B&W puts it in the aluminum base of its flagship 800.
Others epoxy the entire crossover box to prevent vibration between parts. Worst location is behind woofer. Best is that area of box that vibrates least under intense loudness. I assume you're building a box. Put the crossover in a box of 1 inch mdf, lined in & out with heavy rubber u/lay-glued on. Fill w epoxy. Attach with a permanently flexible, non solidifying adhesive like used in soundproofing. Because of size I fexibly mounted mine outside. Enjoy.
Others epoxy the entire crossover box to prevent vibration between parts. Worst location is behind woofer. Best is that area of box that vibrates least under intense loudness. I assume you're building a box. Put the crossover in a box of 1 inch mdf, lined in & out with heavy rubber u/lay-glued on. Fill w epoxy. Attach with a permanently flexible, non solidifying adhesive like used in soundproofing. Because of size I fexibly mounted mine outside. Enjoy.