Newbee...SW crossover frequency depends very much on what your particular subwoofer can do. Based on quite a bit of experementation I have also concluded that the type of music being played also has a big effect, so I have crossovers that enable me to change frequency with the twist of a knob. For some classical music I let the Maggie 1.6 take it from 50 Hz up. For some massive pieces, such as theatre organ, I run the SWs up to 200-300Hz, and there is no doubt that it is better.
An interesting test that I have run is to play white noise and sweep the X/O between 40 Hz to about 400 Hz and higher. With my rig there is no audible change in the sound up to about 300 Hz, which tells me that I have the levels well matched and that the SW (a 12" and a 15" for each channel each driven by their own amp) are not out of gas at 100 Hz. Of course my SW systems are custom designs that have been extensively tweeked, and my results may differ from those using off-the-shelf SW.
An interesting test that I have run is to play white noise and sweep the X/O between 40 Hz to about 400 Hz and higher. With my rig there is no audible change in the sound up to about 300 Hz, which tells me that I have the levels well matched and that the SW (a 12" and a 15" for each channel each driven by their own amp) are not out of gas at 100 Hz. Of course my SW systems are custom designs that have been extensively tweeked, and my results may differ from those using off-the-shelf SW.