of the room. I can't really do a crawl again because of so many other things in my room (it is a bedroom).
And I guess I am kind of stuck with the bass without subs because to fix it there I would have to I am guessing pull my speakers out further which I can't do right now.

Thanks guys for the great thoughts.
Erik, sounds like a good plan.
Miller, should I still use my 18s with the 10s? Like 2 18s and 2 10s?
Strojo: Via RCA from preamp to subs.

The acoustic fields gentlemen says subs in the corners is a big no no by the way.
https://www.youtube.com/watch?v=Gb_yOIuLc_Y

Probably I need to keep playing with speaker positioning as you guys are saying. I'll try to keep moving them around. Right now they are 28 inches off the front wall with 10 degree toe in.

I wonder if diffusers behind my speakers would help? In addition to bass traps. Because I can't pull my speakers out further than a foot off the front wall.

Miller so in a smaller room you cannot get good bass without subs ?

Thanks guys. Interesting anecdote about the speaker flip thing, heh.
Anyway I did some measurements. Both with subs, no subs and at my listening position and at a position that is 3 feet back and 3 feet from the left wall.
www.diabolicaldesign.net/Measure.jpg
Please have a look

@erik_squires: I only have a delay knob on my subs (PSA V1800). Is that what I should play with? I don't have polarity or phase controls.
@millercarbon Oh wow different subs? I thought I wouldn't be able to do that. Which subs do you have. Do you find they give you clean bass with your speakers and are fast enough to keep up?

Here are measurements during each sub off and then both on from the listening position:
www.diabolicaldesign.net/subs.jpg

@millercarbon thanks man, I will play with it.
Oh and I forgot to measure the front wall to the front baffle (I was doing to the back of the speaker). My speakers are 28 inches away from the front wall.
I am gonna try to play with the toe, lateral movement and the forward and back movement until I get the low end fuller while retaining the rest of the range. And once I hear something good I'll measure and compare. I think you guys are right in saying placement is the key here.

Guys thanks for all the suggestions. I will try them and keep tweaking. I did play with the delay of the subs based on what Tom wrote at PSA where he said you should add about 1msec delay for every foot away the sub is from you. So I have 1 sub that is 3 feet away facing me and 1 sub in the back left corner that is 9 feet away so I did adjust that. Can't really tell if that made a big difference though. Maybe slightly better.
But I think Erik is right that the only true way to fix this is to move my speakers around and likely get them more off the front wall. Right now they are about 10 inches off the wall and they probably need to be moved out more.
Here is updated measurements and I zoomed the axis so you can better see the contours.
@audiorusty, interesting idea about the variable crossover points on the subs. That seems cool. The acoustic fields guy also recommended subs at different heights to make things smoother.

www.diabolicaldesign.net/measurefix.jpg

Here is another comparison, this time with left sub, 2 subs and no subs and a bit more smoothing (1/12) to make this more clear.
www.diabolicaldesign.net/smooth.jpg

@erik_squires Its in the picture above called Measurefix. The purple line is with no subs (legend on the top left). I also tried doing 1 or the other sub as well.

Here I did a curve with just mains, no subs and bit more smoothing at 1/12.
http://www.diabolicaldesign.net/nosubs.jpg

http://arqen.com/acoustics-101/speaker-placement-boundary-interference/Hrmmm
No more space right now for more subs

Actually this seems to collapse my sound stage and squash imaging towards the center as well