In GENERAL your looking at a 6.5" mid woofer from about 60-500hz, a 2.5" midrange from about 500-4000hz and a tweeter from about 4000hz and up. That's just an example. You can overlay of underlap the points between speaks, it's all up to your liking. You can also play with the steepness of the cross over. 6db slope will allow the speaker to gradually stop playing the frequency you set it at whereas a 24db/octave slope will cut off the frequency much more abruptly from where you set it.