Overview
Pipe organs use wind moving through pipes to produce sounds. Since the 16th century, pipe organs have used various materials of pipes, which can vary widely in timbre and volume. The pipes are divided into ranks and controlled by the use of hand stops and/or combination pistons. Although the keyboard is not expressive as on a piano and does not affect dynamics (pressing a key only turns the sound on or off), some divisions may be enclosed in a swell box, allowing the dynamics to be controlled by shutters. Some special registers with free reed pipes are expressive. These instruments vary greatly in size, ranging from a cubic yard to a height reaching five floors, and are built in churches, synagogues, concert halls, and homes. Small organs are called positive (easily placed in different locations) or portative (small enough to carry while playing). Increasingly hybrid organs are appearing in which pipes are augmented with electronic additions. Great economies of space as well as cost are possible especially when the lowest (and largest) of the pipes can be replaced.
Non-piped organs include the reed organ or harmonium, which like the accordion, harmonica or mouth organ use air to excite free reeds.
Electronic organs or digital organs generate electronically produced sound through one or more loudspeakers.
Mechanical organs include the barrel organ, water organ, and Orchestrion. These are controlled by mechanical means such as pinned barrels or book music. Little Barrel organs dispense with the hands of an organist and bigger organs are powered in most cases by an organ grinder or today by other means such as an electric motor.
Read more about this topic: Organ (music)