Are the bass and guitar player using their own gear for sound? Or will they also be run through the PA system? How big is the room? What is the setup? Like are these 500 people going to focus their attention on you guys and rocking out? Or is it more a dance hall type thing?

My band typically plays for venues of 500 and up to about 2000, we have a couple different setups for different type gigs.

For a dance hall type thing with people dancing, talking and you don't need that "in your face" sound, we use just two 15" horn subs and two 12" tops. 1000W amps per side for bass and 500W per side for tops. This sounds full and good enough. For rock concerts where people are rocking out and we need to punch out some ear drums we use eight 15" horn subs with 1000W per cab for bass and eight 12" tops with 500W per cab. We like 12" over 15" for tops because they tend to push out more mids faster - the 15" are a little slower and require more power. The reason we don't use 18" or 24" bass cabs is that they work better for disco, hiphop and trance music that require more sub-bass. For anything between 50hz and up a group of 15"s will push out more bass and air than a 18" cab. Atleast in my experience that is

DocZ