whoom instead of BOOM

hi everyone. new into home theater(though been running loudspeakers off a tv since the early 80's). anyway, i'm having a problem with the low frequencies. at the volume at which i get the spls i want(pants rattle a bit, couch vibrates etc.) i get a whooom response and not BOOM and lose definition and clarity. is it possible to acheive these spls without the "whoom" mucking it all up?
the room: 35x25x10 it is not closed in completely
the system: mirage m5si fronts, mirage 595si rears, mirage om-c2 center, mirage bps 150i sub(also working with dialing in a polk psw12 sub together), onyo txds797 processor. the front end is a panasonic dvd-s97.
I had great boom with HSU Research subs, they can pass for music but just barely.....but for movies I actually knocked pictures off the wall twice, one I remember was during Jurasic Park.
Don't know what you mean by whoom....but if you want to rattle the windows and couch and feel the sound pressure on your pants then you need one if not two big subwoofers with 15 inch woofers and 500 watt amplifiers and huge drive motors. I assume you want a room filling sound with excellent transient response rather than just the typical resonant dull whooom you get from most subs(especially ported subs).
My Velodyne HGS-15 is crossed at 80 Hz. It blends seamlessly with my KEF 104/2s, generates that subtle vibration you feel at a pipe organ recital when a big pipe is opened, and can make you feel pressure on your chest during explosions in certain flicks. With a 15 inch woofer, 1200 watt DC amp, and huge motor, it meets Shadorne's specifications. In my application, a 19 X 14 X 8 room, an Auralex SubDude base greatly improves the sound, removing boom and seeming to extend the low end. But it is a 100 pound cube when you want to move it.

thanks guys. just to clarify a bit. "whoom" is trying to describe lf passages that are lacking attack. they're loud but have no definition and totally drown out other lf tones during the passage. i'm just wondering, does everyone have a volume point at which their room acoustics and or equipment turn to this type of response, instead of detailed well defined bass?
I reckon Dbphd has the solution...get a big Velodyne HGS-15 (or two). Small subs just can't handle the transient energy above a certain point (around 100 db which is not loud for frequencies from 20 to 40 Hz) and run out of gas at too low an SPL to be convincing in a large room - they end up lacking definition.
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Bag End is a good choice, but keep in mind that in order to get the deep bass (down to 8Hz), you will also have to get an electronic device which is called an "Infra Integrator" and that will be an additional $1000. Otherwise the woofer will only go down to 60Hz.

Your post is confusing to me. Why would you define deep bass as 8 Hz, and not the 15-20 Hz available with a big sub? What does an infra integrator do? I presume shake you, because you sure as hell can't hear 8 Hz. What woofer will only go down to 60Hz? That's pretty pathetic performance for a woofer.

I wonder if you confused OP as much as you did me.

The large VMPS subs are another option...at least a pair, four would be even better in your room.

You can order them active, or passive, I'd go passive myself.

I had same disappointing problem with my system. Until I installed MIT one in/two out splitter gizmo on end of toooo cheap (Radio Shack) IC going to sub from receiver, that corrects for low frequency phase shifts/smear from general purpose cables not specific to sub woofer use. Had tried placing sub (DefTech 15") different spots in room and reversing phase etc. Not sure if gizmo still available but suspect better sub-specific cable would help. Let us know how it all works out, this change to my system a few years ago was one of my most satisfying upgrades. Mike.
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everyone thank you for your input. i think i may have led us all down the wrong path. 10x18x7 are the exact dimensions of the room, so it is not very big at all. even though a $5000 velodyne dd18 may be a solution it isn't quite my cup of tea. i'd go to a vmps or bag end type. however, i was more wondering if you all knew wether or not, despite decent quality subwoofers, is there a point where they may just get boomy and undefined sounding or is it my room, or are they really not that good. the mirage does sound fantastic at lower volumes. the best i've heard in my limited experience. i am lrking everywhere i know of to try and catch a vmps used for sale. it is tough unting ou there for one on the cheap. i may also go with a clark synthesis. thanks again guys.
Ahhhh I get it...

Clouseau: Do you have a WHOOM?
Inn Keeper: I do not know what a WHOOM iz!
Clouseau: Zimma
Inn Keeper: Ahhh.. a RRRUUUMMM!
Clouseau: That is what I have been saying you idiot! WHOOM!

You mean your Zimma is small and you want more vavoom for your whoom!
HA! very clever mr. bond.
james bond: do you expect me to talk?
evil enemy: no meester bond, i expect you to die...