Hi lightoflife,
If the crossovers are still functional, and the speaker parameters have not changed significantly, the same crossovers can be reused with the new speakers.
Otherwise, if you want to change them for any reason (maybe they are defective or very old and need reconditioning or the speaker specs are different), the situation is a bit different and requires some knowledge on both the parameters of the speakers and those of the enclosure (architecture, resonance frequency, and so on).
Mainly, any crossover unit or pack you can find on the market has three basic parameters:
- maximum power throughput (should be the same or more than the associated speaker power)
- frequency cut-off frequencies and slope (should be inside the...