The pipe organ is the largest musical instrument. 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).
The pipes are divided into ranks and controlled by the use of hand stops and combination pistons. Although the keyboard is not expressive as on a piano and does not affect dynamics (it is binary; 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 organs are totally enclosed, meaning that all the divisions can be controlled by one set of shutters. Some special registers with free reed pipes are expressive.
It has existed in its current form since the 14th century, though similar designs were common in the Eastern Mediterranean from the early Byzantine period (from the 4th century AD) and precursors, such as the hydraulic organ, have been found dating to the late Hellenistic period (1st century BC). Along with the clock, it was considered one of the most complex human-made mechanical creations before the Industrial Revolution. Pipe organs range in size from a single short keyboard to huge instruments with over 10,000 pipes. A large modern organ typically has three or four keyboards (manuals) with five octaves (61 notes) each, and a two-and-a-half octave (32-note) pedal board.
Wolfgang Amadeus Mozart called the organ the "King of instruments". Some of the biggest instruments have 64-foot pipes (a foot here means "sonic-foot", a measure quite close to the English measurement unit), and it sounds to an 8 Hz frequency fundamental tone. Perhaps the most distinctive feature is the ability to range from the slightest sound to the most powerful, plein-jeu impressive sonic discharge, which can be sustained in time indefinitely by the organist. For instance, the Wanamaker organ, located in Philadelphia, USA, has sonic resources comparable with three simultaneous symphony orchestras. Another interesting feature lies in its intrinsic "polyphony" approach: each set of pipes can be played simultaneously with others, and the sounds mixed and interspersed in the environment, not in the instrument itself.
Most organs in Europe, the Americas, and Australasia can be found in Christian churches.
The introduction of church organs is traditionally attributed to Pope Vitalian in the 7th century. Due to its simultaneous ability to provide a musical foundation below the vocal register, support in the vocal register, and increased brightness above the vocal register, the organ is ideally suited to accompany human voices, whether a congregation, a choir, or a cantor or soloist.
Most services also include solo organ repertoire for independent performance rather than by way of accompaniment, often as a prelude at the beginning the service and a postlude at the conclusion of the service.
Today this organ may be a pipe organ (see above), a digital or electronic organ that generates the sound with digital signal processing (DSP) chips, or a combination of pipes and electronics. It may be called a church organ or classical organ to differentiate it from the theatre organ, which is a different style of instrument. However, as classical organ repertoire was developed for the pipe organ and in turn influenced its development, the line between a church and a concert organ became harder to draw.
In the late 19th century and early 20th century, symphonic organs flourished in secular venues in the United States and the United Kingdom, designed to replace symphony orchestras by playing transcriptions of orchestral pieces. Symphonic and orchestral organs largely fell out of favor as the orgelbewegung (organ reform movement) took hold in the middle of the 20th century, and organ builders began to look to historical models for inspiration in constructing new instruments. Today, modern builders construct organs in a variety of styles for both secular and sacred applications.
Theatre and cinema
Theatre organ in State Cinema, Grays. (Compton Organ)
Marimba in the solo chamber at Ann Arbor's Michigan Theatre (3/13 Barton
The theatre organ or cinema organ was designed to accompany silent movies. Like a symphonic organ, it is made to replace an orchestra. However, it includes many more gadgets, such as mechanical percussion accessories and other imitative sounds useful in creating movie sound accompaniments such as auto horns, doorbells, and bird whistles. It typically features the Tibia pipe family as its foundation stops and the regular use of a tremulant possessing a depth greater than that on a classical organ.
Theatre organs tend not to take nearly as much space as standard organs, relying on extension (sometimes called unification) and higher wind pressures to produce a greater variety of tone and larger volume of sound from fewer pipes. Unification gives a smaller instrument the capability of a much larger one, and works well for monophonic styles of playing (chordal, or chords with solo voice). The sound is, however, thicker and more homogeneous than a classically designed organ.
In the USA the American Theater Organ Society (ATOS) has been instrumental in programs to preserve examples of such instruments.
Chamber organ by Pascoal Caetano Oldovini (1762).
A chamber organ is a small pipe organ, often with only one manual, and sometimes without separate pedal pipes that is placed in a small room, that this diminutive organ can fill with sound. It is often confined to chamber organ repertoire, as often the organs have too few voice capabilities to rival the grand pipe organs in the performance of the classics. The sound and touch are unique to the instrument, sounding nothing like a large organ with few stops drawn out, but rather much more intimate. They are usually tracker instruments, although the modern builders are often building electropneumatic chamber organs.
Pre-Beethoven keyboard music may usually be as easily played on a chamber organ as on a piano or harpsichord, and a chamber organ is sometimes preferable to a harpsichord for continuo playing as it is more suitable for producing a sustained tone.