An organ stop is a component of a pipe organ that admits pressurized air to a set of organ pipes. Its name comes from the fact that stops can be used selectively by the organist; each can be "on", or "off".
The choir division of the organ at St. Raphael's Cathedral, Dubuque, Iowa. Shown here are several ranks of pipes, each of which would be controlled from one of the stops on the console.
The organ at the Naval Academy Chapel has 522 stops.
The pipe organ is a musical instrument that produces sound by driving pressurised air through the organ pipes selected from a keyboard. Because each pipe produces a single pitch, the pipes are provided in sets called ranks, each of which has a common timbre, volume, and construction throughout the keyboard compass. Most organs have many ranks of pipes of differing pitch, timbre, and volume that the player can employ singly or in combination through the use of controls called stops.
Pipe organ in the collegiate church of St. Michael in Neunkirchen am Brand
Hydraulis from the 1st century BC, oldest organ found to date, Museum of Dion, Greece
4th century AD "Mosaic of the Female Musicians" from a Byzantine villa in Maryamin, Syria.
9th century image of an organ, from the Utrecht Psalter.
