Final answer:
The substructure should support at least 1.5 to 2 times the speaker array's design weight of 212 lb, which means a minimum of 318 to 424 lb.
Step-by-step explanation:
The minimum weight that the substructure and mounting assembly should be able to support must exceed the published design weight to ensure safety. While specific building codes and safety factors may vary, a common practice is to use a safety factor of at least 1.5 to 2 times the maximum expected load. Therefore, for a speaker array with a design weight of 212 lb, the substructure should have a minimum support capacity of 318 to 424 lb (1.5 to 2 times 212 lb).