Involving reproduction equipment that was relatively inexpensive for exhibitors to license and install, Dolby Stereo soon enough became the norm for market-oriented filmmakers. Its spread was not so endemic as had been that of the Western Electric amplification system that initiated the era of the sound film. With no alternatives except to continue showing silent films, all theater owners who wanted to remain in business in the 1927-30 period were in effect compelled to adopt the Western Electric system; Dolby was optional, a requirement only for those theater owners who wished to capitalize on “blockbuster” hits.