izotope Ozone has multiband stereo imaging which can easily do this. There are also a few freeware vst’s that can do the job.
I’m not sure I follow your thinking completely but just pan the bass into the center and the bass will be “mono.”
However, by it’s very nature, bass frequencies are omni directional below a certain frequency, so, even though you might be panning the bass into the “center” the room will resonate to the left, to the right, above, and even out into the street if it’s loud enough.
But, I think I know what your after and that is “tight, completely centered bottom end.” I’ve heard exceptionally well done mixes where the bottom end is so tight and is so well controlled that it is virtually “pinned” in between the speakers.
You need to remove sub frequencies where appropriate…if it’s film music, you’ll want to keep those cinematic subs…if it’s pop music, try cutting out the fat. You’ll noticed that the more fat you get rid of the tighter and more centered your mix will become.
Compression and even better, side chain compress the bass and the kick drum so they work as a unit.
Duplicate the track, cut the high frequencies of one of them and pan to mono.
Cut the low end of the first track and mix as desired.
No plugin needed…
You should be able to do this without any 3rd-party plugins just using Cubase’s routing and EQ.
Let’s assume you have a project with 8 stereo audio tracks.
Create 1 stereo group, 1 mono group and one stereo track.
Route all your original 8 tracks’ outputs to the stereo group and route the output of that group to the mono group and insert a low-pass – this is your bass in mono.
For the stereo track you added, select the stereo group as its input and insert a hi-pass – this is your main mix minus the bass.
Play around with the frequencies of the low-pass and hi-pass to achieve an overlapping smooth-sounding crossover and mix the mono bass dead centre.