The EBow , short for electronic bow or energy bow , is an electronic device used for playing string instruments, most often the electric guitar . It is manufactured by Heet Sound Products of Los Angeles, California. It was invented by Greg Heet in 1969, introduced in 1976 and patented in 1978.
104-425: The EBow uses a pickup in an inductive string driver feedback circuit, including a sensor coil, driver coil and amplifier, to vibrate strings, producing a sound reminiscent of using a bow on the strings . The EBow was introduced in 1976 at NAMM , and has remained in continuous production since. The first version was activated by plucking the guitar string . The second, introduced in 1983, added an on/off switch and
208-456: A hi-fi system in a private home to huge, heavy subwoofer enclosures with multiple 18-inch (46 cm) or even 21-inch (53 cm) speakers in huge enclosures which are designed for use in stadium concert sound reinforcement systems for rock music concerts. The primary role of an enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open speaker driver interacting with sound waves generated at
312-445: A loudspeaker in a speaker enclosure . The signal from a pickup can also be recorded directly. The first electrical string instrument with pickups, the " Frying Pan " slide guitar, was created by George Beauchamp and Adolph Rickenbacker around 1931. Most electric guitars and electric basses use magnetic pickups. Acoustic guitars , upright basses and fiddles often use a piezoelectric pickup. A typical magnetic pickup
416-460: A Scandinavian driver maker. The design remains uncommon among commercial designs currently available. A reason for this may be that adding damping material is a needlessly inefficient method of increasing damping; the same alignment can be achieved by simply choosing a loudspeaker driver with the appropriate parameters and precisely tuning the enclosure and port for the desired response. A similar technique has been used in aftermarket car audio ; it
520-405: A Wind that Screams" and his cover of T. Rex 's "The Visit". Pickup (music technology) A pickup is a transducer that captures or senses mechanical vibrations produced by musical instruments , particularly stringed instruments such as the electric guitar , and converts these to an electrical signal that is amplified using an instrument amplifier to produce musical sounds through
624-416: A bass reflex design since such corrections can be as simple as mass adjustments to the drone. The disadvantages are that a passive radiator requires precision construction like a driver, thus increasing costs, and may have excursion limitations. A 4th-order electrical bandpass filter can be simulated by a vented box in which the contribution from the rear face of the driver cone is trapped in a sealed box, and
728-404: A bass reflex, but the bass reflex cabinet will have a lower −3 dB point. The voltage sensitivity above the tuning frequency remains a function of the driver, and not of the cabinet design. The isobaric loudspeaker configuration was first introduced by Harry F. Olson in the early 1950s, and refers to systems in which two or more identical woofers (bass drivers) operate simultaneously, with
832-413: A box size that exploits the almost linear air spring resulting in a −3 dB low-frequency cut-off point of 30–40 Hz from a box of only one to two cubic feet or so. The spring suspension that restores the cone to a neutral position is a combination of an exceptionally compliant (soft) woofer suspension, and the air inside the enclosure. At frequencies below system resonance, the air pressure caused by
936-410: A closet or attic. This is often the case with exotic rotary woofer installations, as they are intended to go to frequencies lower than 20 Hz and displace large volumes of air. Infinite baffle ( IB ) is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of
1040-430: A common body of enclosed air adjoining one side of each diaphragm. In practical applications, they are most often used to improve low-end frequency response without increasing cabinet size, though at the expense of cost and weight. Two identical loudspeakers are coupled to work together as one unit: they are mounted one behind the other in a casing to define a chamber of air in between. The volume of this isobaric chamber
1144-444: A design restriction that limits the dynamic range of the circuit. The active circuitry may contain audio filters, which reduce the dynamic range and mildly distort certain ranges. High-output active pickup systems also have an effect on an amplifier's input circuit. Rickenbacker was the first manufacturer to market stereo instruments (guitars and basses). Their proprietary "Ric-O-Sound" circuitry has two separate output jacks, allowing
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#17327910815041248-431: A driver at low frequencies. In conceptual terms an infinite baffle is a flat baffle that extends out to infinity – the so-called endless plate . A genuine infinite baffle cannot be constructed but a very large baffle such as the wall of a room can be considered to be a practical equivalent. A genuine infinite-baffle loudspeaker has an infinite volume (a half-space) on each side of the baffle and has no baffle step. However,
1352-401: A fairly recent development that work by sensing the interruption of a light beam by a vibrating string. The light source is usually an LED, and the detector is a photodiode or phototransistor . These pickups are completely resistant to magnetic or electric interference and also have a very broad and flat frequency response, unlike magnetic pickups. Optical pickup guitars were first shown at
1456-818: A few centimetres or inches), those for mid-range frequencies (perhaps 300 Hz to 2 kHz) much larger, perhaps 30 to 60 cm (1 or 2 feet), and for low frequencies (under 300 Hz) very large, a few metres (dozens of feet). In the 1950s, a few high fidelity enthusiasts actually built full-sized horns whose structures were built into a house wall or basement. With the coming of stereo (two speakers) and surround sound (four or more), plain horns became even more impractical. Various speaker manufacturers have produced folded low-frequency horns which are much smaller (e.g., Altec Lansing, JBL, Klipsch, Lowther, Tannoy) and actually fit in practical rooms. These are necessarily compromises, and because they are physically complex, they are expensive. The multiple entry horn (also known under
1560-614: A few particular models use include: The piezoelectric pickup contains a piezo crystal, which converts the vibrations directly to a changing voltage. Many semi-acoustic and acoustic guitars , and some electric guitars and basses, have been fitted with piezoelectric pickups instead of, or in addition to, magnetic pickups. These have a very different sound, and also have the advantage of not picking up any other magnetic fields, such as mains hum and feedback from monitoring loops. In hybrid guitars , this system allows switching between magnetic pickup and piezo sounds, or simultaneously blending
1664-567: A high input impedance , typically a megohm or more, and a low-impedance load increases attenuation of higher frequencies. Typical maximum frequency of a single-coil pickup is around 5 kHz, with the highest note on a typical guitar fretboard having a fundamental frequency of 1.17 kHz. Single-coil pickups act like a directional antenna and are prone to pick up mains hum —nuisance alternating current electromagnetic interference from electrical power cables, power transformers, fluorescent light ballasts, video monitors or televisions—along with
1768-461: A leaky sealed box or a ported box with large amounts of port damping. By setting up a port, and then blocking it precisely with sufficiently tightly packed fiber filling, it is possible to adjust the damping in the port as desired. The result is control of the resonance behavior of the system which improves low-frequency reproduction, according to some designers. Dynaco was a primary producer of these enclosures for many years, using designs developed by
1872-403: A loss of bass and in comb filtering , i.e., peaks and dips in the response power regardless of the signal that is meant to be reproduced. The resulting response is akin to two loudspeakers playing the same signal but at different distances from the listener, which is like adding a delayed version of the signal to itself, whereby both constructive and destructive interference occurs. Before
1976-421: A magnet, and are the most common type used. They can generate electric potential without need for external power, though their output is relatively low, and the harmonic content of output depends greatly on the winding. "Active" pickups incorporate electronic circuitry to modify the signal. Active circuits are able to filter, attenuate or boost the signal from the pickup. The main disadvantage of an active system
2080-406: A metallic or cloth mesh that are used to protect the speaker by forming a protective cover over the speaker's cone while allowing sound to pass through undistorted. Speaker enclosures are used in homes in stereo systems, home cinema systems, televisions , boom boxes and many other audio appliances. Small speaker enclosures are used in car stereo systems. Speaker cabinets are key components of
2184-520: A more powerful drive. The third, introduced in 1989, had improved sensitivity and faster attack . The EBow Plus, introduced in 1998, adds a blue LED and a switch to allow users to move between normal and harmonic modes (which sounds one octave higher). It is powered by a nine-volt battery . The EBow uses a pickup and a magnetic feedback circuit to vibrate strings without touching them. Whereas guitars traditionally have fast attack and slow release , meaning notes ring immediately and then fade out,
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#17327910815042288-461: A number of commercial applications, including sound reinforcement systems , movie theatre sound systems and recording studios . Electric musical instruments invented in the 20th century, such as the electric guitar , electric bass and synthesizer , among others, are amplified using instrument amplifiers and speaker cabinets (e.g., guitar amplifier speaker cabinets). Early on, radio loudspeakers consisted of horns , often sold separately from
2392-420: A number of features to make them easier to transport, such as carrying handles on the top or sides, metal or plastic corner protectors, and metal grilles to protect the speakers. Speaker enclosures designed for use in a home or recording studio typically do not have handles or corner protectors, although they do still usually have a cloth or mesh cover to protect the woofer and tweeter. These speaker grilles are
2496-406: A patch cable. The pickup is most often mounted on the body of the instrument, but can be attached to the bridge , neck or pickguard . The pickups vary in power, and they vary in style. Some pickups can be single coil, in which one coil picks up the sound of all strings, while other pickups can be double coil humbuckers . A special type of humbucker characteristic for Precision type bass guitars
2600-556: A role in managing vibration induced by the driver frame and moving airmass within the enclosure, as well as heat generated by driver voice coils and amplifiers (especially where woofers and subwoofers are concerned). Sometimes considered part of the enclosure, the base, may include specially designed feet to decouple the speaker from the floor. Enclosures designed for use in PA systems , sound reinforcement systems and for use by electric musical instrument players (e.g., bass amp cabinets ) have
2704-436: A round hole in the cabinet. It was observed that the enclosure had a strong effect on the bass response of the speaker. Since the rear of the loudspeaker radiates sound out of phase from the front, there can be constructive and destructive interference for loudspeakers without enclosures, and below frequencies related to the baffle dimensions in open-baffled loudspeakers (see § Background , below) . This results in
2808-440: A sealed enclosure of the same volume, although it actually has less low frequency output at frequencies well below the cut-off frequency, since the rolloff is steeper (24 dB/octave versus 12 dB/octave for a sealed enclosure). Malcolm Hill pioneered the use of these designs in a live event context in the early 1970s. Vented system design using computer modeling has been practiced since about 1985. It made extensive use of
2912-409: A second passive driver, or drone, to produce similar low-frequency extension, or efficiency increase, or enclosure size reduction, similar to ported enclosures. Small and Hurlburt have published the results of research into the analysis and design of passive-radiator loudspeaker systems. The passive-radiator principle was identified as being particularly useful in compact systems where vent realization
3016-887: A separate signal for each individual string and sends them to an onboard analog/digital converter, then out of the guitar via Ethernet cable . Speaker enclosure A loudspeaker enclosure or loudspeaker cabinet is an enclosure (often rectangular box-shaped) in which speaker drivers (e.g., loudspeakers and tweeters ) and associated electronic hardware, such as crossover circuits and, in some cases, power amplifiers , are mounted. Enclosures may range in design from simple, homemade DIY rectangular particleboard boxes to very complex, expensive computer-designed hi-fi cabinets that incorporate composite materials, internal baffles, horns, bass reflex ports and acoustic insulation. Loudspeaker enclosures range in size from small "bookshelf" speaker cabinets with 4-inch (10 cm) woofers and small tweeters designed for listening to music with
3120-542: A similar inductance. Most electric guitars have two or three magnetic pickups. A combination of pickups is called a pickup configuration , usually notated by writing out the pickup types in order from bridge pickup through mid pickup(s) to neck pickup, using “S” for single-coil and “H” for humbucker. Typically the bridge pickup is known as the lead pickup, and the neck pickup is known as the rhythm pickup. Common pickup configurations include: Less frequently found configurations are: Examples of rare configurations that only
3224-438: A sort of open-backed box. A rectangular cross-section is more common than curved ones since it is easier to fabricate in a folded form than a circular one. The baffle dimensions are typically chosen to obtain a particular low-frequency response, with larger dimensions giving a lower frequency before the front and rear waves interfere with each other. A dipole enclosure has a figure-of-eight radiation pattern, which means that there
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3328-404: A sound', and are not so neutral. On fine jazz guitars, the parallel wiring produces significantly cleaner sound, as the lowered source impedance drives capacitive cable with lower high frequency attenuation. A side-by-side humbucking pickup senses a wider section of each string than a single-coil pickup. By picking up a larger portion of the vibrating string, more lower harmonics are present in
3432-402: A speaker driver appear out of phase from each other because they are generated through the opposite motion of the diaphragm and because they travel different paths before converging at the listener's position. A speaker driver mounted on a finite baffle will display a physical phenomenon known as interference , which can result in perceivable frequency-dependent sound attenuation. This phenomenon
3536-439: A very wide frequency range output compared to the magnetic types and can give large amplitude signals from the strings. For this reason, the buffer amplifier is often powered from relatively high voltage rails (about ±9 V) to avoid distortion due to clipping . A less linear preamp (like a single- FET amplifier) might be preferable due to softer clipping characteristics. Such an amplifier starts to distort sooner, which makes
3640-476: A wider range of available sounds. For early pickup devices using the piezoelectric effect, see phonograph . Some pickup products are installed and used similarly to piezoelectric pickups, but use different underlying technology, for instance electret or condenser microphone technology. There are basically four principles used to convert sound into an alternating current, each with their pros and cons: An amplification system with two transducers combines
3744-491: Is coherent at and around the crossover frequencies in the speaker's normal sound field. The acoustic center of the driver dictates the amount of rearward offset needed to time-align the drivers. Enclosures used for woofers and subwoofers can be adequately modeled in the low-frequency region (approximately 100–200 Hz and below) using acoustics and the lumped component models. Electrical filter theory has been used with considerable success for some enclosure types. For
3848-519: Is a complex sum of the properties of the specific driver, the enclosure and port, because of imperfect understanding of the assorted interactions. These enclosures are sensitive to small variations in driver characteristics and require special quality control concern for uniform performance across a production run. Bass ports are widely used in subwoofers for PA systems and sound reinforcement systems , in bass amp speaker cabinets and in keyboard amp speaker cabinets. A passive radiator speaker uses
3952-435: Is a reduction in sound pressure, or loudness, at the sides as compared to the front and rear. This is useful if it can be used to prevent the sound from being as loud in some places as in others. A horn loudspeaker is a speaker system using a horn to match the driver cone to the air. The horn structure itself does not amplify, but rather improves the coupling between the speaker driver and the air. Properly designed horns have
4056-402: Is a transducer (specifically a variable reluctance sensor ) that consists of one or more permanent magnets (usually alnico or ferrite ) wrapped with a coil of several thousand turns of fine enameled copper wire. The magnet creates a magnetic field which is focused by the pickup's pole piece or pieces. The permanent magnet in the pickup magnetizes the guitar string above it. This causes
4160-436: Is an approximation of this, since the driver is mounted on a panel, with dimensions comparable to the longest wavelength to be reproduced. In either case, the driver would need a relatively stiff suspension to provide the restoring force which might have been provided at low frequencies by a smaller sealed or ported enclosure, so few drivers are suitable for this kind of mounting. The forward- and rearward-generated sounds of
4264-406: Is an example of a combination of transmission line and horn effects. It is highly regarded by some speaker designers. The concept is that the sound emitted from the rear of the loudspeaker driver is progressively reflected and absorbed along the length of the tapering tube, almost completely preventing internally reflected sound being retransmitted through the cone of the loudspeaker. The lower part of
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4368-424: Is called aperiodic membrane (AP). A resistive mat is placed in front of or directly behind the loudspeaker driver (usually mounted on the rear deck of the car in order to use the trunk as an enclosure). The loudspeaker driver is sealed to the mat so that all acoustic output in one direction must pass through the mat. This increases mechanical damping, and the resulting decrease in the impedance magnitude at resonance
4472-444: Is called split coil pickup: two coils, each of them picks up different strings, on a 4-string bass, one coil the E and A string, the second coil the D and G string. The pickup is one of the most important aspects to distinguishing an electric guitar's sound. Most guitar models have a distinction in pickups, which act as a new selling point for guitar companies. Pickups have magnetic polepieces, typically one or two for each string, with
4576-426: Is composed of two coils, with each coil wound reverse to the other. Each set of six magnetic poles is also opposite in polarity. Since ambient hum from electrical devices reaches the coils as common-mode noise , it induces an equal voltage in each coil, but 180 degrees out of phase between the two voltages. These effectively cancel each other, while the signal from the guitar string is doubled. When wired in series, as
4680-465: Is difficult or impossible, but it can also be applied satisfactorily to larger systems. The passive driver is not wired to an amplifier; instead, it moves in response to changing enclosure pressures. In theory, such designs are variations of the bass reflex type, but with the advantage of avoiding a relatively small port or tube through which air moves, sometimes noisily. Tuning adjustments for a passive radiator are usually accomplished more quickly than with
4784-447: Is due primarily to a reduction in the speed of sound propagation through the filler material as compared to air. The enclosure or driver must have a small leak so that the internal and external pressures can equalise over time, to compensate for changes in barometric pressure or altitude; the porous nature of paper cones, or an imperfectly sealed enclosure, is normally sufficient to provide this slow pressure equalisation. A variation on
4888-399: Is generally the desired effect, though there is no perceived or objective benefit to this. Again, this technique reduces efficiency, and the same result can be achieved through selection of a driver with a lower Q factor , or even via electronic equalization . This is reinforced by the purveyors of AP membranes; they are often sold with an electronic processor which, via equalization, restores
4992-516: Is indeed not much output from the line's port. But it is the inherent resonance (typically at 1/4 wavelength) that can enhance the bass response in this type of enclosure, albeit with less absorbent stuffing. Among the first examples of this enclosure design approach were the projects published in Wireless World by Bailey in the early 1970s, and the commercial designs of the now defunct IMF Electronics which received critical acclaim at about
5096-467: Is most common, the overall inductance of the pickup is increased, which lowers its resonance frequency and attenuates the higher frequencies, giving a less trebly tone (i.e., "fatter") than either of the two component single-coil pickups would give alone. An alternative wiring places the coils in buck parallel, which has a more neutral effect on resonant frequency. This pickup wiring is rare, as guitarists have come to expect that humbucking pickups 'have
5200-420: Is not isolated by a buffer amplifier or a DI unit . The turns of wire in proximity to each other have an equivalent self- capacitance that, when added to any cable capacitance present, resonates with the inductance of the winding. This resonance can accentuate certain frequencies, giving the pickup a characteristic tonal quality. The more turns of wire in the winding, the higher the output voltage but
5304-427: Is of different materials and densities, changing as one gets further from the back of the driver's diaphragm. Consequent to the above, practical transmission line loudspeakers are not true transmission lines, as there is generally output from the vent at the lowest frequencies. They can be thought of as a waveguide in which the structure shifts the phase of the driver's rear output by at least 90° , thereby reinforcing
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#17327910815045408-431: Is particularly noticeable at low frequencies where the wavelengths are large enough that interference will affect the entire listening area. Since infinite baffles are impractical and finite baffles tend to suffer poor response as wavelengths approach the dimensions of the baffle (i.e. at lower frequencies), most loudspeaker cabinets use some sort of structure (usually a box) to contain the out of phase sound energy. The box
5512-422: Is requirement of a battery power source to operate the preamp circuitry. Batteries limit circuit design and functionality, in addition to being inconvenient to the musician. The circuitry may be as simple as a single transistor, or up to several operational amplifiers configured as active filters, active EQ and other sound-shaping features. The op amps used must be of a low-power design to optimize battery life,
5616-408: Is typically made of wood, wood composite, or more recently plastic, for reasons of ease of construction and appearance. Stone, concrete, plaster, and even building structures have also been used. Enclosures can have a significant effect beyond what was intended, with panel resonances , diffraction from cabinet edges and standing wave energy from internal reflection/reinforcement modes being among
5720-767: Is usually chosen to be fairly small for reasons of convenience. The two drivers operating in tandem exhibit exactly the same behavior as one loudspeaker in twice the cabinet. Also known as vented (or ported) systems, these enclosures have a vent or hole cut into the cabinet and a port tube affixed to the hole, to improve low-frequency output, increase efficiency, or reduce the size of an enclosure. Bass reflex designs are used in home stereo speakers (including both low- to mid-priced speaker cabinets and expensive hi-fi cabinets), bass amplifier speaker cabinets, keyboard amplifier cabinets, subwoofer cabinets and PA system speaker cabinets. Vented or ported cabinets use cabinet openings or transform and transmit low-frequency energy from
5824-541: The MIDI (musical instrument digital interface) protocol. A hexaphonic pickup and a converter are usually components of a guitar/synthesizer . Such pickups are uncommon (compared to normal ones), and only a few notable models exist, like the piezoelectric pickups on the Moog Guitar . Hexaphonic pickups can be either magnetic or piezoelectric or based on the condensor principle like electronicpickups Optical pickups are
5928-635: The Red Hot Chili Peppers , Van Halen , Metallica and the Foo Fighters . In the 1980s, the Bongos used the EBow in the intro of their song "Numbers With Wings" and in "River To River", "Miss Jean", "Glow", "Flew A Falcon" and "Sweet Blue Cage". Frontman Richard Barone continues to use an EBow on his subsequent solo recordings and much of his production work including his songs "Love is
6032-426: The open baffle approach is to mount the loudspeaker driver in a very large sealed enclosure, providing minimal air spring restoring force to the cone. This minimizes the change in the driver's resonance frequency caused by the enclosure. The low-frequency response of infinite baffle loudspeaker systems has been extensively analysed by Benson. Some infinite baffle enclosures have used an adjoining room, basement, or
6136-423: The 1950s many manufacturers did not fully enclose their loudspeaker cabinets; the back of the cabinet was typically left open. This was done for several reasons, not least because electronics (at that time tube equipment) could be placed inside and cooled by convection in the open enclosure. Most of the enclosure types discussed in this article were invented either to wall off the out of phase sound from one side of
6240-506: The 1969 NAMM Convention in Chicago , by Ron Hoag. In 2000, Christopher Willcox, founder of LightWave Systems, unveiled a new beta technology for an optical pickup system using infrared light. In May 2001, LightWave Systems released their second generation pickup, dubbed the "S2." Pickups can be either active or passive . Pickups, apart from optical types, are inherently passive transducers. "Passive" pickups are usually wire-wound around
6344-705: The 1996 Oasis song " Don't Look Back in Anger ". The EBow was prominently used by the Siouxsie and the Banshees guitarist John McGeoch on "Sin in My Heart", from the 1981 album Juju . The EBow is used by the Radiohead guitarist Ed O'Brien for performances of songs such as " My Iron Lung ", "Talk Show Host", " Jigsaw Falling Into Place ", "Where I End and You Begin" and " Nude ". Other users include Duran Duran ,
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#17327910815046448-568: The EBow "changed everything for me ... [It] basically turns the guitar into a keyboard ... It completely opened up the sound of the guitar." The EBow has been used to create background textures or sustained notes similar to guitar feedback , as in " (Don't Fear) The Reaper " (1976) by Blue Öyster Cult and " Heaven Beside You " (1996) by Alice in Chains . It was used by the Edge on the 1983 U2 album The Unforgettable Fire and by Noel Gallagher on
6552-432: The EBow can sustain notes indefinitely and gives greater control over attack and decay. The EBow can only play one string at a time, but can be moved across the strings to play arpeggios . It can produce sounds similar to cello or violin. The EBow was particularly popular in 1980s music, used by acts such as Big Country , Tones on Tail , Love and Rockets and Bill Nelson . The Love and Rockets guitarist Daniel Ash said
6656-715: The Highlander iP-2, the Verweij VAMP or the LR Baggs dual source and the D-TAR Multisource. Hexaphonic pickups (also called divided pickups and polyphonic pickups ) have a separate output for each string ( Hexaphonic assumes six strings, as on a guitar). This allows for separate processing and amplification for each string. It also allows a converter to sense the pitch coming from individual string signals for producing note commands, typically according to
6760-533: The bass output lost through the mechanical damping. The effect of the equalization is opposite to that of the AP membrane, resulting in a loss of damping and an effective response similar to that of the loudspeaker without the aperiodic membrane and electronic processor. A dipole enclosure in its simplest form is a driver located on a flat baffle panel, similar to older open back cabinet designs. The baffle's edges are sometimes folded back to reduce its apparent size, creating
6864-507: The bass output. Such designs tend to be less dominant in certain bass frequencies than the more common bass reflex designs and followers of such designs claim an advantage in clarity of the bass with a better congruency of the fundamental frequencies to the overtones. Some loudspeaker designers like Martin J. King and Bjørn Johannessen consider the term quarter wave enclosure as a more fitting term for most transmission lines and since acoustically, quarter wavelengths produce standing waves inside
6968-439: The bridge feet and the top of the instrument, or, less frequently, wedged under a wing of the bridge. Some pickups are fastened to the top of the instrument with removable putty . Piezoelectric pickups have a very high output impedance and appear as a capacitance in series with a voltage source . They therefore often have an instrument-mounted buffer amplifier fitted to maximize frequency response . The piezo pickup gives
7072-431: The cone motion is the dominant force. Developed by Edgar Villchur in 1954, this technique was used in the very successful Acoustic Research line of bookshelf speakers in the 1960s–70s. The acoustic suspension principle takes advantage of this relatively linear spring. The enhanced suspension linearity of this type of system is an advantage. For a specific driver, an optimal acoustic suspension cabinet will be smaller than
7176-440: The distortion less "buzzy" and less audible than a more linear, but less forgiving op-amp . However, at least one study indicates that most people cannot tell the difference between FET and op-amp circuits in blind listening comparisons of electric instrument preamps, which correlates with results of formal studies of other types of audio devices. Sometimes, piezoelectric pickups are used in conjunction with magnetic types to give
7280-425: The driver, or to modify it so that it could be used to enhance the sound produced from the other side. In some respects, the ideal mounting for a low-frequency loudspeaker driver would be a rigid flat panel of infinite size with infinite space behind it. This would entirely prevent the rear sound waves from interfering (i.e., comb filter cancellations) with the sound waves from the front. An open baffle loudspeaker
7384-491: The effect of making the speaker cone transfer more of the electrical energy in the voice coil into the air; in effect the driver appears to have higher efficiency. Horns can help control dispersion at higher frequencies which is useful in some applications such as sound reinforcement. The mathematical theory of horn coupling is well developed and understood, though implementation is sometimes difficult. Properly designed horns for high frequencies are small (above say 3 kHz or so,
7488-477: The enclosure that are used to produce the bass response emanating from the port. These designs can be considered a mass-loaded transmission line design or a bass reflex design, as well as a quarter wave enclosure. Quarter wave resonators have seen a revival as commercial applications with the onset of neodymium drivers that enable this design to produce relatively low bass extensions within a relatively small speaker enclosure. The tapered quarter-wave pipe (TQWP)
7592-407: The final sound because the magnet's pull on the strings (called string capture ) can cause problems with intonation as well as damp the strings and reduce sustain . Other high-output pickups have more turns of wire to increase the voltage generated by the string's movement. However, this also increases the pickup's output resistance and impedance , which can affect high frequencies if the pickup
7696-410: The frequencies near the driver's free-air resonance frequency f s . Transmission lines tend to be larger than ported enclosures of approximately comparable performance, due to the size and length of the guide that is required (typically 1/4 the longest wavelength of interest). The design is often described as non-resonant, and some designs are sufficiently stuffed with absorbent material that there
7800-422: The frequency of peak impedance. In a closed-box loudspeaker, the air inside the box acts as a spring, returning the cone to the zero position in the absence of a signal. A significant increase in the effective volume of a closed-box loudspeaker can be achieved by a filling of fibrous material, typically fiberglass, bonded acetate fiber (BAF) or long-fiber wool. The effective volume increase can be as much as 40% and
7904-615: The frequency range is also possible. A uniform pattern is handy for smoothly arraying multiple enclosures. Both sides of a long-excursion high-power driver in a tapped horn enclosure are ported into the horn itself, with one path length long and the other short. These two paths combine in phase at the horn's mouth within the frequency range of interest. This design is especially effective at subwoofer frequencies and offers reductions in enclosure size along with more output. A perfect transmission line loudspeaker enclosure has an infinitely long line, stuffed with absorbent material such that all
8008-455: The front of the speaker driver. Because the forward- and rearward-generated sounds are out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced. As such, a loudspeaker cannot be used without installing it in a baffle of some type, such as a closed box, vented box, open baffle, or a wall or ceiling (infinite baffle). An enclosure also plays
8112-505: The lower frequencies, can be alleviated by the shape of the enclosure, such as by avoiding sharp corners on the front of the enclosure. A comprehensive study of the effect of cabinet configuration on the sound distribution pattern and overall response-frequency characteristics of loudspeakers was undertaken by Harry F. Olson . It involved a very wide number of different enclosure shapes, and it showed that curved loudspeaker baffles reduce some response deviations due to sound wave diffraction. It
8216-407: The lower this resonance frequency . The arrangement of parasitic resistances and capacitances in the guitar, cable, and amplifier input, combined with the inductive source impedance inherent in this type of transducer forms a resistively-damped second-order low-pass filter , producing a non-linearity effect not found in piezoelectric or optical transducers. Pickups are usually designed to feed
8320-426: The lowest output frequency. It is important to distinguish between genuine infinite-baffle topology and so-called infinite-baffle or IB enclosures which may not meet genuine infinite-baffle criteria. The distinction becomes important when interpreting textbook usage of the term (see Beranek (1954, p. 118) and Watkinson (2004) ). Acoustic suspension or air suspension is a variation of the closed-box enclosure, using
8424-518: The musical signal. Mains hum consists of a fundamental signal at a nominal 50 or 60 Hz, depending on local current frequency, and usually some harmonic content. To overcome this, the humbucking pickup was invented by Joseph Raymond "Ray" Butts (for Gretsch ), while Seth Lover also worked on one for Gibson . Who developed it first is a matter of some debate, but Butts was awarded the first patent ( U.S. patent 2,892,371 ) and Lover came next ( U.S. patent 2,896,491 ). A humbucking pickup
8528-464: The musician to send each pickup to its own audio chain (effects device, amplifier, mix console input). Teisco produced a guitar with a stereo option. Teisco divided the two sections in the upper three strings and the lower three strings for each individual output. The Gittler guitar was a limited production guitar with six pickups, one for each string. Gibson created the HD.6X Pro guitar that captures
8632-508: The notable exceptions of rail and lipstick tube pickups. Single polepieces are approximately centered on each string whereas dual polepieces such as the standard pickups on the Fender Jazz Bass and Precision Bass sit either side of each string. On most guitars, the strings are not fully parallel: they converge at the nut and diverge at the bridge. Thus, bridge, neck and middle pickups usually have different polepiece spacings on
8736-409: The output. Solid bodied guitars with only a piezo pickup are known as silent guitars , which are usually used for practicing by acoustic guitarists. Piezo pickups can also be built into electric guitar bridges for conversion of existing instruments. Most pickups for bowed string instruments, such as cello, violin, and double bass, are piezoelectric. These may be inlaid into the bridge , laid between
8840-422: The pipe acts as a horn while the top can be visualised as an extended compression chamber. The entire pipe can also be seen as a tapered transmission line in inverted form. (A traditional tapered transmission line, confusingly also sometimes referred to as a TQWP, has a smaller mouth area than throat area.) Its relatively low adoption in commercial speakers can mostly be attributed to the large resulting dimensions of
8944-514: The ports may generally be replaced by passive radiators if desired. An eighth-order bandpass box is another variation which also has a narrow frequency range. They are often used to achieve sound pressure levels in which case a bass tone of a specific frequency would be used versus anything musical. They are complicated to build and must be done quite precisely in order to perform nearly as intended. This design falls between acoustic suspension and bass reflex enclosures. It can be thought of as either
9048-565: The possible problems. Bothersome resonances can be reduced by increasing enclosure mass or rigidity, by increasing the damping of enclosure walls or wall/surface treatment combinations, by adding stiff cross bracing, or by adding internal absorption. Wharfedale , in some designs, reduced panel resonance by using two wooden cabinets (one inside the other) with the space between filled with sand . Home experimenters have even designed speakers built from concrete , granite and other exotic materials for similar reasons. Many diffraction problems, above
9152-550: The purposes of this type of analysis, each enclosure must be classified according to a specific topology. The designer must balance low bass extension, linear frequency response, efficiency, distortion, loudness and enclosure size, while simultaneously addressing issues higher in the audible frequency range such as diffraction from enclosure edges, the baffle step effect when wavelengths approach enclosure dimensions, crossovers, and driver blending. The loudspeaker driver's moving mass and compliance (slackness or reciprocal stiffness of
9256-426: The qualities of both. A combination of a microphone and a piezoelectric pickup typically produces better sound quality and less sensitivity to feedback, as compared to single transducers. However, this is not always the case. A less frequently used combination is a piezoelectric and a magnetic pickup. This combination can work well for a solid sound with dynamics and expression. Examples of a double system amplifier are
9360-530: The radiation from the front surface of the cone is directed into a ported chamber. This modifies the resonance of the driver. In its simplest form a compound enclosure has two chambers. The dividing wall between the chambers holds the driver; typically only one chamber is ported. If the enclosure on each side of the woofer has a port in it then the enclosure yields a 6th-order band-pass response. These are considerably harder to design and tend to be very sensitive to driver characteristics. As in other reflex enclosures,
9464-407: The radio itself (typically a small wooden box containing the radio's electronic circuits, so they were not usually housed in an enclosure. When paper cone loudspeaker drivers were introduced in the mid 1920s, radio cabinets began to be made larger to enclose both the electronics and the loudspeaker. These cabinets were made largely for the sake of appearance, with the loudspeaker simply mounted behind
9568-408: The rear of the speaker to the listener. They deliberately and successfully exploit Helmholtz resonance . As with sealed enclosures, they may be empty, lined, filled or (rarely) stuffed with damping materials. Port tuning frequency is a function of the cross-sectional area of the port and its length. This enclosure type is very common, and provides more sound pressure level near the tuning frequency than
9672-401: The rear radiation of the driver is fully absorbed, down to the lowest frequencies. Theoretically, the vent at the far end could be closed or open with no difference in performance. The density of and material used for the stuffing is critical, as too much stuffing will cause reflections due to back-pressure, whilst insufficient stuffing will allow sound to pass through to the vent. Stuffing often
9776-406: The same guitar. There are several standards on pickup sizes and string spacing between the poles. Spacing is measured either as a distance between 1st to 6th polepieces' centers (this is also called "E-to-E" spacing), or as a distance between adjacent polepieces' centers. Some high-output pickups employ very strong magnets, thus creating more flux and thereby more output. This can be detrimental to
9880-476: The same time. A variation on the transmission line enclosure uses a tapered tube, with the terminus (opening/port) having a smaller area than the throat. The tapering tube can be coiled for lower frequency driver enclosures to reduce the dimensions of the speaker system, resulting in a seashell like appearance. Bose uses similar patented technology on their Wave and Acoustic Waveguide music systems. Numerical simulations by Augspurger and King have helped refine
9984-424: The signal produced by the pickup in relation to high harmonics, resulting in a "fatter" tone. Humbucking pickups in the narrow form factor of a single coil, designed to replace single-coil pickups, have the narrower aperture resembling that of a single coil pickup. Some models of these single-coil-replacement humbuckers produce more authentic resemblances to classic single-coil tones than full-size humbucking pickups of
10088-409: The string to generate a magnetic field which is in alignment with that of the permanent magnet. When the string is plucked, the magnetic field around it moves up and down with the string. This moving magnetic field induces a voltage in the coil of the pickup as described by Faraday's law of induction . Output voltage depends on the instrument and playing style and which string(s) are played and where on
10192-464: The string, but for example, a Samick TV Twenty guitar played on the bridge measured 16 mV RMS (200 mV peak) for one string and 128 mV RMS (850 mV peak) for a chord. The pickup is connected with a patch cable to an amplifier , which amplifies the signal to a sufficient magnitude of power to drive a loudspeaker (which might require tens of volts). A pickup can also be connected to recording equipment via
10296-436: The suspension) determines the driver's resonance frequency ( F s ). In combination with the damping properties of the system (both mechanical and electrical) all these factors affect the low-frequency response of sealed-box systems. The response of closed-box loudspeaker systems has been extensively studied by Small and Benson, amongst many others. Output falls below the system's resonance frequency ( F c ), defined as
10400-527: The term infinite-baffle loudspeaker can fairly be applied to any loudspeaker that behaves (or closely approximates) in all respects as if the drive unit is mounted in a genuine infinite baffle. The term is often and erroneously used of sealed enclosures which cannot exhibit infinite-baffle behavior unless their internal volume is much greater than the Vas Thiele/Small of the drive unit AND the front baffle dimensions are ideally several wavelengths of
10504-429: The theory and practical design of these systems. A quarter wave resonator is a transmission line tuned to form a standing quarter wave at a frequency somewhat below the driver's resonance frequency F s . When properly designed, a port that is of much smaller diameter than the main pipe located at the end of the pipe then produces the driver's backward radiation in phase with the speaker driver itself; greatly adding to
10608-408: The theory developed by researchers such as Thiele, Benson, Small and Keele, who had systematically applied electrical filter theory to the acoustic behavior of loudspeakers in enclosures. In particular Thiele and Small became very well known for their work. While ported loudspeakers had been produced for many years before computer modeling, achieving optimum performance was challenging, as it
10712-430: The trademarks CoEntrant, Unity or Synergy horn) is a manifold speaker design; it uses several different drivers mounted on the horn at stepped distances from the horn's apex, where the high frequency driver is placed. Depending on implementation, this design offers an improvement in transient response as each of the drivers is aligned in phase and time and exits the same horn mouth. A more uniform radiation pattern throughout
10816-399: Was discovered later that careful placement of a speaker on a sharp-edged baffle can reduce diffraction-caused response problems. Sometimes the differences in phase response at frequencies shared by different drivers can be addressed by adjusting the vertical location of the smaller drivers (usually backwards), or by leaning or stepping the front baffle, so that the wavefront from all drivers
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