A subwoofer (or sub ) is a woofer, or full loudspeaker, dedicated to the reproduction of low-pitched audio frequencies known as bass and sub-bass. The typical frequency range for subwoofers is about 20-200 Hz for consumer products, under 100 Hz for professional live sound, and below 80 Hz in THX approved systems. The subwoofer is intended to add a low frequency range of the loudspeaker that includes a higher frequency band. While the term "subwoofer" technically refers only to the speaker driver, in common language, this term often refers to the subwoofer driver installed in the speaker box (cabinet).
The subwoofer is composed of one or more woofers mounted on the enclosure loudspeaker - often made of wood - capable of withstanding air pressure while resisting deformation. The subwoofer casing is available in a variety of designs, including bass reflexes (with port or ventilation), using a subwoofer and one or more passive radiator speakers in enclosures, acoustic suspensions (enclosed enclosures), unlimited baffles, horn-loaded, and bandpass designs, a unique trade-off with respect to efficiency, low frequency range, cabinet size and cost. Passive subwoofers have subwoofer and enclosures drivers and they are supported by external amplifiers. Active subwoofers include built-in amplifiers.
The first subwoofer was developed in the 1960s to add a bass response to the home stereo system. Subwoofers became a greater popular awareness in the 1970s with the introduction of Sensurround in films such as
Video Subwoofer
Histori
In September 1964, Raymon Dones, of El Cerrito, California, received US patent 3150739 which was the first patent for a subwoofer designed specifically to increase the low frequency range of the modern stereo system omni-directional. Able to reproduce distortion-free low frequencies of up to 15 cycles per second (15 Hz), the specific purpose of the Dones invention is to provide a portable sound enclosure capable of reproducing high fidelity from low frequency sound waves without providing audible indications of direction. where they came from. Loudspeaker Dones are marketed in the US under the trademark "The Octavium" from the early 1960s to the mid-1970s. Octavium was used by several recording artists of that era, notably Grateful Dead, bassist Monk Montgomery, Nathan East bassist, and Pointer Sisters. The Octavium speakers and Dones' subwoofer technology are also used, in select theaters, to reproduce low-tone frequencies for the 1974 blockbuster film Earthquake . During the late 1960s, Done 'Octavium has been well reviewed by audiophile publications including Hi-Fi News and Audio Magazine .
Other early subwoofer enclosures made for home and studio use are separate bass speakers for Static Servo 1 by New Technology Company. Designed as a prototype in 1966 by physicist Arnold Nudell and airline pilot Cary Christie in Nudell's garage, he used a second round around 18-inch Cerwin Vega driver (45 cm) to provide servo control information to the amplifier, and it was offered for $ 1795, about 40% more expensive than other full loudspeakers listed on Stereo Review . In 1968, both found outside investors and reorganized as Infinity. The subwoofer was positively reviewed in the 1968 winter magazine as "SS-1" by Infinity Stereophile . SS-1 received a very good review in 1970 from High Fidelity magazine.
One of the earliest subwoofers was developed in the late 1960s by Ken Kreisel, former president of Miller & amp; Kreisel Sound Corporation in Los Angeles. When Kreisel's business partner Jonas Miller, who owns a high-end audio store in Los Angeles, told Kreisel that some buyers of high-end electrostatic speaker stores complained about the lack of bass response in electrostatic, Kreisel designed a powered woofer that would reproduce only the frequencies too low for electrostatic speakers to deliver. The Infinity full-range speaker system developed during the 1960s also uses a woofer to cover the lower frequency range that is not handled properly by its electrostatic circuit.
The first use of the subwoofer in the recording session was in 1973 to mix the album Steely Dan Pretzel Logic when recording engineer Roger Nichols arranged for Kreisel to bring his subwoofer prototype to the Village Recorder. Further design modifications were made by Kreisel over the next ten years, and in the 1970s and 1980s by engineer John P. D'Arcy; record producer Daniel Levitin serves as a consultant and "gold ear" for crossover network design (used to partition the frequency spectrum so that the subwoofer will not attempt to reproduce frequencies too high for its effective range, and so the main speaker does not need to handle too low frequencies for their effective range ).
The subwoofer received a lot of publicity in 1974 with the movie Earthquake released in Sensurround. Originally installed in 17 US theaters, Cerwin Vega's "Sensurround" system uses a large subwoofer driven by a 500-watt amplifier shelf triggered by a control tone printed on one of the audio tracks on the film. Four of the subwoofers are positioned in front of the audience below (or behind) the movie screen and two more are placed together at the back of the audience on the platform. Strong sound energy and loud rumble in the range of 17 Hz to 120 Hz is produced at the decibel level of 110-120 sound pressure level, abbreviated dB (SPL). New low-frequency entertainment methods help the film become box office success. More Sensurround systems are assembled and installed. In 1976 there were nearly 300 Sensurround systems jumping through the select theater. Other films to use the effects include the epic Navy battles WW II Midway in 1976 and Rollercoaster in 1977. The deep bass speaker used to be an exotic commodity owned by audiophiles. In the mid-1990s, they were much more popular and widely used, with different size and sound output capabilities.
For LP 33-rpm and 45Ã, single, hard bass and owners are limited by the ability of the stylus disc to track the grooves. Some hi-fi fans solve problems by using reel-to-reel tape players capable of delivering accurate and natural bass from acoustic sources, or synthetic bass not found in nature. With the popular introduction of compact cassettes and CDs, it became possible to add more low-frequency content to recordings, and satisfy more consumers. The home subwoofer is getting popular, as it is easy to add to existing multimedia speaker settings and is easily positioned or hidden.
Maps Subwoofer
Construction and features
Loudspeaker and enclosure design
The subwoofer uses the speaker driver (woofer) usually between 8 inches (20 cm) and 21 inches (53 cm) in diameter. Some unusual subwoofers use a larger driver, and a single 60-inch (152 cm) single prototype subwoofer has been created. At the opposite end of the smaller spectrum, a 4-inch (10 cm) subwoofer driver can be used. Small subwoofer drivers in the 4-inch range are commonly used in small computer speaker systems and compact home theater subwoofer cabinets. The size of the driver and the number of drivers in the cabinet depends on the loudspeaker enclosure design, the cabinet size, the desired sound pressure level, the lowest targeted frequency and the permissible level of distortion. The most common subwoofer driver sizes used for sound reinforcement in nightclubs, raves, and pop/rock concerts are models 10, 12, 15, and 18 inches (25 cm, 30 cm, 38 cm, and 45 cm respectively). The largest voice amplifier subwoofer available, a 21-inch (53 cm) driver, is less commonly seen.
Efisiensi driver speaker diberikan oleh:
Where the variables are Thiele/Small. Low in frequency extensions are general purpose for subwoofer and small box volume is also considered desirable, to save space and reduce size for ease of transportation (in case of voice amplification and DJ subwoofer). Therefore, Hofmann's "Iron Law" requires low efficiency under these limits, and indeed most subwoofers require substantial power, far more than any other individual driver.
Jadi untuk contoh kotak speaker yang disegel, volume kotak untuk mencapai Q ts adalah proporsional dengan Vas:
- Di mana:
Oleh karena itu, penurunan volume kotak (yaitu, kabinet speaker yang lebih kecil) dan F 3 yang sama akan menurunkan efisiensi subwoofer. Demikian pula F 3 dari seorang pembicara sebanding dengan Fs:
As efficiency is proportional to Fs 3 , minor improvements in low frequency extensions with the same driver and box volume will result in a very significant reduction in efficiency. For this reason, the subwoofer is usually very inefficient in converting electrical energy into sound energy. A combination of account factors for higher power amplifiers is required to drive the subwoofer, and the need for greater power handling for subwoofer drivers. Variations of enclosures (eg, bass reflex design with cabinet ports) are often used for subwoofers to improve the efficiency of the driver/enclosure system, helping to reduce the power requirements of the amplifier.
The subwoofer has been designed using a number of enclosures approaches: bass reflexes, acoustic suspension, unlimited baffles, loaded horns, tapped horns, transmission lines and bandpasses. Each type of cage has advantages and disadvantages in increasing efficiency, bass extension, cabinet size, distortion, and cost. Subwoofer is usually built by installing one or more woofers in medium density fibreboard cabinets (MDF), oriented strand board (OSB), plywood, fiberglass, aluminum or other rigid materials. Due to the high air pressure they generate in the cabinet, the subwoofer cover often requires an internal buffer to distribute the resulting power.
The smallest subwoofer is usually designed for desktop multimedia systems. The largest common subwoofer enclosure is used for concert sound reinforcement systems or the dance club sound system. An example of a large concert subwoofer is the 1980s' ElectroVoice MT-4 "Bass Cube system, which uses four 18-inch (45 cm) drivers. An example of a subwoofer that uses a bass horn is the Bassmaxx B-Two, which loads an 18-inch (45 cm) driver onto a long horn folded along 11 feet (3.4 m). The folded horn type subwoofers can usually produce a deeper range with greater efficiency than the same driver in a hornless cage. However, the folded horn cabinets are usually larger and heavier than the shooting cage forward, so the folded horn is rarely used. Some fixed subwoofer horns-experimental installations have been constructed using bricks and concrete to produce very long horns that allow very deep sub-bass extensions.
The subwoofer output level can be increased by increasing the cone's surface area or by increasing the cone visits. Because large drivers need large unwanted cabinets, most of the subwoofer's drivers have big trips. Unfortunately, high travel, at high power levels, tends to produce more distortion from mechanical and magnetic effects inherent to the electro-dynamic (most common) driver. Conflict between the various objectives can not be completely resolved; Subwoofer design always involves reciprocity and compromise. Hofmann Iron Law (the efficiency of the woofer system is directly proportional to the volume of the cabinet (as in size) and to the cube of the cutoff frequency, that is, how low the pitch to use) applies to the subwoofer just like all speakers. Thus subwoofer enclosure designers leading to the deepest pitched bass may have to consider using large enclosure sizes; a subwoofer enclosure instructor to make the smallest possible cabinet (to make transport easier) will need to compromise how low the pitch will be generated by their cabinet.
Frequency range and frequency response
The frequency response specification of a speaker describes the range of frequencies or musical tones that a speaker can reproduce, measured in hertz (Hz). The typical frequency range for the subwoofer is between 20-200 Hz. The professional concert subwoofer sound system normally operates under 100 Hz, and THX approved systems operate under 80 Hz. Subwoofers vary in terms of the range of pitches they can produce, depending on a number of factors such as cabinet size and construction and design of the enclosure and driver (s). The frequency response specification depends entirely on the relevance of the accompanying amplitude value - measurements taken with wider amplitude tolerance will provide a wider frequency response loudspeaker. For example, JBL 4688 TCB Subwoofer System, currently discontinued system designed for cinema, has a frequency response of 23-350 Hz when measured within 10 decibels (0dB to -10dB) and is narrower. frequency response of 28-120 Hz when measured within six decibels (Ã, Â ± 3Ã, dB).
Subwoofers also vary in terms of the level of sound pressure that can be achieved and the level of distortion they can generate from their reach. Some subwoofers, such as "The Abyss" by MartinLogan for example can reproduce the pitch down to about 18 Hz (which is the lowest rumble tone on a large pipe organ with 32-foot (9.8 m) -16 Hz- bass pipe) up to 120Ã , Hz (Ã, Â ± 3Ã, dB). However, although the Abyss subwoofer can drop to 18 Hz, the lowest frequency and maximum SPL with a 10% distortion limit is 35.5 Hz and 79.8 dB at 2 meters. This means that someone who chooses a subwoofer needs to consider more than just the lowest tones that the sub can reproduce.
Amplification
'Active subwoofer' includes their own custom amplifier inside the cabinet. Some also include a user-adjustable equalization that enables increased or decreased output at a particular frequency; this varies from a simple "push" switch, to a fully parametric equalizer meant for detailed speakers and space correction. Some such systems are even equipped with a calibrated microphone to measure the response in space in the subwoofer, so the automatic equalizer can improve the subwoofer combination, subwoofer location, and room response to minimize the effect of room mode and improve low frequency performance.
'Passive subwoofers' have subwoofer drivers and enclosures, but they do not include amplifiers. They sometimes combine internal passive crossover, with filter frequency specified at the factory. These are commonly used with third party power amplifiers, taking their input from previous active crossovers in the signal chain. Home Theater Cheap in Box packs often come with a passive subwoofer cabinet reinforced by multi-channel amplifiers. While some high-end home theater systems use passive subwoofers, this format is still popular in the professional sound industry.
Equation
Equivalence can be used to adjust the indoor response of the subwoofer system. Active subwoofer designers sometimes include a level of corrective equalization to compensate for known performance issues (eg, steeper than the desired low end roll-off level). In addition, many amplifiers include adjustable low-pass filters, preventing unwanted high frequencies from reaching the subwoofer drivers. For example, if the speaker main speaker can be used up to 80 Hz, then the subwoofer filter can be set so that the subwoofer only works below 80. Typical filters involve some overlap in the frequency range; Steep filters are generally undesirable for subwoofers. The crossover section may also include an "infrasonic" or "subsonic" high-pass filter that prevents the subwoofer driver from attempting to reproduce frequencies below its secure capabilities. Setting an important subsonic filter on the bass reflex subwoofer cabinet, since the bass reflex design tends to create a cone overexcursion risk on the pitch below that of the port tuning, which can cause distortion and damage the subwoofer driver. For example, in the scope of the ported subwoofer set to 30 Hz, one might want to filter the tone below the tuning frequency; it's under 30 Hz.
Some systems use parametric equalization in an attempt to correct deviations in the frequency response. Equations often can not achieve flat-frequency responses at all partial hearing locations due to resonance patterns (ie, standing waves) at low frequencies in almost all rooms. Careful positioning of the subwoofer indoors can also help flatten the frequency response. Some subwoofers can manage common responses that are flatter because they can often be set to generate space modes more evenly than a single subwoofer, allowing even distribution to be more effective.
Phase control
Changing the relative phase of the subwoofer with respect to the woofer in other speakers may or may not help to minimize unwanted destructive acoustic noise in the frequency region covered by the subwoofer and main speakers. This may not be helpful at all frequencies, and may create further problems with frequency response, but even so it is generally provided as an adjustment for subwoofer amplifiers. Phase control phase can be a simple polarity reversal switch or a more complex continuous variable circuit.
Continuous variable phase circuit control is common in subwoofer amplifiers, and can be found in crossovers and as a do-it-yourself electronic project. The phase control allows the listener to change the arrival time of the subwoofer sound waves relative to the same frequency of the main speakers (that is, at and around the crossover point to the subwoofer). A similar effect can be achieved by delaying control on many home theater receivers. The subwoofer phase control found in many subwoofer amplifiers is actually a polarity inversion switch. This allows the user to reverse the subwoofer's polarity relative to the given audio signal. This type of control allows the subwoofer to be in phase with the source signal, or 180 degrees out of phase.
The subwoofer phase can still be changed by moving the subwoofer closer to or farther from the listening position, but this may not always be practical.
Servo subwoofer
Some active subwoofers use a servo feedback mechanism based on cone movement that alters the signal sent to the voice coil. The servo feedback signal comes from the ratio of the input signal to the amplifier versus the actual movement of the cone. The usual source of the feedback signal is the multiple rotation of the voice coil attached to the cone or microkip based accelerometer placed on the cone itself. The advantage of a well-implemented servo subwoofer design is to reduce distortion to make the size of the cage smaller. The main disadvantages are cost and complexity.
The servo-controlled subwoofer is not the same as the Servodrive subwoofer whose main mechanism of sound reproduction avoids normal voice coils and magnetic combinations that support high-belt-driven servomotor drives. The Servodrive design improves output power, reduces harmonic distortion and virtually eliminates loss of loudspeaker output resulting from increased voice coil impedance due to overheating of voice coil (called power compression .) This feature allows high power operation for a time long. Intersonics was nominated for the TEC Award for the design of the Servo Drive Loudspeaker (SDL) in 1986 and for the Bass Tech 7 model in 1990.
Apps
Home audio
The use of the subwoofer adds the bass capability of the main speakers, and allows them to become smaller without sacrificing low-frequency capabilities. Subwoofers do not always provide superior bass performance compared to large conventional loudspeakers on ordinary music recordings because of the lack of very low frequency of content on the source. However, there are recordings with substantially low frequency content that most conventional loudspeakers are not well equipped to handle without the help of subwoofers, especially at high-level playbacks, such as music for pipe organs with 32 '(9.75 meters) bass pipes (16 Hz) very large bass drums on symphonic orchestras and electronic music recordings with very low bass synth parts, such as bass or bass track tests.
The low enough frequencies are not easily localized by humans, so many stereo and multichannel audio systems only feature one subwoofer channel and one subwoofer can be placed outside the center without affecting the perceived sound stage, as the resulting sound will be difficult to localize.. Intentions in systems with subwoofer often use small main speakers (two for stereo and five or more for surround sound or movie track) and to hide subwoofers elsewhere (eg behind furniture or under tables), or to add speakers there to save him from having to deal with low frequencies that damage the woofer at high levels. This effect is only possible if the subwoofer is limited to very low frequencies, usually taken to, say, 100 Hz and below - still less localization possible if restricted to even lower maximum frequencies. The higher upper limit for the subwoofer (eg, 125 Hz) is much easier to localize, making a single subwoofer impractical. Home theater systems typically use a subwoofer cabinet ("1" in surround 5.1 sound). However, to "increase bass distribution in a room with multiple seating locations, and prevent" nodes "or" zeroes "with weakened baseball responses, some home cinema fans use the" 5.2 "or" 7.2 "surround sound system with two cabinets subwoofer in the same space.
Some users add subwoofers because of the high desired low bass levels, even beyond what is on the original recording, as in the case of home music fans. Thus, the subwoofer can be part of a package that includes satellite speakers, can be purchased separately, or can be built into the same cabinet with a conventional speaker system. For example, some floor standing tower speakers include subwoofer drivers at the bottom of the same cabinet. Physical separation of the subwoofer and "satellite" speakers not only allow placement in non-conspicuous locations, but because sub-bass frequencies are very sensitive to the location of the rooms (due to the resonance spaces and 'mode' echoes), the best position for the subwoofer is not possible where the speakers " satellite "is located.
For the greatest efficiency and the best coupling for room air volume, the subwoofer can be placed in a corner of the room, away from large room openings, and closer to the listener. This is possible because low bass frequencies have long wavelengths; then there is little difference between information reaching the right and left ear of the listener, so they can not be immediately localized. All low frequency information is sent to the subwoofer. However, unless the sound tracks have been carefully mixed for a single subwoofer channel, it is possible to have some low frequency cancellation if the bass information in one channel's speakers out of phase with another.
The physically separated subwoofer/satellite arrangement, with small satellite speakers and a large subwoofer cabinet that can be hidden behind furniture has been popularized by multimedia speaker systems such as Bose Acoustimass Home Entertainment System, Polk Audio RM2008 Series and Klipsch Audio Technologies ProMedia, among many other. Inexpensive "home theater in the box" systems advertise their integration and simplicity.
Especially among "Home Theater in the Box" systems at low cost and with a "boom box", however, subwoofer inclusion may be little more than a marketing tool. It is unlikely that a small woofer in a cheap, compactly built plastic cabinet will have better bass performance than conventional (and usually larger) speakers that are well designed in a plywood or MDF cabinet. The use of the term "subwoofer" is not a guarantee of good or extended bass performance. Many multimedia "subwoofers" might be better termed mid bass cabinets (60 Hz to 160 Hz) because they are too small to produce bass in the 30 Hz to 59 Hz range.
Furthermore, poorly designed systems often leave everything below about 120 Hz (or even higher) to the subwoofer, meaning that the subwoofer handles frequencies that can be used for ear localization of sound sources, thus introducing unwanted "subwoofer" localization effects. This is usually due to poor design or crossover options (too high crossover points or inadequate crossover slope) used on many computers and home theater systems; localization also comes from port noise and from the usual harmonic distortion in subwoofer design. Individually sold home subwoofers typically include crossover circuits to assist integration into existing systems.
Car audio
Cars are not suitable for "hidden" subwoofer approaches due to space limitations in the passenger compartment. It is not possible, in many situations, to install such large drivers and enclosures to a door or dash, so that the subwoofer is installed in the trunk or rear room. Some car audio enthusiasts compete to produce a very high level of sound pressure within the limits of their vehicle cabins; sometimes very high. The "SPL War" has attracted much attention on the subwoofer in general, but the subjective competition in sound quality ("SQ") has not gained an equal popularity. Top SPL cars can not play normal music, or maybe even drive normally because it's designed solely for competition. Many non-competition subwoofers are also capable of producing high levels in the car due to the small volume of typical car interiors. High sound levels can cause hearing loss and tinnitus if a person is exposed to them for long periods of time.
In 2000, several car audio manufacturers have produced subwoofers using non-circle shapes from manufacturers including Boston Acoustic, Kicker, Sony, Bazooka, and X-Tant. These forms usually carry a kind of distortion penalty. In situations of limited mounting space, they provide a larger cone area and assume all other variables are constant, the maximum output is greater. An important factor in the argument "sub square vs. rounded" is the effect of the enclosures used. In a closed scope, the maximum displacement is determined by
where
- V d represents the displacement volume (in m 3 )
- x max for the number of linear travel the speakers are mechanically capable (in m)
- S d to the cone plane of the sub-woofer (in m 2 ).
These are some Thiele/Small parameters that can be measured or found with driver specifications.
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After the introduction of Sensurround, cinema owners started to install a permanent subwoofer system. Dolby Stereo 70 mm Six Track is a six channel voice format introduced in 1976 that uses two subwoofer channels for stereo reproduction of low frequency. In 1981, Altec introduced a special cinema subwoofer model tuned to around 20 Hz: 8182. Beginning in 1983, THX certification of the cinema sound experience quantifies good audio parameters for watching movies, including requirements for subwoofer performance levels and sufficient isolation of sound outside so that the sound does not interfere with the listening experience. This helps provide guidance for multiplex cinema owners who want to isolate each cinema from their neighbors, even when the harder subwoofer makes isolation more difficult. Special cinema subwoofer models emerge from JBL, Electro-Voice, Eastern Acoustic Works, Kintek, Meyer Sound Laboratories and BGW Systems in the early 1990s. In 1992, the six-channel Dolby Digital movie sound format incorporates one LFE channel, "one spot" in 5.1 surround sound.
Tom Horral, a Boston-based acoustic, blames complaints about the modern films that are too loud on the subwoofer. He said that before the subwoofer makes it possible to have a hard and relatively undistorted bass, the sound level of the film is limited by distortion in less-able systems at low frequencies and high levels.
Sound reinforcement
Professional audio subwoofers used in rock concerts at stadiums, DJ performances on dance music venues (eg, Electronic dance music) and similar events should be able to produce very high sound output levels, at very low frequencies, with low distortion. This is reflected in the design attention given in 2010 to subwoofer applications for voice reinforcement, public address systems, club systems and concert systems. Cerwin Vega states that when a subwoofer cabinet is added to the existing full-range speaker system, this is advantageous, since it moves "... the lowest frequency of your PA [full-range] main speakers" so that "... eliminat [ing] the big overwork that will be duplicated by your main [full-range] main box.That result, your main [full-range] cabinet will run more efficiently and at higher volumes. "Different arguments for adding subwoofer cabinets are that they can increase "clarity" and "perceived loudness" of the whole PA system, even if the SPL does not actually increase. Sound on Sound states that adding the subwoofer enclosure to the full-range system will reduce the "cone excursion", thereby lowering the distortion, leading to an overall clean sound.
Consumer applications (such as in home use) are less demanding because of the much smaller listening space and lower playback rates. Subwoofers are now almost universal in professional sound applications such as live concert voices, churches, nightclubs, and amusement parks. The THX-certified theaters for playback always include a highly capable subwoofer. Some professional applications require a subwoofer designed for very high sound levels, using multiple drivers 12, 15, 18, or 21 inches (30 cm, 40 cm, 45 cm, 53 cm) respectively. A driver as small as 10-inches (25 cm) is sometimes used, generally in a horned horn enclosure.
The number of subwoofer enclosures used in the concert depends on a number of factors, including the size of the venue, whether indoor or outdoor, the amount of low frequency content in the band sound, the desired concert volume, and the design and construction of the enclosure (eg, direct-radiating versus horn-loaded A small coffee shop requires only a 10-inch subwoofer cabinet to add bass provided by full-range speakers A small bar can use one or more two 15-inch direct (40 cm) sub-cabinets. large may have a row of four or five 18-inch (45 cm) twin subwoofer cabinets, or more). In place of the largest stadium, there may be a large number of subwoofer covers. For example, 2009-2010 U2 360Ã,      Tour using 24 Clair Brothers BT-218 subwoofer (box 18 inches (45 cm)) around the circle of center circle, and 72 subwoofers Clair Brothers cardioid S4 placed under it stage "B" shaped ring that surrounds the central main stage.
The keynote speaker may be 'flown' from the ceiling of the place in the chain hoist, and the 'flying point' (ie, the attachment points) is built into many professional loudspeaker enclosures. Subwoofer can be flown or stacked on the ground near the stage. One of the reasons why a subwoofer is installed on the ground is that mounting on the ground can improve bass performance, especially if the sub is placed in the corner of a room (otherwise, if the sub cabinet is considered too hard, alternatives to on-ground or at-angle installations may be considered. of 50 double-18-inch cabinets (45 cm) in a typical rock concert system. Just as consumers of subwoofer attachments can be made from medium density fiberboard (MDF), Oriented-oriented Board (OSB), plywood, plastics or other solid materials, professional subwoofer enclosures can be built from the same material.B MDF is commonly used to build subwoofers for permanent installations because of their relatively high density and is not weather resistant.Other permanent installation subwoofers have been using very thick plywood: Altec 8182 (1981) using plywood 28-ply 28-ply beer birf, Touring subwoofer usually built from 18-20 mm thick void-free Ba ​​ka yu lapis ltic birch (Betula pendula or Betula pubescens) from Finland, Estonia or Russia; Such plywoods provide greater strength for the cages that are often transported. Unable to weather the weather naturally, Baltic birch is coated with carpet, thick paint or spray bedliner on a truck to provide a larger endurance cage subwoofer.
The subwoofer's tour cabinets are usually designed with features that facilitate the transfer of the enclosure (eg wheel, handle "towel handle" and hidden handles), protective grills for speakers (in direct transmitter cabinets), metal or plastic protection for cabinets to protect the finish as cabinets are being shifted one on top of the others, and hardware to facilitate stacking cabinets (for example, interlocking corners) and to "fly" cabinets from the stage rigging. In the 2000s, many small to medium subwoofer designed for live sound band and DJ applications were "powered subs"; that is, they have an integrated power amplifier. These models usually have built-in crossovers. Some models have metal-reinforced holes in which the speaker pole can be mounted to lift the full frequency range cabinet.
Use in full range system
In a professional concert sound system design, the subwoofer can be seamlessly integrated with the main speaker into a full-range stereo or mono system using active crossovers. Audio engineers typically adjust the frequency point where low frequency noise is routed o subwoofer (s) speakers, and medium and high frequency sounds are sent to full-range speakers. Such systems receive signals from the main mono or mix bus console stereo and amplify all frequencies together in the desired balance. If the main sound system is stereo, the subwoofer can also be stereo. Otherwise, the mono subwoofer channel can be lowered in the crossover of the stereo mix, depending on the manufacture and crossover model. While the 2010 subwoofer era cabinet manufacturer suggested placing a subwoofer on either side of the stage (as implied by the inclusion of a mast cup for a complete PA cabinet, Dave Purton argues that for a club show, having two subwoofer cabinets on either side of the stage will cause a gap in bass coverage in place he states that placing two subwoofer together will create a more even, omnidirectional sub-bass tone
PA system based on size and subwoofer approach
Subwoofer aux-fed
Instead of being incorporated into full-range systems, concert subwoofers can be supplied with their own signals from separate mixed buses in the mixing console; often one of the additional shipments ("aux" or "auxes") is used. This configuration is called the "aux-fed subwoofer", and it has been observed to significantly reduce the low frequency "turbidity" that can accumulate in concert sound systems that have multiple microphones at each level taking low frequencies and each having a different phase. the relationship of these low frequencies. The subs aux-eat method greatly reduces the number of sources that feed the subwoofer to include only those instruments that have the desired low-frequency information; sources such as kick drums, bass guitar, samplers, and keyboard instruments. It simplifies signals sent to the subwoofer and makes greater clarity and lower blow. Additional sub-vessel chargers may be stereo, if desired, using two additional mixed buses.
Bass pointer
In order to keep the low-frequency sound focused on the area of ​​the audience and not on stage, and to keep the low frequencies from disturbing the people outside the event space, various techniques have been developed in concert sounds to convert the natural omnidirectional radiation of the subwoofer into a more directional pattern. Some examples of sound reinforcement system applications where sound engineers strive to provide more focused bass sounds are music festivals, which often have multiple bands performing at the same time at different stages; big rave or EDM show, where there are several DJs performing at the same time in different rooms or stages; and multiplex movie theaters, where there are many films simultaneously displayed in the auditorium that share common walls. These techniques include arranging subwoofers in vertical arrays; using a combination of delay and inversion polarity; and setting up a shady-delay system. With the cardioid dispersal pattern, two end-fire subwoofer can be placed one in front of the other. The listener's closest enclosure is delayed by a few milliseconds The second subwoofer postponed the exact amount according to the time it takes the sound to traverse the distance between the speaker grilles.
Vertical array
Stacking or subwoofer rigging in a vertical arrangement focuses the low frequency forward to a greater or lesser extent depending on the physical length of the array. Longer arrays have a more directional effect on lower frequencies. The directions are clearer in the vertical dimension, resulting in a wide but not high radiation pattern. It helps reduce the number of low-frequency sounds bouncing on the ceiling of the room and help reduce external noise complaints outdoors.
Back delay array
Another cardioid subwoofer arrangement pattern can be used horizontally, taking multiple processing channels and no change in the required physical space. This method is often called "cardioid array subwoofer" or "CSA" although the all directional subwoofer method is cardioid. The CSA method reverses the orientation of the enclosure and reverses the polarity of one of each of the three subwoofers on the front of the stage, and delayed the attachment for the maximum cancellation of target frequency on stage. The inversion polarity can be implemented electronically, by reversing the polarity of the cable, or by physically positioning the enclosures to the rear. This method reduces the forward output relative to the flat array of the subwoofer, but can solve the problem of unexpected low frequency energy coming to the microphone on stage. Compared to end-fire arrays, this method has less axle energy but pattern control is more evenly distributed across the audience, and more predictable cancellations backward. The effect covers a little more than an octave range.
The second method of the rear delay array incorporates a flame-end topology with polarity reversal, using two subwoofers positioned front to back, drivers spaced one quarter wavelength apart, reversed backslide in polarity and delayed by several milliseconds for maximum cancellation on stage. of the target frequency. This method has the lowest output power that is directed to audiences, compared to other directional methods.
End-fire array
The end-fire subwoofer method, also called "forward steered arrays", places the subwoofer drivers co-axially in one or more lines, using destructive interference to reduce emissions to the sides and back. This can be done with a separate subwoofer enclosure positioned front to back with the distance between them with a quarter wavelength of the target frequency, the least desirable frequency on stage or the most desirable among the audience. Each line is delayed outside the first line by the amount associated with the speed of sound in the air; usually a few milliseconds. The arrival time of sound energy from all subwoofers is almost simultaneous from the perspective of the audience, but is canceled to a large level behind the subwoofer due to the arrival time of the offset sound waveform. The directionality of the target frequency can achieve rear attenuation of 25 dB, and the coherent forward noise is summed according to the subwoofer. The technique of positioning the end-fire subwoofer began to be widely used at European concert concerts in 2006.
The end-of-flame array trades several decibels of power output for directionality, so this requires more enclosures for the same output power as a closed, closed array of enclosures. Sixteen enclosures in four rows were used in 2007 at one stage of the Ultra Music Festival, to reduce low-frequency interference to the neighboring stage. Due to the physical size of the final-fire array, some concert venues can apply it. The output pattern suffers from off-axis comb-filter, but can be further formed by adjusting the frequency response of each subwoofer line.
Reared array
A long line of subwoofers placed horizontally along the front edge of the stage can be suspended so that the center fires a few milliseconds before flanking it, firing a few milliseconds before its , continuing this mode until the last subwoofer is reached on the outside edge of the line subwoofer (beamforming). This method helps to counteract the extreme constriction of the horizontal dispersion patterns seen with the horizontal subwoofer arrangement. This delay can be used to reshape the array loudspeaker.
Referrer frame
Some subwoofer enclosure designs rely on drivers facing sideways or backwards to achieve directionality levels. The end-fire propulsion can be positioned in a cage that holds more than one driver.
Variant
Some of the less commonly used bass enclosures are variants of the normal range of subwoofer enclosures, such as mid-bass cabinet (60-160 Hz) and infrasonic subwoofer (extra low) (below 30 Hz).
Design enclosures
The front subwoofer has one or more subwoofer speakers in the cabinet, usually with a grille to protect the speakers. In practice, many subwoofer cabinets fitted to the front have vents or ports in the speaker cabinet, thus creating a bass reflex enclosure. Although the bass or vent reflex port creates phase delays, it adds SPL, which is often a key factor in PA and sound amplifier system applications. Thus, an unventilated front subwoofer cabinet is rarely present in a pro audio application.
The horned subwoofer has a subwoofer speaker that has a path following the loudspeaker. To save space, this path is often folded, so the folded path will fit into the box-style cabinet. Caber-Vega states that its folded horned subwoofer cabinet, "... on average, produces 6 dB more output at 1 watt than an 18 "vented box that gives" four times the output by half the number of drivers. "Cerwin Vega JE-36C has a long five-foot long horn folded in a wooden cabinet.
The Subwoofer Manifold has two or more subwoofer speakers that feed a single horn throat. This increases the SPL for the subwoofer, with increasing distortion costs. EV has a multiple speaker cabinet in which four drivers are installed as close as possible as practically. This is a different design from the "multiple drivers in one throat" approach. An unusual example of the subwoofer manifold design is the Thomas Mundorf (TM) approach that features four subwoofer facing each other and sitting adjacent, which is used for theater in a round show, where the audience surrounds the players in large circles (for example, Metallica has used this in some concerts). TM's approach produces omnidirectional bass sound. Cerwin Vega defines the enclosure manifold as a place where "..the driver is facing the port port you are tuning in. You hear the sound directly from the rear of the driver in addition to the sound coming out of the port.This type of enclosure design extends the driver's frequency capability lower than that which will reproduce automatically.
Bandpass subwoofers have cabinets sealed in other cabinets, with "outer" cabinets usually ventilated or ported.
Bass instrument amplification
In rare cases, sound subwoofer amplifier attachments are also used for bass instrument amplification by electric bass players and bass synth players. For most bands and most small to medium sized places (eg, nightclubs and bars), standard guitar bass speaker boxes or keyboard amplifiers will provide sufficient level of sound pressure for monitoring on stage. Because the usual electric bass has a low "E" (41Ã, Hz) as its lowest tone, most of the standard bass guitar cabinets are only designed with the range down to around 40Ã ¢, Hz. However, in some cases, players want to extend sub-bass responses that are not available from the standard instrument speaker enclosures, so they use the subwoofer cabinet. Just as some electric guitarists add a huge pile of guitar cabinets especially for the show, some bassist will add a very large subwoofer wardrobe with an 18-inch woofer especially for the show, and the extension sub cabinet will operate at lower volume than the main bass cabinet.
Bass guitar players who may use subwoofer cabinets include players playing long-range bass that includes low "B" strings (around 31 Hz); bassist playing in a style where very strong sub-bass responses are an important part of sound (eg, funk, Latin, gospel, R & B, etc.); and/or bass players performing in stadium venues or large outdoor venues. Keyboards using subwoofers for on-stage monitoring include electric organs using a bass pedal keyboard (which drops to low "C" which is about 33Ã, Hz) and a bass synth player that plays low rumble sub-bass parts as 18 Hz. Of all the keyboard instruments reinforced on stage, synthesizers can produce some of the lowest notes, because unlike traditional electric pianos or electric organs, which have low "A" low and "C" lows, respectively, the synth does not have the lowest octave permanent. The synth player can add a lower octave to the patch by pressing the "octave down" button, which can produce a tone that is within the limits of human hearing.
Several producers of subwoofer sound concerts suggest that their submarines can be used to strengthen the bass instrument. Meyer Sound shows that the 650-R2 Concert Series Subwoofer, a 14-foot-square (1.3 m 2 ) enclosure with two 18-inch (45 cm) drivers, can be used for bass instrument amplification. While players using sound concert subwoofers for on-stage monitoring can love the powerful sub-bass sound they get on stage, voice technicians can find the use of large subwoofers (for example, two 18 "(45 cm) drivers for instrument monitoring on stage. problematic, as it may interfere with the sub-bass sound "Home Home".
Bass shaker
Because the infrasound bass is felt, sub-bass can be added using a tactile transducer. Unlike typical subwoofer drivers, which produce audible vibrations, the tactile transducer produces low-frequency vibrations designed to be perceived by individuals touching the transducers or indirectly through a piece of wooden furniture or floor. Tactile transducers have recently emerged as a class of devices, called various "bass shakers", "butt shakers" and "throne shakers". They are attached to a seat, such as a drummer's bench or gamer chair, car seat or home theater seat, and the vibrations of the driver are transmitted to the body and then to the ear in a way similar to bone conduction.. They are connected to an amplifier like a normal subwoofer. They can be attached to large flat surfaces (eg floor or platform) to create large low-frequency conduction areas, although low frequency transmissions through the foot are not as efficient as seats.
The advantage of tactile transducers that are used for low frequencies is that they allow a non-charged listening environment with low frequency low waves. It helps drummers in rock bands to monitor their kick drum performance without filling the stage with a powerful low-frequency sound from a 15 "(40 cm) subwoofer monitor and amplifiers, which can" leak "to other mic drums and lower sound mix quality With no large and powerful subwoofer monitors, the bass beaters also allow drummers to lower the level of sound pressure they encounter during the show, reduce the risk of hearing damage, home cinema or video game use, bass shakers help users avoid disturbing others in nearby apartments or rooms , because even strong sound effects like explosive sounds in a war video game or a rowdy earthquake simulation in an adventure movie will not sound. However, some critics argue that perceived vibration is disconnected from the hearing experience, and they claim that music is less than satisfactory by "butt shaker "rather than sound effects have claimed b the bass beater itself can be ticked during a loud sound effect, which may distract the listener's attention.
Claim a world record
With the various sizes on which the claims are based, some subwoofers have been said to be the largest in the world, the hardest or the lowest.
Matterhorn
Matterhorn is a subwoofer model completed in March 2007 by Danley Sound Labs in Gainesville, Georgia after US military requests for loudspeakers that can project infrasound waves from a distance. The Matterhorn is designed to reproduce continuous sine waves from 15 to 20 Hz, and produces 94 dB at a distance of 250 meters (820 ft), and more than 140 dB for music playback is measured on the horn's mouth. It can produce a constant sine wave tone of 15 Hz at 140 dB for 24 hours a day, seven days a week with very low harmonic distortion. The subwoofer has a flat frequency response from 15 to 80 Hz, and drops
Source of the article : Wikipedia
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