Setting Sub Crossover Freq

I like a slight overlap of 10-15 hz. any where from 55-60 seems like a good starting point for the frequency of your speakers. Placement of the sub and of the speakers is critical. If your sub is in the corner then you'll have more bass but not the best bass. If the sub sounds boomy then pull it away from the corner. Also, and this is personal taste, find a song that you're familiar with on the bass and turn the sub volume down until it's not enough and then start turning it up until the bass notes are to your liking. I like my bass to be an enhancment to the mains instead of thundering and overpowering. But thats just me. Hope this helps. Zmanastronomy

Not neccesarily. What happens is that the frequency changes to a lower and less used freq. Once the music hits the lower freq it will still have the same volume just a lower freq responce. Play around with it and you'll get it just to your liking. It takes time, several weeks or more to tune a system in. Aiming the mains is very critical for stage and imaging. Tweek and listen for a while and tweek somemore and when you get something you don't like just go back to were you had it before.

As far as polarity goes it's 0 or 180 according to the room. Have someone switch the polarity while you listen to a song with constant bass and choose the polarity based on which one has the most sound pressure. The loudest pressure is the correct phase.