538:—may be used. The advantage of aluminum is its light weight, which reduces the moving mass compared to copper. This raises the resonant frequency of the speaker and increases its efficiency. A disadvantage of aluminum is that it is not easily soldered, and so connections must be robustly crimped together and sealed. Voice-coil wire cross sections can be circular, rectangular, or hexagonal, giving varying amounts of wire volume coverage in the magnetic gap space. The coil is oriented co-axially inside the gap; it moves back and forth within a small circular volume (a hole, slot, or groove) in the magnetic structure. The gap establishes a concentrated magnetic field between the two poles of a permanent magnet; the outside ring of the gap is one pole, and the center post (called the pole piece) is the other. The pole piece and backplate are often made as a single piece, called the poleplate or yoke.
555:, may be included as a thin copper cap fitted over the pole tip or as a heavy ring situated within the magnet-pole cavity. The benefits of this complication is reduced impedance at high frequencies, providing extended treble output, reduced harmonic distortion, and a reduction in the inductance modulation that typically accompanies large voice coil excursions. On the other hand, the copper cap requires a wider voice-coil gap, with increased magnetic reluctance; this reduces available flux, requiring a larger magnet for equivalent performance.
518:, treated paper or a ring of corrugated, resin-coated fabric; it is attached to both the outer cone circumference and to the upper frame. These diverse surround materials, their shape and treatment can dramatically affect the acoustic output of a driver; each implementation has advantages and disadvantages. Polyester foam, for example, is lightweight and economical, though usually leaks air to some degree and is degraded by time, exposure to ozone, UV light, humidity and elevated temperatures, limiting useful life before failure.
133:
602:
36:
581:, which are made from a mix of ceramic clay and fine particles of barium or strontium ferrite. Although the energy per kilogram of these ceramic magnets is lower than alnico, it is substantially less expensive, allowing designers to use larger yet more economical magnets to achieve a given performance. Due to increases in transportation costs and a desire for smaller, lighter devices, there is a trend toward the use of more compact
305:
281:
332:
440:. For example, paper is light and typically well-damped, but is not stiff; metal may be stiff and light, but it usually has poor damping; plastic can be light, but typically, the stiffer it is made, the poorer the damping. As a result, many cones are made of some sort of composite material. For example, a cone might be made of cellulose paper, into which some
727:); these are generally used only in woofers and especially subwoofers, due to the greatly increased cone excursions required at those frequencies in a driver whose cone size is well under the wavelength of some of the sounds it is made to reproduce (ie, bass frequencies below perhaps 100 Hz or so).
739:
range. Small diaphragms are not well suited to moving the large volume of air that is required for good low-frequency response. Conversely, large drivers may have heavy voice coils and cones that limit their ability to move at very high frequencies. Drivers pressed beyond their design limits may have
706:
that causes the diaphragm to be alternately forced one way or the other, by the magnetic field produced by current flowing in the voice coil, against the field established in the magnetic gap by the fixed magnet structure as the electrical signal varies. The resulting back-and-forth motion drives the
649:) attached to the neck of the driver's cone. In a ribbon speaker, the voice coil may be printed or bonded onto a sheet of very thin paper, aluminum, fiberglass or plastic. This cone, dome or other radiator is mounted at its outer edge by a flexible surround to a rigid frame which supports a permanent
477:
from thin sheet steel in lighter-structure drivers. Other materials such as molded plastic and damped plastic compound baskets are becoming common, especially for inexpensive, low-mass drivers. A metallic chassis can play an important role in conducting heat away from the voice coil; heating during
722:
working against the centering "spring tension" of the spider and surround. If there were no restriction on travel distance imposed by the spider and surround, the voice coil could be ejected from the magnet assembly at high power levels, or travel inward deep enough to collide with the back of the
714:
The spider and surround act as a spring-restoring mechanism for motion away from the balanced position established when the driver was assembled at the factory. In addition, each contributes to centering the voice coil and cone, both concentrically within the magnet assembly, and front-to-back,
427:
The diaphragm is usually manufactured with a cone- or dome-shaped profile. A variety of different materials may be used, but the most common are paper, plastic, and metal. The ideal material is rigid, to prevent uncontrolled cone motions, has low mass to minimize starting force requirements and
617:
in the air column in front, and depending on the application, at some angle to the sides. The diaphragm is typically in the shape of a cone for low and mid frequencies or a dome for higher frequencies, or less commonly, a ribbon, and is usually made of coated or uncoated paper or polypropylene
653:
in close proximity to the voice coil. For the sake of efficiency, the relatively lightweight voice coil and cone are the moving parts of the driver, whereas the much heavier magnet remains stationary. Other typical components are a spider or damper, used as the rear suspension element, simple
723:
magnet assembly. The majority of speaker drivers work only against the centering forces of the spider and surround and do not actively monitor the position of the driver element or attempt to precisely position it. Some speaker driver designs have provisions to do so (typically termed
546:
The size and type of magnet and details of the magnetic circuit differ, depending on design goals. For instance, the shape of the pole piece affects the magnetic interaction between the voice coil and the magnetic field, and is sometimes used to modify a driver's behavior. A
410:, generating a mechanical force that moves the coil (and thus, the attached cone). Application of alternating current moves the cone back and forth, accelerating and reproducing sound under the control of the applied electrical signal coming from the amplifier.
468:
The chassis, frame, or basket, is designed to be rigid, preventing deformation that could change critical alignments with the magnet gap, perhaps allowing the voice coil to rub against the magnet around the gap. Chassis are typically
573:, an alloy of aluminum, nickel, and cobalt became popular after WWII, since it dispensed with the problems of field-coil drivers. Alnico was commonly used until the 1960s, despite the problem of alnico magnets being partially
486:
The suspension system keeps the coil centered in the gap and provides a restoring (centering) force that returns the cone to a neutral position after moving. A typical suspension system consists of two parts: the
562:
cabinets well into the 1950s; there were economic savings in those using tube amplifiers as the field coil could, and usually did, do double duty as a power supply choke. Very few manufacturers still produce
478:
operation changes resistance, causes physical dimensional changes, and if extreme, broils the varnish on the voice coil; it may even demagnetize permanent magnets.
436:
frequency as determined by its usage. In practice, all three of these criteria cannot be met simultaneously using existing materials; thus, driver design involves
460:
fibers have been added; or it might use a honeycomb sandwich construction; or a coating might be applied to it so as to provide additional stiffening or damping.
686:, or other acoustically neutral screen is generally provided to cosmetically conceal the drivers and hardware, and to protect the driver from physical damage.
821:
507:. Variations of this topology included the addition of a felt disc to provide a barrier to particles that might otherwise cause the voice coil to rub.
744:. In a multi-way loudspeaker system, specialized drivers are provided to produce specific frequency ranges, and the incoming signal is split by a
53:
100:
780:
Speaker drivers are the primary means for sound reproduction. They are used among other places in audio applications such as loudspeakers,
495:, which helps center the coil/cone assembly and allows free pistonic motion aligned with the magnetic gap. The spider is usually made of a
72:
499:
fabric disk, impregnated with a stiffening resin. The name comes from the shape of early suspensions, which were two concentric rings of
79:
406:
in the voice coil, making it a variable electromagnet. The coil and the driver's magnetic system interact in a manner similar to a
86:
878:
185:, each reproducing a different part of the audible frequency range. In this case the individual speakers are referred to as
491:, which connects the diaphragm or voice coil to the lower frame and provides the majority of the restoring force, and the
68:
17:
926:
119:
894:
715:
restoring the voice coil to a critical position within the magnetic gap, neither toward one end nor the other.
221:
694:
In operation, a signal is delivered to the voice coil by means of electrical wires, from the amplifier through
57:
827:
674:
or speaker box isolates the acoustic energy from the front of the cone from that of the back of the cone. A
670:
Drivers are almost universally mounted into a rigid enclosure of wood, plastic, or occasionally metal. This
559:
93:
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to reduce vibrations continuing after the signal has stopped with little or no audible ringing due to its
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back-and-forth motion. Typically there is a tightly wound coil of insulated wire (known as a
610:
422:
403:
360:
253:
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mechanism most widely used in speakers to convert the electric current to sound waves is the
793:
8:
413:
The following is a description of the individual components of this type of loudspeaker.
173:), it is usually applied to specialized transducers that reproduce only a portion of the
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air in front of the diaphragm, resulting in pressure differentials that travel away as
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853:"The development of the loudspeaker Prof. Dr.–Ing. Dietmar Rudolph March 23, 2013"
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Cutaway view of a dynamic tweeter with acoustic lens and a dome-shaped membrane.
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reproduction of sound, multiple loudspeakers are often mounted in the same
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plastic. More exotic materials are used on some drivers, such as woven
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Speaker drivers may be designed to operate within a broad or narrow
35:
824:, chief electrical characteristic of a dynamic loudspeaker's driver
812:, and in many electronics devices that are designed to emit sound.
635:
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577:. In the 1960s, most driver manufacturers switched from alnico to
193:. Drivers made for reproducing high audio frequencies are called
163:. While the term is sometimes used interchangeably with the term
27:
Transducer that converts an electrical audio signal to sound waves
753:
565:
electrodynamic loudspeakers with electrically powered field coils
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from aluminum alloy, in heavier magnet-structure speakers; or
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may be employed to increase efficiency and directionality. A
284:
Cutaway view of a dynamic loudspeaker for the bass register.
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515:
453:
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glued in the cone's center prevents dust, most importantly
398:
When an electrical signal is applied to the voice coil, a
331:
809:
634:, pure cross carbon and a very few use PEI, polyimide,
828:
Loudspeaker § Driver design: dynamic loudspeakers
658:
to connect the audio signal, and possibly a compliant
873:(6th ed.). Oxford, UK: Focal Press. p. 81.
748:. Drivers can be sub-categorized into several types:
662:
to seal the joint between the chassis and enclosure.
665:
248:. There are others that are far less widely used:
240:, which creates sound with a coil of wire called a
60:. Unsourced material may be challenged and removed.
895:"Speaker Geeks: Alnico or Ceramic ... What Gives?"
822:Electrical characteristics of dynamic loudspeakers
355:The most common type of driver, commonly called a
641:All speaker drivers have a means of electrically
387:through a cylindrical magnetic gap. A protective
201:drivers and those for low frequencies are called
954:
943:"Electrodynamic loudspeaker patent US7676053B2"
868:
375:, via a flexible suspension, commonly called a
730:
718:The voice coil and magnet essentially form a
638:plastic film as the cone, dome or radiator.
526:The wire in a voice coil is usually made of
308:Cutaway view of a dynamic midrange speaker.
151:when the type is implicit, is an individual
702:to the moving coil. The current creates a
205:, while those for very low bass range are
197:, those for middle frequencies are called
567:, as was common in the earliest designs.
120:Learn how and when to remove this message
869:Rumsey, Francis; McCormick, Tim (2009).
600:
503:material, joined by six or eight curved
330:
303:
279:
131:
14:
955:
605:Cut-away view of a dynamic loudspeaker
921:. Taylor & Francis. p. 361.
209:. Less common types of drivers are
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613:that moves back and forth to create
58:adding citations to reliable sources
29:
24:
558:Electromagnets were often used in
428:energy storage issues and is well
25:
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666:Enclosures and acoustic isolation
244:suspended between the poles of a
189:and the entire unit is called a
34:
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395:debris, from entering the gap.
69:"Electrodynamic speaker driver"
45:needs additional citations for
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560:musical instrument amplifiers
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481:
232:driver, invented in 1925 by
145:electrodynamic speaker driver
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585:made from materials such as
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155:that converts an electrical
7:
918:Audio Engineering Explained
815:
731:Performance characteristics
402:is created by the electric
10:
979:
609:Speaker drivers include a
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315:Cooler (sometimes present)
541:
510:The cone surround can be
463:
275:
698:, then through flexible
147:, often called simply a
367:, connected to a rigid
262:Heil air motion drivers
258:planar magnetic drivers
915:Self, Douglas (2012).
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352:
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833:Loudspeaker enclosure
794:instrument amplifiers
672:loudspeaker enclosure
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423:Diaphragm (acoustics)
359:, uses a lightweight
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307:
283:
270:other speaker designs
254:piezoelectric drivers
250:electrostatic drivers
135:
379:, that constrains a
54:improve this article
871:Sound and Recording
357:dynamic loudspeaker
18:Dynamic loudspeaker
607:
583:rare-earth magnets
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141:
880:978-0-240-52163-3
796:, television and
234:Edward W. Kellogg
175:audible frequency
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65:Find sources:
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43:This article
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963:Loudspeakers
937:
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898:. Retrieved
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776:Applications
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720:linear motor
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624:carbon fiber
608:
575:demagnetized
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557:
553:Faraday loop
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52:Please help
47:verification
44:
709:sound waves
700:tinsel wire
191:loudspeaker
177:range. For
171:loudspeaker
161:sound waves
839:References
800:speakers,
790:megaphones
786:telephones
782:headphones
770:subwoofers
750:full-range
742:distortion
647:voice coil
620:fiberglass
597:Components
522:Voice coil
497:corrugated
482:Suspension
438:trade-offs
381:voice coil
348:Suspension
321:Suspension
294:Suspension
242:voice coil
207:subwoofers
153:transducer
80:newspapers
900:April 26,
804:systems,
764:drivers,
762:mid-range
746:crossover
737:frequency
690:Operation
682:, fabric
611:diaphragm
587:neodymium
530:, though
434:resonance
417:Diaphragm
361:diaphragm
345:Diaphragm
342:Voicecoil
324:Diaphragm
318:Voicecoil
297:Diaphragm
291:Voicecoil
199:mid-range
183:enclosure
957:Category
816:See also
754:tweeters
643:inducing
636:PET film
632:titanium
628:aluminum
532:aluminum
501:Bakelite
493:surround
408:solenoid
389:dust cap
383:to move
268:, among
195:tweeters
798:monitor
766:woofers
475:stamped
404:current
385:axially
226:dynamic
203:woofers
187:drivers
166:speaker
94:scholar
925:
877:
768:, and
680:grille
660:gasket
651:magnet
571:Alnico
542:Magnet
536:silver
528:copper
512:rubber
489:spider
464:Basket
458:bamboo
446:Kevlar
430:damped
377:spider
369:basket
339:Magnet
312:Magnet
288:Magnet
276:Design
264:, and
246:magnet
137:Woofer
96:
89:
82:
75:
67:
856:(PDF)
740:high
551:, or
450:glass
373:frame
371:, or
363:, or
101:JSTOR
87:books
923:ISBN
902:2024
875:ISBN
810:toys
684:mesh
676:horn
589:and
516:foam
505:legs
471:cast
454:hemp
365:cone
236:and
220:The
213:and
73:news
456:or
256:,
228:or
217:.
159:to
143:An
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