title: Oak Ridge, Tennessee

text: In 1942, the United States federal government purchased nearly 60,000 acres of farmland in the Clinch River Valley for the development of a planned city supporting 75,000 residents. It was constructed with assistance from architectural and engineering firm Skidmore, Owings & Merrill, from 1942 to 1943. Oak Ridge was established in 1942 as a production site for the Manhattan Project—the massive American, British, and Canadian operation that developed the atomic bomb. Being the site of Oak Ridge National Laboratory and Y-12 National Security Complex, scientific and technological development still plays a crucial role in the city's economy and culture in general.


title: Oak Ridge, Tennessee

text: The earliest substantial occupation of the Oak Ridge area occurred during the Woodland period (c. 1000 BC – 1000), although artifacts dating to the Paleo-Indian period have been found throughout the Clinch Valley. Two Woodland mound sites—the Crawford Farm Mounds and the Freels Farm Mounds—were uncovered in the 1930s as part of the Norris Basin salvage excavations. Both sites were just southeast of the former Scarboro community. The Bull Bluff site, which was occupied during the Woodland and Mississippian (c. 1000–1600) periods, was uncovered in the 1960s in anticipation of the construction of Melton Hill Dam. Bull Bluff is a cliff immediately southeast of Haw Ridge, opposite Melton Hill Park. The Oak Ridge area was largely uninhabited when Euro-American explorers and settlers arrived in the late 18th century, although the Cherokee claimed the land as part of their hunting grounds.


title: Oak Ridge, Tennessee

text: During the early 19th century, several rural farming communities developed in the Oak Ridge area, namely Edgemoor and Elza in the northeast, East Fork and Wheat in the southwest, Robertsville in the west, and Bethel and Scarboro in the southeast. The European-American settlers who founded these communities arrived in the late 1790s after the American Revolutionary War and after the Cherokee signed the Treaty of Holston, ceding what is now Anderson County to the United States.


title: Oak Ridge, Tennessee

text: A popular legend holds that John Hendrix (1865-1915), a largely unknown local man, predicted the creation of the city of Oak Ridge around 40 years before construction on the project began. Hendrix lacked any formal education, and was a simple logger for much of his life. Following the death of his youngest daughter, Ethel, to diphtheria, and the subsequent departure of his wife and three remaining children, Hendrix began hearing voices in his head. These voices urged him to stay in the woods and pray for guidance for 40 days and 40 nights, which Hendrix proceeded to do. As the story is told, following these 40 days spent in rugged isolation, Hendrix began seeing visions of the future, and sought to spread his prophetic message to any who would listen. According to published accounts, one vision that he described repeatedly was a description of the city and production facilities built 28 years after his death, during World War II.


title: Oak Ridge, Tennessee

text: Hendrix, in light of his tales of prophetic visions, was considered insane by most, and at one point was institutionalized. His grave lies in an area of Oak Ridge now known as the Hendrix Creek Subdivision. There are ongoing concerns over the preservation of his gravestone, as the man who owns the lot adjacent to the grave wishes to build a home there, while members of the Oak Ridge Heritage and Preservation Association are fighting to have a monument placed on the site of his grave.


title: Oak Ridge, Tennessee

text: In 1942, the United States federal government chose the area as a site for developing materials for the Manhattan Project. Major general Leslie Groves, military head of the Manhattan Project, liked the area for several reasons. Its relatively low population made acquisition affordable, yet the area was accessible by highway and rail, and utilities such as water and electricity were readily available due to the recent completion of Norris Dam. Finally, the project location was established within a valley. This feature was linear and partitioned by several ridges, providing natural protection against the spread of disasters at the four major industrial plants—so they wouldn't blow up "like firecrackers on a string".


title: Oak Ridge, Tennessee

text: When the Governor of Tennessee Prentice Cooper was officially handed by a junior officer (a lieutenant) the July 1943 presidential proclamation making Oak Ridge a military district not subject to state control, he tore it up and refused to see the MED engineer, Lieutenant colonel James C. Marshall. The new District Engineer Kenneth Nichols had to placate him. Cooper came to see the project (except for the production facilities under construction) on November 3, 1943; and he appreciated the bourbon-laced punch served (although Anderson County was "dry"). House and dormitory accommodations at the Clinton Engineer Works (CEW) in Oak Ridge and Hanford Engineer Works in Washington State were basic, with coal rather than oil or electric furnaces. But they were of a higher standard than Director Groves wanted, and were better than at Los Alamos. Medical care was provided by Army doctors and hospitals, with civilians paying $2.50 per month ($5 for families) to the medical insurance fund.


title: Oak Ridge, Tennessee

text: The location and low population helped keep the town a secret, though the settlement grew from 3,000 to 3,750 in 1942 to about 75,000 by 1945. The K-25 uranium separation facility covered , then the largest building in the world. The name "Oak Ridge" was chosen for the settlement in 1943 from suggestions submitted by project employees. The name evoked the settlement's location along Black Oak Ridge, and officials thought the rural-sounding name "held outside curiosity to a minimum". The name wasn't formally adopted until 1949, and the site was referred to as the Clinton Engineer Works or CEW until then. All workers wore badges. The town was surrounded by guard towers and a fence with seven gates.


title: Oak Ridge, Tennessee

text: In October 1942, the United States Army Corps of Engineers began acquiring more than in the Oak Ridge area for the United States' Manhattan Project. Unlike the earlier land acquisitions by the Tennessee Valley Authority for Norris Dam—which were still fresh on the minds of many Anderson Countians—the Corps' "declaration of taking" was much more swift and final. Many residents came home to find eviction notices tacked to their doors. Most were given six weeks to evacuate, although several had as little as two weeks. Some were forced out before they received compensation.


title: Oak Ridge, Tennessee

text: By March 1943, the COE had removed the area's earlier communities and established fences and checkpoints. Anderson County lost one-seventh of its land and $391,000 in annual property tax revenue. The manner by which the Oak Ridge area was acquired by the government created a tense, uneasy relationship between the Oak Ridge complex and the surrounding towns that lasted throughout the Manhattan Project. Although the area's original residents were allowed to be buried in existing cemeteries, every coffin was reportedly opened for inspection.


title: Oak Ridge, Tennessee

text: The Corps' Manhattan Engineer District (MED) managed the acquisition and clearing. The K-25, S-50, and Y-12 plants were each built in Oak Ridge to separate the fissile isotope uranium-235 from natural uranium, which consists almost entirely of the isotope uranium-238. During construction of the electromagnets required for the uranium separation process at the Y-12 site, a shortage of copper forced the MED to borrow 14,700 tons of silver bullion from the United States Treasury as a copper substitute in wire for the electromagnet coils. The X-10 site, now the site of Oak Ridge National Laboratory, was established as a pilot plant for production of plutonium using the Graphite Reactor.


title: Oak Ridge, Tennessee

text: Because of the large number of workers recruited to the area for the Manhattan Project, the Army planned a town for project workers at the eastern end of the valley. The time required for the project's completion caused the Army to opt for a relatively permanent establishment rather than an enormous camp.


title: Oak Ridge, Tennessee

text: The architecture firm Skidmore, Owings and Merrill (SOM) was contracted to provide the layout for the town and house designs. SOM Partner John O. Merrill moved to Tennessee to take charge of designing the secret buildings at Oak Ridge. He directed the creation of a town, which soon had of roads, of railroad track, ten schools, seven theaters, 17 restaurants and cafeterias, and 13 supermarkets. A library with 9,400 books, a symphony orchestra, sporting facilities, church services for 17 denominations, and a Fuller Brush Company salesman served the new city and its 75,000 residents. No airport was built, for security reasons. Prefabricated modular homes, apartments, and dormitories, many made from cemesto (bonded cement and asbestos) panels, were quickly erected. Streets were laid out in the manner of a "planned community".


title: Oak Ridge, Tennessee

text: The original streets included several main east-to-west roads, namely the Oak Ridge Turnpike, Tennessee Avenue, Pennsylvania Avenue, Hillside Road, Robertsville Road, and Outer Drive. North-to-south oriented streets connecting these main roads were designated "Avenues", and streets branching off from the avenues were designated "Roads", "Places", "Lanes", or "Circles". "Roads" connected two streets, while "Lanes" and "Places" were dead ends. The names of the main avenues generally progressed alphabetically from east to west (e.g., Alabama Avenue in the east, Vermont Avenue in the west), and the names of the smaller streets began with the same letter as the main avenue from which they started (e.g., streets connected to Florida Avenue began with "F").


title: Oak Ridge, Tennessee

text: Construction personnel swelled the wartime population of Oak Ridge to as much as 70,000. The dramatic population increase, and the secret nature of the project, meant chronic shortages of housing and supplies during the war years. The town was administered by Turner Construction Company through a subsidiary named the Roane-Anderson Company. For most residents, however, their "landlord" was known as "MSI" (Management Services, Inc.).


title: Oak Ridge, Tennessee

text: The news of the use of the first atomic bomb against Japan on August 6, 1945, revealed to the people at Oak Ridge what they had been working on.


title: Oak Ridge, Tennessee

text: Oak Ridge was developed by the federal government as a segregated community, required by the Southern bloc of Democrats in Congress to authorize funding for the project. Due to generally holding lower-ranked jobs, their assigned dwellings were predominantly government-built "hutments" (one-room shacks) located very close to the Y-12 plant, in the one residential area designated as colored. Kenneth Nichols, the MED District Engineer, was told by the main construction contractor for the K-25 plant that the Negro construction labor force had a large turnover rate, so Nichols gave permission to set up a separate black women's camp. When Leslie Groves visited the plant with K. T. Keller of Chrysler, Keller saw twelve Negro women sweeping the thirty-foot wide alley between the production units, and said "Nichols, don't you know there is a machine made to sweep a concrete floor like this?" Nichols replied "Sure I do, but these gals can do more than one of those machines". The men now had an opportunity to "fracas" on Saturday night, and labor turnover had reduced. During the war, plans were made for a colored neighborhood of houses equal in quality to those provided for whites, but it was not implemented due to limited resources. After the war, all hutments were dismantled, and a colored neighborhood of permanent houses was developed in the Gamble Valley area of Oak Ridge, which during wartime had been occupied by a white trailer community.


title: Oak Ridge, Tennessee

text: Oak Ridge elementary education prior to 1954 was totally segregated; it was legally part of the Anderson County system though built and operated primarily with federal funds. Black children could attend only the Scarboro Elementary School. Oak Ridge High School was closed to black students, who had to be bused to Knoxville for an education. Starting in 1950, Scarboro High School was established at Scarboro Elementary School to offer classes for African-American students. It operated until Oak Ridge High School was desegregated in the fall of 1955.


title: Oak Ridge, Tennessee

text: In 1953, the Oak Ridge Town Council encouraged desegregation of Oak Ridge High School; this resulted in an unsuccessful attempt by some residents to recall council member Waldo Cohn.


title: Oak Ridge, Tennessee

text: Following the U.S. Supreme Court decision in "Brown v. Board of Education" (1954) that the segregation of public schools was unconstitutional, Oak Ridge officials changed their policy and desegregated the schools. The nearby high school in Clinton was desegregated in the fall of 1956. It was later bombed and closed. Oak Ridge provided space at a recently vacated elementary school building (the original Linden Elementary School) for the education of high school students from Clinton for two years while Clinton High School was being rebuilt. Robertsville Junior High School, serving the west half of Oak Ridge, was desegregated at the same time as the high school. Elementary schools in other parts of the city and Jefferson Junior High School, serving the east half of the city, were desegregated slowly as African-American families moved into housing outside of Gamble Valley. In 1967, Scarboro Elementary School was closed, and African-American students from Gamble Valley were bused to other schools around the city.


title: Oak Ridge, Tennessee

text: Following the "Brown" decision, public accommodations in Oak Ridge were also integrated, although this took a number of years. In the early 1960s, Oak Ridge briefly experienced protest picketing against racial segregation in public accommodations, notably outside a local cafeteria and a laundromat.


title: Oak Ridge, Tennessee

text: Two years after World War II ended, Oak Ridge was shifted to civilian control, under the authority of the U.S. Atomic Energy Commission (AEC). The Roane Anderson Company administered community functions, including arranging housing and operating buses, under a government contract. In 1959 the town was incorporated. The community adopted a city manager and City Council form of government rather than direct federal control.


title: Oak Ridge, Tennessee

text: The S-50 liquid thermal diffusion plant was demolished soon after the war. K-25, where uranium was enriched by the gaseous diffusion process until 1985, was demolished in 2013–15. Two of the four major facilities created for the wartime bomb production remain standing:


title: Oak Ridge, Tennessee

text: In 1983, the Department of Energy declassified a report showing that significant amounts of mercury had been released from the Oak Ridge Reservation into the East Fork Poplar Creek between 1950 and 1977. A federal court ordered the DOE to bring the Oak Ridge Reservation into compliance with federal and state environmental regulations.


title: Oak Ridge, Tennessee

text: The Department of Energy runs Oak Ridge National Laboratory (ORNL), a nuclear and high-tech research establishment. In June 2018 IBM and the ORNL unveiled Summit, the "world's fastest supercomputer", claimed to be more than twice as powerful as the previous world leader, with a peak performance of 200,000 trillion calculations per second.


title: Oak Ridge, Tennessee

text: Tours of parts of the original facility are available to American citizens from March through November. The tour is so popular that there is a waiting list.


title: Oak Ridge, Tennessee

text: Oak Ridge's scientific heritage is curated in the American Museum of Science and Energy. Its role in the Manhattan Project is preserved in the Manhattan Project National Historical Park (along with sites in Hanford, Washington and Los Alamos, New Mexico), run cooperatively by the National Park Service and the Department of Energy.


title: Oak Ridge, Tennessee

text: In 2003, the city extended its borders west beyond the Clinch River boundary for the annexation of the master planned community, the Preserve at Oak Ridge, paving the way for economic growth into the 21st century.


title: Oak Ridge, Tennessee

text: In January 2020, the city council of Oak Ridge approved the "Wilson Street Corridor" project plan, intended to develop and construct a downtown area in the city situated along Wilson Street. The plan consists of a mixed-use development of retail, residential usage, and restaurants with a primary focus of multi-story residential space.


title: Oak Ridge, Tennessee

text: Immediately northeast of Oak Ridge, the southwestward-flowing Clinch River bends sharply to the southeast for roughly toward Solway, where it turns again to the southwest. After flowing for approximately , the river bends sharply to the northwest at Copper Ridge, and continues in this direction for nearly . At the K-25 plant, the Clinch turns southwest again and flows for another to its mouth along the Tennessee River at Kingston. This series of bends creates a half-rectangle formation—surrounded by water on the northeast, east, and southwest—in which Oak Ridge is situated.


title: Oak Ridge, Tennessee

text: The Oak Ridge area is striated by five elongated ridges that run roughly parallel to one another in a northeast-to-southwest direction. In order from west-to-east, the five ridges are Blackoak Ridge—which connects the Elza and K-25 bends of the Clinch and thus "walls off" the half-rectangle—East Fork Ridge, Pine Ridge, Chestnut Ridge, and Haw Ridge. The five ridges are divided by four valleys—East Fork Valley (between Blackoak and East Fork Ridge), Gamble Valley (between East Fork Ridge and Pine Ridge), Bear Creek Valley (between Pine Ridge and Chestnut), and Bethel Valley (between Chestnut and Haw). These ridges and valleys are part of the Ridge-and-Valley Appalachians physiographic province. The main section of the city is located in the northeast, where East Fork and Pine Ridge give way to low, scattered hills. Many of the city's residences are located along the relatively steep northeastern slope of Blackoak Ridge.


title: Oak Ridge, Tennessee

text: The completion of Melton Hill Dam (along the Clinch near Copper Ridge) in 1963 created Melton Hill Lake, which borders the city on the northeast and east. The lakefront on the east side of the city is a popular recreation area, with bicycling trails and picnic areas lining the shore. The lake is also well known as a venue for rowing competitions. Watts Bar Lake, an impoundment of the Tennessee River which covers the lower of the Clinch, borders Oak Ridge to the south and southwest.


title: Oak Ridge, Tennessee

text: According to the United States Census Bureau, the city has a total area of , of which is land and , or 5.25%, is water.


title: Oak Ridge, Tennessee

text: Like much of the rest of the state, Oak Ridge has a humid subtropical climate ("Cfa" in the Köppen climate classification); it is part of USDA hardiness zone 7a. The normal monthly mean temperature ranges from in January to in July, while, on average, there are 4.3 days where the temperature stays at or below freezing and 39 days with a high at or above per year. The all-time record low is , set on January 21, 1985, while the all-time record high is , set on June 30, 2012, and July 28, 1952. However, temperatures reaching either or are uncommon, having last occurred February 5, 1996 (the date of the all-time record low for February) and July 1, 2012.


title: Oak Ridge, Tennessee

text: Precipitation is high, averaging annually, but reaches a low during late summer. The rainiest calendar day on record is August 10, 1960, when of rain fell; monthly precipitation has ranged from trace amounts in October 1963 to in July 1967.


title: Oak Ridge, Tennessee

text: As of the 2020 United States census, there were 31,402 people, 12,008 households, and 7,641 families residing in the city.


title: Oak Ridge, Tennessee

text: As of the 2010 United States Census, there were 29,330 people, 12,772 households, and 7,921 families residing in the city. The population density was 344.0 people per square mile (132.8/km). There were 14,494 housing units at an average density of 161.2 per square mile (62.2/km). The racial makeup of the city was 86.8% White (81.8% non-Hispanic), 8.1% African American, 0.4% Native American or Alaska Native, 2.5% Asian, 0.03% Pacific Islander, 2.0% from other races, and 3.0% from two or more races. Hispanics or Latinos of any race were 4.6% of the population.


title: Oak Ridge, Tennessee

text: There were 12,772 households, with 25.2% having children under the age of 18 living with them, 45.2% being married couples living together, 12.9% having a female householder with no husband present, 3.9% having a male householder with no wife present, and 38.0% being non-families. 33.3% of all households were made up of individuals, and 14.0% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 2.86.


title: Oak Ridge, Tennessee

text: The age distribution was 22.0% under the age of 18, 7.1% from 18 to 24, 22.8% from 25 to 44, 28.9% from 45 to 64, and 19.3% who were 65 years of age or older. The median age was 43.5 years. For every 100 females, there were 89.4 males. For every 100 females age 18 and over, there were 86.3 males.


title: Oak Ridge, Tennessee

text: The median income for a household in the city was $48,716, and the median income for a family was $69,333. Full-time, year-round male workers had a median income of $54,316 versus $36,140 for females in the same employment situation. The per capita income for the city was $30,430. About 10.7% of families and 16.0% of the population were below the poverty line, including 28.1% of those under age 18 and 6.7% of those age 65 or over.


title: Oak Ridge, Tennessee

text: Oak Ridge uses the council-manager government system, which was established in 1959 when the city was incorporated. It is governed by a seven-member city council composed of the mayor and six council members.


title: Oak Ridge, Tennessee

text: Oak Ridge is represented in the Tennessee House of Representatives in the 33rd District in Anderson County, and the 32nd district in Roane County, by Representatives John Ragan and Kent Calfee respectively, both of whom are Republican.


title: Oak Ridge, Tennessee

text: In the Tennessee State Senate, Oak Ridge is represented in the 5th district in Anderson County, and the 12th district in Roane County, by Lieutenant Governor of Tennessee and Senator Randy McNally, and Senator Ken Yager respectively, both of whom are Republican.


title: Oak Ridge, Tennessee

text: Oak Ridge is represented in the United States House of Representatives by Republican Chuck Fleischmann of the 3rd congressional district.


title: Oak Ridge, Tennessee

text: The federal government projects at Oak Ridge are reduced in size and scope, but are still the city's principal economic activity and one of the biggest employers in the Knoxville metropolitan area. The Department of Energy owns the federal sites and maintains a major office in the city. Oak Ridge National Laboratory is the largest multipurpose lab in the Department of Energy's National Laboratory system. It is home to the Spallation Neutron Source, a 1.4 billion dollar project completed in 2006, and "Titan", one of the world's most powerful scientific supercomputers, which has peak performance of more than one quadrillion operations per second.


title: Oak Ridge, Tennessee

text: The Y-12 National Security Complex is a component of the U.S. nuclear weapons complex. The Department of Energy's Environmental Management office is conducting an extensive program of decontamination and decommissioning, environmental cleanup, and waste management to remove or stabilize the hazardous residues remaining from decades of government production and research activities.


title: Oak Ridge, Tennessee

text: The Department of Energy Office of Scientific and Technical Information, which disseminates government research and development information and operates the science.gov website, is located in the city. The Oak Ridge Institute for Science and Education, operated by Oak Ridge Associated Universities, conducts research and education programs for the DOE, Department of Homeland Security, and other federal agencies. The Atmospheric Turbulence and Diffusion Division (ATDD), one of several field divisions of the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory, is also located in the city. ATDD began under AEC sponsorship in 1948 as a Weather Bureau research office providing meteorological information and expertise for the AEC. Currently its main function is to perform air quality-related research directed toward issues of national and global importance.


title: Oak Ridge, Tennessee

text: The nuclear industry continues to grow in Oak Ridge following the demolition of the K-25 site. Currently planned in Oak Ridge are a nuclear power plant, two nuclear fuel plants, a nuclear research reactor, and a nuclear medicine plant.


title: Oak Ridge, Tennessee

text: Boeing operated a manufacturing plant in the city beginning in the early 1980s, but closed in 2007. IPIX, Remotec (now a subsidiary of Northrop Grumman), and several other technology-based companies have been founded in Oak Ridge, including Greg LeMond's carbon fiber-manufacturing business, LeMond Composites. Several radioactive waste processing companies, including EnergySolutions, have operations in Oak Ridge.


title: Oak Ridge, Tennessee

text: The infrastructure that was new in the 1940s is aging. The once-isolated city is now incorporated into the Knoxville metropolitan area. Oak Ridge is now challenged to blend into the suburban orbit of Knoxville as its heritage as a "super secret" government installation subsides. Changing economic forces have led to continuing changes in the commercial sector. For example, the Oak Ridge City Center, a shopping center built in the 1950s and converted to an indoor shopping mall in the 1980s, sat largely empty in the years leading to its eventual partial demolition and redevelopment.


title: Oak Ridge, Tennessee

text: The city operates a preschool, four elementary schools enrolling kindergarten through grade 4, two middle schools enrolling grades 5 through 8, and one high school enrolling grades 9 through 12.


title: Oak Ridge, Tennessee

text: In an August 2004 referendum, city voters approved an increase in local sales taxes to fund a $55 million project for Oak Ridge High School. Following demolition of one wing of the main building, construction on the first wall of the new building began in April 2005. Temporary classrooms were set up to house science classes; they will continue to be used for different purposes as the multi-year project progresses.


title: Oak Ridge, Tennessee

text: Roane State Community College has its largest branch campus in Oak Ridge. Other higher education organizations present in the community, but not offering classes locally, include the Oak Ridge Institute for Science and Education, Oak Ridge Associated Universities, and the University of Tennessee Forestry Stations and Arboretum.


title: Oak Ridge, Tennessee

text: Independent schools in the city include the Montessori School of Oak Ridge (preschool and kindergarten founded in 1977), St. Mary's School (Roman Catholic, pre-kindergarten through grade 8), and several preschools. The Oak Ridge Institute for Continued Learning offers a diverse array of educational opportunities for adults.


title: Oak Ridge, Tennessee

text: The Oak Ridge school district was ranked number one in the state of Tennessee, and Oak Ridge High School was ranked the number three high school in the state of Tennessee, in the Niche 2017 Best School Districts.


title: Oak Ridge, Tennessee

text: Oak Ridge is served by a daily newspaper, "The Oak Ridger", and was for many years the home of AM radio station WATO.


title: Oak Ridge, Tennessee

text: A smaller daily newspaper in the area was "The Oak Ridge Observer," which ceased publication after a nine-year run in January 2014.


title: Oak Ridge, Tennessee

text: A Minor League Baseball team called the Oak Ridge Pioneers played at the city's Ridgeview Park for one season in 1954. Another team, the Oak Ridge Bombers, played briefly in 1948 before relocating.


title: Oak Ridge, Tennessee

text: The Oak Ridge Boys draw their name from the group's frequent performances at Oak Ridge National Laboratory during their earliest incarnation under Wally Fowler.


title: Oscar Zeta Acosta

text: Oscar "Zeta" Acosta Fierro (; April 8, 1935 – disappeared 1974) was a Mexican-American attorney, politician, novelist and activist in the Chicano Movement. He was most well known for his novels "Autobiography of a Brown Buffalo" (1972) and "The Revolt of the Cockroach People" (1973), and for his friendship with American author Hunter S. Thompson. Thompson characterized him as a heavyweight Samoan attorney, Dr. Gonzo, in his 1971 novel "Fear and Loathing in Las Vegas". Acosta disappeared in 1974 during a trip in Mexico and is presumed dead.


title: Oscar Zeta Acosta

text: Oscar Acosta was born in El Paso, Texas, to Manuel and Juanita ("née" Fierro) Acosta, from Mexico and El Paso, respectively. He was the third child born but second to survive childhood. Acosta had an older brother, Roberto, born in 1934. After the family moved to California, the children were raised in the small San Joaquin Valley rural community of Riverbank, near Modesto. Acosta's father was drafted during World War II.


title: Oscar Zeta Acosta

text: After finishing high school, Acosta joined the United States Air Force. Following his discharge, he worked his way through Modesto Junior College. Acosta went on to San Francisco State University where he studied creative writing, becoming the first member of his family to get a college education. He attended night classes at San Francisco Law School and passed the state bar exam in 1966. In 1967, Acosta began working locally as an antipoverty attorney for the East Oakland Legal Aid Society.


title: Oscar Zeta Acosta

text: In 1968, Acosta moved to East Los Angeles and joined the Chicano Movement as an activist attorney, defending Chicano groups and activists. He represented the Chicano 13 of the East L.A. walkouts, members of the Brown Berets, Rodolfo Gonzales, and other residents of the East L.A. barrio. Acosta's controversial defenses earned him the ire of the Los Angeles Police Department, who often followed and harassed him. In 1970, he ran for sheriff of Los Angeles County against Peter J. Pitchess, and received more than 100,000 votes. During the campaign, Acosta was jailed for two days for contempt of court. He vowed that if elected, he would do away with the Sheriff's Department as it was then constituted. Known for loud ties and a flowered attaché case with a Chicano Power sticker, Acosta lost to Pitchess' 1.3 million votes but beat Everett Holladay, chief of police of Monterey Park.


title: Oscar Zeta Acosta

text: In 1972, Acosta published his first novel, "Autobiography of a Brown Buffalo," about a lawyer fighting for the rights of a marginalized people. In 1973, he published "The Revolt of the Cockroach People", a fictionalized version of the 1970 Chicano Moratorium as well as an account of the death of "Los Angeles Times" columnist Rubén Salazar.


title: Oscar Zeta Acosta

text: In the summer of 1967, Acosta met author Hunter S. Thompson. In 1971, Thompson wrote an article on Acosta and the injustice in the barrios of East Los Angeles, as well as the death of Salazar, for "Rolling Stone" magazine, titled "Strange Rumblings in Aztlan". While working on the article, Thompson and Acosta decided that a trip to Las Vegas, Nevada, was in order, so that they could freely discuss the subject matter of the article away from any police supervision. Thompson wrote about this trip in his 1971 novel "Fear and Loathing in Las Vegas".


title: Oscar Zeta Acosta

text: The legal department of the publisher of "Fear and Loathing" said the book could not be published without clearance by Acosta, as references to him were recognizable. Acosta initially refused the clearance, saying that he was insulted by Thompson's alteration of his race—Thompson had described him as a "300-pound Samoan." He understood, however, that inserting his real name and race would necessitate extensive rewriting and delay publication of the book, so he promised clearance provided that his name and picture would appear on the dustjacket.


title: Oscar Zeta Acosta

text: Scholar David S. Wills, in "High White Notes: The Rise and Fall of Gonzo Journalism", argued that it was Acosta who pushed Thompson to pursue the theme of the American Dream and indeed provided much of the plot of the novel through his actions in Las Vegas. He asserts that this is likely the reason why Acosta felt so aggrieved, citing various letters and audio recordings of the two men. Acosta even complained to one of Thompson's editors, “Hunter has stolen my soul. He has taken my best lines and has used me.”


title: Oscar Zeta Acosta

text: Although Thompson and Acosta attempted to work together one more time, their relationship was strained by the dispute over "Fear and Loathing in Las Vegas" and it never fully recovered. After Acosta's death, it took Thompson several years before he wrote an obituary for his friend, “The Banshee Screams for Buffalo Meat.” In it, Thompson called Acosta, “a stupid, vicious quack with no morals at all and the soul of a hammerhead shark.” Ralph Steadman explained that Thompson "berated most of his friends a lot, but somehow it was funny. His way of expressing love for people was to be both angry and insulting."


title: Oscar Zeta Acosta

text: In May 1974, Acosta disappeared while traveling in Mazatlán, Sinaloa, Mexico. His son, Marco Acosta, believes that he was the last person to talk to his father. Acosta telephoned his son from Mazatlán, telling him that he was "about to board a boat full of white snow." Marco is later quoted in reference to his father's disappearance: "The body was never found, but we surmise that probably, knowing the people he was involved with, he ended up mouthing off, getting into a fight, and getting killed."


title: Oscar Zeta Acosta

text: In 1977, Thompson's investigation of Acosta's disappearance, titled "The Banshee Screams For Buffalo Meat," was published in "Rolling Stone". According to Thompson, Acosta was a powerful attorney and spokesman, but suffered from an addiction to amphetamines and had a predilection for LSD. Thompson wrote that he believed Acosta was either murdered by drug dealers or was the victim of a political assassination. Others have speculated that Acosta overdosed or suffered a nervous breakdown during his trip.


title: Oscar Zeta Acosta

text: The film "Where the Buffalo Roam" (1980) loosely depicts Acosta's life and his relationship with Thompson. Its name is derived from Thompson's article about Acosta, "The Banshee Screams for Buffalo Meat," in reference to Acosta's book "Autobiography of a Brown Buffalo". Actor Peter Boyle portrayed Acosta, whose character is named "Carl Lazlo, Esquire" and Bill Murray portrayed Thompson.


title: Oscar Zeta Acosta

text: "Fear and Loathing in Las Vegas" (1998) is a film adaptation of Thompson's 1971 novel of the same name, a fictionalized account of Thompson and Acosta's trip to Las Vegas in 1971. Benicio del Toro portrays Acosta, referred to in the film and novel as "Dr. Gonzo," while Johnny Depp portrayed Thompson (under the alias of Raoul Duke).


title: Oscar Zeta Acosta

text: "The Rise and Fall of the Brown Buffalo" (2017) is a documentary of the life and career of Acosta with dramatic reenactments. The documentary was directed by Phillip Rodriguez and produced by Benicio del Toro.


title: Mud dauber

text: Mud dauber (or "mud wasp" or "dirt dauber") is a name commonly applied to a number of wasps from either the family Sphecidae or Crabronidae which build their nests from mud; this excludes members of the family Vespidae (especially the subfamily Eumeninae), that are instead referred to as "potter wasps". Mud daubers belong to different families and are variable in appearance. Most are long, slender wasps about in length. The name refers to the nests that are made by the female wasps, which consist of mud molded into place by the wasp's mandibles. Mud daubers are not normally aggressive, but can become belligerent when threatened. Stings are uncommon.


title: Mud dauber

text: The organ pipe mud dauber, one of many mud daubers in the family Crabronidae, builds nests in the shape of a cylindrical tube resembling an organ pipe or pan flute. Common sites include vertical or horizontal faces of walls, cliffs, bridges, overhangs and shelter caves or other structures.


title: Mud dauber

text: The nest of a black and yellow mud dauber species "Sceliphron caementarium" is a simple, one, two or sometimes three celled, cigar-shaped mass that is attached to crevices, cracks and corners. Each cell contains one egg. Usually several cells are clumped together and covered in mud. The blue mud dauber species "Chalybion californicum", another sphecid, builds mud nests, but occasionally refurbishes the abandoned nests of other species; it preys primarily on spiders. The two species commonly occupy the same barns, porches, or other nest sites.


title: Mud dauber

text: All mud daubers may occupy the same sites year after year, creating large numbers of nests in protected locations; such sites are often used as nest sites by other kinds of wasps and bees, as well as other types of insects.


title: Mud dauber

text: One disadvantage to making nests is that most, if not all, of the nest-maker’s offspring are concentrated in one place, making them highly vulnerable to predation. Once a predator finds a nest, it can plunder it cell by cell. A variety of parasitic wasps, ranging from extremely tiny chalcidoid wasps to larger, bright green chrysidid wasps attack mud dauber nests. They pirate provisions and offspring as food for their own offspring.


title: Mud dauber

text: Like most other solitary wasps, mud daubers are parasitoids, but unlike the majority of parasitoids, they actively capture and paralyze the prey upon which they lay their eggs. The females build the nests, and hunt to provision them. Males of pipe-organ mud daubers have been observed bringing spiders to the nest, and nest guarding, an extremely rare appearance of male parental care, otherwise virtually unknown among Hymenoptera.


title: Mud dauber

text: Black and yellow mud daubers primarily prey on relatively small, colorful spiders, such as crab spiders (and related groups), orb weavers and some jumping spiders. They usually find them in and around vegetation. Blue mud daubers are the main predator of the black and brown widow spiders.


title: Mud dauber

text: Adults of both sexes frequently drink flower nectar, but they stock their nests with spiders, which serve as food for their offspring. Mud daubers prefer particular kinds and sizes of spiders for their larders. Instead of stocking a nest cell with one or two large spiders, mud daubers cram as many as two dozen small spiders into a nest cell.


title: Mud dauber

text: To capture a spider, the wasp grabs it and stings it. The venom from the sting does not kill the spider, but paralyzes and preserves it so it can be transported and stored in the nest cell until consumed by the larva. A mud dauber usually lays its egg on the prey item and then seals it into the nest cell with a mud cap. It then builds another cell or nest. The young survive the winter inside the nest.


title: Mud dauber

text: On February 6, 1996, Birgenair Flight 301, a 757 jet flying from Puerto Plata in the Dominican Republic, crashed into the Atlantic Ocean. All 13 crew members and 176 passengers were killed. A key part of the accident was a blocked pitot tube. Although the tubes were never recovered from the ocean floor, the plane had been sitting on the tarmac for twenty-five days with uncovered pitot tubes. Investigators believe a black and yellow mud dauber, "Sceliphron caementarium", got into the tube and built its cylindrical nest inside, causing faulty air-speed readings that were a large part of the crash. The main and primary cause of the crash, however, was pilot error due to the flight crew's improper response to inaccurate air-speed and the stick-shaker stall warning.


title: Mud dauber

text: On April 10, 2015, about 18:45 Eastern Daylight Time, a Gulfstream Aerospace G-IV, N450KK, was substantially damaged during a cabin over-pressurization event over the Caribbean Sea while en route to Fort Lauderdale, Florida, United States. An initial examination of the fuselage revealed that the outflow valve safety port, located on the outer fuselage, was completely plugged with a foreign material resembling dried soil from a mud dauber.


title: Oti Mabuse

text: Otlile "Oti" Mabuse (born 8 August 1990) is a South African talent show judge, presenter, dancer and Latin dance champion currently based in the United Kingdom. She is best known for being a professional dancer on the British television series "Strictly Come Dancing", which she won in 2019 and 2020, and its German equivalent, "Let's Dance". She was a Dance Captain on "The Greatest Dancer". Since 2021, she has been a panellist on "The Masked Dancer" and became a judge on "Dancing on Ice" in 2022.


title: Oti Mabuse

text: Mabuse was born in Pretoria, and studied civil engineering at university before embarking on a career in professional ballroom dancing. Her elder sister, Motsi Mabuse, is also a professional ballroom dancer. Oti has participated in the German series "Let's Dance" both as a professional dancer and as a judge, and as a professional dancer in Britain's "Strictly Come Dancing".


title: Oti Mabuse

text: Mabuse won the South African Latin American Championship eight times, after which she moved to Germany to broaden her dancing horizons. She has earned a number of titles in her dancing career; including:


title: Oti Mabuse

text: In 2015, Mabuse appeared as a professional dancer on the eighth season of "Let's Dance", the German version of "Strictly Come Dancing".


title: Oti Mabuse

text: She was partnered with singer Daniel Küblböck. The couple were eliminated in week 9, finishing in sixth place.


title: Oti Mabuse

text: In 2016, Mabuse returned as a professional dancer for the ninth season of "Let's Dance". She was partnered with television presenter Niels Ruf. The couple were the first to be eliminated in week 2, leaving in 14th place.


title: Oti Mabuse

text: In 2015, Mabuse appeared as a professional on the 13th series of "Strictly Come Dancing". She was partnered with Olympic boxer Anthony Ogogo. The couple were eliminated in Week 3, finishing in 14th place. That year, she also participated in the Children in Need and Christmas specials of the show, in which she partnered with actors Jack Ashton and Tom Chambers respectively.


title: Oti Mabuse

text: In 2016, Mabuse was partnered with former "Hollyoaks" actor Danny Mac for the show's 14th series. The couple reached the final and finished as runners-up. For the show's 15th series in 2017, she was partnered with Paralympic sprinter Jonnie Peacock, they were eliminated in Week 9 in eighth place. She was paired with England cricketer Graeme Swann for the show's 16th series, they were eliminated in Week 10 in seventh place.


title: Oti Mabuse

text: In 2019, for her fifth stint on the show, she was partnered with former "Emmerdale" actor Kelvin Fletcher, who replaced her originally announced partner, "Made in Chelsea" star Jamie Laing, who had to withdraw from the show after sustaining a foot injury when dancing on the launch show. They went on to become the winners of the series. Laing was confirmed as a contestant for the 18th series the following year, but was re-partnered with fellow professional Karen Hauer, in which Mabuse was partnered with comedian and actor, Bill Bailey, reaching the final and became series winners, with Mabuse becoming the second pro to win the show twice (the other being Aliona Vilani who won series 9 and series 13) and the only pro to win twice in succession.


title: Oti Mabuse

text: On 18 April 2021, two weeks after being unveiled as part of 19th series of the show, Mabuse revealed that this would most likely be her last. On 22 February 2022, Mabuse confirmed she was leaving the show after seven years.


title: Oti Mabuse

text: Mabuse was originally paired with Jamie Laing, however he had to pull out due to a foot injury whilst the recording of the launch show. Laing was replaced with Kelvin Fletcher, just before the start of the live shows.


title: Oti Mabuse

text: In 2014, Mabuse married Romanian dancer Marius Iepure, whom she met in Germany. They currently live in London after moving there from Germany in 2015.


title: Subwoofer

text: A subwoofer (or sub) is a loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be (optimally) generated by a woofer. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-certified systems. Subwoofers are never used alone, as they are intended to "augment" the low-frequency range of loudspeakers that cover the higher frequency bands. While the term "subwoofer" technically only refers to the speaker driver, in common parlance, the term often refers to a subwoofer driver mounted in a speaker enclosure (cabinet), often with a built-in amplifier.


title: Subwoofer

text: Subwoofers are made up of one or more woofers mounted in a loudspeaker enclosure—often made of wood—capable of withstanding air pressure while resisting deformation. Subwoofer enclosures come in a variety of designs, including bass reflex (with a port or vent), using a subwoofer and one or more passive radiator speakers in the enclosure, acoustic suspension (sealed enclosure), infinite baffle, horn-loaded, tapped horn, transmission line, bandpass or isobaric designs. Each design has unique trade-offs with respect to efficiency, low-frequency range, cabinet size and cost. Passive subwoofers have a subwoofer driver and enclosure and they are powered by an external amplifier. Active subwoofers include a built-in amplifier.


title: Subwoofer

text: The first home audio subwoofers were developed in the 1960s to add bass response to home stereo systems. Subwoofers came into greater popular consciousness in the 1970s with the introduction of Sensurround in movies such as "Earthquake", which produced loud low-frequency sounds through large subwoofers. With the advent of the compact cassette and the compact disc in the 1980s, the reproduction of deep "and" loud bass was no longer limited by the ability of a phonograph record stylus to track a groove, and producers could add more low-frequency content to recordings. As well, during the 1990s, DVDs were increasingly recorded with "surround sound" processes that included a low-frequency effects (LFE) channel, which could be heard using the subwoofer in home theater systems. During the 1990s, subwoofers also became increasingly popular in home stereo systems, custom car audio installations, and in PA systems. By the 2000s, subwoofers became almost universal in sound reinforcement systems in nightclubs and concert venues.


title: Subwoofer

text: From about 1900 to the 1950s, the "lowest frequency in practical use" in recordings, broadcasting and music playback was 100 Hz. When sound was developed for motion pictures, the basic RCA sound system was a single 8-inch (20.3 cm) speaker mounted in straight horn, an approach which was deemed unsatisfactory by Hollywood decisionmakers, who hired Western Electric engineers to develop a better speaker system. The early Western Electric experiments added a set of 18-inch drivers for the low end in a large, open-backed baffle (extending the range down to 50 Hz) and a high-frequency unit, but MGM was not pleased with the sound of the three-way system, as they had concerns about the delay between the different drivers.


title: Subwoofer

text: In 1933, the head of MGM's sound department, Douglas Shearer, worked with John Hilliard and James B. Lansing (who would later found Altec Lansing in 1941 and JBL in 1946) to develop a new speaker system that used a two-way enclosure with a W-shaped bass horn that could go as low as 40 Hz. The Shearing-Lansing 500-A ended up being used in "screening rooms, dubbing theaters, and early sound reinforcement". In the late 1930s, Lansing created a smaller two-way speaker with a woofer in a vented enclosure, which he called the Iconic system; it was used as a studio monitor and in high-end home hi-fi set-ups.


title: Subwoofer

text: During the 1940s swing era, to get deeper bass, "pipelike opening[s]" were cut into speaker enclosures, creating bass reflex enclosures, as it was found that even a fairly inexpensive speaker enclosure, once modified in this way, could "transmit the driving power of a heavy...drumbeat—and sometimes not much else—to a crowded dancefloor." Prior to the development of the first subwoofers, woofers were used to reproduce bass frequencies, usually with a crossover point set at 500 Hz and a loudspeaker in an infinite baffle or in professional sound applications, a "hybrid horn-loaded" bass reflex enclosure (such as the 15-inch Altec Lansing A-7 enclosure nicknamed the "Voice of the Theater", which was introduced in 1946). In the mid-1950s, the Academy of Motion Picture Arts and Sciences selected the "big, boxy" Altec A-7 as the industry standard for movie sound reproduction in theaters.


title: Subwoofer

text: In September 1964, Raymon Dones, of El Cerrito, California, received the first patent for a subwoofer specifically designed to augment omnidirectionally the low frequency range of modern stereo systems (US patent 3150739). It was able to reproduce distortion-free low frequencies down to 15 cycles per second (15 Hz). A specific objective of Dones's invention was to provide portable sound enclosures capable of high fidelity reproduction of low frequency sound waves without giving an audible indication of the direction from which they emanated. Dones's loudspeaker was marketed in the US under the trade name "The Octavium" from the early 1960s to the mid-1970s. The Octavium was utilized by several recording artists of that era, most notably the Grateful Dead, bassist Monk Montgomery, bassist Nathan East, and the Pointer Sisters. The Octavium speaker and Dones's subwoofer technology were also utilized, in a few select theaters, to reproduce low pitch frequencies for the 1974 blockbuster movie "Earthquake". During the late 1960s, Dones's Octavium was favorably reviewed by audiophile publications including "Hi-Fi News" and "Audio Magazine".


title: Subwoofer

text: Another early subwoofer enclosure made for home and studio use was the separate bass speaker for the Servo Statik 1 by New Technology Enterprises. Designed as a prototype in 1966 by physicist Arnold Nudell and airline pilot Cary Christie in Nudell's garage, it used a second winding around a custom Cerwin-Vega 18-inch (45 cm) driver to provide servo control information to the amplifier, and it was offered for sale at $1795, some 40% more expensive than any other complete loudspeaker listed at "Stereo Review". In 1968, the two found outside investors and reorganized as Infinity. The subwoofer was reviewed positively in "Stereophile" magazine's winter 1968 issue as the SS-1 by Infinity. The SS-1 received very good reviews in 1970 from "High Fidelity" magazine.


title: Subwoofer

text: Another of the early subwoofers was developed during the late 1960s by Ken Kreisel, the former president of the Miller & Kreisel Sound Corporation in Los Angeles. When Kreisel's business partner, Jonas Miller, who owned a high-end audio store in Los Angeles, told Kreisel that some purchasers of the store's high-end electrostatic speakers had complained about a lack of bass response in the electrostatics, Kreisel designed a powered woofer that would reproduce only those frequencies that were too low for the electrostatic speakers to convey. Infinity's full range electrostatic speaker system that was developed during the 1960s also used a woofer to cover the lower frequency range that its electrostatic arrays did not handle adequately.


title: Subwoofer

text: The first use of a subwoofer in a recording session was in 1973 for mixing the Steely Dan album "Pretzel Logic", when recording engineer Roger Nichols arranged for Kreisel to bring a prototype of his subwoofer to Village Recorders. Further design modifications were made by Kreisel over the next ten years, and in the 1970s and 1980s by engineer John P. D'Arcy; record producer Daniel Levitin served as a consultant and "golden ears" for the design of the crossover network (used to partition the frequency spectrum so that the subwoofer would not attempt to reproduce frequencies too high for its effective range, and so that the main speakers would not need to handle frequencies too low for their effective range). In 1976, Kreisel created the first satellite speakers and subwoofer system, named "David and Goliath".


title: Subwoofer

text: Subwoofers received a great deal of publicity in 1974 with the movie "Earthquake", which was released in Sensurround. Initially installed in 17 U.S. theaters, the Cerwin-Vega "Sensurround" system used large subwoofers that were driven by racks of 500 watt amplifiers, triggered by control tones printed on one of the audio tracks on the film. Four of the subwoofers were positioned in front of the audience under (or behind) the film screen and two more were placed together at the rear of the audience on a platform. Powerful noise energy and loud rumbling in the range of 17 to 120 Hz were generated at the level of 110–120 decibels of sound pressure level, abbreviated dB(SPL). The new low frequency entertainment method helped the film become a box office success. More Sensurround systems were assembled and installed. By 1976, there were almost 300 Sensurround systems leapfrogging through select theaters. Other films to use the effect include the WW II naval battle epic "Midway" in 1976 and "Rollercoaster" in 1977.


title: Subwoofer

text: For owners of 33 rpm LPs and 45 rpm singles, loud "and" deep bass was limited by the ability of the phonograph record stylus to track the groove. While some hi-fi aficionados had solved the problem by using other playback sources, such as reel-to-reel tape players which were capable of delivering accurate, naturally deep bass from acoustic sources, or synthetic bass not found in nature, with the popular introduction of the compact cassette in the late 1960s it became possible to add more low frequency content to recordings. By the mid-1970s, 12-inch vinyl singles, which allowed for "more bass volume", were used to record disco, reggae, dub and hip-hop tracks; dance club DJs played these records in clubs with subwoofers to achieve "physical and emotional" reactions from dancers.


title: Subwoofer

text: In the early 1970s, David Mancuso hired sound engineer Alex Rosner to design additional subwoofers for his disco dance events, along with "tweeter arrays" to "boost the treble and bass at opportune moments" at his private, underground parties at The Loft. The demand for sub-bass sound reinforcement in the 1970s was driven by the important role of "powerful bass drum" in disco, as compared with rock and pop; to provide this deeper range, a third crossover point from 40 to 120 Hz (centering on 80 Hz) was added. The Paradise Garage discotheque in New York City, which operated from 1977 to 1987, had "custom designed 'sub-bass' speakers" developed by Alex Rosner's disciple, sound engineer Richard ("Dick") Long that were called "Levan Horns" (in honor of resident DJ Larry Levan).


title: Subwoofer

text: By the end of the 1970s, subwoofers were used in dance venue sound systems to enable the playing of "[b]ass-heavy dance music" that we "do not 'hear' with our ears but with our entire body". At the club, Long used four Levan bass horns, one in each corner of the dancefloor, to create a "haptic and tactile quality" in the sub-bass that you could feel in your body. To overcome the lack of sub-bass frequencies on 1970s disco records (sub-bass frequencies below 60 Hz were removed during mastering), Long added a DBX 100 "Boom Box" subharmonic pitch generator into his system to synthesize 25 to 50 Hz sub-bass from the 50 to 100 Hz bass on the records.


title: Subwoofer

text: By the later 1970s, disco club sound engineers were using the same large Cerwin-Vega Sensurround-style folded horn subwoofers that were used in "Earthquake" and similar movies in dance club system installations. In the early 1980s, Long designed a sound system for the Warehouse dance club, with "huge stacks of subwoofers" which created "deep and intense" bass frequencies that "pound[ed] through your system" and "entire body", enabling clubgoers to "viscerally experience" the DJs' house music mixes.


title: Subwoofer

text: In Jamaica in the 1970s and 1980s, sound engineers for reggae sound systems began creating "heavily customized" subwoofer enclosures by adding foam and tuning the cabinets to achieve "rich and articulate speaker output below 100 Hz". The sound engineers who developed the "bass-heavy signature sound" of sound reinforcement systems have been called "deserving as much credit for the sound of Jamaican music as their better-known music producer cousins". The sound engineers for Stone Love Movement (a sound system crew), for example, modified folded horn subwoofers they imported from the US to get more of a bass reflex sound that suited local tone preferences for dancehall audiences, as the unmodified folded horn was found to be "too aggressive" sounding and "not deep enough for Jamaican listeners".


title: Subwoofer

text: In sound system culture, there are both "low and high bass bins" in "towering piles" that are "delivered in large trucks" and set up by a crew of "box boys", and then positioned and adjusted by the sound engineer in a process known as "stringing up", all to create the "sound of reggae music you can literally feel as it comes off these big speakers". Sound system crews hold 'sound clash' competitions, where each sound system is set up and then the two crews try to outdo each other, both in terms of loudness and the "bass it produced".


title: Subwoofer

text: In the 1980s, the Bose Acoustimass AM-5 became a popular subwoofer and small high-range satellite speaker system for home listening. Steve Feinstein stated that with the AM-5, the system's "appearance mattered as much as, if not more than, great sound" to consumers of this era, as it was considered to be a "cool" look. The success of the AM-5 led to other makers launching subwoofer-satellite speaker systems, including Boston Acoustics Sub Sat 6 and 7, and the Cambridge SoundWorks Ensemble systems (by Kloss). Claims that these sub-satellite systems showed manufacturers and designers that home theater systems with a hidden subwoofer could be "feasible and workable in a normal living room" for mainstream consumers. Despite criticism of the AM-5 from audio experts, regarding a lack of bass range below 60 Hz, an "acoustic hole" in the 120 to 200 Hz range and a lack of upper range above 13 kHz for the satellites, the AM-5 system represented 30% of the US speaker market in the early 1990s.


title: Subwoofer

text: In the 1980s, Origin Acoustics developed the first residential in-wall subwoofer named Composer. It used an aluminum 10-inch (25.4 cm) driver and a foam-lined enclosure designed to be mounted directly into wall studs during the construction of a new home. The frequency response for the Composer is 30 to 250 Hz.


title: Subwoofer

text: While in the 1960s and 1970s deep bass speakers were once an exotic commodity owned by audiophiles, by the mid-1990s they were much more popular and widely used, with different sizes and capabilities of sound output. An example of 1990s subwoofer use in sound reinforcement is the Ministry of Sound dance club which opened in 1991 in London. The dancefloor's sound system was based on Richard Long's design at Paradise Garage. The club spent about £500,000 on a sound system that used Martin Audio components in custom-built cabinets, including twelve 21" 9,500 watt active subwoofers, twelve 18-inch subwoofers and twelve Martin Audio W8C mid-high speakers.


title: Subwoofer

text: The popularity of the CD made it possible to add more low frequency content to recordings and satisfy a larger number of consumers. Home subwoofers grew in popularity, as they were easy to add to existing multimedia speaker setups and they were easy to position or hide.


title: Subwoofer

text: In 2018, some electronic dance music (EDM) sound systems for venues that play hardcore bass have multiple subwoofer arrays to deal with mid-bass (80–150 Hz), bass (40–80 Hz), and "infra-bass" (20–40 Hz).


title: Subwoofer

text: In 2015, Damon Krukowski wrote an article entitled "Drop the Bass: A Case Against Subwoofers" for "Pitchfork" magazine, based on his performing experience with Galaxie 500; he argues that "for certain styles of music", especially acoustic music genres, "these low-end behemoths are actually ruining our listening experience" by reducing the clarity of the low end. In 2015, John Hunter from REL Acoustics stated that audiophiles tend to "have a love/hate relationship with subwoofers" because most subs have "awful", "entry-level" sound quality and they are used in an "inappropriate way", without integrating the bass seamlessly.


title: Subwoofer

text: Subwoofers use speaker drivers (woofers) typically between 8-inch (20 cm) and 21-inch (53 cm) in diameter. Some uncommon subwoofers use larger drivers, and single prototype subwoofers as large as 60-inch (152 cm) have been fabricated. On the smaller end of the spectrum, subwoofer drivers as small as 4-inch (10 cm) may be used. Small subwoofer drivers in the 4-inch range are typically used in small computer speaker systems and compact home theatre subwoofer cabinets. The size of the driver and number of drivers in a cabinet depends on the design of the loudspeaker enclosure, the size of the cabinet, the desired sound pressure level, the lowest frequency targeted and the level of permitted distortion. The most common subwoofer driver sizes used for sound reinforcement in nightclubs, raves and pop/rock concerts are 10-, 12-, 15- and 18-inch models (25 cm, 30 cm, 38 cm, and 45 cm respectively). The largest available sound reinforcement subwoofers, 21-inch (53 cm) drivers, are less commonly seen.


title: Subwoofer

text: where the variables are Thiele/Small parameters. Deep low-frequency extension is a common goal for a subwoofer and small box volumes are also considered desirable, to save space and reduce the size for ease of transportation (in the case of sound reinforcement and DJ subwoofers). Hofmann's "Iron Law" therefore mandates low efficiency under those constraints, and indeed most subwoofers require considerable power, much more than other individual drivers.


title: Subwoofer

text: So, for the example of a sealed speaker box, the box volume to achieve a given formula_2 is proportional to formula_3:


title: Subwoofer

text: Therefore, a decrease in box volume (i.e., a smaller speaker cabinet ) and the same formula_6 will decrease the efficiency of the subwoofer. Similarly the formula_6 of a speaker is proportional to formula_8:


title: Subwoofer

text: As the efficiency is proportional to formula_10, small improvements in low-frequency extension with the same driver and box volume will result in very significant reductions in efficiency. For these reasons, subwoofers are typically very inefficient at converting electrical energy into sound energy. This combination of factors accounts for the higher amplifier power required to drive subwoofers, and the requirement for greater power handling for subwoofer drivers. Enclosure variations (e.g., bass reflex designs with a port in the cabinet) are often used for subwoofers to increase the efficiency of the driver/enclosure system, helping to reduce the amplifier power requirements.


title: Subwoofer

text: Subwoofers are typically constructed by mounting one or more woofers in a cabinet of medium-density fibreboard (MDF), oriented strand board (OSB), plywood, fiberglass, aluminum or other stiff materials. Because of the high air pressure they produce in the cabinet, subwoofer enclosures often require internal bracing to distribute the resulting forces.


title: Subwoofer

text: Subwoofers have been designed using a number of enclosure approaches: bass reflex (with a port or vent), using a subwoofer and one or more passive radiator speakers in the enclosure, acoustic suspension (sealed enclosure), infinite baffle, horn-loaded, tapped horn, transmission line and bandpass. Each enclosure type has advantages and disadvantages in terms of efficiency increase, bass extension, cabinet size, distortion, and cost.


title: Subwoofer

text: Multiple enclosure types may even be combined in a single design, such as in computer audio with the subwoofer design of the Labtec LCS-2424 (later acquired by Logitech and used for their Z340/Z540/Z640/Z3/Z4), which is a (primitive) passive radiator bandpass enclosure with a bass reflex dividing chamber.


title: Subwoofer

text: While not necessarily an enclosure type, isobaric (such as push-pull) coupled loading of two drivers has sometimes been used in subwoofer products of computer, home cinema and sound reinforcement class, and also DIY versions in automotive applications, to provide relatively deep bass for their size. Self-contained "isobaric-like" driver assemblies have been manufactured since the 2010s.


title: Subwoofer

text: The smallest subwoofers are typically those designed for desktop multimedia systems. The largest common subwoofer enclosures are those used for concert sound reinforcement systems or dance club sound systems. An example of a large concert subwoofer enclosure is the 1980s-era Electro-Voice MT-4 "Bass Cube" system, which used four 18-inch (45 cm) drivers. An example of a subwoofer that uses a bass horn is the Bassmaxx B-Two, which loads an 18-inch (45 cm) driver onto an long folded horn. Folded horn-type subwoofers can typically produce a deeper range with greater efficiency than the same driver in an enclosure that lacks a horn. However, folded horn cabinets are typically larger and heavier than front-firing enclosures, so folded horns are less commonly used. Some experimental fixed-installation subwoofer horns have been constructed using brick and concrete to produce a very long horn that allows a very deep sub-bass extension.


title: Subwoofer

text: Subwoofer output level can be increased by increasing cone surface area or by increasing cone excursion. Since large drivers require undesirably large cabinets, most subwoofer drivers have large excursions. Unfortunately, high excursion, at high power levels, tends to produce more distortion from inherent mechanical and magnetic effects in electro-dynamic drivers (the most common sort). The conflict between assorted goals can never be fully resolved; subwoofer designs necessarily involve tradeoffs and compromises. Hofmann's Iron Law (the efficiency of a woofer system is directly proportional to its cabinet volume (as in size) and to the cube of its cutoff frequency, that is how low in pitch it will go) applies to subwoofers just as it does to all loudspeakers. Thus a subwoofer enclosure designer aiming at the deepest-pitched bass will probably have to consider using a large enclosure size; a subwoofer enclosure designer instructed to create the smallest possible cabinet (to make transportation easier) will need to compromise how low in pitch their cabinet will go.


title: Subwoofer

text: The frequency response specification of a speaker describes the range of frequencies or musical tones a speaker can reproduce, measured in hertz (Hz). The typical frequency range for a subwoofer is between 20–200 Hz. Professional concert sound system subwoofers typically operate below 100 Hz, and THX-certified systems operate below 80 Hz. Subwoofers vary in terms of the range of pitches that they can reproduce, depending on a number of factors such as the size of the cabinet and the construction and design of the enclosure and driver(s). Specifications of frequency response depend wholly for relevance on an accompanying amplitude value—measurements taken with a wider amplitude tolerance will give any loudspeaker a wider frequency response. For example, the JBL 4688 TCB Subwoofer System, a now-discontinued system which was designed for movie theaters, had a frequency response of 23–350 Hz when measured within a 10-decibel boundary (0 dB to −10 dB) and a narrower frequency response of 28–120 Hz when measured within a 6-decibel boundary (±3 dB).


title: Subwoofer

text: Subwoofers also vary in regard to the sound pressure levels achievable and the distortion levels that they produce over their range. Some subwoofers, such as "The Abyss" by MartinLogan for example, can reproduce pitches down to around 18 Hz (which is about the pitch of the lowest rumbling notes on a huge pipe organ with 16 Hz bass pipes) to 120 Hz (±3 dB). Nevertheless, even though the Abyss subwoofer can go down to 18 Hz, its lowest frequency and maximum SPL with a limit of 10% distortion is 35.5 Hz and 79.8 dB at 2 meters. This means that a person choosing a subwoofer needs to consider more than just the lowest pitch that the subwoofer can reproduce.


title: Subwoofer

text: 'Active subwoofers' include their own dedicated amplifiers within the cabinet. Some also include user-adjustable equalization that allows boosted or reduced output at particular frequencies; these vary from a simple "boost" switch, to fully parametric equalizers meant for detailed speaker and room correction. Some such systems are even supplied with a calibrated microphone to measure the subwoofer's in-room response, so the automatic equalizer can correct the combination of subwoofer, subwoofer location, and room response to minimize the effects of room modes and improve low-frequency performance.


title: Subwoofer

text: 'Passive subwoofers' have a subwoofer driver and enclosure, but they do not include an amplifier. They sometimes incorporate internal passive crossovers, with the filter frequency determined at the factory. These are generally used with third-party power amplifiers, taking their inputs from active crossovers earlier in the signal chain. Inexpensive Home Theatre in a Box packages often come with a passive subwoofer cabinet that is amplified by the multi-channel amplifier. While few high-end home-theater systems use passive subwoofers, this format is still popular in the professional sound industry.


title: Subwoofer

text: Equalization can be used to adjust the in-room response of a subwoofer system. Designers of active subwoofers sometimes include a degree of corrective equalization to compensate for known performance issues (e.g., a steeper than desired low end roll-off rate). In addition, many amplifiers include an adjustable low-pass filter, which prevents undesired higher frequencies from reaching the subwoofer driver. For example, if a listener's main speakers are usable down to 80 Hz, then the subwoofer filter can be set so the subwoofer only works below 80 Hz. Typical filters involve some overlap in frequency ranges; a steep 4th-order 24 dB/octave low-pass filter is generally desired for subwoofers in order to minimize the overlap region. The filter section may also include a high-pass "infrasonic" or "subsonic" filter, which prevents the subwoofer driver from attempting to reproduce frequencies below its safe capabilities. Setting an infrasonic filter is important on bass reflex subwoofer cabinets, as the bass reflex design tends to create the risk of cone overexcursion at pitches below those of the port tuning, which can cause distortion and damage the subwoofer driver. For example, in a ported subwoofer enclosure tuned to 30 Hz, one may wish to filter out pitches below the tuning frequency; that is, frequencies below 30 Hz.


title: Subwoofer

text: Some systems use parametric equalization in an attempt to correct for room frequency response irregularities. Equalization is often unable to achieve flat frequency response at all listening locations, in part because of the resonance (i.e., standing wave) patterns at low frequencies in nearly all rooms. Careful positioning of the subwoofer within the room can also help flatten the frequency response. Multiple subwoofers can manage a flatter general response since they can often be arranged to excite room modes more evenly than a single subwoofer, allowing equalization to be more effective.


title: Subwoofer

text: Changing the relative phase of the subwoofer with respect to the woofers in other speakers may or may not help to minimize unwanted destructive acoustic interference in the frequency region covered by both the subwoofer and the main speakers. It may not help at all frequencies, and may create further problems with frequency response, but even so is generally provided as an adjustment for subwoofer amplifiers. Phase control circuits may be a simple polarity reversal switch or a more complex continuously variable circuit.


title: Subwoofer

text: Continuously variable phase control circuits are common in subwoofer amplifiers, and may be found in crossovers and as do-it-yourself electronics projects. Phase controls allow the listener to change the arrival time of the subwoofer sound waves relative to the same frequencies from the main speakers (i.e., at and around the crossover point to the subwoofer). A similar effect can be achieved with the delay control on many home theater receivers. The subwoofer phase control found on many subwoofer amplifiers is actually a polarity inversion switch. It allows users to reverse the polarity of the subwoofer relative to the audio signal it is being given. This type of control allows the subwoofer to either be in phase with the source signal, or 180 degrees out of phase.


title: Subwoofer

text: The subwoofer phase can still be changed by moving the subwoofer closer to or further from the listening position, however this may not be always practical.


title: Subwoofer

text: Some active subwoofers use a servo feedback mechanism based on cone movement that modifies the signal sent to the voice coil. The servo feedback signal is derived from a comparison of the input signal to the amplifier versus the actual motion of the cone. The usual source of the feedback signal is a few turns of voice coil attached to the cone or a microchip-based accelerometer placed on the cone itself. An advantage of a well-implemented servo subwoofer design is reduced distortion making smaller enclosure sizes possible. The primary disadvantages are cost and complexity.


title: Subwoofer

text: Servo-controlled subwoofers are not the same as Tom Danley's ServoDrive subwoofers, whose primary mechanism of sound reproduction avoids the normal voice coil and magnet combination in favor of a high-speed belt-driven servomotor. The ServoDrive design increases output power, reduces harmonic distortion and virtually eliminates power compression, the loss of loudspeaker output that results from an increase in voice coil impedance due to overheating of the voice coil. This feature allows high-power operation for extended periods of time. Intersonics was nominated for a TEC Award for its ServoDrive Loudspeaker (SDL) design in 1986 and for the Bass Tech 7 model in 1990.


title: Subwoofer

text: The use of a subwoofer augments the bass capability of the main speakers, and allows them to be smaller without sacrificing low-frequency capability. A subwoofer does not necessarily provide superior bass performance in comparison to large conventional loudspeakers on ordinary music recordings due to the typical lack of very low frequency content on such sources. However, there are recordings with substantial low-frequency content that most conventional loudspeakers are ill-equipped to handle without the help of a subwoofer, especially at high playback levels, such as music for pipe organs with 32' (9.75 meter) bass pipes (16 Hz), very large bass drums on symphony orchestra recordings and electronic music with extremely low synth bass parts, such as bass tests or bass songs.


title: Subwoofer

text: Frequencies which are sufficiently low are not easily localized by humans, hence many stereo and multichannel audio systems feature only one subwoofer channel and a single subwoofer can be placed off-center without affecting the perceived sound stage, since the sound that it produces will be difficult to localize. The intention in a system with a subwoofer is often to use small main speakers (of which there are two for stereo and five or more for surround sound or movie tracks) and to hide the subwoofer elsewhere (e.g. behind furniture or under a table), or to augment an existing speaker to save it from having to handle woofer-destroying low frequencies at high levels. This effect is possible only if the subwoofer is restricted to quite low frequencies, usually taken to be, say, 100 Hz and below—still less localization is possible if restricted to even lower maximum frequencies. Higher upper limits for the subwoofer (e.g., 125 Hz) are much more easily localized, making a single subwoofer impractical. Home theatre systems typically use one subwoofer cabinet (the "1" in 5.1 surround sound). However, to "improve bass distribution in a room that has multiple seating locations, and prevent "node" or "null points" with weakened bass response, some home cinema enthusiasts use "5.2" or "7.2" surround sound systems with two subwoofer cabinets in the same room.


title: Subwoofer

text: Some users add a subwoofer because high levels of low-frequency bass are desired, even beyond what is in the original recording, as in the case of house music enthusiasts. Thus, subwoofers may be part of a package that includes satellite speakers, may be purchased separately, or may be built into the same cabinet as a conventional speaker system. For instance, some floor-standing tower speakers include a subwoofer driver in the lower portion of the same cabinet. Physical separation of subwoofer and "satellite" speakers not only allows placement in an inconspicuous location, but since sub-bass frequencies are particularly sensitive to room location (due to room resonances and reverberation 'modes'), the best position for the subwoofer is not likely to be where the "satellite" speakers are located.


title: Subwoofer

text: Higher end home theater systems and enthusiasts may also opt to take low-frequency bass reproduction even further by incorporating 2 or more external subwoofers. Having two subwoofers placed around the living room ensures even distribution of bass, reducing subwoofer localization and pressurizing the room with low frequency notes that can be felt, just like the cinemas.


title: Subwoofer

text: For greatest efficiency and best coupling to the room's air volume, subwoofers can be placed in a corner of the room, far from large room openings, and closer to the listener. This is possible since low bass frequencies have a long wavelength; hence there is little difference between the information reaching a listener's left and right ears, and so they cannot be readily localized. All low-frequency information is sent to the subwoofer. However, unless the sound tracks have been carefully mixed for a single subwoofer channel, it is possible to have some cancellation of low frequencies if bass information in one channel's speaker is out of phase with another.


title: Subwoofer

text: The physically separate subwoofer/satellite arrangement, with small satellite speakers and a large subwoofer cabinet that can be hidden behind furniture, has been popularized by multimedia speaker systems such as Bose Acoustimass Home Entertainment Systems, Polk Audio RM2008 Series and Klipsch Audio Technologies ProMedia, among many others.


title: Subwoofer

text: Further, poorly-designed systems often leave everything below about 120 Hz (or even higher) to the subwoofer, meaning that the subwoofer handles frequencies which the ear can use for sound source localization, thus introducing an undesirable subwoofer "localization effect". This is usually due to poor crossover designs or choices (too high a crossover point or insufficient crossover slope) used in many computer and home theater systems; localization also comes from port noise and from typically large amounts of harmonic distortion in the subwoofer design. Home subwoofers sold individually usually include crossover circuitry to assist with the integration of the subwoofer into an existing system.


title: Subwoofer

text: Automobiles are not well suited for the "hidden" subwoofer approach due to space limitations in the passenger compartments. It is not possible, in most circumstances, to fit such large drivers and enclosures into doors or dashboards, so subwoofers are installed in the trunk or back seat space. Some car audio enthusiasts compete to produce very high sound pressure levels in the confines of their vehicle's cabin; sometimes dangerously high sound pressure levels. The "SPL wars" have drawn much attention to subwoofers in general, but subjective competitions in sound quality ("SQ") have not gained equivalent popularity. Top SPL cars are not able to play normal music, or perhaps even to drive normally as they are designed solely for competition. Many non-competition subwoofers are also capable of generating high levels in cars due to the small volume of a typical car interior. High sound levels can cause hearing loss and tinnitus if one is exposed to them for an extended period of time.


title: Subwoofer

text: In the 2000s, several car audio manufacturers produced subwoofers using non-circular shapes, including Boston Acoustic, Kicker, Sony, Bazooka, and X-Tant. Other major car audio manufacturers like Rockford Fosgate did not follow suit since non-circular subwoofer shapes typically carry some sort of distortion penalties. In situations of limited mounting space they provide a greater cone area and assuming all other variables are constant, greater maximum output. An important factor in the "square sub vs round sub" argument is the effects of the enclosure used. In a sealed enclosure, the maximum displacement is determined by


title: Subwoofer

text: These are some of the Thiele/Small parameters which can either be measured or found with the driver specifications.


title: Subwoofer

text: After the introduction of Sensurround, movie theater owners began installing permanent subwoofer systems. Dolby Stereo 70 mm Six Track was a six-channel film sound format introduced in 1976 that used two subwoofer channels for stereo reproduction of low frequencies. In 1981, Altec introduced a dedicated cinema subwoofer model tuned to around 20 Hz: the 8182. Starting in 1983, THX certification of the cinema sound experience quantified the parameters of good audio for watching films, including requirements for subwoofer performance levels and enough isolation from outside sounds so that noise did not interfere with the listening experience. This helped provide guidelines for multiplex cinema owners who wanted to isolate each individual cinema from its neighbors, even as louder subwoofers were making isolation more difficult. Specific cinema subwoofer models appeared from JBL, Electro-Voice, Eastern Acoustic Works, Kintek, Meyer Sound Laboratories and BGW Systems in the early 1990s. In 1992, Dolby Digital's six-channel film sound format incorporated a single LFE channel, the "point one" in 5.1 surround sound systems.


title: Subwoofer

text: Tom Horral, a Boston-based acoustician, blames complaints about modern movies being too loud on subwoofers. He says that before subwoofers made it possible to have loud, relatively undistorted bass, movie sound levels were limited by the distortion in less capable systems at low frequency and high levels.


title: Subwoofer

text: Professional audio subwoofers used in rock concerts in stadia, DJ performances at dance music venues (e.g., electronic dance music) and similar events must be capable of very high bass output levels, at very low frequencies, with low distortion. This is reflected in the design attention given in the 2010s to the subwoofer applications for sound reinforcement, public address systems, dance club systems and concert systems. Cerwin-Vega states that when a subwoofer cabinet is added to an existing full-range speaker system, this is advantageous, as it moves the "...lowest frequencies from your main [full-range] PA speakers" thus "...eliminat[ing] a large amount of the excess work that your main top [full-range] box was trying to reproduce. As a result, your main [full-range] cabinets will run more efficiently and at higher volumes." A different argument for adding subwoofer cabinets is that they may increase the "level of clarity" and "perceived loudness" of an overall PA system, even if the SPL is not actually increased. "Sound on Sound" states that adding a subwoofer enclosure to a full-range system will reduce "cone excursion", thus lowering distortion, leading to an overall cleaner sound.


title: Subwoofer

text: Consumer applications (as in home use) are considerably less demanding due to much smaller listening space and lower playback levels. Subwoofers are now almost universal in professional sound applications such as live concert sound, churches, nightclubs, and theme parks. Movie theatres certified to the THX standard for playback always include high-capability subwoofers. Some professional applications require subwoofers designed for very high sound levels, using multiple 12-, 15-, 18- or 21-inch drivers (30 cm, 40 cm, 45 cm, 53 cm respectively). Drivers as small as 10-inch (25 cm) are occasionally used, generally in horn-loaded enclosures.


title: Subwoofer

text: The number of subwoofer enclosures used in a concert depends on a number of factors, including the size of the venue, whether it is indoors or outdoors, the amount of low-frequency content in the band's sound, the desired volume of the concert, and the design and construction of the enclosures (e.g., direct-radiating versus horn-loaded). A tiny coffeehouse may only need a single 10-inch subwoofer cabinet to augment the bass provided by the full-range speakers. A small bar may use one or two direct-radiating 15-inch (40 cm) subwoofer cabinets. A large dance club may have a row of four or five twin 18-inch (45 cm) subwoofer cabinets, or more. In the largest stadium venues, there may be a very large number of subwoofer enclosures. For example, the 2009–2010 U2 360° Tour used 24 Clair Brothers BT-218 subwoofers (a double 18-inch (45 cm) box) around the perimeter of the central circular stage, and 72 proprietary Clair Brothers cardioid S4 subwoofers placed underneath the ring-shaped "B" stage which encircles the central main stage.


title: Subwoofer

text: The main speakers may be 'flown' from the ceiling of a venue on chain hoists, and 'flying points' (i.e., attachment points) are built into many professional loudspeaker enclosures. Subwoofers can be flown or stacked on the ground near the stage. One of the reasons subwoofers may be installed on the ground is that on-the-ground installation can increase the bass performance, particularly if the subwoofer is placed in the corner of a room (conversely, if a subwoofer cabinet is perceived as too loud, alternatives to on-the-ground or in-corner installation may be considered). There can be more than 50 double-18-inch (45 cm) cabinets in a typical rock concert system. Just as consumer subwoofer enclosures can be made of medium-density fibreboard (MDF), oriented strand board (OSB), plywood, plastic or other dense material, professional subwoofer enclosures can be built from the same materials. MDF is commonly used to construct subwoofers for permanent installations as its density is relatively high and weatherproofing is not a concern. Other permanent installation subwoofers have used very thick plywood: the Altec 8182 (1981) used 7-ply 28 mm birch-faced oak plywood. Touring subwoofers are typically built from 18–20 mm thick void-free Baltic birch (Betula pendula or Betula pubescens) plywood from Finland, Estonia or Russia; such plywood affords greater strength for frequently transported enclosures. Not naturally weatherproof, Baltic birch is coated with carpet, thick paint or spray-on truck bedliner to give the subwoofer enclosures greater durability.


title: Subwoofer

text: Touring subwoofer cabinets are typically designed with features that facilitate moving the enclosure (e.g., wheels, a "towel bar" handle and recessed handles), a protective grille for the speaker (in direct radiating-style cabinets), metal or plastic protection for the cabinets to protect the finish as the cabinets are being slid one on top of another, and hardware to facilitate stacking the cabinets (e.g., interlocking corners) and for "flying" the cabinets from stage rigging. In the 2000s, many small- to mid-size subwoofers designed for bands' live sound use and DJ applications are "powered subs"; that is, they have an integrated power amplifier. These models typically have a built-in crossover. Some models have a metal-reinforced hole in which a speaker pole can be mounted for elevating full-frequency range cabinets.


title: Subwoofer

text: In professional concert sound system design, subwoofers can be incorporated seamlessly with the main speakers into a stereo or mono full-range system by using an active crossover. The audio engineer typically adjusts the frequency point at which lower frequency sounds are routed to the subwoofer speaker(s), and mid-frequency and higher frequency sounds are sent to the full-range speakers. Such a system receives its signal from the main mono or stereo mixing console mix bus and amplifies all frequencies together in the desired balance. If the main sound system is stereo, the subwoofers can also be in stereo. Otherwise, a mono subwoofer channel can be derived within the crossover from a stereo mix, depending on the crossover make and model. While 2010-era subwoofer cabinet manufacturers suggest placing subwoofers on either side of a stage (as implied by the inclusion of pole cups for the full-range PA cabinets), Dave Purton argues that for club gigs, having two subwoofer cabinets on either side of a stage will lead to gaps in bass coverage in the venue; he states that putting the two subwoofer cabinets together will create a more even, omnidirectional sub-bass tone.


title: Subwoofer

text: Instead of being incorporated into a full-range system, concert subwoofers can be supplied with their own signal from a separate mix bus on the mixing console; often one of the auxiliary sends ("aux" or "auxes") is used. This configuration is called "aux-fed subwoofers", and has been observed to significantly reduce low-frequency "muddiness" that can build up in a concert sound system which has on stage a number of microphones each picking up low frequencies and each having different phase relationships of those low frequencies. The aux-fed subwoofers method greatly reduces the number of sources feeding the subwoofers to include only those instruments that have desired low-frequency information; sources such as kick drum, bass guitar, samplers and keyboard instruments. This simplifies the signal sent to the subwoofers and makes for greater clarity and low punch. Aux-fed subwoofers can even be stereo, if desired, using two auxiliary mix buses.


title: Subwoofer

text: To keep low-frequency sound focused on the audience area and not on the stage, and to keep low frequencies from bothering people outside of the event space, a variety of techniques have been developed in concert sound to turn the naturally omnidirectional radiation of subwoofers into a more directional pattern. Several examples of sound reinforcement system applications where sound engineers seek to provide more directional bass sound are: music festivals, which often have several bands performing at the same time on different stages; large raves or EDM events, where there are multiple DJs performing at the same time in different rooms or stages; and multiplex movie theatres, in which there are many films being shown simultaneously in auditoriums that share common walls. These techniques include: setting up subwoofers in a vertical array; using combinations of delay and polarity inversion; and setting up a delay-shaded system. With a cardioid dispersion pattern, two end-fire subwoofers can be placed one in front of the other. The enclosure nearest the listener is delayed by a few milliseconds. The second subwoofer is delayed a precise amount corresponding to the time it takes sound to traverse the distance between speaker grilles.


title: Subwoofer

text: Stacking or rigging the subwoofers in a vertical array focuses the low frequencies forward to a greater or lesser extent depending on the physical length of the array. Longer arrays have a more directional effect at lower frequencies. The directionality is more pronounced in the vertical dimension, yielding a radiation pattern that is wide but not tall. This helps reduce the amount of low-frequency sound bouncing off the ceiling indoors and assists in mitigating external noise complaints outdoors.


title: Subwoofer

text: Another cardioid subwoofer array pattern can be used horizontally, one which takes few channels of processing and no change in required physical space. This method is often called "cardioid subwoofer array" or "CSA" even though the pattern of "all" directional subwoofer methods is cardioid. The CSA method reverses the enclosure orientation and inverts the polarity of one out of every three subwoofers across the front of the stage, and delays those enclosures for maximum cancellation of the target frequency on stage. Polarity inversion can be implemented electronically, by reversing the wiring polarity, or by physically positioning the enclosure to face rearward. This method reduces forward output relative to a tight-packed, flat-fronted array of subwoofers, but can solve problems of unwanted low-frequency energy coming into microphones on stage. Compared to the end-fire array, this method has less on-axis energy but more even pattern control throughout the audience, and more predictable cancellation rearward. The effect spans a range of slightly more than one octave.


title: Subwoofer

text: A second method of rear delay array combines end-fire topology with polarity reversal, using two subwoofers positioned front to back, the drivers spaced one-quarter wavelength apart, the rear enclosure inverted in polarity and delayed by a few milliseconds for maximum cancellation on stage of the target frequency. This method has the least output power directed toward the audience, compared to other directional methods.


title: Subwoofer

text: The end-fire subwoofer method, also called "forward steered arrays", places subwoofer drivers co-axially in one or more rows, using destructive interference to reduce emissions to the sides and rear. This can be done with separate subwoofer enclosures positioned front to back with a spacing between them of one-quarter wavelength of the target frequency, the frequency that is least wanted on stage or most desired in the audience. Each row is delayed beyond the first row by an amount related to the speed of sound in air; the delay is typically a few milliseconds. The arrival time of sound energy from all the subwoofers is near-simultaneous from the audience's perspective, but is canceled out to a large degree behind the subwoofers because of offset sound wave arrival times. Directionality of the target frequency can achieve as much as 25 dB rear attenuation, and the forward sound is coherently summed in line with the subwoofers. The positional technique of end-fire subwoofers came into widespread use in European live concert sound in 2006.


title: Subwoofer

text: The end-fire array trades a few decibels of output power for directionality, so it requires more enclosures for the same output power as a tight-packed, flat-fronted array of enclosures. Sixteen enclosures in four rows were used in 2007 at one of the stages of the Ultra Music Festival, to reduce low-frequency interference to neighboring stages. Because of the physical size of the end-fire array, few concert venues are able to implement it. The output pattern suffers from comb-filtering off-axis, but can be further shaped by adjusting the frequency response of each row of subwoofers.


title: Subwoofer

text: A long line of subwoofers placed horizontally along the front edge of the stage can be delayed such that the center subwoofers fire several milliseconds prior to the ones flanking them, which fire several milliseconds prior to "their" neighbors, continuing in this fashion until the last subwoofers are reached at the outside ends of the subwoofer row (beamforming). This method helps to counteract the extreme narrowing of the horizontal dispersion pattern seen with a horizontal subwoofer array. Such delay shading can be used to virtually reshape a loudspeaker array.


title: Subwoofer

text: Some subwoofer enclosure designs rely on drivers facing to the sides or to the rear in order to achieve a degree of directionality. End-fire drivers can be positioned within a single enclosure that houses more than one driver.


title: Subwoofer

text: Some less commonly-used bass enclosures are variants of the subwoofer enclosure's normal range, such as the mid-bass cabinet (60–160 Hz) and the infrasonic (extra low) subwoofer (below 30 Hz).


title: Subwoofer

text: Front-loaded subwoofers have one or more subwoofer speakers in a cabinet, typically with a grille to protect the speakers. In practice, many front-loaded subwoofer cabinets have a vent or port in the speaker cabinet, thus creating a bass reflex enclosure. Even though a bass reflex port or vent creates some additional phase delay, it adds SPL, which is often a key factor in PA and sound reinforcement system applications. As such, non-vented front-firing subwoofer cabinets are rare in pro audio applications.