This page will contain additional articles about Shimano, as they become available.|
Shimano ((OTCBB: SHMDF), FWB: SHM) is a Japanese manufacturer of cycling, fishing, snowboarding, and until 2005, golf components.
Shimano products include drivetrain, brake, wheel and pedal components for leisure, road and mountain bikes. These components are generally organised and sold as groupsets intended to be supplied as a near complete collection of a bicycle's mechanical parts.
Groupsets commonly include: crankset comprising cranks and chainrings; bottom bracket; chain; rear gear cogs or cassette; front and rear wheel hubs; gear shift levers; brakes; brake levers; cables; front and rear gear mechanisms or derailleurs.
The Italian firm Campagnolo is a competitor as the other major manufacturer of road groupsets. SRAM is a competitor as the other major manufacturer of mountain bike groupsets, though they are now introducing a road groupset as well.
When the 1970s United States bike boom exceeded the capacity of the American and European bicycle component manufacturers, Japanese manufacturers SunTour and Shimano rapidly stepped in to fill the void. While both companies provided products for all price-ranges of the market, SunTour also focused on refinement of existing systems and designs for higher end products, while Shimano paid more attention to rethinking the basic systems and bringing out innovations such as index shifting and front freewheel systems. SunTour eventually lost the commercial battle. In contrast to the near-universal marketing technique of introducing innovations on the expensive side of the marketplace and relying on consumer demand to emulate early adopters along with economy of scale to bring them into the mass market, Shimano introduced new technologies at the lowest end of the bicycle market, using lower cost and often heavier and less durable materials and techniques, only moving them further upscale if they established themselves in the lower market segments.
Lance Armstrong's 1999 victory in the Tour de France on a Shimano Dura-Ace equipped Trek was the first time Shimano components had been used to win the grand tour. In 2002, Dura-Ace equipped bikes were ridden to victory in the Tour de France (Lance Armstrong), Giro d'Italia (Paolo Savoldelli), and Vuelta a España (Aitor González), marking the first time Shimano componentry had been used to win all three grand tours. World championships in both the road and time trial disciplines were won on Shimano equipment.
In 2003 Shimano introduced "Dual Control" to mountain bikes, where the gear shift mechanism is integrated into the brake levers, and reintroduced the "Rapid Rise" rear derailler which works in the opposite direction to traditional deraillers. This development was controversial: critics viewed it as an attempt to monopolise the mountain bike components market because the use of Dual Control integrated shifting requires the use of Shimano brakes, and the Rapid Rise derailler is believed to work more effectively with the Dual Control system. Shimano also introduced new proprietary standards for disc brakes and hubs, and for bottom brackets and cranksets, further fueling speculation about monopolistic intentions.
Many people believe that "VIA", which is stamped on all Shimano parts, is a form of corporate logo, since it does not appear on Campagnolo parts, for instance. In fact, VIA is an official approval stamp used to certify parts of Japanese vehicles - including bicycles.
Racing bicycle groupsets
Current road bicycle groupsets include:
Mountain bike groupsets
Current mountain bicycle groupsets include:
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Current mountain bicycle groupsets include:. This improves the bass response of the system. Current road bicycle groupsets include:. These incorporate a small hole, (called a port), in the speaker cabinet to allow the low frequencies generated by the rear of the woofer cone to escape from the cabinet in phase with that radiated from the front of the cone. In fact, VIA is an official approval stamp used to certify parts of Japanese vehicles - including bicycles. Many multi driver systems use a bass reflex, or ported, design. Many people believe that "VIA", which is stamped on all Shimano parts, is a form of corporate logo, since it does not appear on Campagnolo parts, for instance. 'Multi driver' refers to any speaker system that contains two or more separate drive units, including woofers, midranges, tweeters, and sometimes horns or supertweeters.
Shimano also introduced new proprietary standards for disc brakes and hubs, and for bottom brackets and cranksets, further fueling speculation about monopolistic intentions. Home cinema systems generally include multi-driver systems. This development was controversial: critics viewed it as an attempt to monopolise the mountain bike components market because the use of Dual Control integrated shifting requires the use of Shimano brakes, and the Rapid Rise derailler is believed to work more effectively with the Dual Control system. Despite its name, however, the unit is really a wireless receiver, amplifier and loudspeaker in a single box. In 2003 Shimano introduced "Dual Control" to mountain bikes, where the gear shift mechanism is integrated into the brake levers, and reintroduced the "Rapid Rise" rear derailler which works in the opposite direction to traditional deraillers. So-called wireless loudspeakers are becoming popular in many applications, such as home theater, due to their convenience, removing the need to run speaker wire. World championships in both the road and time trial disciplines were won on Shimano equipment. See also: Home theater in a box.
In 2002, Dura-Ace equipped bikes were ridden to victory in the Tour de France (Lance Armstrong), Giro d'Italia (Paolo Savoldelli), and Vuelta a España (Aitor González), marking the first time Shimano componentry had been used to win all three grand tours. It is important to note that the sound channels offered to the speakers may be original individual channels (normal 5.1) or they may decode additional channels from the surround channels (This distribution can be accomplished by a Dolby Digital EX decoder, a THX Surround EX decoder) or they may be simulated (where the two surround channels are spread to center rear or twin rear speakers. Lance Armstrong's 1999 victory in the Tour de France on a Shimano Dura-Ace equipped Trek was the first time Shimano components had been used to win the grand tour. They include :. In contrast to the near-universal marketing technique of introducing innovations on the expensive side of the marketplace and relying on consumer demand to emulate early adopters along with economy of scale to bring them into the mass market, Shimano introduced new technologies at the lowest end of the bicycle market, using lower cost and often heavier and less durable materials and techniques, only moving them further upscale if they established themselves in the lower market segments. There are various different speaker set-ups for home cinema speaker systems. SunTour eventually lost the commercial battle. See also sound reproduction, electronics.
While both companies provided products for all price-ranges of the market, SunTour also focused on refinement of existing systems and designs for higher end products, while Shimano paid more attention to rethinking the basic systems and bringing out innovations such as index shifting and front freewheel systems. See AudioSpotlights.com for more information. When the 1970s United States bike boom exceeded the capacity of the American and European bicycle component manufacturers, Japanese manufacturers SunTour and Shimano rapidly stepped in to fill the void. There are currently two devices available on the market that use ultrasound to create an audible "beam" of sound: the Audio Spotlight and Hypersonic Sound. SRAM is a competitor as the other major manufacturer of mountain bike groupsets, though they are now introducing a road groupset as well. Pompei. The Italian firm Campagnolo is a competitor as the other major manufacturer of road groupsets. The technology, termed the Audio Spotlight, was first made commercially available in 2000 by Holosonics, a company founded by Dr.
Groupsets commonly include: crankset comprising cranks and chainrings; bottom bracket; chain; rear gear cogs or cassette; front and rear wheel hubs; gear shift levers; brakes; brake levers; cables; front and rear gear mechanisms or derailleurs. Joseph Pompei of the Massachusetts Institute of Technology in 1998 (105th AES Conv, Preprint 4853, 1998) fully described a working device that reduced audible distortion essentially to that of a traditional loudspeaker. These components are generally organised and sold as groupsets intended to be supplied as a near complete collection of a bicycle's mechanical parts. F. Shimano products include drivetrain, brake, wheel and pedal components for leisure, road and mountain bikes. These problems went unsolved until a paper published by Dr. . This technology was originally developed by the US (and Russian) Navy for underwater sonar in the mid-1960s, and was briefly investigated by Japanese researchers in the early 1980s, but these efforts were abandoned due to extremely poor sound quality (high distortion) and substantial system cost.
Shimano ((OTCBB: SHMDF), FWB: SHM) is a Japanese manufacturer of cycling, fishing, snowboarding, and until 2005, golf components. Anyone or anything that disrupts the path of the beam will disturb the dispersion of the signal, and there are limitations, both to the frequency response and to the dispersion pattern of such devices. Tourney - this includes several different levels of quality, and can be found on department-store bicycles. There are some criticisms of this approach. Altus. This effect cannot be achieved with conventional loudspeakers, because sound at audible frequencies cannot be focused into such a narrow beam. Acera. A listener outside the beam hears nothing.
Alivio. The practical effect of this technology is that a beam of sound can be projected over a long distance to be heard only in a small, well-defined area. Deore. The air within the beam behaves in a nonlinear way and demodulates the ultrasound, resulting in sound that is audible only along the path of the beam, or that appears to radiate from any surface that the beam strikes. LX. The ultrasound is modulated-- it consists of an audible signal mixed with an ultrasonic frequency. XT. A transducer can be made to project a narrow beam of ultrasound that is powerful enough, (100 to 110 dBSPL) to change the speed of sound in the air that it passes through.
XTR - This is the top of the range for CrossCountry(XC) mountain bikes. Some speakers are electrostatically driven rather than via the usual electromechanical voice coil, thereby giving a more linear response; the disadvantage, however, is that the signal must be converted to a very high voltage and low current, which can be problematic for reliability and maintenance as they attract dust, and develop a tendency to arc, particularly where the dust provides a partial path; the point where the arc occurs often becomes more prone to arcing, as carbon builds up from the burned dust. Hone. A newer implementation of the Flat Panel involves the panel and an "exciter", such as the NXT technology. Saint - This is the top of the range for DownHill(DH)/FreeRide(FR) bikes. Flat panel loudspeaker designs also work well as electrostatic loudspeakers. Sora. An advantage of flat panel speakers is that the sound is perceived as being of uniform intensity over a wide range of distances from the speaker.
Tiagra. Some progress has been made using such rigid yet damped material as styrofoam, and there have been several flat panel systems demonstrated in recent years. 105. There are two, related problems with flat panel technology; firstly, that the flat panel is more flexible than the cone shape and therefore fails to move as a solid unit, and secondly that resonances in the panels are difficult to control, leading to considerable distortion in the reproduced sound. Ultegra. These can then be either made in a neutral colour and hung on walls where they will be less noticeable, or can be deliberately painted with patterns in which case they can function decoratively. Dura-Ace. One such attempt is the development of flat panels to act as sound sources.
There have also been many attempts to reduce the size of loudspeakers, or alternatively to make them less obvious. In electronic digital to analog conversion, this is addressed by the use of Low-pass filters to eliminate the spurious upper frequencies produced; however, this approach cannot be used to solve the problem with this digital loudspeaker, since it is the last link in the audio chain. Even accounting for the vastly lower efficiency of speaker drivers at such high frequencies, the result was to generate an unacceptably high level of ultrasonics accompanying the desired output. Secondly, since this system is converting digital signal to analog, the effect of aliasing is unavoidable, so that the audio output is "reflected" at equal amplitude in the frequency domain, on the other side of the sampling frequency.
For example, a 16 bit system to be compatible with the 16 bit audio CD standard, starting with a reasonable 2 square inch driver for the least significant bit, would require a total area for the drivers of over 900 square feet. There are two problems with this design which led to its being abandoned as hopelessly impractical, however; firstly, a quick calculation shows that for a reasonable number of bits required for reasonable sound reproduction quality, the size of the system becomes very large. The next least significant bit drives a speaker of twice this area, and so on. The next least significant bit drives a speaker of twice the area (most often, but not necessarily, a ring around the previous driver), again to either full amplitude, or off.
(This allows for high efficiency in the amplifier, which at any time is either passing zero current, or required to drop the voltage by zero volts, therefore theoretically dissipating zero watts at all times). The design of these is disarmingly simple; the least significant bit drives a tiny speaker driver, of whatever physical design seems appropriate; a value of "1" causes this driver to be driven full amplitude, a value of "0" causes it to be completely shut off. Actual digital speaker driver technology not only exists, but is quite mature, having been experimented with extensively by Bell Labs as far back as the 1920s. Unfortunately, the recent marketing of plasma displays as high-end television sets and computer monitors has caused the "me-too" labeling of many speakers as "plasma" which have nothing whatsoever to do with plasma , much as the advent of digital audio caused the marketing of a large number of "digital" headphones and speakers, when all drive-units are analog in nature.
A lower-priced variation on this theme is the use of a flame for the driver , flames being commonly electrically charged. As might be guessed, problems of maintenance and reliability for this design tend to make it very unsuitable for the mass market; the plasma is generated from a tank of helium which must be periodically refilled, for instance. Since plasma has minimal mass, but is charged and therefore can be manipulated by an electric field, the result is a very linear output at frequencies far higher than the audible range. The most exotic speaker design is undoubtedly the plasma arc loudspeaker, using electrical plasma as a driver , once commercially sold as the Ionovac .
Piezos have several advantages over conventional loudspeakers when applied to such purposes:. Computer speakers and portable radios are common examples. Piezoelectric transducers, frequently used as beepers in watches etc., are often used as tweeters in cheap speaker systems. These include piezoelectric, electrostatic, and plasma arc loudspeakers.
Other technologies can be used to convert the electrical signal into an audio signal. See more details here. However, in practice it was found necessary to use a very complex cone made up of various materials at different points along its length, in order to maintain the waveform traveling evenly. This created a very effective omnidirectional radiator (although it suffered the same "planarity" effect as ribbon tweeters for higher-frequency sounds) and eliminated all problems of multiple drivers, such as crossover design, phase anomalies between drivers, etc.
As the waves moved down the truncated cone, the effect was to reproduce the omnidirectional soundwave, as with a cylinder that changed diameter. This turned normal speaker driver design problems on their head; whereas the normal problem with designing a driver is how to keep the cone as stiff as possible (without adding mass), so that it moved as a unit and did not become subject to traveling waves on its surface, the Ohm drivers were designed so that the entire purpose of the electromagnetic driver was to generate traveling waves that traversed the cone from the electromagnet at the top downwards to the bottom. The Ohm model "F" speakers invented by Lincoln Walsh feature a single driver mounted vertically as though it were firing downwards into the top of the cabinet, but instead of the normal almost flat cone, having a very-much extended cone entirely exposed at the top of the speaker. Ribbon tweeters often emit sound that exits the speaker concentrated into a flat plane at the level of the listeners' ears; above and below the plane there is often less treble sound.
Ribbon loudspeakers can be very fragile but recently designed planar tweeters have the metal film printed on a strong lightweight material for reinforcement. The advantage of the ribbon loudspeaker is that the ribbon has very little mass; as such, it can accelerate very quickly, yielding good high-frequency response (although its shape is far from ideal). The electrical signal is applied to the ribbon which vibrates creating the sound. The ribbon loudspeaker consists of a thin metal-film ribbon suspended between two magnets.
The stiffness moves self resonances upward in frequency. The dome is used because it is an easily manufactured stiff structure - as anyone who has attempted to crush an egg the long way can attest to. Perhaps contrary to intuition, making the moving component in the form of a dome rather than an inverted cone does not help to direct sound evenly in all directions. Because the wavelength of high-frequency sound is short (approximately 15 mm at 20 kHz), tweeters must have a physically small moving component or they will create a "beam" of sound rather than sending sound omnidirectionally (as is usually desired).
This design is typically used for tweeters and sometimes for mid-range speakers. For high frequencies, a variation on the common dynamic loudspeaker design uses a small dome as the moving part instead of an inverted cone. Amar Bose of MIT spent many years trying to reproduce this spherical wavefront by constructing a one-eighth sphere covered in small drivers that would be situated in the corner of a room, thus mimicking one-eighth of a spherical wavefront emanating from that corner; in practice this idea never became workable, but Bose's experience with combining multiple small drivers in one loudspeaker cabinet gave rise to the popular Bose speakers which use multiple four-inch drivers, either to direct sound rearwards to reflect it from a wall behind the speakers, for home use, or to provide high power capacity when aimed directly at the listeners, for professional use. Several approaches have attempted to remedy this by approximating the sphere.
A point source or a sphere that varies in size with the amplitude of the desired pressure wave would avoid this problem of beam-formation but is generally physically impossible or impractical. This is especially a problem for high frequencies where the loudspeaker may be physically large compared to the wavelength of the sound being reproduced. One problem with loudspeakers is that the essentially-planar form of most loudspeakers creates a soundwave that is somewhat directional, that is, the intensity of the sound produced varies depending on the listener's angle relative to the central axis of the speaker. are mainly due to advantageous interactions with a particular speaker-room combination.
It has been theorized by some of the audiophile world that the perceived differences in sound between amplifier/loudspeaker combinations are in fact only differences in their interaction with their environment, rather than absolute differences in sound quality; and similarly, that any perceived differences in speaker cables, past a minimum set of specifications regarding resistance, inductance, capacitance, etc. This interaction affects the speaker's electromechanical behavior and thus the load it represents to the amplifier, making it difficult to predict the sound a given system will produce in its intended environment without listening tests. A complication is the interaction of the speaker with the listening environment. and optionally,.
Speaker specifications generally include:. In general a higher quality speaker will have a higher sensitivity rating, larger and or heavier magnet, and a higher Xmax. As shown in this example, sometimes the speaker with the lower sensitivity rating outputs a far higher amount of acoustic watt output. However at full power may achieve 160+ decibels at 20% to 40% "true" efficiency.
80 to 86 dB/(W·m) (sensitivity efficiency of 0.01%). A few top of the line woofers have a very low "sensitivity" rating i.e. A higher Xmax indicates that the driver can move a larger volume of air as power increases. In closed or small environments (such as cars or bedrooms) it is far more important to have a speaker with a high Xmax (cone eXcursion maximum) as opposed to high (dB/(W·m)) rating.
above 140 decibels. The ratio of the sound output to the mass of the cone/coil combination grows significantly at high sound pressure levels i.e. This is partly due to a very high magnetic field and partly to a high amplitude displacement (speaker cone pumping in and out). Current state-of-the-art loudspeakers can approach efficiencies of 70% or higher.
True or absolute efficiency is the ratio of "desired" output power divided by total input power. As an example, a simple cheerleader's horn makes more sound output in the direction it is pointed than the cheerleader could by herself, but the horn did not improve or increase the cheerleader's total efficiency. From a technical standpoint "sensitivity" is not the absolute reference of efficiency. Large horn loudspeakers that used to be used in cinemas, were very efficient by today's hi-fi speaker standards.
The better the matching, the higher the efficiency. This is especially difficult at lower frequencies. The main reason for this low efficiency is the difficulty of achieving proper impedance matching between the acoustic impedance of the drive unit and that of the air. The remainder is converted to heat.
Only about 1% of the electrical energy put into the speaker is converted to acoustic energy. Loudspeakers are very inefficient transducers. This is called the "sensitivity" rating. The efficiency is measured as dB/(W·m)—decibels output for an input of one nominal watt measured at one metre from the loudspeaker usually on the axis of the speaker.
The sound pressure level (SPL) that a loudspeaker produces is measured in decibels (dBSPL). In all cases, replacement or full repair of the driver are the only options. The latter two typically happen when the amplifier dumps a large DC current into the speaker - a condition typical of a failing (or failed) amplifier. Electrical damage occurs when the voice coil burns out.
A large DC fed to the woofer may cause twisting or deformation of the voice coil such that it rubs against the pole-pieces or magnet. In rare cases, a very loud signal may cause the coupling between the parts of the woofer to simply give way. Physical damage occurs if the signal causes the woofer's cone displacement to exceed the safe Xmech limits for prolonged periods. Woofers will usually take a lot of power before burning out or suffering damage to their moving systems.
Most woofers (and mid-ranges) can easily take up to 1.5 times or more power than what they are rated for - however this is dependent on the particular driver and the duration of the abuse or overload. A badly clipping amplifier may also damage the tweeter despite a crossover, since a clipped waveform generates high-frequency harmonics which can contain sufficient power to heat up the tweeter's voice coil. Thus, feeding a low frequency (or a DC) signal to a tweeter even though electrically it may be within the tweeter's specification may cause permanent damage to the tweeter. Thus a tweeter rated for 50 W is meant to be used with a 50 W amplifier only if the signals below the tweeter's lower operating frequency are filtered out.
Tweeters are usually designed (and rated) keeping in mind that a typical music signal doesn't contain a lot of power or energy at the higher end of the audio spectrum. The tweeters are usually the first to go under circumstances of abuse, since they have the lightest voice coil made of thin wire which easily melts if the temperature rises excessively. However they do have limits and exceeding them by a large factor almost always causes permanent damage. Loudspeakers are rugged devices and can take some amount of abuse.
Some of the issues in speaker design are lobing, phase effects, off axis response and time coherence. Speaker designers will use an anechoic chamber (essentially a room with soundproofing that inhibits any reverberation or echo) to ensure the speaker will perform the way it is intended to. Adjusting a design is done with instruments and with the ear. The nature of speaker design is considered both an art and science.
The inverse sound waves and external noise cancel each other out and produce near silence. The headphones produce the inverse sound waves of the external noise. A similar effect is used in sound-cancelling headphones. The second most noticed will be an unsettling feeling.
The most prominent effect to the untrained ear will be a loss of bass response. This won't cause silence because reflections from surfaces diminish the effect somewhat but resulting in a major loss of sound quality. This type of wiring error creates inverse sound waves which cancel out (to a degree) the sound of the other speaker. In this case, any motion one cone makes will be 180 degrees opposite the other.
If both sets of wires for left and right (in a stereo setup) are not connected in phase, the speakers will be out of phase from each other. All speakers have two wires that must connected from the source of the signal (the amplifier or receiver) to the speaker's input terminals in correct polarity, or phase. The Tapered Quarter Wave Pipe (TQWP) is an example of a combination of transmission line and horn effects. This compromise is extremely attractive and used 90 percent of the time in bass horns.
This reduces the theoretical output by 3, but it is still maybe 5 times the output of a simple speaker in a box (no horn). This means instead of using the perfect large size length of say 10ft, they cut it off at a length of say 3.3ft. To minimize the size, some bass horns are designed as a "modified" or "cut" horn. Despite this, they are used about 70 to 90 percent of the time in large stadiums or arenas.
Designs that use horn woofers occupy a large space, and are heavy. Some low frequency horns employ a folded horn design to conserve space. For the bass or low-frequency region the size of the horn becomes exceedingly large and impractical (3ft x 2ft x 2ft, for example). This type has a very high efficiency and reasonably small size for reproducing mid to high frequencies.
A horn (like a cheerleader horn) is an enclosure which has a flare or cone shaped structure attached to the front of the driver (speaker). The baffle dimensions are chosen to get the desired response, with larger dimensions giving a lower frequency before the front and rear waves combine and cancel. A rectangular cross-section is more common than a circular one since it is much easier to fabricate in folded form than a circular cross-section. The baffle may be folded in order to conserve space.
A dipole enclosure in its simplest form is a driver located on a flat baffle. . The payoff is an extended low end response and a characteristic sound that's appealing to many. Transmission lines tend to be larger than the other systems, due to the size and length of the line required by the design.
The transmission line system is a waveguide system in which the guide reverses the phase of the driver's rear output, thereby reinforcing the frequencies near the driver's Fs. PR's do add considerable cost to the system, however. Due to the lack of vent turbulence and vent pipe resonances, many prefer the sound of PR's to reflex ports. Passive radiators add a complication to vented systems which causes a notch in frequency response at the PR's free air resonant frequency and this causes a steeper rolloff below the drone's tuning frequency Fb and poorer transient response than standard vented loudspeakers.
Passive radiators are tuned by their mass (Mmp) and the way their compliance interacts with the compliance of the air in the box. They are also used to eliminate port turbulence and reduce power compression caused by high velocity airflow in ports. Passive radiators are used primarily to tune small volumes to low frequencies, where a port would need to be very long. Sometimes a passive radiator (PR) or drone, similar to a speaker driver but without an electrically activated voice coil, is used instead of a reflex port.
This enclosure is considerably harder to design and tends to be driver-specific. If the enclosure on each side of the woofer has a port in it then the enclosure yields a 6th order band-pass response. The dividing wall between the chambers has the driver mounted on it and the panel opposite to it (or the chamber into which the driver faces) has a port. In its simplest form it has two chambers.
A 4th order bandpass is really just the same as a vented box where the contribution from the driver is trapped in a sealed box which modifies the resonance of the driver. This enclosure is the most common as it lends itself to small size and reasonable bass. Reflex ports are tuned by amount of mass within the vent, using appropriate diameter and length to reach this point. The interior of such enclosures are also often lined with fiberglass matting for absorption.
Other types of enclosures attempt to improve the low frequency response or overall efficiency of the loudspeaker by using various combinations of reflex ports or passive radiating elements to transmit the energy from the rear of the speaker to the listener; these enclosures may also be referred to as vented/ported enclosures, bass reflex, transmission lines (see below). The drawback of these speakers is their low efficiency, due to the loss of the power absorbed inside the cabinet. In this case, the true suspension of the driver's cone is the air trapped inside the box which acts as a spring with very close to ideal behavior rather than the mechanical suspension of the speaker driver, which for this application must be very weak, just strong enough to keep the cone centered in the absence of any signal. The box is typically designed with a very small rate of leakage so that internal and external pressures can slowly equilibrate over time, allowing the speaker to adjust to changes in barometric pressure or altitude.
The closed-box or 'acoustic suspension' enclosure, rather than using a large box to avoid the effect of the internal air pressure, uses a smaller, tightly sealed box. The box is usually filled loosely with foam, pillow stuffing, fiberglass, or other wadding, converting the speaker's thermodynamic properties from adiabatic to isothermal, and giving the effect of a larger cabinet. The box must be large enough that the internal pressure caused when the driver cone moves backwards into the cabinet does not rise high enough to affect this. The designer trades off bass response for flatness; the larger the resonant peak in the bass, the lower the speaker will seem to reproduce, but the more over-emphasized the resonant frequency will be.
The loudspeaker driver's mass and compliance, i.e. the stiffness of the suspension of the cone, determines the resonant frequency and damping properties of the system, which affect the low-frequency response of the speaker; the response falls off very sharply below the cabinet resonant frequency (Fcb). A variation on the 'open baffle' is to place the loudspeaker in a very large sealed box. The most common enclosure types are listed below. For the purposes of this type of analysis, each enclosure has a loudspeaker topology.
Enclosures used for woofer and subwoofer are applications that can be adequately modelled in the low frequency range (approximately 100–200 Hz and below) using acoustics and the lumped component model. The Acoustic Center of the driver, or physical position of each driver's voice coil, dictates the amount of rearward offset to time-align the drivers. Sometimes the differences in reaction time of the different size drivers is addressed by setting the smaller drivers further back, by leaning or stepping the front baffle, so that the resulting wavefront from all drivers is coherent when it reaches the listener. Diffraction problems are addressed in the shape of the enclosure; avoiding sharp corners on the front of the enclosure for instance.
Home experimenters have designed speakers built from concrete sewer pipes for similar reasons. The speaker manufacturer Wharfedale has addressed the problem of cabinet resonance by using two layers of wood with the space between filled with sand. Problems with resonance are usually reduced by increasing enclosure rigidity, added internal damping and increasing the enclosure mass. Enclosures play a significant role in the sound production, adding resonances, diffraction, and other unwanted effects.
However, for many purposes this is impractical and the enclosures must use other techniques to maximize the output of the loudspeaker (called loading). An 'open baffle' loudspeaker is an approximation to this - the transducer is mounted on a simple board of size comparable to the lowest wavelength to be reproduced. Thus the rear soundwaves cannot cancel the front soundwaves. The ideal mount for a loudspeaker would be a flat board of infinite size with infinite space behind it.
The major role of the enclosure is to prevent the out-of-phase sound waves from the rear of the speaker combining with the positive phase sound waves from the front of the speaker, which would result in interference patterns and cancellation causing the efficiency of the speaker to be compromised, particularly in the low frequencies where the wavelengths are large enough that interference will affect the entire listening area. A loudspeaker is commonly mounted in an enclosure (or cabinet). When used with speakers that do not reproduce low frequencies well, a subwoofer will often be configured to reproduce both the LFE channel and all other bass in the system, the latter being referred to as "bass management". This is because most full-range speakers are incapable of delivering the acoustic power required by the LFE in movies or in some cases, music.
When teamed with a modern surround sound receiver and full range speakers, they are typically driven with the specific LFE (low frequency effects) output channel (the ".1" in 5.1, 6.1, or 7.1 specifications) provided by the receiver. Amplified subwoofers frequently accept both speaker-level and line-level audio signals. Extended periods of high volume bass can cause items throughout a room to "walk" on a flat surface until they fall off. A subwoofer's powerful bass can often cause items in the room or even the structure of the room itself to vibrate or buzz.
Placing it in the corner of a room may produce louder bass sounds. It can instead be hidden out of sight. For the same reason, the subwoofer does not need a special placement in the sound field (for example, centered between the Left Front and Right Front speakers). Because of this phenomenon, it is usually satisfactory to provide just a single subwoofer no matter how many individual channels are being used for the full-spectrum sound.
Localization starts to happen above the 150 Hz point. The very long wavelength of the very low frequency bass sounds reproduced by the subwoofer usually makes it impossible for the listener to localize the source of these sounds. Subwoofers often contain integrated power amplifiers that may incorporate sophisticated feedback mechanisms to assure the least distortion of the reproduced bass acoustic waveform. Because the range of frequencies that must be reproduced is quite limited, the design of the subwoofer is usually quite simple, often consisting of a single, large, down-firing woofer enclosed in a cubical "bass-reflex" cabinet.
A typical subwoofer only reproduces sounds below 120 Hz (although some subwoofers allow a choice of the cross-over frequency). This speaker (and its enclosure) is referred to as a subwoofer. Modern speaker systems often include a single speaker dedicated to reproducing the very lowest bass frequencies. A subwoofer driver is a woofer optimised for the lowest range of the audio spectrum.
A whizzer is a small, light cone attached to the woofer's apex around the dust cap. These employ an additional cone called a whizzer to extend the high frequency response. A full-range speaker is designed to have as wide a frequency response as possible. A tweeter is a loudpeaker which is capable of reproducing the higher end of the audio spectrum, usually from about 1 kHz to 20 or perhaps 35 kHz.
Mid-ranges typically appear where large (>16 cm or 8") woofers are used for the bass end of the audio spectrum. These are used when the bass driver (or woofer) is incapable of covering the mid audio range. The distinction between woofers and mid-ranges is blurred however since many woofers can operate up to 3 kHz. A mid-range loudspeaker, also known as a squawker is designed to cover the middle of the audio spectrum, typically from about 200 Hz to about 4-5 kHz.
The frequency range varies widely according to design and hence while some woofers can cover the audio band from 50 Hz to 3 kHz, yet others may only work up to 1 kHz. A woofer is a loudspeaker capable of reproducing the bass frequencies. . However a loudspeaker of say, a rated impedance of 8Ω/100W can easily overload an amp designed purely with a resistive load of 8Ω/100W as a target.
A typical amplifier is most usually quoted for a given power into a resistive load. It is a combination of resistive, capacitive, inductive as well as mechanical effects. A dynamic loudspeaker presents a complex load to the amplifier as opposed to a pure resistance. The weight and damping of the cone in a dynamic speaker should be appropriate for the characteristics of the rest of the driver and enclosure in order to produce accurate sound.
Despite marketing claims, lighter and more rigid cones do not always sound better. Tweeters are subject to a unique set of variables and parameters; their design and construction is extremely variable. Generally, larger and more powerful magnets are associated with higher quality speakers. The size and type of magnets can also differ.
Baskets must be designed in order to preserve rigidity and are typically cast or stamped metal, although injection-molded plastic baskets are becoming much more common in recent years. Driver cones may be constructed of a variety of materials, including paper, metal, various polypropylenes, and kevlar. When a multi-frequency signal is applied, the complex vibration results in reproduction of the applied signal as an audio signal. The coil and the permanent magnet interact with magnetic force which causes the coil and a semi-rigid cone (diaphragm) to vibrate and reproduce sound at the frequency of the applied electrical signal.
When an electrical signal is applied, a magnetic field is induced by the electric current in the coil which becomes an electromagnet. The parts are held together by a chassis or basket. A typical suspension system includes the 'spider', which is at the apex of the cone, often of 'concertina' form; and the 'surround', which is at the base of the cone. In addition to the magnet, voice coil, and cone, dynamic speakers usually also include a suspension system to provide lateral stability and make the speaker components return to a neutral point after moving.
One magnetic pole is outside the coil, whilst the other is inside the voice coil. The gap is also where the magnetic field is concentrated. The coil is oriented coaxially inside the gap made with a permanent magnet. A "gap" is a small circular hole, slot or groove which allows the voice coil and cone to move back and forth.
The traditional design is a semi-rigid paper fibre cone and a coil of fine wire (usually copper), called the voice coil attached to the apex of the cone. Additional improvements to loudspeaker technology occurred in the 1970s, with the introduction of higher temperature adhesives, improved permanent magnet materials, and improved thermal management. Polypropylene and aluminium are also used as diaphragm materials. For Example, Paper cones (or doped paper cones, where the paper is treated with a substance to improve its performance) are still in use today, and can provide good performance.
acoustic suspension) and changes in materials used in the actual loudspeaker, led to audible improvements. Developments in cabinet technology (e.g. The quality of loudspeaker systems until the 1950s was, to modern ears, very poor. This winding usually served a dual role, acting also as a choke coil filtering the power supply of the amplifier which the loudspeaker was connected to.
The coil of the electromagnet is called a field coil and is energized by direct current through a second pair of terminals. These first loudspeakers used electromagnets because large, powerful permanent magnets were not freely available at reasonable cost. Voigt produced the first effective full range unit in 1928, and he also developed what may have been the first system designed for the home, although using electromagnets rather than permanent magnets. There is some controversy in that an application was made earlier by the Briton Paul Voigt but not granted until later.
Kellogg. Rice and Edward W. The moving coil principle was patented in 1924 by two Americans, Chester W. .
The modern design of moving-coil loudspeaker was established by Oliver Lodge in England (1898). This was soon followed by an improved version from Ernst Siemens in Germany and England (1878). Alexander Bell patented the first loudspeaker as part of his telephone in 1876. However, the first documented  device that might fit this description was created in 1881.
Nikola Tesla is believed to have put electrically charged carbon dust in a cup-shaped device to create the first telephone loudspeaker. . The loudspeaker is the most variable element in an audio system, and is responsible for marked audible differences between systems. The term loudspeaker is used to refer to both the device itself, and a complete system consisting of one or more loudspeaker drivers (as the individual units are often called) in an enclosure.
A loudspeaker, or simply speaker, is an electromechanical transducer which converts an electrical signal into sound. In SDDS, 7.1 is the same as 5.1 but adding center-left and center-right speakers in the front of the listener for better audio positioning. 7.1 channel sound in home theater is identical to 6.1 except that it has left and right rear speakers. 6.1 channel sound is similar to 5.1 but there is an added center rear channel.
This is usually achieved by an amplifier setting of 'large' or 'small' defining the speaker type. This speaker can reproduce the bass frequency from all the main channels or may only do so for those speakers incapable of doing so. A subwoofer (which is counted as ".1" channel because of the narrow frequency band that it reproduces). Left and right surround speakers.
Left, center, and right front speakers. This requires:
Piezoelectric transducers are resistant to overloads that would normally burn out the voice coil of a conventional loudspeaker. Piezoelectric transducers are physically small yet powerful, leading to good dispersion, although the fidelity of such devices remains in question when it comes to critical listening. Piezoelectric transducers have no voice-coil, therefore there is no electrical inductance to overcome; it is easy to couple high-frequency electrical energy into the piezoelectric transducer, especially under the low-power, non-critical applications in which they are usually employed. Thiele/Small parameters (Individual units only) – These include the driver's Fs (resonance frequency), Qts (the driver's Q or damping factor at resonance), and Vas (the equivalent air compliance volume of the driver).
Frequency response – The measured or specified variance in sound pressure level over a range of frequencies. Crossover frequency(ies) (Finished systems only) – The frequency or frequencies where electrical filtering occurs. Number of drivers (Finished systems only) – 2-way, 3-way, etc. Baffle or enclosure type (Finished systems only) – Sealed, bass reflex, etc.
Impedance – 4 Ω, 8 Ω, etc. Rated Power – Nominal or continuous or RMS power and peak or maximum short-term power. Speaker or driver type (Individual units only) – Full-range, woofer, tweeter or mid-range. video of 158 dB woofer at 80 millimeter amplitude 450 kB mpeg.
Rock concert, stadium speakers have a sensitivity of 103 to 110 dB/(W·m). Nightclub speakers have a sensitivity of 95 to 102 dB/(W·m). Normal loudspeakers have a sensitivity of 85 to 95 dB/(W·m).