Most theater organs use many sets (ranks) of reed and flue pipes of various shapes, pipe scales, and so forth to generate a variety of timbres.
1980, Harvey E[lliott] White, Donald H. White, “Wind Instruments”, in Physics and Music: The Science of Musical Sound, Philadelphia, Pa.: Saunders College Pub./Holt, Rinehart and Winston, page 245; republished Mineola, N.Y.: Dover Publications, 2014, part 3 (Musical Instruments), section 18.7 (The Theater Organ), page 245