Public address system

A public address system (PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound source or recorded sound or music. PA systems are used in any public venue that requires that an announcer, performer, etc. be sufficiently audible at a distance or over a large area. Typical applications include sports stadiums, public transportation vehicles and facilities, and live or recorded music venues and events. A PA system may include multiple microphones or other sound sources, a mixing console to combine and modify multiple sources, and multiple amplifiers and loudspeakers for louder volume or wider distribution.

Simple PA systems are often used in small venues such as school auditoriums, churches, and small bars. PA systems with many speakers are widely used to make announcements in public, institutional and commercial buildings and locations—such as schools, stadiums, and passenger vessels and aircraft. Intercom systems, installed in many buildings, have both speakers throughout a building, and microphones in many rooms so occupants can respond to announcements. PA and Intercom systems are commonly used as part of an emergency communication system.

The term, sound reinforcement system generally means a PA system specifically for live music or performance.[1] In Britain any PA system is sometimes colloquially referred to as a Tannoy, after the company of that name now owned by TC Electronic Group, which supplied a great many of the PA systems used previously in Britain.[2]

Hornloudspeaker
Horn loudspeakers are often used to broadcast sound in outdoor locations
US Navy 091222-N-2564M-106 Rear Adm. Michelle Howard commends the crew of USS Wasp (LHD 1) during ship's return to Norfolk
An officer uses a ship's PA system

Early systems

Megaphone

MOHAI - firefighter's speaking trumpet 01A
A late 19th-century speaking trumpet used by firefighters.
HPIM0145 megaphone
A small sports megaphone for cheering at sporting events, next to a 3 in. cigarette lighter for scale

From the Ancient Greek era to the nineteenth century, before the invention of electric loudspeakers and amplifiers, megaphone cones were used by people speaking to a large audience, to make their voice project more to a large space or group. Megaphones are typically portable, usually hand-held, cone-shaped acoustic horns used to amplify a person’s voice or other sounds and direct it towards a given direction. The sound is introduced into the narrow end of the megaphone, by holding it up to the face and speaking into it. The sound projects out the wide end of the cone. The user can direct the sound by pointing the wide end of the cone in a specific direction. In the 2010s, cheerleading is one of the few fields where a nineteenth century-style cone is still used to project the voice. The device is also called “speaking-trumpet”, “bullhorn” or “loud hailer”.

Automatic Enunciator

In 1910, the Automatic Electric Company of Chicago, Illinois, already a major supplier of automatic telephone switchboards, announced it had developed a loudspeaker, which it marketed under the name of the Automatic Enunciator. Company president Joseph Harris foresaw multiple potential uses, and the original publicity stressed the value of the invention as a hotel public address system, allowing people in all public rooms to hear announcements.[3] In June 1910, an initial "semi-public" demonstration was given to newspaper reporters at the Automatic Electric Company building, where a speaker's voice was transmitted to loudspeakers placed in a dozen locations "all over the building".[4]

A short time later, the Automatic Enunciator Company formed in Chicago order to market the new device, and a series of promotional installations followed.[5] In August 1912 a large outdoor installation was made at a water carnival held in Chicago by the Associated Yacht and Power Boat Clubs of America. Seventy-two loudspeakers were strung in pairs at forty-foot (12 meter) intervals along the docks, spanning a total of one-half mile (800 meters) of grandstands. The system was used to announce race reports and descriptions, carry a series of speeches about "The Chicago Plan", and provide music between races.[6]

In 1913, multiple units were installed throughout the Comiskey Park baseball stadium in Chicago, both to make announcements and to provide musical interludes,[7] with Charles A. Comiskey quoted as saying: "The day of the megaphone man has passed at our park." The company also set up an experimental service, called the Musolaphone, that was used to transmitted news and entertainment programming to home and business subscribers in south-side Chicago,[8] but this effort was short-lived. The company continued to market the enunciators for making announcements in establishments such as hospitals, department stores, factories, and railroad stations, although the Automatic Enunciator Company was dissolved in 1926.[5]

Factory, February 1918, page 361
The Modern Hospital Yearbook, 1919, pages 256-257

Magnavox

Early vacuum tube public address system
Early public-address system from around 1920 using a Magnavox speaker. The microphone had a metal reflector that concentrated the sound waves, allowing the speaker to stand back so it wouldn't obscure his or her face. The early vacuum tubes couldn't produce much gain, and even with six tubes the amplifier had low power. To produce enough volume, the system used a horn loudspeaker. The cylindrical driver unit under the horn contained the diaphragm, which the voice coil vibrated to produce sound through a flaring horn. It produced far more volume from a given amplifier than a cone speaker. Horns were used in virtually all early PA systems, and are still used in the 2010s in most systems, at least for the high-range tweeters.

Peter Jensen and Edwin Pridham of Magnavox began experimenting with sound reproduction in the 1910s. Working from a laboratory in Napa, California, they filed the first patent for a moving coil loudspeaker in 1911.[9] Four years later, in 1915, they built a dynamic loudspeaker with a 1-inch (2.5 cm) voice coil, a 3-inch (7.6 cm) corrugated diaphragm and a horn measuring 34 inches (86 cm) with a 22-inch (56 cm) aperture. The electromagnet created a flux field of approximately 11,000 Gauss.[9]

Their first experiment used a carbon microphone. When the 12 V battery was connected to the system, they experienced one of the first examples of acoustic feedback,[9] a typically unwanted effect often characterized by high-pitched sounds. They then placed the loudspeaker on the laboratory's roof, and claims say that the amplified human voice could be heard 1 mile (1.6 km) away.[9] Jensen and Pridham refined the system and connected a phonograph to the loudspeaker so it could broadcast recorded music.[10] They did this on a number of occasions, including once at the Napa laboratory, at the Panama–Pacific International Exposition,[9] and on December 24, 1915 at San Francisco City Hall alongside Mayor James Rolph.[10] This demonstration was official presentation of the working system, and approximately 100,000 people gathered to hear Christmas music and speeches "with absolute distinctness".[9]

The first outside broadcast was made one week later, again supervised by Jensen and Pridham.[1][11] On December 30, when Governor of California Hiram Johnson was too ill to give a speech in person, loudspeakers were installed at the Civic Auditorium in San Francisco, connected to Johnson's house some miles away by cable and a microphone, from where he delivered his speech.[9] Jensen oversaw the governor using the microphone while Pridham operated the loudspeaker.

The following year, Jensen and Pridham applied for a patent for what they called their "Sound Magnifying Phonograph". Over the next two years they developed their first valve amplifier. In 1919 this was standardized as a 3-stage 25 watt amplifier.[9]

This system was used by former US president William Howard Taft at a speech in Grant Park, Chicago, and first used by a current president when Woodrow Wilson addressed 50,000 people in San Diego, California.[11][12] Wilson's speech was part of his nationwide tour to promote the establishment of the League of Nations.[13] It was held on September 9, 1919 at City Stadium. As with the San Francisco installation, Jensen supervised the microphone and Pridham the loudspeakers. Wilson spoke into two large horns mounted on his platform, which channelled his voice into the microphone.[13] Similar systems were used in the following years by Warren G. Harding and Franklin D. Roosevelt.[9]

Marconi

By the early 1920s, Marconi had established a department dedicated to public address and began producing loudspeakers and amplifiers to match a growing demand.[9] In 1925, George V used such a system at the British Empire Exhibition, addressing 90,000 via six long-range loudspeakers.[9] This public use of loudspeakers brought attention to the possibilities of such technology. The 1925 Royal Air Force Pageant at Hendon Aerodrome used a Marconi system to allow the announcer to address the crowds, as well as amplify the band.[9] In 1929, the Schneider Trophy race at Calshot Spit used a public address system that had 200 horns, weighing a total of 20 tons.[9]

Late 1920s-1930s

Engineers invented the first loud, powerful amplifier and speaker systems for public address systems and movie theaters. These large PA systems and movie theatre sound systems were very large and very expensive, and so they could not be used by most touring musicians. After 1927, smaller, portable AC mains-powered PA systems that could be plugged into a regular wall socket "quickly became popular with musicians"; indeed, "...Leon McAuliffe (with Bob Wills) still used a carbon mic and a portable PA as late as 1935." During the late 1920s to mid-1930s, small portable PA systems and guitar combo amplifiers were fairly similar. These early amps had a "single volume control and one or two input jacks, field coil speakers" and thin wooden cabinets; remarkably, these early amps did not have tone controls or even an on-off switch.[14] Portable PA systems you could plug into wall sockets appeared in the early 1930s when the introduction of electrolytic capacitors and rectifier tubes enabled economical built-in power supplies that could plug into wall outlets. Previously, amplifiers required heavy multiple battery packs.

Electric megaphone

"Geração à Rasca" Demonstration
A woman using a small handheld electric megaphone at a demonstration in Portugal. Electric megaphones use a type of horn loudspeaker called a reflex or reentrant horn.

In the 1960s, an electric-amplified version of the megaphone, which used a loudspeaker, amplifier and a folded horn, largely replaced the basic cone-style megaphone. Small handheld, battery-powered electric megaphones are used by fire and rescue personnel, police, protesters, and people addressing outdoor audiences. With many small handheld models, the microphone is mounted at the back end of the device, and the user holds the megaphone in front of her/his mouth to use it, and presses a trigger to turn on the amplifier and loudspeaker. Larger electric megaphones may have a microphone attached by a cable, which enables a person to speak without having their face obscured by the flared horn.

Small systems

Pa system
Public address system in an old high school

The simplest, smallest PA systems consist of a microphone, an amplifier, and one or more loudspeakers. PA systems of this type, often providing 50 to 200 watts of power, are often used in small venues such as school auditoriums, churches, and coffeehouse stages. Small PA systems may extend to an entire building, such as a restaurant, store, elementary school or office building. A sound source such as a compact disc player or radio may be connected to a PA system so that music can be played through the system. Smaller, battery-powered 12 volt systems may be installed in vehicles such as tour buses or school buses, so that the tour guide and/or driver can speak to all the passengers. Portable systems may be battery powered and/or powered by plugging the system into an electric wall socket. These may also be used for by people addressing smaller groups such as information sessions or team meetings. Battery-powered systems can be used by guides who are speaking to clients on walking tours.

Public address systems consist of input sources (microphones, sound playback devicrs, etc.), amplifiers, control and monitoring equipment (e.g., LED indicator lights, VU meters, headphones), and loudspeakers. Usual input include microphones for speech or singing, direct inputs from musical instruments, and a recorded sound playback device. In non-performance applications, there may be a system that operators or automated equipment uses to select from a number of standard prerecorded messages. These input sources feed into preamplifiers and signal routers that direct the audio signal to selected zones of a facility (e.g., only to one section of a school). The preamplified signals then pass into the amplifiers. Depending on local practices, these amplifiers usually amplify the audio signals to 50V, 70V, or 100V speaker line level.[15] Control equipment monitors the amplifiers and speaker lines for faults before it reaches the loudspeakers. This control equipment is also used to separate zones in a PA system. The loudspeaker converts electrical signals into sound.

Large systems

Public Address System rack 1
Public address system consisting of amplifiers, mixers, and routers for a major international airport

Some PA systems have speakers that cover more than one building, extending to an entire campus of a college, office or industrial site, or an entire outdoor complex (e.g., an athletic stadium). A large PA system may also be used as an alert system during an emergency.

PA systems by size and subwoofer approach

PA system set-up Venue size
Small system: 2 pole-mounted mid/high frequency PA speaker cabinets and 2 small subwoofer cabinets with 15” or 18” subwoofers (Note: this would be used in club where jazz, acoustic music, country music or soft rock is played) Small club with capacity for up to 300 people
Small high amplifier power system: 2 high amplifier power-rated mid/high frequency PA speakers with 15” woofers and a large horn-loaded tweeter; two high amplifier power-rated subwoofer cabinets with one or two 18” subwoofer cabs (front-firing, also known as "front loaded", or manifold-loaded subwoofer cabinets) Small club with capacity for up to 500 people
Mid-size PA system: 4 larger multiwoofer mid/high frequency PA speaker cabs (e.g., each with two 15” woofers) and four subwoofer cabinets, either front-firing, manifold loaded or a folded horn Large clubs with capacity for 500+ people, small music festivals, fairs
Large-size PA system: Multiple mid/high frequency PA speakers, possibly “flown” up high in rigging, and a number of subwoofer cabinets (either front firing, manifold loaded or folded horn) Large venues with capacity for 1000+ people, larger music festivals

[16]

Telephone paging systems

Some private branch exchange (PBX) telephone systems use a paging facility that acts as a liaison between the telephone and a PA amplifier. In other systems, paging equipment is not built into the telephone system. Instead the system includes a separate paging controller connected to a trunk port of the telephone system. The paging controller is accessed as either a designated directory number or central office line. In many modern systems, the paging function is integrated into the telephone system, so the system can send announcements to the phone speakers.

Many retailers and offices choose to use the telephone system as the sole access point for the paging system, because the features are integrated. Many schools and other larger institutions are no longer using the large, bulky microphone PA systems and have switched to telephone system paging, as it can be accessed from many different points in the school.

PA over IP

PA over IP refers to PA paging and intercom systems that use an Internet Protocol (IP) network, instead of a central amplifier, to distribute the audio signal to paging locations across a building or campus, or anywhere else in the reach of the IP network, including the Internet. Network-attached amplifiers and intercom units are used to provide the communication function. At the transmission end, a computer application transmits a digital audio stream via the local area network, using audio from the computer's sound card inputs or from stored audio recordings. At the receiving end, either specialized intercom modules (sometimes known as IP speakers) receive these network transmissions and reproduce the analog audio signal. These are small, specialized network appliances addressable by an IP address, just like any other computer on the network.[17]

WMT PA Systems

Wireless Mobile Telephony (WMT) PA Systems refers to PA paging and [intercom] systems that use any form of Wireless mobile telephony system such as GSM networks instead of a centralized amplifier to distribute the audio signal to paging locations across a building or campus, or other location. The GSM mobile Networks are used to provide the communication function. At the transmission end, a PSTN Telephone, mobile phone, VOIP phone or any other communication device that can access and make audio calls to a GSM based mobile SIM card can communicate with it. At the receiving end, a GSM transceiver receives these network transmissions and reproduce the analogue audio signal via a Power Amplifier and speaker. This was pioneered by Stephen Robert Pearson of Lancashire, England who was granted patents for the systems, which also incorporate control functionality. Using a WMT (GSM) network means that live announcements can be made to anywhere in the world where there is WMT connectivity. The patents cover all forms of WMT i.e., 2G, 3G, 4G ..... xxG. A UK company called Remvox Ltd (REMote VOice eXperience) has been appointed under license to develop and manufacture products based on the technology.

Long line PA

Long Line Public Address Announcement
London Underground employee making a Long Line Public Address system announcement using an RPA01 Radio Microphone at Bank Station

A Long-Line Public Address (LLPA) system is any public address system with a distributed architecture, normally across a wide geographic area. Systems of this type are commonly found in the rail, light rail, and metro industries, and let announcements be triggered from one or several locations to the rest of the network over low bandwidth legacy copper, normally PSTN lines using DSL modems, or media such as optical fiber, or GSM-R, or IP-based networks.[18]

Rail systems typically have an interface with a passenger information system (PIS) server, at each station. These are linked to train describers, which state the location of rolling stock on the network from sensors on trackside signaling equipment. The PIS invokes a stored message to play from a local or remote digital voice announcement system, or a series of message fragments to assemble in the correct order, for example: " / the / 23.30 / First_Great_Western / Night_Riviera_sleeper_service / from / London_Paddington / to / Penzance / .... / will depart from platform / one / this train is formed of / 12_carriages /." Messages are routed via an IP network and are played on local amplification equipment. Taken together, the PA, routing, DVA, passenger displays and PIS interface are referred to as the customer information system (CIS), a term often used interchangeably with passenger information system.

Small venue systems

Small clubs, bars and coffeehouses use a fairly simple set-up, with front of house speaker cabinets (and subwoofers, in some cases) aimed at the audience, and monitor speaker cabinets aimed back at the performers so they can hear their vocals and instruments. In many cases, front of house speakers are elevated, either by mounting them on poles or by "flying" them from anchors in the ceiling. The Front of House speakers are elevated to prevent the sound from being absorbed by the first few rows of audience members. The subwoofers do not need to be elevated, because deep bass is omnidirectional. In the smallest coffeehouses and bars, the audio mixer may be onstage so that the performers can mix their own sound levels.[19] In larger bars, the audio mixer may be located in or behind the audience seating area, so that an audio engineer can listen to the mix and adjust the sound levels. The adjustments to the monitor speaker mix may be made by a single audio engineer using the main mixing board, or they may be made by a second audio engineer who uses a separate mixing board.

Vera Project 12
This small venue's stage shows a typical PA system.

Large venue systems

For popular music concerts, a more powerful and more complicated PA System is used to provide live sound reproduction. In a concert setting, there are typically two complete PA systems: the "main" system and the "monitor" system. Each system consists of a mixing board, sound processing equipment, amplifiers, and speakers. The microphones that are used to pick up vocals and amplifier sounds are routed through both the main and monitor systems. Audio engineers can set different sound levels for each microphone on the main and monitor systems. For example, a backup vocalist whose voice has a low sound level in the main mix may ask for a much louder sound level through her monitor speaker, so she can hear her singing.

  • The "main" system (also known as Front of House, commonly abbreviated FOH), which provides the amplified sound for the audience, typically uses a number of powerful amplifiers that drive a range of large, heavy-duty loudspeakers—including low-frequency speaker cabinets called subwoofers, full-range speaker cabinets, and high-range horns. A large club may use amplifiers to provide 3000 to 5000 watts of power to the "main" speakers. An outdoor concert may use 10,000 or more watts.
  • The monitor system reproduces the sounds of the performance and directs them towards the onstage performers (typically using wedge-shaped monitor speaker cabinets), to help them to hear the instruments and vocals. In British English, the monitor system is referred to as the "foldback". The monitor system in a large club may provide 500 to 1000 watts of power to several foldback speakers; at an outdoor concert, there may be several thousand watts of power going to the monitor system.

At a concert using live sound reproduction, sound engineers and technicians control the mixing boards for the "main" and "monitor" systems, adjusting tone, levels, and overall volume.

Line Array and Subs
A line array speaker system and subwoofer cabinets at a live music concert

Touring productions travel with relocatable large line-array PA systems, sometimes rented from an audio equipment hire company. The sound equipment moves from venue to venue along with various other equipment such as lighting and projection.

Acoustic feedback

All PA systems have the potential for audio feedback, which occurs when a microphone picks up sound from the speakers, which is re-amplified and sent through the speakers again. It often sounds like a loud high-pitched squeal or screech, and can occur when the volume of the system is turned up too high. Feedback only occurs when the loop gain of the feedback loop is greater than one, so it can always be stopped by reducing the volume sufficiently.

Sound engineers take several steps to maximize gain before feedback, including keeping microphones at a distance from speakers, ensuring that directional microphones are not pointed towards speakers, keeping the onstage volume levels down, and lowering gain levels at frequencies where the feedback is occurring, using a graphic equalizer, a parametric equalizer, or a notch filter. Some 2010s-era mixing consoles and effects units have automatic feedback preventing circuits.

Feedback prevention devices detect the start of unwanted feedback and use a precise notch filter to lower the gain of the frequencies that are feeding back. Some automated feedback detectors require the user to “set” the feedback-prone frequencies by purposely increasing gain (during a sound check) until some feedback starts to occur. The device then retains these frequencies in its memory and it stands by ready to cut them. Some automated feedback prevention devices can detect and reduce new frequencies other than those found in the sound check.

See also

References

  1. ^ a b Bruce Borgerson (November 1, 2003). "Is it P.A. or SR?". Sound & Video Contractor. Prism Business Media. Archived from the original on May 20, 2015. Retrieved May 19, 2015.
  2. ^ "Tannoy definition". Cambridge Online Dictionary. Retrieved 19 May 2015. a system of equipment that is used for making speech loud enough for a large number of people to hear, especially to give information
  3. ^ "Replaces Bell Boy", The (Culbertson, Montana) Searchlight, July 22, 1910, page 6.
  4. ^ "Hear Sermon, Enjoy Pipe", The (Ottawa Kansas) Evening Herald, June 25, 1910, page 4.
  5. ^ a b Robert D. Fisher Manual of Valuable and Worthless Securities: Volume 6 (1938), page 75.
  6. ^ "Automatic Telephone and Enunciator Carnival Features", Telephony, August 24, 1912, pages 246-247.
  7. ^ "Loud-Speaking Telephone Enunciators in Baseball Grand Stand", Electrical World, August 2, 1913, page 251.
  8. ^ "Increasing the Revenue Producing Efficiency of a Plant" by Stanley R. Edwards, Telephony, October 11, 1913, pages 21-23.
  9. ^ a b c d e f g h i j k l m Yaxleys Sound Systems (2002). "The First Outside Broadcast 1915". History of PA. History of PA Charity Trust. Retrieved 25 November 2011.
  10. ^ a b Shepherd, Gerald A (1986). "When the President Spoke at Balboa Stadium". The Journal of San Diego History. Retrieved 25 November 2011.
  11. ^ a b Crow, Michael M (1998). Limited by design: R&D laboratories in the U.S. national innovation system. New York City, NY: Columbia University Press. p. 145. ISBN 0231109822.
  12. ^ Hogan, Michael (2006). Woodrow Wilson's Western Tour: Rhetoric, Public Opinion, And the League of Nations. Texas A&M University Press. p. 10. ISBN 9781585445332. Retrieved 16 November 2015.
  13. ^ a b Schoenherr, Steven (2001). "Woodrow Wilson in San Diego 1919". Recording Technology History Notes. Archived from the original on 13 January 2012. Retrieved 25 November 2011.
  14. ^ https://www.vintageguitar.com/1804/antique-guitar-amps-1928-1934
  15. ^ Nigel, Williams. "100 volt line". www.audeval.co.uk. Retrieved 20 November 2015.
  16. ^ "UNDERSTANDING BASS MANAGEMENT IN PA SYSTEMS: A Guide for Performers" (PDF). www.cerwinvega.com. Cerwin Vega. Retrieved 8 January 2017.
  17. ^ Bob Mesnik. "How Network Attached Amplifiers and IP Intercoms Work". Kintronics.com. Retrieved 2017-01-25.
  18. ^ "User Manual for an IP based Long Line PA System" (PDF). Asl-control.co.uk. Archived from the original (PDF) on 2013-06-03. Retrieved 2017-01-25.
  19. ^ "Bands Who Do Their Own Sound. Audio Engineering Music Column". Cleverjoe.com. Retrieved 2017-01-25.
1929 New York Giants (MLB) season

The 1929 New York Giants season was the franchise's 47th season. The team finished in third place in the National League with an 84-67 record, 13½ games behind the Chicago Cubs. In a home game against the Pittsburgh Pirates on July 5 at the Polo Grounds, the Giants used the first public address system to be used in a major league ballpark.

Asylum Tour (Kiss)

The Asylum Tour was a concert tour by Kiss. It was the first Kiss tour since the Dynasty Tour to stay inside North America. Kiss also performed The Who's "Won't Get Fooled Again", usually in the encore. Paul Stanley does his guitar-smashing ritual after "Lick It Up".

On February 2, 1986, Paul Stanley dedicated the Tucson, Arizona concert at the McKale Center to the astronauts that were killed in the Space Shuttle Challenger explosion.

On February 17, 1986, Kiss played the Salt Palace in Salt Lake City, Utah. W.A.S.P. was the opening act. The power went out in the middle of "Rock and Roll All Nite" and the concert ended when Kiss walked off the stage, waving to the audience.

On March 30, 1986, Kiss played at the Hammond Civic Center in Hammond, Indiana. Local church groups protested the entire event due to its being scheduled on Easter Sunday. During the show, the band blew out half of the windows on the outside west wall of the arena. Their public address system on this tour was rated at 120 decibels. Before the show Gene Simmons and Eric Carr walked around the perimeter of the building trying to hold polite conversations with the church groups. The concert in Hammond only sold 1,900 tickets.

On April 8, 1986, Kiss played at Maple Leaf Gardens in Toronto. Opening act King Kobra was invited and appeared on stage to sing "Lick it Up" with Kiss, making King Kobra the first group to ever share the stage with Kiss. W.A.S.P. opened in Chicago and Los Angeles (Inglewood).

Ball Diamond

Ball Diamond is a baseball venue located on the campus of Ball State University in Muncie, Indiana, United States. It is home to the Ball State Cardinals baseball team, a member of the Division I Mid-American Conference. The field has a capacity of 1,700 people. Recent renovations to the field have added a new backstop, public address system, fencing, and scoreboard.

Brooks Park

Brooks Park is a softball field in Washington, Pennsylvania, United States, used by the Washington & Jefferson Presidents softball team. The field dimensions are 200 feet (61 m) down the lines and 205 feet (62 m) to center field. It also has home and away dugouts and separate bullpens.In 2004, the field was renovated with funding provided by the Robert and Susan Brooks and the Brooks Foundation. The entire field was re-sodded and an outfield wall was added. Off the field, a new scoreboard was installed and a public address system and press box were added.

Candlelight vigil

A candlelight vigil or candlelit vigil is an outdoor assembly of people carrying candles, held after sunset in order to show support for a specific cause. Such events are typically held either to protest the suffering of some marginalized group of people, or in memory of the dead. In the latter case, the event is often called a candlelight memorial. A large candlelight vigil will usually have invited speakers with a public address system and may be covered by local or national media. Speakers give their speech at the beginning of the vigil to explain why they are holding a vigil and what it represents. Vigils may also have a religious or spiritual purpose. On Christmas Eve many churches hold a candlelight vigil.

Candlelight vigils are seen as a nonviolent way to raise awareness of a cause and to motivate change, as well as uniting and supporting those attending the vigil.

Code word (figure of speech)

A code word is a word or a phrase designed to convey a predetermined meaning to a receptive audience, while remaining inconspicuous to the uninitiated. For example, a public address system may be used to make an announcement asking for "Inspector Sands" to attend a particular area, which staff will recognise as a code word for a fire or bomb threat, and the general public will ignore.

Eaglescliffe railway station

Eaglescliffe railway station serves the town of Eaglescliffe in the borough of Stockton-on-Tees, England. It is located on the Tees Valley Line at the junction with the Northallerton-Eaglescliffe Line and is operated by Northern. Direct intercity services are provided by Grand Central between London and Sunderland.

Station facilities here have been improved. The package for this station included new digital information screens displaying live departures, renewed station signage and the installation of CCTV. The long-line Public Address system (PA) has been renewed and upgraded with pre-recorded train announcements.

General quarters

General quarters, battle stations, or action stations is an announcement made aboard a naval warship to signal that all hands (everyone available) aboard a ship must go to battle stations as quickly as possible.According to The Encyclopedia of War, formerly "[i]n naval service, the phrase "beat to quarters" indicated a particular kind of drum roll that ordered sailors to their posts for a fight where some would load and prepare to fire the ship's guns and others would arm with muskets and ascend the rigging as sharpshooters in preparation for combat."Aboard U.S. Navy Vessels, the following announcement would be made using the vessel’s public address system (known as the 1MC):

“General Quarters, General Quarters. All hands man your battle stations. The direction of travel is up and forward on your starboard side, down and aft on your port side.”

Gypsy Lane railway station

Gypsy Lane railway station serves the Middlesbrough suburbs of Nunthorpe and Marton; the station lies just within the borough of Redcar and Cleveland in the ceremonial county of North Yorkshire, England. It is located on the Esk Valley Line and is operated by Northern who provide all of the station's passenger services. The station was originally opened by British Rail in 1976.

Station facilities here have recently been improved as part of the successful Tees Valley Metro project. The package for this station included new fully lit waiting shelters, renewed station signage and the installation of CCTV. The long-line Public Address system (PA) has been renewed and upgraded with pre-recorded train announcements. A passenger information screen with details of train times was installed at the station in February 2016.

Hagemeister Park

Hagemeister Park was the name of a park in Green Bay, Wisconsin. It was the home of the Green Bay Packers from their founding in 1919 and their first two seasons playing in the National Football League, 1921 and 1922.

Owned by Hagemeister brewery, the park was located on the northern end of Washington Park (now Johannes Park). It was a classic sandlot, located near Baird and Walnut Streets, adjacent to the East River. The playing field was roped off from the spectators' standing area. There were no ushers, band, or public address system. There also were no gates, since there was not a fence. Spectators would jump off the streetcar and walk over to the sideline to watch. Fans who drove to the game could park their cars about ten yards behind the ropes. Fans often sat in their cars or on top of them, although most stood on the sidelines, following the action up and down the field. At halftime, the teams adjourned to opposite end zones and discuss tactics for the second half. Spectators would form a ring around the players and join in on the discussions.

George Whitney Calhoun, a writer for the Green Bay Press-Gazette and the club's unofficial press representative, would pass a hat among the spectators for donations.

In 1920, a small section of grandstand was built on one side of the field, with a capacity of a few hundred, and a fee was charged to sit there. In 1921, a portable canvas fence was erected around the entire field, and a regular admission fee was inaugurated.

Hagemeister Park was torn down in 1923 to make way for the new Green Bay East High School, and the Packers moved their games to Bellevue Park. They would return to a site just north of the park two years later, at City Stadium.

Marske railway station

Marske railway station serves the village of Marske-by-the-Sea in the borough of Redcar and Cleveland and the ceremonial county of North Yorkshire, England. The station is located on the Tees Valley Line and operated by Northern which provides all passenger train services.

The railway station is the oldest in the large village of Marske with the other (Longbeck) being built in the 1980s. The station was also mentioned in George Bradshaws 1863 railway guide.

Station facilities here have been improved. The package for this station included new fully lit waiting shelters, renewed station signage and the installation of CCTV. The long-line Public Address system (PA) has been renewed and upgraded with pre-recorded train announcements.

Pompano Beach Municipal Stadium

Pompano Beach Municipal Stadium was a stadium in Pompano Beach, Florida. Primarily used for baseball, it was home to the Pompano Beach Mets and Pompano Beach Cubs and served as the spring training home of the Washington Senators from 1961 to 1971 and the Texas Rangers from 1972 to 1986. The 1989 Gold Coast Suns split their home games between Bobby Maduro-Miami Stadium and Municipal Stadium. The ballpark was dedicated on March 22, 1957. It held 4,500 people. In 1980 new night lighting, seat and fences were installed at a cost of $227,000. Improvements in 1984 included a new practice infield, public address system, re-carpeting of the clubhouse and rewiring of the concession stands. It was also used as the Pompano Beach High School baseball team (Tornadoes) home field. The Fort Lauderdale Strikers of the APSL used it as their home soccer ground for one season in 1990 after the Broward School District via the school board, denied them access to Lockhart Stadium. The stadium also hosted the Florida State League's Miami Miracle in 1990 and 1991.This stadium was demolished in 2008 and re-built as several baseball fields, although without grandstands. The baseball complex, no longer a stadium, is managed by the City of Pompano Beach and hosts Federal League Semi-Pro Baseball and high school baseball games.

Professional audio

Professional audio, abbreviated as pro audio, refers to both an activity and a category of high quality, studio-grade audio equipment. Typically it encompasses sound recording, sound reinforcement system setup and audio mixing, and studio music production by trained sound engineers, audio engineers, record producers, and audio technicians who work in live event support and recording using audio mixers, recording equipment and sound reinforcement systems. In contrast, consumer audio equipment is a lower grade of gear which is used by regular people for the reproduction of sound in a private home on a home stereo or home cinema system.

Professional audio can include, but is not limited to broadcast radio, audio mastering in a recording studio, television studio, and sound reinforcement such as a live concert, DJ performances, audio sampling, public address system set up, surround sound design in movie theatres, and design and setup of piped music in hotels and restaurants. Professional audio equipment is sold at professional audio stores and music stores. While consumer electronics stores sell some of the same categories of equipment (e.g., power amplifiers and subwoofer cabinets), the equipment that consumer stores sells is a lower consumer-grade type of equipment, which does not meet the standards for low noise and low distortion that are required in pro audio applications.

Redcar East railway station

Redcar East railway station serves the town of Redcar in the borough of Redcar and Cleveland and the ceremonial county of North Yorkshire, England. It is located on the Tees Valley Line and operated by Northern who provide all passenger train services. It is unmanned, so passengers wishing to travel must buy tickets before boarding or on the train.

In 2014, the station facilities were improved. The package for this station included new fully lit waiting shelters, renewed station signage, digital CIS displays and the installation of CCTV. The long-line Public Address system (PA) has been renewed and upgraded with pre-recorded train announcements.

Royal Bafokeng Stadium

The Royal Bafokeng Sports Palace is a football, rugby and athletics stadium in Phokeng near Rustenburg, South Africa. It was built and is managed by the Royal Bafokeng Nation. It is used as the home stadium for Premier Soccer League club Platinum Stars. The Leopards rugby team host large attendance matches during the Currie Cup at the stadium, instead of their usual home ground, Olën Park.

The capacity of the stadium was increased from 38,000 to 42,000 to be able to host five first round matches and one second round match at the 2010 FIFA World Cup.For the 2010 tournament, the main west stand was upgraded and enlarged and given a new cantilever roof. Other improvements include the installation of new electronic scoreboards, new seats, and the upgrading of the floodlights and public address system.

The stadium upgrade was completed in March 2009 for hosting 4 matches of the 2009 FIFA Confederations Cup.

School assembly

A school assembly is a gathering of all or part of a school for any variety of purposes, such as special programs or communicating information on a daily or weekly basis. In some schools, students gather to perform a common song or prayer, and to receive common announcements. A routine attendance check may also be done in such gatherings. At larger schools, these morning rituals may be substituted by smaller classroom assemblies and announcements broadcast over a public address system. Periodic school assemblies are also a forum for special presenters of educational, health, or safety materials, or for school plays, talent shows, etc.

The Celtic Song

"The Celtic Song" is the song played over the public address system at Celtic Park, Glasgow when the Scottish football team Celtic run onto the pitch before kick-off. Part of the song is set to an arrangement of part of the tune of "With cat-like tread", from the 1879 Gilbert and Sullivan comic opera The Pirates of Penzance, with lyrics adapted from the American song "Hail, Hail, the Gang's All Here". The "It's a grand old team" section, however, bears no resemblance to "With cat-like tread".There are many versions of the song. However, the original version, played at Parkhead, was recorded by Glen Daly in 1961. To mark the 50th anniversary of the original release, Shane MacGowan recorded his version in 2011.Versions of the song are sung by supporters of other clubs around Britain, most notably by Tottenham Hotspur fans (since the 1967 FA Cup Final), fans of Hibernian in Edinburgh, and Everton Fans – "The Everton Song" is a more ribald rendition by the fans of Everton.

WVHC

WVHC (91.5 FM) is a radio station broadcasting a Variety format. Licensed to Herkimer, New York, United States, the station is owned by Herkimer County Community College and operated by the college's Radio/TV Department.WVHC was established in 1973 under the name of WHCR as a public address system, only providing a signal to the Robert McLaughlin College Center building. In 1986, WHCR began simulcasting on the college's television station HCTV, a Public-access television cable TV channel airing on Group W Cable (now Charter Spectrum), the authorized cable provider for Herkimer County. The station applied for a FCC license in the early 1990s. Since the WHCR call letters were already taken by WHCR-FM in New York City, the station applied for the call letters WVHC. The application was granted in February 1993, and WVHC began operations that October.Initially, programming was presented during class hours (7am-10pm), but in 1999 WVHC began full-time 24-hour operations. The station is best known for its jazz and blues programming, the only non-commercial station broadcasting such programming in the Mohawk Valley. It also airs a mix of student-produced programs during the fall and spring semesters. Student-produced programs are usually heard in the early afternoon, with further programs broadcast on Fridays.

The station also streams its broadcast signal, which can be heard at www.herkimer.edu/wvhc.

Wall of Sound (Grateful Dead)

The Wall of Sound was an enormous public address system designed specifically for the Grateful Dead's live performances in 1974. It was the creation of audio engineer Owsley "Bear" Stanley. The Wall of Sound fulfilled Owsley's desire for a distortion-free sound system that could also serve as its own monitoring system. The Wall of Sound was the largest concert sound system built at that time.

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