Thanks for the recommendations. My speaker distance settings are correct, 10 feet for each of the front 3 speakers. I also calibrated all speakers with my Radio Shack sound meter. The way I was given to understand to do it, and the way I did, was to set the receiver master volume setting to 0db, and then calibrate each speaker to 75db. I am not sure of what advantage your suggestion would offer me, as I would just end with a different master volume for regular listening.
The settings I was talking about, with regard to my dissatisfaction with the sound from the center, are speaker size and crossover for the center speaker. It doesn't seem to matter what crossover settings I select, in that whenever I switch the center speaker selection from "None" to "small" or "large", I lose all the bass out of male voices. I had thought that the sub would pick that up, but it just doesn't, and I have the crossover setting on the sub turned up as high as it goes, and have tried all the crossover frequencies available on the receiver.
This is why I am thinking a really big center speaker is indispensable for accurate movie dialog reproduciton.