A well designed center channel speaker, driver and timbre matched is preferred. AS pointed out, it is easy to slip into poorly done center channel speakers which of course due stink heartily compared to using a fullrange speaker.
But I am referring to getting a center actually designed well, (not cheaply or offhand by a non-HT focused manufacturer) and matched. A good center is not a speaker on its side and is not designed that way. DTS concert DVDs are often produced to emphasize center vocals in balance with background vocals to the mains.A Center channel is necessary to hear the optimal intent of the sound engineer, because this is how it was mixed to be heard. And an intended center channel speaker is the best choice. Of course using a standard 80hz crossover makes a full range even less of a consideration. in that scenario signal frequency below 60 HZ ( 80hz is not a brick wall) is all gone to the subwoofer(s) so full range mains and centers in HT is largely a waste anyway.
I've set up HTs both ways with decent results in each case. But a dedicated center is definetly the way to go.
But I am referring to getting a center actually designed well, (not cheaply or offhand by a non-HT focused manufacturer) and matched. A good center is not a speaker on its side and is not designed that way. DTS concert DVDs are often produced to emphasize center vocals in balance with background vocals to the mains.A Center channel is necessary to hear the optimal intent of the sound engineer, because this is how it was mixed to be heard. And an intended center channel speaker is the best choice. Of course using a standard 80hz crossover makes a full range even less of a consideration. in that scenario signal frequency below 60 HZ ( 80hz is not a brick wall) is all gone to the subwoofer(s) so full range mains and centers in HT is largely a waste anyway.
I've set up HTs both ways with decent results in each case. But a dedicated center is definetly the way to go.