when i place my subs in my sitting room, i can experience low frequency(25-40) very well. BUT beats and punches of 50hz to 200 hz sound is not heard so well. when i place my subs in my bedroom it goes the other way round. low frequencies are not heard and bass having frequency 50-200 are heard fantasticly. i want to have the same effects in my sitting room. i dont understand how to do it. CAN ANYONE PLEASE HELP ?

I hate to say this, but usually there is not one "magic" spot that will make everything sound great all of the time. People try and put it in a corner to get the most reinforcement and typically they also try to put it close to the listening postition. The room dimensions have allot to due with what is accented and not. The best bet is to find a place in the room that is room friendly and has as close to what you want in SQ. Another "trick" that people sometimes use is put the sub at your listening position. Then play a track with allot of bass and walk around the room. Place the sub in the area or general area where the bass sounds the best for you. The next bet might be to get some room treatments and(or) an EQ to tailor the sound to your liking.
Also, the following has some basic "rules" that may be helpful in setup if you already did not know them.
http://www.robbroy.net/HT/SubwooferErrors.cfm

There are a couple of things you can try. Sometimes, a change of a foot or two in either your listening position or the sub position can make a tremendous difference. Try experimenting with incrementally small changes in positioning.

If you really want to see what's going on, think about doing an in-room frequency response check using the free REW software and an SPL meter.