Editing Loudspeaker (section)

==System design==
[[File:SpeakerSymbol.png|thumb|Electronic symbol for a speaker]]

===Crossover===
<!--"Multi-driver speaker systems" redirects here.-->
{{Main|Audio crossover}}
[[File:Passive Crossover.svg|thumb|A passive crossover]]
[[File:Active Crossover.svg|thumb|A bi-amplified system with an active crossover]]

Used in '''multi-driver speaker systems''', the crossover is an assembly of filters that separate the input signal into different [[frequency band]]s according to the requirements of each driver. Hence the drivers receive power only in the sound frequency range they were designed for, thereby reducing distortion in the drivers and interference between them. Crossovers can be ''passive'' or ''active''.

A [[Audio crossover#Passive crossovers|passive crossover]] is an electronic circuit that uses a combination of one or more [[resistor]]s, inductors and [[capacitor]]s. These components are combined to form a filter network and are most often placed between the full frequency-range power amplifier and the loudspeaker drivers to divide the amplifier's signal into the necessary frequency bands before being delivered to the individual drivers. Passive crossover circuits need no external power beyond the audio signal itself, but have some disadvantages: they may require larger inductors and capacitors due to power handling requirements. Unlike active crossovers which include a built-in amplifier, passive crossovers have an inherent attenuation within the [[passband]], typically leading to a reduction in [[damping factor]] before the voice coil.{{Citation needed|date=April 2024}}

An [[Audio crossover#Active crossovers|active crossover]] is an electronic filter circuit that divides the signal into individual frequency bands ''before'' power amplification, thus requiring at least one power amplifier for each band.{{Citation needed|date=April 2024}} Passive filtering may also be used in this way before power amplification, but it is an uncommon solution, being less flexible than active filtering. Any technique that uses crossover filtering followed by amplification is commonly known as bi-amping, tri-amping, quad-amping, and so on, depending on the minimum number of amplifier channels.<ref>Boston Acoustic Society. ''The B.A.S. Speaker'', September 1978. Peter W. Mitchell: "The D-23 crossover can be used for bi-amping, tri-amping, or even quad-amping."</ref>

Some loudspeaker designs use a combination of passive and active crossover filtering, such as a passive crossover between the mid- and high-frequency drivers and an active crossover for the low-frequency driver.<ref>{{cite web |publisher=EAW |url=http://www.eaw.com/products/KF/kf300.html |title=KF300/600 Series&nbsp;— Compact three-way VAT Systems |archive-url=https://web.archive.org/web/20120424065507/http://www.eaw.com/products/kf/kf300.html |archive-date=April 24, 2012 }}</ref><ref>{{cite web |url=http://www.yorkville.com/products.asp?cat=38&id=268&type=29 |title=U215 Speaker&nbsp;– 1600w 2x15 / 3x5 inch / 1 inch |publisher=Yorkville |archive-url=https://web.archive.org/web/20120322012059/http://www.yorkville.com/products.asp?cat=38&id=268&type=29 |archive-date=March 22, 2012 }}</ref>

Passive crossovers are commonly installed inside speaker boxes and are by far the most common type of crossover for home and low-power use. In car audio systems, passive crossovers may be in a separate box, necessary to accommodate the size of the components used. Passive crossovers may be simple for low-order filtering, or complex to allow steep slopes such as 18 or 24&nbsp;dB per octave. Passive crossovers can also be designed to compensate for undesired characteristics of driver, horn, or enclosure resonances, and can be tricky to implement, due to component interaction. Passive crossovers, like the driver units that they feed, have power handling limits, have [[insertion loss]]es, and change the load seen by the amplifier. The changes are matters of concern for many in the hi-fi world.{{Citation needed|date=April 2024}} When high output levels are required, active crossovers may be preferable. Active crossovers may be simple circuits that emulate the response of a passive network or may be more complex, allowing extensive audio adjustments. Some active crossovers, usually digital loudspeaker management systems, may include electronics and controls for precise alignment of phase and time between frequency bands, equalization, [[dynamic range compression]] and [[limiting]].{{Citation needed|date=April 2024}}
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===Enclosures===
{{Main|Loudspeaker enclosure}}
[[File:4-Wege Lautsprecher.jpg|thumb|upright|An unusual three-way speaker system. The cabinet is narrow to raise the frequency where a diffraction effect called the ''baffle step'' occurs]]

Most loudspeaker systems consist of drivers mounted in an enclosure, or cabinet. The role of the enclosure is to prevent sound waves emanating from the back of a driver from interfering destructively with those from the front.  The sound waves emitted from the back are 180° [[out of phase]] with those emitted forward, so without an enclosure they typically cause cancellations which significantly degrade the level and quality of sound at low frequencies.

The simplest driver mount is a flat panel (''baffle'') with the drivers mounted in holes in it. However, in this approach, sound frequencies with a wavelength longer than the baffle dimensions are canceled out because the antiphase radiation from the rear of the cone interferes with the radiation from the front. With an infinitely large panel, this interference could be entirely prevented. A sufficiently large sealed box can approach this behavior.<ref>{{cite web |url=http://www.soundonsound.com/sos/jun04/articles/qa0604-6.htm |publisher=Sound on Sound |date=June 2004 |title=Q. What's the Difference between Ported and Un-Ported Monitors? }}</ref><ref>{{cite web |url=http://www.record-producer.com/learn.cfm?a=97 |publisher=Record Producer |title=Infinite Baffle |archive-url=https://web.archive.org/web/20051112115053/http://www.record-producer.com/learn.cfm?a=97 |archive-date=November 12, 2005 }}</ref>

Since panels of infinite dimensions are impossible, most enclosures function by containing the rear radiation from the moving diaphragm. A sealed enclosure prevents transmission of the sound emitted from the rear of the loudspeaker by confining the sound in a rigid and airtight box. Techniques used to reduce the transmission of sound through the walls of the cabinet include thicker cabinet walls, internal bracing and lossy wall material.

However, a rigid enclosure reflects sound internally, which can then be transmitted back through the loudspeaker diaphragm—again resulting in degradation of sound quality. This can be reduced by internal absorption using absorptive materials such as [[glass wool]], wool, or synthetic fiber batting, within the enclosure. The internal shape of the enclosure can also be designed to reduce this by reflecting sounds away from the loudspeaker diaphragm, where they may then be absorbed.

Other enclosure types alter the rear sound radiation so it can add constructively to the output from the front of the cone. Designs that do this (including ''[[bass reflex]]'', ''passive radiator'', ''transmission line'', etc.) are often used to extend the effective low-frequency response and increase the low-frequency output of the driver.

To make the transition between drivers as seamless as possible, system designers have attempted to time align the drivers by moving one or more driver mounting locations forward or back so that the acoustic center of each driver is in the same vertical plane. This may also involve tilting the driver back, providing a separate enclosure mounting for each driver, or using electronic techniques to achieve the same effect. These attempts have resulted in some unusual cabinet designs.

The speaker mounting scheme (including cabinets) can also cause diffraction, resulting in peaks and dips in the frequency response. The problem is usually greatest at higher frequencies, where wavelengths are similar to, or smaller than, cabinet dimensions.
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====Horn loudspeakers====
{{Main|Horn loudspeaker}}
[[File:3-way horn speaker.png|thumb|A three-way loudspeaker that uses horns in front of each of the three drivers: a shallow horn for the tweeter, a long, straight horn for mid frequencies and a folded horn for the woofer]]
[[File:Klipschorn speaker drawing 1948 (cropped).png|Klipschorn speaker drawing, 1948|thumb]]

[[Horn loudspeaker]]s are the oldest form of loudspeaker system. The use of [[Horn (acoustic)|horns]] as voice-amplifying [[megaphone]]s dates at least to the 17th century,<ref>{{Cite EB1911|wstitle=Trumpet, Speaking and Hearing}}</ref> and horns were used in mechanical [[Phonograph|gramophones]] as early as 1877. Horn loudspeakers use a shaped [[waveguide]] in front of or behind the driver to increase the directivity of the loudspeaker and to transform a small diameter, high-pressure condition at the driver cone surface to a large diameter, low-pressure condition at the mouth of the horn. This improves the acoustic—electro/mechanical impedance match between the driver and ambient air, increasing efficiency, and focusing the sound over a narrower area.

The size of the throat, mouth, the length of the horn, as well as the area expansion rate along it must be carefully chosen to match the driver to properly provide this transforming function over a range of frequencies.{{efn|Every horn performs poorly outside its acoustic limits, at both high and low frequencies.}} The length and cross-sectional mouth area required to create a bass or sub-bass horn dictates a horn many feet long. ''Folded'' horns can reduce the total size, but compel designers to make compromises and accept increased cost and construction complications. Some horn designs not only fold the low-frequency horn but use the walls in a room corner as an extension of the horn mouth. In the late 1940s, horns whose mouths took up much of a room wall were not unknown among hi-fi fans. Room-sized installations became much less acceptable when two or more were required.

A horn-loaded speaker can have a [[Sensitivity (electroacoustics)|sensitivity]] as high as 110&nbsp;dB<sub>SPL</sub> at 2.83 volts (1 watt at 8 ohms) at 1 meter. This is a hundredfold increase in output compared to a speaker rated at 90&nbsp;dB sensitivity (given the aforementioned specifications) and is invaluable in applications where high sound levels are required or amplifier power is limited.

==== Transmission line loudspeaker ====
{{Main|Transmission line loudspeaker}}

A [[transmission line loudspeaker]] is a loudspeaker enclosure design that uses an [[acoustic transmission line]] within the cabinet, compared to the simpler enclosure-based designs. Instead of reverberating in a fairly simple damped enclosure, sound from the back of the bass speaker is directed into a long (generally folded) damped pathway within the speaker enclosure, which allows greater control and efficient use of speaker energy.
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===Wiring connections===
[[File:Lautsprecherkabel Anschlussterminal Vistaon Klemme Makro.jpg|thumb|left|Grip connectors on a loudspeaker to connect it to a [[speaker terminal]]]]
[[File:Banana plugs speaker.jpg|thumb|[[Binding post|Two-way binding posts]] on a loudspeaker, connected using [[Banana connector|banana plugs]]]]
[[File:Bi-amp capable.jpg|thumb|upright|A 4-ohm loudspeaker with two pairs of binding posts capable of accepting bi-wiring after the removal of two metal straps]]

Most home hi-fi loudspeakers use two wiring points to connect to the source of the signal (for example, to the audio amplifier or [[Receiver (radio)|receiver]]). To accept the wire connection, the loudspeaker enclosure may have [[binding post]]s, spring clips, or a panel-mount jack. If the wires for a pair of speakers are not connected with respect to the proper [[electrical polarity]],{{efn|The + and − connections on the speaker and amplifier should be connected + to + and − to −;  speaker cable is almost always marked so that one conductor of a pair can be distinguished from the other, even if it has run under or behind things in its run from amplifier to speaker location.}} the loudspeakers are said to be ''out of phase'' or more properly ''out of polarity''.<ref>{{cite book |url=https://books.google.com/books?id=d7ft6F8ZUdcC&pg=PA186 |title=The Sound Reinforcement Handbook |first1=Gary |last1=Davis|first2=Gary D. |last2=Davis |date=April 14, 1989 |publisher=Hal Leonard Corporation |access-date=April 14, 2018 |via=Google Books |isbn=9780881889000 }}</ref><ref>{{cite book |url=https://books.google.com/books?id=L38MrvScG3gC&pg=PA298|title=The Audio Dictionary: Third Edition, Revised and Expanded |first1=Glenn D. |last1=White |first2=Gary J. |last2=Louie |date=October 1, 2011 |publisher=University of Washington Press |access-date=April 14, 2018 |via=Google Books |isbn=9780295801704 }}</ref> Given identical signals, motion in the cone of an out of polarity loudspeaker is in the opposite direction of the others. This typically causes monophonic material in a stereo recording to be canceled out, reduced in level, and made more difficult to localize, all due to destructive interference of the sound waves. The cancellation effect is most noticeable at frequencies where the loudspeakers are separated by a quarter wavelength or less; low frequencies are affected the most. This type of miswiring error does not damage speakers, but is not optimal for listening.<ref>{{cite book|url=https://books.google.com/books?id=lesWAAAAQBAJ&pg=PA57|title=Audio in Media|first=Stanley R.|last=Alten|date=January 22, 2013|publisher=Cengage Learning|access-date=April 14, 2018|via=Google Books|isbn=9781285675299}}</ref><ref>{{cite book|url=https://books.google.com/books?id=K1t0GxyvVbMC&pg=PA130|title=Guide to Sound Systems for Worship|first=Jon F.|last=Eiche|date=April 14, 1990|publisher=Hal Leonard Corporation|access-date=April 14, 2018|via=Google Books|isbn=9780793500291}}</ref>

With sound reinforcement system, [[PA system]] and [[instrument amplifier]] speaker enclosures, cables and some type of jack or connector are typically used. Lower- and mid-priced sound system and instrument speaker cabinets often use [[1/4" jack]]s. Higher-priced and higher-powered sound system cabinets and instrument speaker cabinets often use [[Speakon]] connectors. Speakon connectors are considered to be safer for high-wattage amplifiers, because the connector is designed so that human users cannot touch the connectors.

===Wireless speakers===
{{Main|Wireless speaker}}
[[File:HP Roar Wireless Speaker.jpg|thumb|HP Roar Wireless Speaker]]

Wireless speakers are similar to wired [[powered speakers]], but they receive audio signals using radio frequency (RF) waves rather than over audio cables. There is an amplifier integrated in the speaker's cabinet because the RF waves alone are not enough to drive the speaker. Wireless speakers still need power, so require a nearby AC power outlet, or onboard batteries. Only the wire for the audio is eliminated.
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