What is a Theatre Pipe Organ? Here's your opportunity to find out. TOSDV is having an Open House to introduce to you our 3/24 Wurlitzer theatre pipe organ. What does "3/24" mean? How is a "theatre" organ different from a "church" organ? What is a "Unit Orchestra"? We'll explain what you see (the console) and what you don't see (the blower, the pipes, the percussions, the "toy counter", etc.). How does it all work?