The "sweetspot" in an HT system is supposed to be taken care of ( primarily ) by the center channel speaker, not the right and left mains. The right and left mains are primarily there to provide spatial cues and extend the imaging that is presented by the center channel as called upon to do so.
Multi-channel musical reproduction is a bit different, but once again, having the left / center / right speakers too close together tends to blurr the imaging that would normally take place.
When properly situated, one should be able to follow / point to the sound of a test tone as it slowly travels across the fronts. Just as there is "stereo seperation" from the left to right in a two channel system, you should have separation from left to center and center to right. With proper recording techniques, you can have images that are presented hard left, directly in-between the left speaker and center speaker, centered, directly in-between the center speaker and the right speaker and hard right.
Most people don't hear all of the spatial cues on multi-channel recordings simply because their system / speaker selection / speaker placement lacks the proper amount of separation. On top of that, their speakers are not mounted at the same appr height, further skewing the imaging that takes place.
Quite honestly, this is a relatively hard thing to do, especially if one has larger speakers and / or a large TV set. My center speaker is a bit higher than the equivalent mid & tweeter height of my mains, but it is the best that i can do with my given installation specifics.
Since we're on the subject, my HT system utilizes speakers that share several design similarities to the larger Dunlavy's. That is, they all have "acoustic blankets" on the baffles, which helps to focus the imagery and minimize baffle related diffraction. They also utilize two large acoustic suspension woofers per cabinet. Like the Dunlavy's, the two woofers load into the room asymmetrically. Like the Dunlavy's, these speakers are tuned to a Qts of appr .5 for optimum bass transient characteristics. Like the Dunlavy's, they also work best with GOBS of power on hand. Sean
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