Here are three simple crossover circuits that can be used in the construction of two-way and three-way closed box or reflex cabinets.
Unless you have experience putting together printed circuit boards, we’d recommend using a pre-drilled printed circuit board (such as Veroboard). It’s worth gluing the components down if the cabinet is likely to be transported frequently.
Follow the circuit diagrams carefully, and test by connecting up to the drivers and running the system at very low levels. Also check that the drivers are all connected in the correct phase.
The attached PDF document (see below) contains the crossover diagrams and all the information you need on on component values and power handling.