Theatre organs have horseshoe-shaped arrangements of stop tabs (tongue-shaped switches) above and around the instrument's keyboards on their consoles.
Organs in the UK had a common feature: large translucent surrounds extending from both sides of the console, with internal colored lighting.
Theatre organs began to be installed in other venues, such as civic auditoriums, sports arenas, private residences, and churches.
Though there are few original instruments, hundreds of theatre pipe organs are installed in public venues throughout the world today,[1] while many more exist in private residences.
The earliest concepts of the theatre organ were modified pianos with a few ranks of pipes and various sound effects, housed in one cabinet, and typically located in the pit area.
Robert Hope-Jones's concept, which he called a "unit orchestra", was developed and promoted, initially by the Rudolph Wurlitzer Company of North Tonawanda, New York.
After the "golden years" of the 1920s and 1930s, many were scrapped or sold to churches, private homes, museums, ice rinks, rollatoriums, and restaurants.
All signals from the console were transmitted by an electric cable to an electro-pneumatic relay, and from there to the pipes and effects in the organ chambers.