Bass Response

Do you hear more bass or does it just sound like more because you are not hearing all the highs which tend to be more directional?

It has to do with standing waves in the room. You can effect this by moving the speakers or the listening position. Also take the traps out and then slowly add them until you have the sound you want

Too many bass traps. Two in the front corners should be sufficient. Experimentation, as Ahendler suggested will give you the answer.

Thank You All
There are more bass at standing position or on the sides along th ewall. I meant so much more bass which create a much more fuller sounding.
I've tried to move speakers without any affect, moving listening position closer to back wall improves bass response at listening chair position but not as good as at standing position.
I don't know if i need the address the issue through the use of ceiling treatment E.g. ceiling bass trap or diffusers
Room: 6 meters x 5 meters x 2.4 meters (L x W x H). Speakers are placed along the width of the room.
Gear types: Wilson Sophia 3, McIntosh MC501, ARC Ref 3, Esoteric K03, Weizhi PRS6, Shunyata Hydra 2, Lessloss Sig PCs (amps), Stefan Audio PCs (cdp, pre), Nordost Quatro Fil ICs, Grover SX SCs, Finite spider racks, Vibrapod cones and dedicated power supplies

I've done my simple mod calculation but really have no idea where are the problems or how/ where to apply acoustic treatments.
Appologise for this as i'm new to these acoustic treatments. Your helps will be much appreciated

L 19.7
W 16.5
H 7.9
Cu.Ft. 2567.895
L-1 28.68020305
W-1 34.24242424
H-1 71.51898734
L-2 57.36040609
W-2 68.48484848
H-2 143.0379747
L-3 86.04060914
W-3 102.7272727
H-3 214.556962
L-4 114.7208122
W-4 136.969697
H-4 286.0759494
L-5 143.4010152
W-5 171.2121212
H-5 357.5949367
L-6 172.0812183
W-6 205.4545455
H-6 429.1139241
L-7 200.7614213
W-7 239.6969697
H-7 500.6329114
L-8 229.4416244
W-8 273.9393939
L-9 258.1218274
W-9 308.1818182
L-10 286.8020305
L-11 315.4822335

I tried panel bass traps (Gik 244) in the front corners and like yourself wasn't satisfied with the results. The addition of Acoustic Science Corporation 16" Supertrap Tube Traps in the front corners was a huge improvement in bass management!!! Your speakers appear to be close to the back wall, how far away are the outside rear corners to the back wall? Side wall? Try playing a record with acoustic bass, I like Ray Brown's "Solar Energy", move the speaker away from the front wall in small increments until bass becomes light, I use rear outside corner for measurements this allows changing toe in and not changing distances. Now start moving towards front wall in small increments until you like the definition and size of the bass, did this move the null and improve the overall balance of the sound in the listening position. I didn't mention the side walls or toe in adjustments to keep variables to a minimum for now.

Thanks Samhar
The speaker outside rear corners are about 3 feet away from the back wall.
I've tried Cardas speaker placement method last night and found that it made very little difference in the bass response at the seated position.
I've also bass tested using Jennifer Warnes Deep Way Down song. There was plenty of bass at the seated postion which make one thing that an active sub is running in the room. (Very nice, I like it!). However, with certain songs, the bass is still flying half way height in the room.

Updated Mode Cal base on precise room measurements...
Can someone please explain what are the main issues in my room and recommended treatment methods? It seems there are freq. jumps on H values
Your help will be much Appreciated!

L 16.08 H-4 287.1664549
W 14.1 L-5 175.6840796
H 7.87 W-5 200.3546099
Cu.Ft. 1784.34936 H-5 358.9580686
L-1 35.13681592 L-6 210.8208955
W-1 40.07092199 W-6 240.4255319
H-1 71.79161372 H-6 430.7496823
L-2 70.27363184 L-7 245.9577114
W-2 80.14184397 W-7 280.4964539
H-2 143.5832274 H-7 502.5412961
L-3 105.4104478 L-8 281.0945274
W-3 120.212766 W-8 320.5673759
H-3 215.3748412 L-9 316.2313433
L-4 140.5472637 W-9 360.6382979
W-4 160.2836879 L-10 351.3681592
L-11 386.5049751

Firstly, have you considered reading Dr Floyd Toole's book? It will educate you about room physics and help you understand why you're hearing what you're hearing. A little education can go a long way towards effectively treating your room to get the sound you want.

Secondly, have you a room mesurement tool such as the OmniMic, XTZ, or REW so that you can take "Freq VS SPL" and "Reverb (RT60)" or "Bass Decay" measurements? These tools will help you see what your ears are hearing and help diagnose what the problem is. Without tools and data you're blind and only with infinite time and trial and error will you get things right.

Lastly, bass is always stronger near or at a surface so when you stand up from your chair your head is closer to the ceiling (than it was when sitting) so unless your ceiling is really tall you should hear more bass. Similarly when you walk around the room and go close to a wall. This can be verified with a basic Radio Shack SPL meter.

Read the book first though . . .

Thanks Kevinzoe
I'm currently chewing through Master Handbook in Acoustics with over 400 pages! Very good reading...
I have more understanding on room modes and what they meant. However, i still can't work out a solution to my bass fly issue. I think toward the end of the book will have a chapter on room, acoustic and speaker placement topic
I'll post my findings hopefully in a couple of months!