Electro-pneumatic action

Last updated

The electro-pneumatic action is a control system by the mean of air pressure for pipe organs, whereby air pressure, controlled by an electric current and operated by the keys of an organ console, opens and closes valves within wind chests, allowing the pipes to speak. This system also allows the console to be physically detached from the organ itself. The only connection was via an electrical cable from the console to the relay, with some early organ consoles utilizing a separate wind supply to operate combination pistons.

Contents

Invention

Although early experiments with Barker lever, tubular-pneumatic and electro-pneumatic actions date as far back as the 1850s, credit for a feasible design is generally given to the English organist and inventor, Robert Hope-Jones. [1] He overcame the difficulties inherent in earlier designs by including a rotating centrifugal air blower and replacing banks of batteries with a DC generator, which provided electrical power to the organ. This allowed the construction of new pipe organs without any physical linkages whatsoever. Previous organs used tracker action, which requires a mechanical linkage between the console and the organ windchests, or tubular-pneumatic action, which linked the console and windchests with a large bundle of lead tubing. [1]

Operation

When an organ key is depressed, an electric circuit is completed by means of a switch connected to that key. This causes a low-voltage current to flow through a cable to the windchest, upon which a rank, or multiple ranks of pipes are set. Within the chest, a small electro-magnet associated with the key that is pressed becomes energized. This causes a very small valve to open. This, in turn, allows wind pressure to activate a bellows or "pneumatic" which operates a larger valve. This valve causes a change of air pressure within a channel that leads to all pipes of that note. A separate "stop action" system is used to control the admittance of air or "wind" into the pipes of the rank or ranks selected by the organist's selection of stops, while other ranks are "stopped" from playing. The stop action can also be an electro-pneumatic action, or may be another type of action

This pneumatically assisted valve action is in contrast to a direct electric action in which each pipe's valve is opened directly by an electric solenoid which is attached to the valve.

As this is the operation of an electro pnematic system

Advantages and disadvantages

The console of an organ which uses either type of electric action is connected to the other mechanisms by an electrical cable. This makes it possible for the console to be placed in any desirable location. It also permits the console to be movable, or to be installed on a "lift", as was the practice with theater organs.

While many consider tracker action organs to be more sensitive to the player's control, others find some tracker organs heavy to play and tubular-pneumatic organs to be sluggish, and so prefer electro-pneumatic or direct electric actions.

An electro-pneumatic action requires less current to operate than a direct electric action. This causes less demand on switch contacts. An organ using electro-pneumatic action was more reliable in operation than early direct electric organs until improvements were made in direct electric components. [2]

A disadvantage of an electro-pneumatic organ is its use of large quantities of thin perishable leather, usually lambskin. This requires an extensive "re-leathering" of the windchests every twenty-five to forty years depending upon the quality of the material used, the atmospheric conditions and the use of the organ. [2]

Like tracker and tubular action, electro-pneumatic action—when employing the commonly used pitman-style windchests—is less flexible in operation than direct electric action [ citation needed ]. When electro-pneumatic action uses unit windchests (as does the electro-pneumatic action constructed by organ builder Schoenstein & Co. [3] ), then it works similarly to direct electric action, in which each rank operates independently, allowing "unification", where each individual rank on a windchest can be played at various octave ranges.

A drawback to older electric action organs was the large amount of wiring required for operation. With each stop tab and key being wired, the transmission cable could easily contain several hundred wires. The great number of wires required between the keyboards, the banks of relays and the organ itself, with each solenoid requiring its own signal wire, made the situation worse, especially if a wire was broken (this was particularly true with consoles located on lifts and/or turntables), which made tracing the break very difficult.

These problems increased with the size of the instrument, and it would not be unusual for a particular organ to contain over a hundred miles of wiring. The largest pipe organ in the world, the Boardwalk Hall Auditorium Organ, is said to contain more than 137,500 miles (221,300 km) of wire. [4] Modern electronic switching has largely overcome these physical problems.

Modern methods

In the years after the advent of the transistor, and later, integrated circuits and microprocessors, miles of wiring and electro-pneumatic relays have given way to electronic and computerized control and relay systems, which have made the control of pipe organs much more efficient. But for its time, the electro-pneumatic action was considered a great success, and even today modernized versions of this action are used in many new pipe organs, especially in the United States and the United Kingdom.

Related Research Articles

Pipe organ Wind instrument controlled by keyboard

The pipe organ is a musical instrument that produces sound by driving pressurized 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 and volume throughout the keyboard compass. Most organs have many ranks of pipes of differing timbre, pitch, and volume that the player can employ singly or in combination through the use of controls called stops.

Railway air brake Fail-safe power braking system with compressed air as the operating medium

A railway air brake is a railway brake power braking system with compressed air as the operating medium. Modern trains rely upon a fail-safe air brake system that is based upon a design patented by George Westinghouse on April 13, 1869. The Westinghouse Air Brake Company was subsequently organized to manufacture and sell Westinghouse's invention. In various forms, it has been nearly universally adopted.

Pneumatics Branch of engineering

Pneumatics is a branch of engineering that makes use of gas or pressurized air.

Thermostat Component which maintains a setpoint temperature

A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint.

Aeolian-Skinner

Æolian-Skinner Organ Company, Inc. of Boston, Massachusetts was an American builder of a large number of pipe organs from its inception as the Skinner Organ Company in 1901 until its closure in 1972. Key figures were Ernest M. Skinner (1866–1960), Arthur Hudson Marks (1875–1939), Joseph Silver Whiteford (1921-1978), and G. Donald Harrison (1889–1956). The company was formed from the merger of the Skinner Organ Company and the pipe organ division of the Æolian Company in 1932.

Theatre organ Type of pipe organ

A theatre organ is a distinct type of pipe organ originally developed to provide music and sound effects to accompany silent films during the first 3 decades of the 20th century.

Tremulant

A tremulant is a device on a pipe organ which varies the wind supply to the pipes of one or more divisions. This causes their amplitude and pitch to fluctuate, producing a tremolo and vibrato effect. A large organ may have several tremulants, affecting different ranks (sets) of pipes. Many tremulants are variable, allowing for the speed and depth of tremolo to be controlled by the organist. The tremulant has been a part of organ building for many centuries, dating back to Italian organs of the sixteenth century.

Tracker action

Tracker action is a term used in reference to pipe organs and steam calliopes to indicate a mechanical linkage between keys or pedals pressed by the organist and the valve that allows air to flow into pipe(s) of the corresponding note. This is in contrast to "direct electric action" and "electro-pneumatic action", which connect the key to the valve through an electrical link or an electrically assisted pneumatic system respectively, or "tubular-pneumatic action" which utilizes a change of pressure within lead tubing which connects the key to the valve pneumatic.

Tubular may refer to:

Robert Hope-Jones

Robert Hope-Jones was an English musician who is considered to be the inventor of the theatre organ in the early 20th century. He thought that a pipe organ should be able to imitate the instruments of an orchestra, and that the console should be detachable from the organ.

Boardwalk Hall Auditorium Organ

The Boardwalk Hall Auditorium Organ is the pipe organ in the Main Auditorium of the Boardwalk Hall in Atlantic City, New Jersey, built by the Midmer-Losh Organ Company. It is the largest organ in the world, as measured by the number of pipes.

Klais Orgelbau

Orgelbau Klais is a German firm that designs, builds and restores pipe organs. It is a family run company, founded in 1882 by Johannes Klais senior and is now run by his great-grandson Philipp Klais. The firm is based in Bonn, Germany, and has completed many large-scale building and restoration projects around the globe in more than a century of organ building.

The Electro-pneumatic brake system on British railway trains was introduced in 1950 and remains the primary braking system for multiple units in service today. The Southern Region of British Railways operated a self-contained fleet of electric multiple units for suburban and middle-distance passenger trains. From 1950, an expansion of the fleet was undertaken and the new build adopted a braking system that was novel in the UK, the electro-pneumatic brake in which compressed air brake operation was controlled electrically by the driver. This was a considerable and successful technical advance, enabling a quicker and more sensitive response to the driver's operation of brake controls.

Electronically controlled pneumatic brakes are a type of modern railway braking system which offer improved performance compared to traditional railway air brakes.

Tubular-pneumatic action

"Tubular-pneumatic action" refers to an apparatus used in many pipe organs built during the late 19th and early 20th centuries. The term "tubular" refers to the extensive use of lead tubing to connect the organ's console to the valves that control the delivery of "wind" to the organ's pipes. Many such organs are extant 100 or more years after their construction.

Direct electric action is one of various systems used in pipe organs to control the flow of air (wind) into the organ's pipes when the corresponding keys or pedals are depressed. In direct electric action, the valves beneath the pipes are opened directly by electro-magnet solenoids, while with electro-pneumatic action, the electro-magnet's action admits air into a pneumatic or small bellows which in turn operates the pipe's valve.

Schoenstein Organ at the Conference Center Pipe organ in Salt Lake City, Utah, U.S.

The Schoenstein Organ at the Conference Center is a pipe organ built by Schoenstein & Co., San Francisco, California located in the Conference Center of The Church of Jesus Christ of Latter-day Saints in Salt Lake City, Utah. The organ was completed in 2003. It is composed of 160 speaking stops spread over five manuals and pedals. Along with the nearby Salt Lake Tabernacle organ, it is typically used to accompany the Tabernacle Choir at Temple Square. Schoenstein & Co.'s president and tonal director, Jack Bethards, describes it as "an American Romantic organ" that is "probably more English than anything else."

Logan Tabernacle United States historic place

The Logan Tabernacle is a tabernacle of The Church of Jesus Christ of Latter-day Saints and is located in Logan, Cache County, Utah. It is used regularly for church meetings, most often semi-annual Stake Conferences as well as seminary graduations, musical concerts of various kinds and lectures. The tabernacle welcomes visitors and is open for tours each summer from June to September. It is the site of many local celebrations, including the city's annual Summerfest Arts Faire held each June on the tabernacle grounds.

Casavant Frères Ltée. Opus 1841 (Highland Arts Centre Organ) Musical artist

Casavant Frères Ltée. Opus 1841 is a pipe organ built by the famous Casavant Frères of Saint-Hyacinthe, Quebec. The organ was first completed in 1911 as Casavant Brothers - Opus 452 for St. Andrew's Presbyterian Church at 40 Bentinck Street, Sydney, Nova Scotia, Canada. St. Andrew's later became St. Andrew's United Church and is now the Highland Arts Theatre.

In engineering, a solenoid is a device that converts electrical energy to mechanical energy, using an electromagnet formed from a coil of wire. The device creates a magnetic field from electric current, and uses the magnetic field to create linear motion. In electromagnetic technology, a solenoid is an actuator assembly with a sliding ferromagnetic plunger inside the coil. Without power, the plunger extends for part of its length outside the coil; applying power pulls the plunger into the coil. Electromagnets with fixed cores are not considered solenoids. In simple terms, a solenoid converts electrical energy into mechanical work. Typically, it has a multiturn coil of magnet wire surrounded by a frame, which is also a magnetic flux carrier to enhance its efficiency. In engineering, the term may also refer to a variety of transducer devices that convert energy into linear motion, more sophisticated than simple two–position actuators. The term "solenoid" also often refers to a solenoid valve, an integrated device containing an electromechanical solenoid which actuates either a pneumatic or hydraulic valve, or a solenoid switch, which is a specific type of relay that internally uses an electromechanical solenoid to operate an electrical switch; for example, an automobile starter solenoid or linear solenoid. Solenoid bolts, a type of electromechanical locking mechanism, also exist.

References

  1. 1 2 George Laing Miller (1909). The Recent Revolution in Organ Building . (also at Gutenberg.org)
  2. 1 2 William H. Barnes (1959). The Contemporary American Organ .
  3. "Schoenstein & Co. -- The Schoenstein System - Expansion Cell™" -- Individual Wind Valve Chest". www.schoenstein.com. Archived from the original on 2008-11-20.
  4. Foort, Reginald (1970). The Cinema Organ, pp 74–78. Second Edition, New York: The Vestral Press.

Further reading