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84-583: Coaxial loudspeakers in professional audio enable sound from two drivers to come from one source. This characteristic allows a wider field of listening to a synchronized summation of speaker drivers than loudspeaker enclosures containing physically separated drivers. As well, the pattern of response is symmetric around the axis of the loudspeaker. Since the 1943 introduction of the Altec Lansing Duplex 601 coaxial driver, recording studio monitors have often been coaxial loudspeaker designs. In 1945

168-456: A hi-fi system in a private home to huge, heavy subwoofer enclosures with multiple 18-inch (46 cm) or even 21-inch (53 cm) speakers in huge enclosures which are designed for use in stadium concert sound reinforcement systems for rock music concerts. The primary role of an enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open speaker driver interacting with sound waves generated at

252-460: A Scandinavian driver maker. The design remains uncommon among commercial designs currently available. A reason for this may be that adding damping material is a needlessly inefficient method of increasing damping; the same alignment can be achieved by simply choosing a loudspeaker driver with the appropriate parameters and precisely tuning the enclosure and port for the desired response. A similar technique has been used in aftermarket car audio ; it

336-416: A bass reflex design since such corrections can be as simple as mass adjustments to the drone. The disadvantages are that a passive radiator requires precision construction like a driver, thus increasing costs, and may have excursion limitations. A 4th-order electrical bandpass filter can be simulated by a vented box in which the contribution from the rear face of the driver cone is trapped in a sealed box, and

420-404: A bass reflex, but the bass reflex cabinet will have a lower −3 dB point. The voltage sensitivity above the tuning frequency remains a function of the driver, and not of the cabinet design. The isobaric loudspeaker configuration was first introduced by Harry F. Olson in the early 1950s, and refers to systems in which two or more identical woofers (bass drivers) operate simultaneously, with

504-413: A box size that exploits the almost linear air spring resulting in a −3 dB low-frequency cut-off point of 30–40 Hz from a box of only one to two cubic feet or so. The spring suspension that restores the cone to a neutral position is a combination of an exceptionally compliant (soft) woofer suspension, and the air inside the enclosure. At frequencies below system resonance, the air pressure caused by

588-416: A budget speaker made a few years ago by Insignia. Coaxial speakers in automobiles are 2- or 3-way loudspeakers in which the tweeter , or the tweeter and a mid-range driver, are mounted in front of the woofer , partially obscuring it. The advantage of this design is the ability to use a smaller area, hence their popularity in car audio. The low frequency sound waves from the woofer are not reduced too much by

672-410: A closet or attic. This is often the case with exotic rotary woofer installations, as they are intended to go to frequencies lower than 20 Hz and displace large volumes of air. Infinite baffle ( IB ) is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of

756-430: A common body of enclosed air adjoining one side of each diaphragm. In practical applications, they are most often used to improve low-end frequency response without increasing cabinet size, though at the expense of cost and weight. Two identical loudspeakers are coupled to work together as one unit: they are mounted one behind the other in a casing to define a chamber of air in between. The volume of this isobaric chamber

840-487: A compression driver for high frequencies, but differed in that the woofer itself served as the final horn flare for the high frequency driver. Thus, its output pattern was radially symmetric, not just mirror-image symmetric as in the Altec. Both designs placed the high frequency driver behind the low frequency driver, and both were not initially time aligned. The high frequencies arrived at the listener's ear slightly later than

924-431: A driver at low frequencies. In conceptual terms an infinite baffle is a flat baffle that extends out to infinity – the so-called endless plate . A genuine infinite baffle cannot be constructed but a very large baffle such as the wall of a room can be considered to be a practical equivalent. A genuine infinite-baffle loudspeaker has an infinite volume (a half-space) on each side of the baffle and has no baffle step. However,

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1008-818: A few centimetres or inches), those for mid-range frequencies (perhaps 300 Hz to 2 kHz) much larger, perhaps 30 to 60 cm (1 or 2 feet), and for low frequencies (under 300 Hz) very large, a few metres (dozens of feet). In the 1950s, a few high fidelity enthusiasts actually built full-sized horns whose structures were built into a house wall or basement. With the coming of stereo (two speakers) and surround sound (four or more), plain horns became even more impractical. Various speaker manufacturers have produced folded low-frequency horns which are much smaller (e.g., Altec Lansing, JBL, Klipsch, Lowther, Tannoy) and actually fit in practical rooms. These are necessarily compromises, and because they are physically complex, they are expensive. The multiple entry horn (also known under

1092-461: A leaky sealed box or a ported box with large amounts of port damping. By setting up a port, and then blocking it precisely with sufficiently tightly packed fiber filling, it is possible to adjust the damping in the port as desired. The result is control of the resonance behavior of the system which improves low-frequency reproduction, according to some designers. Dynaco was a primary producer of these enclosures for many years, using designs developed by

1176-403: A loss of bass and in comb filtering , i.e., peaks and dips in the response power regardless of the signal that is meant to be reproduced. The resulting response is akin to two loudspeakers playing the same signal but at different distances from the listener, which is like adding a delayed version of the signal to itself, whereby both constructive and destructive interference occurs. Before

1260-406: A metallic or cloth mesh that are used to protect the speaker by forming a protective cover over the speaker's cone while allowing sound to pass through undistorted. Speaker enclosures are used in homes in stereo systems, home cinema systems, televisions , boom boxes and many other audio appliances. Small speaker enclosures are used in car stereo systems. Speaker cabinets are key components of

1344-730: A more even sound field because of the single-source characteristic. As well, the enclosure may be made more compact. In the 1980s, Professional Audio Systems (PAS), using Time Alignment technology from Ed Long, sold the popular SW series of compact stage wedges, offered with a 12- or 15-inch woofer, and having a projecting high-frequency horn as in the 604. Other stage monitors using coaxial designs are made by Clair Brothers, L-Acoustics , Radian Audio Engineering, RCF, Beyma, dB Technologies, Fulcrum Acoustic, and Rat Sound in partnership with Eastern Acoustic Works . David Gunness and Fulcrum Acoustic have designed coaxial loudspeakers beginning in 2009, notably collaborating with PreSonus in 2013 to create

1428-461: A number of commercial applications, including sound reinforcement systems , movie theatre sound systems and recording studios . Electric musical instruments invented in the 20th century, such as the electric guitar , electric bass and synthesizer , among others, are amplified using instrument amplifiers and speaker cabinets (e.g., guitar amplifier speaker cabinets). Early on, radio loudspeakers consisted of horns , often sold separately from

1512-420: A number of features to make them easier to transport, such as carrying handles on the top or sides, metal or plastic corner protectors, and metal grilles to protect the speakers. Speaker enclosures designed for use in a home or recording studio typically do not have handles or corner protectors, although they do still usually have a cloth or mesh cover to protect the woofer and tweeter. These speaker grilles are

1596-859: A retail model the next month. This was followed by designs from Sparkomatic, Clarion , Infinity and others. Loudspeaker enclosure A loudspeaker enclosure or loudspeaker cabinet is an enclosure (often rectangular box-shaped) in which speaker drivers (e.g., loudspeakers and tweeters ) and associated electronic hardware, such as crossover circuits and, in some cases, power amplifiers , are mounted. Enclosures may range in design from simple, homemade DIY rectangular particleboard boxes to very complex, expensive computer-designed hi-fi cabinets that incorporate composite materials, internal baffles, horns, bass reflex ports and acoustic insulation. Loudspeaker enclosures range in size from small "bookshelf" speaker cabinets with 4-inch (10 cm) woofers and small tweeters designed for listening to music with

1680-556: A role in managing vibration induced by the driver frame and moving airmass within the enclosure, as well as heat generated by driver voice coils and amplifiers (especially where woofers and subwoofers are concerned). Sometimes considered part of the enclosure, the base, may include specially designed feet to decouple the speaker from the floor. Enclosures designed for use in PA systems , sound reinforcement systems and for use by electric musical instrument players (e.g., bass amp cabinets ) have

1764-436: A round hole in the cabinet. It was observed that the enclosure had a strong effect on the bass response of the speaker. Since the rear of the loudspeaker radiates sound out of phase from the front, there can be constructive and destructive interference for loudspeakers without enclosures, and below frequencies related to the baffle dimensions in open-baffled loudspeakers (see §   Background , below) . This results in

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1848-440: A sealed enclosure of the same volume, although it actually has less low frequency output at frequencies well below the cut-off frequency, since the rolloff is steeper (24 dB/octave versus 12 dB/octave for a sealed enclosure). Malcolm Hill pioneered the use of these designs in a live event context in the early 1970s. Vented system design using computer modeling has been practiced since about 1985. It made extensive use of

1932-409: A second passive driver, or drone, to produce similar low-frequency extension, or efficiency increase, or enclosure size reduction, similar to ported enclosures. Small and Hurlburt have published the results of research into the analysis and design of passive-radiator loudspeaker systems. The passive-radiator principle was identified as being particularly useful in compact systems where vent realization

2016-438: A sort of open-backed box. A rectangular cross-section is more common than curved ones since it is easier to fabricate in a folded form than a circular one. The baffle dimensions are typically chosen to obtain a particular low-frequency response, with larger dimensions giving a lower frequency before the front and rear waves interfere with each other. A dipole enclosure has a figure-of-eight radiation pattern, which means that there

2100-402: A speaker driver appear out of phase from each other because they are generated through the opposite motion of the diaphragm and because they travel different paths before converging at the listener's position. A speaker driver mounted on a finite baffle will display a physical phenomenon known as interference , which can result in perceivable frequency-dependent sound attenuation. This phenomenon

2184-491: Is coherent at and around the crossover frequencies in the speaker's normal sound field. The acoustic center of the driver dictates the amount of rearward offset needed to time-align the drivers. Enclosures used for woofers and subwoofers can be adequately modeled in the low-frequency region (approximately 100–200 Hz and below) using acoustics and the lumped component models. Electrical filter theory has been used with considerable success for some enclosure types. For

2268-519: Is a complex sum of the properties of the specific driver, the enclosure and port, because of imperfect understanding of the assorted interactions. These enclosures are sensitive to small variations in driver characteristics and require special quality control concern for uniform performance across a production run. Bass ports are widely used in subwoofers for PA systems and sound reinforcement systems , in bass amp speaker cabinets and in keyboard amp speaker cabinets. A passive radiator speaker uses

2352-435: Is a reduction in sound pressure, or loudness, at the sides as compared to the front and rear. This is useful if it can be used to prevent the sound from being as loud in some places as in others. A horn loudspeaker is a speaker system using a horn to match the driver cone to the air. The horn structure itself does not amplify, but rather improves the coupling between the speaker driver and the air. Properly designed horns have

2436-436: Is an approximation of this, since the driver is mounted on a panel, with dimensions comparable to the longest wavelength to be reproduced. In either case, the driver would need a relatively stiff suspension to provide the restoring force which might have been provided at low frequencies by a smaller sealed or ported enclosure, so few drivers are suitable for this kind of mounting. The forward- and rearward-generated sounds of

2520-406: Is an example of a combination of transmission line and horn effects. It is highly regarded by some speaker designers. The concept is that the sound emitted from the rear of the loudspeaker driver is progressively reflected and absorbed along the length of the tapering tube, almost completely preventing internally reflected sound being retransmitted through the cone of the loudspeaker. The lower part of

2604-424: Is called aperiodic membrane (AP). A resistive mat is placed in front of or directly behind the loudspeaker driver (usually mounted on the rear deck of the car in order to use the trunk as an enclosure). The loudspeaker driver is sealed to the mat so that all acoustic output in one direction must pass through the mat. This increases mechanical damping, and the resulting decrease in the impedance magnitude at resonance

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2688-465: Is difficult or impossible, but it can also be applied satisfactorily to larger systems. The passive driver is not wired to an amplifier; instead, it moves in response to changing enclosure pressures. In theory, such designs are variations of the bass reflex type, but with the advantage of avoiding a relatively small port or tube through which air moves, sometimes noisily. Tuning adjustments for a passive radiator are usually accomplished more quickly than with

2772-447: Is due primarily to a reduction in the speed of sound propagation through the filler material as compared to air. The enclosure or driver must have a small leak so that the internal and external pressures can equalise over time, to compensate for changes in barometric pressure or altitude; the porous nature of paper cones, or an imperfectly sealed enclosure, is normally sufficient to provide this slow pressure equalisation. A variation on

2856-399: Is generally the desired effect, though there is no perceived or objective benefit to this. Again, this technique reduces efficiency, and the same result can be achieved through selection of a driver with a lower Q factor , or even via electronic equalization . This is reinforced by the purveyors of AP membranes; they are often sold with an electronic processor which, via equalization, restores

2940-516: Is indeed not much output from the line's port. But it is the inherent resonance (typically at 1/4 wavelength) that can enhance the bass response in this type of enclosure, albeit with less absorbent stuffing. Among the first examples of this enclosure design approach were the projects published in Wireless World by Bailey in the early 1970s, and the commercial designs of the now defunct IMF Electronics which received critical acclaim at about

3024-427: Is of different materials and densities, changing as one gets further from the back of the driver's diaphragm. Consequent to the above, practical transmission line loudspeakers are not true transmission lines, as there is generally output from the vent at the lowest frequencies. They can be thought of as a waveguide in which the structure shifts the phase of the driver's rear output by at least 90° , thereby reinforcing

3108-431: Is particularly noticeable at low frequencies where the wavelengths are large enough that interference will affect the entire listening area. Since infinite baffles are impractical and finite baffles tend to suffer poor response as wavelengths approach the dimensions of the baffle (i.e. at lower frequencies), most loudspeaker cabinets use some sort of structure (usually a box) to contain the out of phase sound energy. The box

3192-408: Is typically made of wood, wood composite, or more recently plastic, for reasons of ease of construction and appearance. Stone, concrete, plaster, and even building structures have also been used. Enclosures can have a significant effect beyond what was intended, with panel resonances , diffraction from cabinet edges and standing wave energy from internal reflection/reinforcement modes being among

3276-767: Is usually chosen to be fairly small for reasons of convenience. The two drivers operating in tandem exhibit exactly the same behavior as one loudspeaker in twice the cabinet. Also known as vented (or ported) systems, these enclosures have a vent or hole cut into the cabinet and a port tube affixed to the hole, to improve low-frequency output, increase efficiency, or reduce the size of an enclosure. Bass reflex designs are used in home stereo speakers (including both low- to mid-priced speaker cabinets and expensive hi-fi cabinets), bass amplifier speaker cabinets, keyboard amplifier cabinets, subwoofer cabinets and PA system speaker cabinets. Vented or ported cabinets use cabinet openings or transform and transmit low-frequency energy from

3360-426: The open baffle approach is to mount the loudspeaker driver in a very large sealed enclosure, providing minimal air spring restoring force to the cone. This minimizes the change in the driver's resonance frequency caused by the enclosure. The low-frequency response of infinite baffle loudspeaker systems has been extensively analysed by Benson. Some infinite baffle enclosures have used an adjoining room, basement, or

3444-457: The 1950s including their highly regarded triaxial models. Several other manufacturers introduced coaxial speakers and drivers in the 1950s including University, however due to their higher cost most did not last in the consumer market. In 1988, KEF introduced an extension of the coaxial loudspeaker concept. Their Uni-Q driver is a coincident driver, where the two drivers share the same acoustic center and therefore are closer in time alignment. This

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3528-423: The 1950s many manufacturers did not fully enclose their loudspeaker cabinets; the back of the cabinet was typically left open. This was done for several reasons, not least because electronics (at that time tube equipment) could be placed inside and cooled by convection in the open enclosure. Most of the enclosure types discussed in this article were invented either to wall off the out of phase sound from one side of

3612-419: The 2000s, digital signal processing (DSP) was used by Fulcrum Acoustic to reduce some of the coaxial drawbacks such the diffraction of the woofer's upper range around the central horn, by filling in this "shadow" with low frequency sound from the compression driver, and by countering the out-of-time reflections bouncing off of the woofer. Coaxial loudspeakers have been used in stage monitors , giving musicians

3696-625: The Altec 604 for the McCune SM-4, a large proprietary stage wedge, using John Meyer 's patented high-compliance compression driver diaphragm, a higher-power woofer, and processor-controlled bi-amplification with line-level all-pass time alignment. The McCune SM-4 was the first multi-angle stage monitor , and was used by many McCune clients such as the Playboy Jazz Festival and the Monterey Jazz Festival . In

3780-498: The Altec 604 have further problems with diffraction of the low frequencies around the central horn, and with rearward emanations from the horn body reflected forward by the woofer out of time with direct sound. All of the problems with sound waves tend to increase with sound pressure level, causing significant shifts in tone as the loudspeaker changes volume. In the late 1970s, Bill Putnam of Universal Audio worked with Ed Long and his patented Time Alignment crossover design to fix

3864-504: The KF850 loudspeaker system. For many years this system was the standard among loudspeakers used for professional touring shows. Carlo Sound and Sun Sound were among the first regional sound rental companies to receive the KF850's. EAW also became well known for creating custom loudspeaker designs for specific projects and applications. Since its earliest days, Eastern Acoustic Works has always been defined by an ongoing quest to redefine

3948-533: The bass output lost through the mechanical damping. The effect of the equalization is opposite to that of the AP membrane, resulting in a loss of damping and an effective response similar to that of the loudspeaker without the aperiodic membrane and electronic processor. A dipole enclosure in its simplest form is a driver located on a flat baffle panel, similar to older open back cabinet designs. The baffle's edges are sometimes folded back to reduce its apparent size, creating

4032-507: The bass output. Such designs tend to be less dominant in certain bass frequencies than the more common bass reflex designs and followers of such designs claim an advantage in clarity of the bass with a better congruency of the fundamental frequencies to the overtones. Some loudspeaker designers like Martin J. King and Bjørn Johannessen consider the term quarter wave enclosure as a more fitting term for most transmission lines and since acoustically, quarter wavelengths produce standing waves inside

4116-431: The cone motion is the dominant force. Developed by Edgar Villchur in 1954, this technique was used in the very successful Acoustic Research line of bookshelf speakers in the 1960s–70s. The acoustic suspension principle takes advantage of this relatively linear spring. The enhanced suspension linearity of this type of system is an advantage. For a specific driver, an optimal acoustic suspension cabinet will be smaller than

4200-425: The driver, or to modify it so that it could be used to enhance the sound produced from the other side. In some respects, the ideal mounting for a low-frequency loudspeaker driver would be a rigid flat panel of infinite size with infinite space behind it. This would entirely prevent the rear sound waves from interfering (i.e., comb filter cancellations) with the sound waves from the front. An open baffle loudspeaker

4284-453: The drivers in their path. Without time-alignment correction, the sound from the tweeter may arrive slightly before the sound from the woofer; this misalignment is not generally addressed in automobile sound systems. This design was popularized in the 1970s with Electronic Industries, Inc. of South Holland, Illinois introducing the general concept in May 1973, and Jensen Loudspeakers introducing

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4368-491: The effect of making the speaker cone transfer more of the electrical energy in the voice coil into the air; in effect the driver appears to have higher efficiency. Horns can help control dispersion at higher frequencies which is useful in some applications such as sound reinforcement. The mathematical theory of horn coupling is well developed and understood, though implementation is sometimes difficult. Properly designed horns for high frequencies are small (above say 3 kHz or so,

4452-477: The enclosure that are used to produce the bass response emanating from the port. These designs can be considered a mass-loaded transmission line design or a bass reflex design, as well as a quarter wave enclosure. Quarter wave resonators have seen a revival as commercial applications with the onset of neodymium drivers that enable this design to produce relatively low bass extensions within a relatively small speaker enclosure. The tapered quarter-wave pipe (TQWP)

4536-410: The frequencies near the driver's free-air resonance frequency f s . Transmission lines tend to be larger than ported enclosures of approximately comparable performance, due to the size and length of the guide that is required (typically 1/4 the longest wavelength of interest). The design is often described as non-resonant, and some designs are sufficiently stuffed with absorbent material that there

4620-422: The frequency of peak impedance. In a closed-box loudspeaker, the air inside the box acts as a spring, returning the cone to the zero position in the absence of a signal. A significant increase in the effective volume of a closed-box loudspeaker can be achieved by a filling of fibrous material, typically fiberglass, bonded acetate fiber (BAF) or long-fiber wool. The effective volume increase can be as much as 40% and

4704-615: The frequency range is also possible. A uniform pattern is handy for smoothly arraying multiple enclosures. Both sides of a long-excursion high-power driver in a tapped horn enclosure are ported into the horn itself, with one path length long and the other short. These two paths combine in phase at the horn's mouth within the frequency range of interest. This design is especially effective at subwoofer frequencies and offers reductions in enclosure size along with more output. A perfect transmission line loudspeaker enclosure has an infinitely long line, stuffed with absorbent material such that all

4788-455: The front of the speaker driver. Because the forward- and rearward-generated sounds are out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced. As such, a loudspeaker cannot be used without installing it in a baffle of some type, such as a closed box, vented box, open baffle, or a wall or ceiling (infinite baffle). An enclosure also plays

4872-548: The improved Altec 604 was introduced, and it soon became the recording industry standard studio monitor in the U.S. First shown in 1947 in England, the Tannoy Dual Concentric design assumed the same role across Europe from the 1950s onward. The Altec 604 combined a 15-inch (380 mm) woofer with a compression driver attached to a horn to carry the high frequencies. The Tannoy also used a 15-inch woofer and

4956-583: The long-standing problem of the two bandpasses not being aligned in time at their crossover point. The Altec 604 was given this elaborate new crossover feature and incorporated into the UREI 813 studio monitor, which also had a second woofer physically separate from the coaxial pair. This design dominated recording studios of the 1980s, and time alignment became a feature of competing manufacturers. In 1977, Bob Cavin of McCune Sound in San Francisco modified

5040-426: The low frequencies. One drawback of the design is the production line difficulty in mating the two drivers, and in replacing or reconing the woofer. Another drawback is that the low frequencies tend to modulate the high frequencies, causing greater intermodulation distortion . The Tannoy style of coaxial, with the woofer forming part of the high frequency horn, had greater intermodulation distortion. Designs similar to

5124-505: The lower frequencies, can be alleviated by the shape of the enclosure, such as by avoiding sharp corners on the front of the enclosure. A comprehensive study of the effect of cabinet configuration on the sound distribution pattern and overall response-frequency characteristics of loudspeakers was undertaken by Harry F. Olson . It involved a very wide number of different enclosure shapes, and it showed that curved loudspeaker baffles reduce some response deviations due to sound wave diffraction. It

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5208-426: The lowest output frequency. It is important to distinguish between genuine infinite-baffle topology and so-called infinite-baffle or IB enclosures which may not meet genuine infinite-baffle criteria. The distinction becomes important when interpreting textbook usage of the term (see Beranek (1954, p. 118) and Watkinson (2004) ). Acoustic suspension or air suspension is a variation of the closed-box enclosure, using

5292-422: The pipe acts as a horn while the top can be visualised as an extended compression chamber. The entire pipe can also be seen as a tapered transmission line in inverted form. (A traditional tapered transmission line, confusingly also sometimes referred to as a TQWP, has a smaller mouth area than throat area.) Its relatively low adoption in commercial speakers can mostly be attributed to the large resulting dimensions of

5376-514: The ports may generally be replaced by passive radiators if desired. An eighth-order bandpass box is another variation which also has a narrow frequency range. They are often used to achieve sound pressure levels in which case a bass tone of a specific frequency would be used versus anything musical. They are complicated to build and must be done quite precisely in order to perform nearly as intended. This design falls between acoustic suspension and bass reflex enclosures. It can be thought of as either

5460-565: The possible problems. Bothersome resonances can be reduced by increasing enclosure mass or rigidity, by increasing the damping of enclosure walls or wall/surface treatment combinations, by adding stiff cross bracing, or by adding internal absorption. Wharfedale , in some designs, reduced panel resonance by using two wooden cabinets (one inside the other) with the space between filled with sand . Home experimenters have even designed speakers built from concrete , granite and other exotic materials for similar reasons. Many diffraction problems, above

5544-550: The purposes of this type of analysis, each enclosure must be classified according to a specific topology. The designer must balance low bass extension, linear frequency response, efficiency, distortion, loudness and enclosure size, while simultaneously addressing issues higher in the audible frequency range such as diffraction from enclosure edges, the baffle step effect when wavelengths approach enclosure dimensions, crossovers, and driver blending. The loudspeaker driver's moving mass and compliance (slackness or reciprocal stiffness of

5628-530: The radiation from the front surface of the cone is directed into a ported chamber. This modifies the resonance of the driver. In its simplest form a compound enclosure has two chambers. The dividing wall between the chambers holds the driver; typically only one chamber is ported. If the enclosure on each side of the woofer has a port in it then the enclosure yields a 6th-order band-pass response. These are considerably harder to design and tend to be very sensitive to driver characteristics. As in other reflex enclosures,

5712-407: The radio itself (typically a small wooden box containing the radio's electronic circuits, so they were not usually housed in an enclosure. When paper cone loudspeaker drivers were introduced in the mid 1920s, radio cabinets began to be made larger to enclose both the electronics and the loudspeaker. These cabinets were made largely for the sake of appearance, with the loudspeaker simply mounted behind

5796-408: The rear of the speaker to the listener. They deliberately and successfully exploit Helmholtz resonance . As with sealed enclosures, they may be empty, lined, filled or (rarely) stuffed with damping materials. Port tuning frequency is a function of the cross-sectional area of the port and its length. This enclosure type is very common, and provides more sound pressure level near the tuning frequency than

5880-401: The rear radiation of the driver is fully absorbed, down to the lowest frequencies. Theoretically, the vent at the far end could be closed or open with no difference in performance. The density of and material used for the stuffing is critical, as too much stuffing will cause reflections due to back-pressure, whilst insufficient stuffing will allow sound to pass through to the vent. Stuffing often

5964-476: The same time. A variation on the transmission line enclosure uses a tapered tube, with the terminus (opening/port) having a smaller area than the throat. The tapering tube can be coiled for lower frequency driver enclosures to reduce the dimensions of the speaker system, resulting in a seashell like appearance. Bose uses similar patented technology on their Wave and Acoustic Waveguide music systems. Numerical simulations by Augspurger and King have helped refine

6048-449: The self-powered line of Sceptre S6 and S8 coaxial studio monitors, and releasing Fulcrum's own FH15 full-range horn-loaded loudspeaker series in 2018. All of the coaxial Fulcrum designs use digital signal processing to reduce distortion modes. Fulcrum's proprietary process is called Temporal Equalization (TQ). In 2015, Fluid Audio launched the FX8 studio monitor, featuring a coaxial design with

6132-412: The speaker produced and the expense of manufacturing a rigid tapering tube. The TQWP is also known as a Voigt pipe , and was introduced in 1934 by Paul G. A. H. Voigt, Lowther's original driver designer. Eastern Acoustic Works Eastern Acoustic Works ( EAW ) is an American manufacturer of professional audio reinforcement tools, such as loudspeaker systems and processors. From 1978 to 1988 it

6216-541: The state of the art in loudspeaker systems that offer practical solutions targeted toward professional sound reinforcement users and installers. Technologies developed for these designs have led to the development of many of EAW's standard products, including the ADAPTive line, which are mainly used in professional and commercial sound reinforcement applications, such as concert venues, music and dance clubs, theaters, stadiums, theme parks, and houses of worship. In 2000 EAW

6300-436: The suspension) determines the driver's resonance frequency ( F s ). In combination with the damping properties of the system (both mechanical and electrical) all these factors affect the low-frequency response of sealed-box systems. The response of closed-box loudspeaker systems has been extensively studied by Small and Benson, amongst many others. Output falls below the system's resonance frequency ( F c ), defined as

6384-527: The term infinite-baffle loudspeaker can fairly be applied to any loudspeaker that behaves (or closely approximates) in all respects as if the drive unit is mounted in a genuine infinite baffle. The term is often and erroneously used of sealed enclosures which cannot exhibit infinite-baffle behavior unless their internal volume is much greater than the Vas Thiele/Small of the drive unit AND the front baffle dimensions are ideally several wavelengths of

6468-429: The theory and practical design of these systems. A quarter wave resonator is a transmission line tuned to form a standing quarter wave at a frequency somewhat below the driver's resonance frequency F s . When properly designed, a port that is of much smaller diameter than the main pipe located at the end of the pipe then produces the driver's backward radiation in phase with the speaker driver itself; greatly adding to

6552-408: The theory developed by researchers such as Thiele, Benson, Small and Keele, who had systematically applied electrical filter theory to the acoustic behavior of loudspeakers in enclosures. In particular Thiele and Small became very well known for their work. While ported loudspeakers had been produced for many years before computer modeling, achieving optimum performance was challenging, as it

6636-430: The trademarks CoEntrant, Unity or Synergy horn) is a manifold speaker design; it uses several different drivers mounted on the horn at stepped distances from the horn's apex, where the high frequency driver is placed. Depending on implementation, this design offers an improvement in transient response as each of the drivers is aligned in phase and time and exits the same horn mouth. A more uniform radiation pattern throughout

6720-451: The tweeter mounted directly in front of the woofer on a fixed post. The tweeter is housed in a plastic waveguide reducing intermodulation distortion . Tannoy has produced coaxial loudspeakers, for the hi fidelity home consumer market since the early 1950s. Their "Dual Concentric" drivers early series included in order of introduction: Tannoy Blacks, Tannoy Silvers, Tannoy Reds, and Tannoy Golds. Jensen introduced several coaxial speakers in

6804-399: Was discovered later that careful placement of a speaker on a sharp-edged baffle can reduce diffraction-caused response problems. Sometimes the differences in phase response at frequencies shared by different drivers can be addressed by adjusting the vertical location of the smaller drivers (usually backwards), or by leaning or stepping the front baffle, so that the wavefront from all drivers

6888-678: Was located at 59 Fountain Street in Framingham, Massachusetts , and subsequently One Main Street in Whitinsville, Massachusetts . It is now headquartered at 19 National Drive in Franklin, Massachusetts. Eastern Acoustic Works was co-founded in 1978 by partners Kenneth Berger and Kenton Forsythe , who had previously worked together at Forsythe Audio . EAW's first single enclosure system

6972-421: Was made possible by using the then newly affordable powerful yet small neodymium magnets for the tweeter making the whole tweeter assembly small enough, magnet included, to fit inside the woofer's voice coil. Other home audio speaker companies making coaxial speakers include TAD, Cabasse with their 4-way Concentric QC-55 Driver as seen in their flagship model - La Sphère, Hsu, Vandersteen, until recently Theil, and

7056-550: Was the CS-3 designed for Carlo Sound in Nashville, Tennessee . It combined a B-215 dual 15-in low-frequency horn, a MR102 12-in mid-frequency horn and a Community BRH90 high frequency horn into one gigantic box, and was the first commercially available horn-loaded single enclosure box system. In the late 1970s and 80s, EAW’s MK, FR, and KF Series loudspeaker systems were pivotal in the industry. In 1985 EAW became famous by developing

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