A theatre organ (also known as a cinema organ) is a pipe organ originally designed specifically for imitation of an orchestra. New designs have tended to be around some of the sounds and blends unique to the instrument itself.
Theatre organs took the place of the orchestra when installed in a cinema (movie theatre) during the heyday of silent films. Most theatre organs were modelled after the style originally devised by Robert Hope-Jones, which he called a "unit orchestra".
Such instruments were typically built to provide the greatest possible variety of timbres with the fewest possible pipes, and often had pianos and other percussion instruments built in, as well as a variety of sound effects such as a siren.
Theatre organs are usually identified by their distinctive horseshoe-shaped consoles, which are frequently painted white with gold trim. An original example is the 3/13 Barton from Ann Arbor's historic Michigan Theatre. The organ was installed in 1927 and is currently played daily before most film screenings. There were over 7,000 such organs installed in American theatres from 1915 to 1933, but fewer than 40 original instruments remain in their original theatres. Though there are few original instruments in their original theatres, hundreds of theatre pipe organs are installed in public venues throughout the world, while hundreds more (typically rescued from defunct theaters) exist in private residences.
Many organ builders supplied instruments to theatres. The Rudolph Wurlitzer company, to whom Robert Hope-Jones licensed his name and patents, was the most prolific and well-known manufacturer (2,234 were built), and the phrase Mighty Wurlitzer was the hallmark of quality.
Many of the innovations which furthered the evolution of theatre organ design simply allowed it to do its job better. Although not all of these ideas originated with Robert Hope-Jones, he was the first to successfully employ and combine many of these innovations within a single organ aesthetic. Some of these important developments are: electro-pneumatic action, which allows the console to be physically detached from the pipe chambers, connected only by a cable; unification, the process whereby pipe ranks are extended and tuned in sympathy with other ranks, and allowing any rank of pipes to be played from any manual or the pedals; imitative stops, where pipe ranks are more imitative of their symphonic counterparts; and development of pipes able to speak successfully on higher wind pressures.
After some major disagreements with the Wurlitzer management, Robert Hope-Jones took his own life in 1914—but not before profoundly influencing the development of the theatre organ. The Wurlitzer company continued to flourish, becoming the largest manufacturer of theatre pipe organs in the world. Indeed, while there were many other builders of these instruments, the name "Wurlitzer" became generically synonymous with the theatre organ.
Other manufacturers included Page, Marr & Colton, Compton, Möller, Robert-Morton (the "Wonder Morton"), Conacher, Hilsdon, Kimball, Barton, Hillgreen-Lane, Kilgen, E. M. Skinner, Austin, Christie, and Hill Norman & Beard. These last two were both brand names for the same company, which specialized at the time in standardized extension organs with electro-pneumatic action, ideal for the theatre and then promoted as convenient and cost-effective for churches. In general, the Christie brand was used for theatre organs, which came with contemporary-styled consoles, while the firm's own name Hill Norman & Beard appeared on similar and sometimes identical pipes and actions supplied to customers seen as less frivolous, controlled by a traditional drawknob-stop console. Their standardized pipe, relay and blower packages were called unit organs, and for theatre use were augmented with percussion and other additional effects. The Möller firm specialized in unit organs for church use, many of which remain in service in small churches to this day.
Compton cinema organs, built by the John Compton Organ Company of Acton, were the most prevalent of theatre organs in the UK; 261 were installed in cinemas and theatres in the British Isles. Comptons made many fine church and concert organs as well. Their cinema organs employed state of the art technology and engineering and many are still in existence today. One of the most notable is the large 5-manual example at the Odeon Cinema Leicester Square in central London.
Several organ builders were also known for their specialities. Wurlitzer was well known for its reeds and special effects; Kimball was an innovator in string tones; Barton constructed lush tibias for their organs; Möller was famous for its foundation ranks. And although not an organ manufacturer, the J. C. Deagan Company built many of the chromatic percussions (xylophone, chrysoglott -Wurlitzer's name for a celesta, glockenspiel, etc.) that are found in most theatre organs.
During the silent movie era and into the early 1930s, theatre organs were built in large numbers in the US and few in the United Kingdom. They were built in a variety of sizes, filling the gap between a simple piano accompaniment and a full orchestra. Indeed, when theatre owners hired orchestras to accompany silent movies, they frequently included a pipe organ to provide relief to the orchestra, and to play for less-expensive showings.
On the European continent the theatre organ appeared only after World War I in the cinemas. Some instruments came from Wurlitzer, but there were European organbuilders like M. Welte & Söhne and Walcker in Germany, and there were also Dutch manufacturers like Standaart.
After the development of sound movies, theatre organs remained installed in many theatres to provide live music between features. However, after the 'golden years' of the 1930s, many were scrapped or sold to churches, private homes, museums, ice rinks, rollatoriums, and restaurants. In that era, commonly known as the theatre organ's second golden age (the 1950s), many of the tonal characteristics of theatre organs became somewhat more exaggerated than they had been in the silent movie era. This second age also saw the formation of the American Theatre Organ Society.
Many composers got their start by playing the theatre organ. Oliver Wallace, arguably America's first real theatre organist, was soon employed by Walt Disney, and composed, among other things, the score to Dumbo. Jesse Crawford, the first organist ever to sell over a million recordings, was known in households across America as the "poet of the organ". He was also responsible for developing many of the techniques and registrations used in the performance of popular music on the instrument. Rex Khoury composed the Gunsmoke theme. Reginald Dixon MBE was probably the most popular organist of all time, being a household name all over the UK and the British Empire. Probably the most legendary theatre organist of modern times, the late George Wright, was credited with saving the medium from certain demise in the 1950s and 60s, when he created a huge series of studio recordings which sold millions, as he was clever enough to have them included in the new stereo format used in early systems such as Zenith, Admiral and Magnavox. The late Richard Purvis, who was for many years the organist and master of choristers at Grace Cathedral in San Francisco, was also an enthusiastic promoter of theatre organ, and wrote many arrangements for it.
As in a traditional pipe organ, a theatre organ uses pressurized air to produce musical tones. Five important things that distinguish a theatre organ from traditional church organs are unification and extension, the exclusive use of electric action, high wind pressures, percussion instruments, and the horseshoe console.
Unification and extension gives the theatre organ its unique flexibility. A rank is extended by adding pipes above and below the original pitch, allowing the organist to play that rank at various pitches by drawing separate stops or tabs. A simple example of unification follows:
The Tibia Clausa at 8' pitch has 61 pipes. The Tibia can be made available at 4' pitch by adding 12 pipes to the top of the Tibia 8'. Tibia 2' is similarly accomplished by adding 12 more pipes. The Tibia Clausa 16' as a pedal voice is accomplished by adding 12 pipes to the bottom of the Tibia 8'. Hence, in a unified organ, four "ranks" (really tabs or draw-stops) can be obtained from a total of 97 pipes. In a classically designed organ, four "straight" ranks would require 244 pipes. Additionally, up to five mutated stops can be drawn from this 97-pipe rank, resulting in a total of nine stops from a single unified and extended 8' Tibia Clausa.
These ranks are voiced in relation to other pipe ranks in the organ, allowing a handful of ranks in a typical theatre organ to imitate a wide range of instruments. Unification also makes it possible to play any rank of pipes from any manual and the pedals independently, unlike a traditional church organ, where a rank of pipes is playable only from one manual or the pedals, or from two manuals via couplers.
The electro-pneumatic action was invented by Robert Hope-Jones, and is considered by many to be the single most significant development in pipe organs. Up to the turn of the 20th century, all pipe organs were operated by a tracker, tubular pneumatic, or pneumatic Barker-lever action, where the keys and pedals were physically connected to the pipe valves via wooden trackers, except in the case of tubular pneumatic, where all actions were operated by air pressure. Hope-Jones' electro-pneumatic action eliminated this by using wind pressure, controlled by electric solenoids, to operate the pipe valves, and solenoids and pistons to control and operate the various stop tabs, controls, keys and pedals on the console. This action allowed the console to be physically detached from the organ. 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.
Hope-Jones believed that higher wind pressures would allow pipes to more accurately imitate orchestral instruments by causing the pipes to produce harmonic overtones which, when mixed with other pipe ranks, produced tones more imitative of actual instruments. The high wind pressures also led to the development of instruments that are unique in theatre organs (such as the diaphone and tibia clausa), and allowed any rank in the organ to function as a solo instrument. These higher pressures were possible due to the development of high-velocity, motor-driven blowers and wind regulators.
Another hallmark of theatre organs is the addition of chromatic (tuned) percussions. In keeping with his idea of a "unit orchestra," Hope-Jones added pneumatically- and electrically operated instruments such as xylophones, wood harps, chimes, sleigh bells, chrysoglotts and glockenspiels to reproduce the orchestral versions of these instruments.
Later, Wurlitzer added other effects, such as drums, cymbals, wood blocks and other non-chromatic percussions and effects to allow the theatre organ to accompany silent movies.
A traditional organ console was not adequate to control a theatre organ, as the large number of draw knobs required made the console so huge an organist could not possibly reach all of them while playing. Thus, the horseshoe console was born. Based on a curved French console design and using stop "tabs" instead of drawknobs, the horseshoe console now allowed the organist to reach any stop or control while playing any piece of music, eliminating the need to move around awkwardly on the bench. The smaller stop tabs also permitted the addition of many more stops on the console than could be added on a traditional console.
After the advent of unification and the electro-pneumatic action, builders of church organs started to see the advantages of these systems. As a result, several organ builders began adopting these concepts for use in their church organs. Among these were Austin, Möller, Aeolian-Skinner and Kimball, who used electro-pneumatic action in many of their organs. Today, approximately one fourth of all new or rebuilt church pipe organs use an electro-pneumatic action either exclusively, or as an augmentation to existing tracker actions. In the same vein, some amount of unification was utilized in some church organs, and even today many church pipe organs utilize some degree of unification in areas where it is not critical to the "classical" sound sought in such instruments, or in instruments where space for pipes is limited. With stops such as the 32' bourdon in the pedal division, or a 16' reed in a manual division, the basic theatre organ concept of "extension" is commonly—but discreetly—used by even the most noted organ builders.
Current status 
There are many theatre organs still in operation but only a handful are in their original installation.
Most notable of these are the world's largest original installation theatre organs (in order of number of ranks).
North America 
United States 
- Radio City Music Hall New York, New York - 4 manuals, 58 ranks (Wurlitzer, 1932)
- Atlantic City Boardwalk Hall Ballroom Theatre/Concert Organ - 4 manuals, 55 ranks (Kimball, 1931)
- Fox Theatre, Atlanta - 4 manuals, 42 ranks (Möller, 1929)
- Fox Theatre, Detroit - 4 manuals, 36 ranks (Wurlitzer, 1928)
- Fox Theatre, St. Louis - 4 manuals, 36 ranks (Wurlitzer, 1929)
- Ohio Theatre, Columbus - 4 manuals, 34 ranks (Robert Morton, 1928)
- Chicago Theatre, Chicago - 4 manuals, 29 ranks (Wurlitzer, 1921)
- Alabama Theatre, Birmingham, 4 manuals, 29 ranks (Wurlitzer, 1927)
- Shea's Performing Arts Center, Buffalo, 4 manuals, 28 ranks (Wurlitzer, 1926)
- Rialto Square Theatre, Joliet, Illinois, 4 manuals, 28 ranks (Barton, 1926)
- Paramount Theatre, Denver - 4 manuals, 20 ranks, 2 consoles (Wurlitzer, 1930)
- Paramount Theatre, Seattle - 4 manuals, 20 ranks (Wurlitzer, 1928)
- Byrd Theatre, Richmond, Virginia - 4 manuals, 17 ranks (Wurlitzer, 1928)
- Embassy Theatre, Fort Wayne, Indiana - 4 manuals, 16 ranks (Grande Page, 1928)
- Avalon Casino, Avalon, California - 4 manuals, 16 ranks (Page, 1929)
- Riviera Theatre (North Tonawanda, New York) - 3 manuals, 20 ranks (Wurlitzer, 1926)
- Tampa Theatre, (Tampa, Florida) - 3 manuals, 14 ranks (Wurlitzer, 1926)(One of the top 10 iconic show places in the world - Delta Sky magazine)
- Orpheum Theatre, Los Angeles - 3 manuals, 14 ranks (Wurlitzer, 1926)
- Michigan Theatre, Ann Arbor - 3 manuals, 13 ranks (Barton, 1927)
- Paramount Theatre (Anderson, Indiana) - 3 manuals, 12 ranks (Page 1929)
- Redford Theatre, Detroit - 3 manuals, 10 ranks (Barton, 1928)
- Mt. Baker Theatre, Bellingham, Washington - 2 manual 10 ranks (Wurlitzer Style 215 Opus 1558, 1927)
- Temple Theatre, Tacoma, Washington - 2 manuals, 9 ranks (Wurlitzer, 1926)
- California Theatre, San Bernardino - 2 manuals, 10 ranks (Wurlitzer, 1928)
- Jefferson Theatre, Beaumont, Texas - 3 manuals, 8 ranks (Robert Morton, 1927.)
- Virginia Theatre, Champaign, Illinois - 2 manuals, 8 rank (Wurlitzer, 1921)
- Weinberg Center, Frederick, Maryland - 2 manuals, 8 ranks (Wurlitzer, 1926)
- 19th Street Theatre, Allentown, Pennsylvania - 3 manuals, 7 ranks (Möller Style 70, 1928)
- Capitol Theatre, Rome, New York - 3 manuals, 7 ranks (expanded to 10) (Möller Style 70, 1928)
- Temple Theatre, Saginaw, Michigan - 3 manuals, 11 ranks (Barton, 1927)
- Ironwood Theatre, Ironwood, Michigan - 2 manuals, 7 ranks (Barton, 1927)
- Saenger Theatre (Pensacola, Florida), Pensacola, Florida - 4 manuals, under restoration and expansion by Helms Organs
- O'Brien Theatre, Renfrew, Ontario - 3 manuals, 20 ranks (Warren and Robert-Morton pipe-work, former ex-Capitol, Winnipeg ca. 1920)
- Casa Loma, Toronto - 4 manuals, 21 ranks (Wurlitzer Opus 558, July 1922) (Warren console)
- Orpheum Theatre, Vancouver - 3 manuals, 13 ranks (Wurlitzer, 1927)
Great Britain 
- See also Wurlitzers in the United Kingdom
- Southampton Guildhall Compton, Southampton, Hampshire - 4 manuals (Theatre Console) plus 4 manuals (Classical Console), 51 ranks (Compton, 1936)
- Dome Concert Hall, Brighton - 4 manual, 40 ranks (Hill, Norman & Beard - refurbished - 2007)
- Pavilion Theatre Compton, Bournemouth, Dorset - 4 manuals, 24 ranks (Compton, 1929)
- Odeon, Leicester Square, London - 5 manuals, 17 ranks, (Compton, 1937)
- Gaumont State Theatre, Kilburn, London - 4 manuals, 16 ranks (Wurlitzer 1937)
- EMD (Granada), Walthamstow, Christie Theatre Organ (in original situ) last in the UK
- Hammersmith Apollo, London - 4 manuals, 15 ranks (Compton, 1932)
- Granada, Tooting, London - 4 manuals, 14 ranks (Wurlitzer 1931)
- The Broadway Theatre, Catford, London - 3 manuals, 14 ranks (Compton 1932)
- Blackpool Tower Ballroom - 3 manuals, 14 ranks (Wurlitzer, 1935)
- Blackpool Opera House - 3 manuals, 13 ranks (Wurlitzer, 1939) - the last new Wurlitzer in the UK 
- Stockport Plaza, Stockport
-  Wolverhampton Civic Hall-4 Manuals, 44 ranks. (Compton 1938)
- Shrewsbury, The Buttermarket Theatre - 3 manuals, 8 ranks (Wurlitzer)
- Golds Gym (Former Granada Harrow), London - 3 manuals, 8 ranks (Wuritzer 1937)
- New Gallery, Regent Street, London - 2 manuals, 8 ranks (Wurlitzer 1925)
- Odeon Cinama, Weston-super-Mare - 3 manuals, 6 ranks (Compton 1935)
- The Cameo Polytechnic (University of Westminster), London - 3 manuals, 5 ranks (Compton 1937)
Continental Europe 
- Technoseum Mannheim, 2 manuals, 10 ranks (2/10), M. Welte & Söhne
- Norddeutscher Rundfunk (NDR, North German Broadcasting), Hamburg - 3/128, M. Welte & Söhne, 1930
- Berlin Musical Instrument Museum, 4/15, Wurlitzer, 1929
- Filmmuseum Düsseldorf, 2/9, M. Welte & Söhne, 1929/30
- Kino Babylon Berlin - 2/66, Philipps (Frankfurt), 1929
- Siegfried's Mechanisches Musikkabinett, Rüdesheim, 2/11, M. Welte & Söhne, 1928/29
- Filmmuseum Potsdam, 2/12, M. Welte & Söhne, 1928/29
- Grassi Museum, Leipzig, 2/7, M. Welte & Söhne, 1931
- City-Theater, Amsterdam, 4/17, Strunk
- Pathé Tuschinski, Amsterdam, 4/10, Wurlitzer-Strunk, 1940
- Theater aan de Schie, Schiedam, 3/11, Standaart
- De Meenthe Building, former in Asta Theater, Steenwijk, 4/29, Strunk
- Concert Hall, Middleburg, 3/11 Compton
- Dream Factory, Degersheim, 3/14 Wurlitzer
- Collège Claparède, Geneva, 3/8 Wurlitzer
- Theatre Barnabè, Servion, M. Welte & Söhne
New vs. original technology 
So called "New" organs have been recently built, mainly from parts of other theatre organs, with some construction of new pipework, windchests and consoles. Among the largest of these are the 5-manual (keyboard), 80-rank (sets of pipes) organ at the Sanfilippo Residence in Barrington, Illinois; the 4-manual, 78-rank organ at the Organ Stop Pizza Restaurant in Mesa, Arizona; and the 4-manual, 77-rank organ of The Nethercutt Collection at San Sylmar in Sylmar, California.
- The largest theatre pipe organ in a publicly owned building is the Dickinson High School Kimball Theatre pipe organ in Wilmington, Delaware, consisting of identical 3-manual consoles which play 66 ranks of pipes.
- The Civic Hall in Wolverhampton (UK) houses what was originally a 40-rank Compton concert/orchestral organ which has, in recent years, been enhanced by four theatre organ ranks, including the main voice of the theatre organ, a Tibia Clausa. 
- The Singing Hills Wurlitzer, Albourne, proudly boasts two consoles. The smaller 2-manual console controls five of the available ranks and the larger 3-manual console controls all of the available 23 ranks. Originally specified by Michael Maine and built by David Houlgate, re-specified by Michael Wooldridge and refurbished with extra ranks added by Alan Baker and Michael Wooldridge. Regularly used for concerts throughout the year, in the non-golfing season.
- The East Sussex National Wurlitzer, Uckfield, sports a Wurlitzer replica 'Modernistic' console built by Ken Crome and has 4 manuals controlling the 32 available pipe ranks and traps. Available for functions and regularly used for fortnightly Sunday tea dances.
Other theatre organs that have been silent for years are being refurbished and installed in new venues.
Some of these refurbished organs have had their original electro-pneumatic relays replaced with electronic and/or computerized relays and modern, electronic consoles.
- Manufacturers such as Uniflex Relay Systems , Essential Technology OPUS-TWO , Peterson, Z-tronics, Syndyne, Arndt, Organ Supply Industries, and Artisan Instruments  provide hardware, reproduction parts, and electronics for theatre organs.
Digital theatre organ 
Built by companies such as Walker Theatre Organs , Allen and Rodgers, incorporating sampling, a MIDI interface, and newly-designed speaker systems, are being produced in the attempt to recreate authentic-sounding pipe tones, thus providing an affordable alternative to an actual pipe organ.
Virtual theatre organ 
Recently, a virtual theatre organ called the MidiTzer was developed by Jim Henry. It is available as a free download, runs on a Windows-based PC or Linux machines under Wine (software), and uses MIDI keyboards. The MidiTzer  makes the theatre organ sound and experience convenient for home setup and portable for use at silent film shows where a theatre pipe organ is not available. Predating MidiTzer is the Linux platform GENPO  virtual organ project. GENPO is used on professional digital audio workstations such as the Marschall Acoustics Instruments MkII and MkIII workstations which were used for the Peter Carroll-Held album recently released by Move Records . GENPO uses buttons rather than tongue-tab icons to represent the stop switches, this allows more stops to be shown in an equivalent amount of video display screen 'real-estate'. MidiTzer, on the other hand, aims to recreate a visual layout similar to a WurliTzer theatre organ. First issued in 2002 Hauptwerk Virtual Organ was developed to cater for virtual organs in general and has been found to be highly suitable for use by amateurs and professional alike, with an interest in Theatre Organs. It uses 'sample sets' which contain all of the digitised samples required for a Theatre Organ, along with an Organ Definition File (ODF) which specifies how an entire organ is defined. Sample sets are supplied by many suppliers, with a few devoted exclusively to Theatre Organs and most suppliers allow the use of their samples by ODFs that have been written by users to suit their own particular requirement, often using the Custom Organ Design Module (CODM) supplied with the Hauptwerk package. Physical console controls may be connected to Hauptwerk via MIDI MIDI and for those with limuted space, touch screen control is often available. Hauptwerk is highly thought of within the Virtual Theatre Organ fraternity and is rated as probably the ultimate in virtual organ software. There are currently three modes of operation - Free, Basic and Advanced with the Advanced Edition containing all possible facilities that Hauptwerk has to offer. The Free Edition allows you to 'try before you buy' and there is even a free to use sample set, containing a fully featured 3 manual, 10 rank Theatre Organ, supplied by Paramount Organ Works . Other Theatre Organ sample set suppliers are Milan Digital Audio  and Key Media Productions .
The future 
The theatre organ and its progenitors 
The future of the theatre organ is always fluid, but several organizations are active in preserving and promoting these grand, old instruments. Among these are the American Theatre Organ Society (ATOS) and numerous independent theatre organ clubs who exist to refurbish and reinstall theatre organs to their former glory. Similar work is being done in the UK by the Cinema Organ Society and the Theatre Organ Club; in Australia the various divisions of TOSA have "saved" many theatre organs once in cinemas and theatres. Many of these rebuilt instruments have been installed in restaurants and auditoriums, as well as in a few theatres and churches, allowing the public to gain access to them.
Independent chapters of ATOS, individuals and venue operators have produced and continue to produce various events and shows to promote the theatre organ. In recent years, increased interest in silent films and the use of the theatre organ in conjunction with orchestras, concert bands, and other instrumentalists has helped to broaden the appeal of the theatre organ to newer audiences.
Within the past several years, ATOS has become very active in promoting young theatre organists and enthusiasts, primarily through its work in hosting the ATOS Summer Youth Camp. The ATOS Summer Camp is a week-long educational event aimed at instructing budding, young theatre organists in the art form. Beginning in 2007, the ATOS Summer Camp has hosted dozens of new, young theatre organists. With the help of its core educational staff of Jonas Nordwall, Donna Parker, Jelani Eddington, and Martin Ellis, the Summer Camp program has developed an extensive and successful curriculum for teaching the art of the theatre organ.
Organists then and now 
By the late 1920s, there were over 7,000 organists employed in theatres across the United States. Today, there are none of those original silent film organists still alive. Today's theatre organists present the art form to the public in a variety of ways, through concert appearances, silent film accompaniment, and commercial recordings. Organists such as Walt Strony, Jelani Eddington, Jonas Nordwall, Donna Parker, David Peckham, Martin Ellis, Ken Double, Chris Elliott, Dave Wickerham, Lew Williams, and Bob Ralston maintain active concert schedules and continue to promote the instrument and its preservation through their worldwide travels and musical talents. Other organists such as Clark Wilson, Steven Ball of Ann Arbor's Michigan Theatre, Bob Mitchell, and Rob Richards, frequently accompany silent films and/or are resident "staff" organists for a commercial theatre.
There are many other full- or part-time theatre organists in other parts of the world, with a large proliferation in the United Kingdom. Phil Kelsall, resident organist of the Tower Ballroom Wurlitzer in the world-famous Blackpool Tower, is the most well known in the UK and plays mainly in a unique style called the Blackpool Style, which was originally developed by Reginald Dixon, a previous resident organist. Robert Wolfe , Donald Mackenzie, John Mann, Simon Gledhill, Richard Hills Nigel Ogden, Len Rawle, Matthew Bason and Michael Wooldridge are just a few of the many British organists who play regularly to audiences throughout the world. In Australia there are also many wonderful musicians who play the theatre organ, with Margaret Hall, Wendy Hambly, Peter Carroll-Held, David Johnston, Bill Schumacher, Tony Fenelon, John Giacchi, Paul Fitzgerald, John Atwell, Robert Wetherall and Chris McPhee being among the most prolific. In France Jean-Philippe Le Trévou, Titular Organist at Sainte-Claire Church in Paris and one of the rare theatre organists in France, continues the tradition by accompanying silent films at the Kinopanorama in Paris, at the Vidéothèque de Paris for the Ciné-Mémoire Festival, as well as at the Cinema Museum in Frankfurt, Germany, during the Music Fair.
- Steven Ball. The Barton Organ of the Michigan Theatre. Journal of the American Theatre Organ Society (September/October 1998).
- Steven Ball. The Story of The Hollywood Barton. Journal of the American Theatre Organ Society (November/December), citing The Hollywood Theatre, Detroit, MI Detroit News March 17, 1963.
- American Theatre Organ Society.  Theatre Organ Locator
- Theatre organs varied in styles from the very first organ, The Wurlitzer Style 1, an upright piano console modified with the addition of an organ manual, pedals, 4 ranks of pipes, 4 percussions and traps, to the largest organs with 50+ pipe ranks, 4- and 5-manual consoles, and many percussions and traps (some of the larger organs also incorporated dual consoles).
- The earliest unit orchestras utilized a separate wind supply to the console to operate combination pistons, which at that time were pneumatically operated. Later designs electrified the combination action, eliminating the need for the console wind supply.
- Various builders of church organs, notably Möller, Austin, Aeolian-Skinner and Kimball, added a limited number of chromatic percussions to their church instruments.
- Original installation refers to a theatre pipe organ that is still located in its originally-installed venue (never removed and installed elsewhere) and still contains its original specification (organ retains its original pipes and chamber layout and console, no additions or deletions except for update of relays). The addition and/or deletion of only one rank of pipes negates this status.
- Marschall Acoustics Instruments DAW Mk III
- Sketches of a better time – Peter Carroll-Held, 2011 Move Records
See also 
- Capri Theatre, home of Australia's second largest theatre organ
- Photoplayer, an automatic piano and orchestra used by smaller theatres to accompany silent films
- Winter Gardens, Blackpool
- Wurlitzers in the United Kingdom
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