I don't use a center channel speaker. In fact, I don't use surround speakers, strictly two channel with rear subs. The soundstage is extremely wide. tall, and deep. It is kind of an Imax effect, yes, just with two speakers. In fact, there have been several times when someone hears the system the first time that they ask me to turn off the sound from the TV (centered between the speakers), which of course was never on. Speech, as everything else, is just as clear from the extreme left or right as from the center listening position.
The speakers, acting as a virtual point source, have an extremely wide and tall dispersion throughout the audio range and above, so even seated or standing directly in front of the left or right speaker, there is still a wide soundstage extending to the opposite speaker, again with a solid and clear center image.
The system includes a pair of 15 inch subwoofers at the rear of the listening room with phase offset and low pass dialed in. These subs are an integrated component of the speakers with their signal derived from the front bass driver's speaker input. This way, the back EMF from the bass is integrated with the signal. The purpose of the subs is to neutralize room resonances and to reproduce the natural hall ambience that is embedded in the signal.
The speakers are 6 foot towers using a WWMTMWW vertical array. They're 13 feet apart (center to center) with the drivers 6 feet from the front wall. The ceiling is 9 ft at the side arched to 10.5 ft in the center. The room is 21 ft wide and 50 to 70 ft long. The subs are 46 ft from the front drivers. The normal center listening position is ~13 ft from each speakers, making an equilateral triangle with the towers.
Apologies for the long post.
Robert