1.
Positive feedback
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Positive feedback is a process that occurs in a feedback loop in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn more of A. In contrast, a system in which the results of an act to reduce or counteract it has negative feedback. Both concepts play an important role in science and engineering, including biology, chemistry, mathematically, positive feedback is defined as a positive loop gain around a closed loop of cause and effect. That is, positive feedback is in phase with the input, Positive feedback tends to cause system instability. When the loop gain is positive and above 1, there will typically be exponential growth, increasing oscillations, system parameters will typically accelerate towards extreme values, which may damage or destroy the system, or may end with the system latched into a new stable state. Positive feedback may be controlled by signals in the system being filtered, damped, or limited, Positive feedback is used in digital electronics to force voltages away from intermediate voltages into 0 and 1 states. On the other hand, thermal runaway is a positive feedback that can destroy semiconductor junctions, Positive feedback in chemical reactions can increase the rate of reactions, and in some cases can lead to explosions. Positive feedback in mechanical design causes tipping-point, or over-centre, mechanisms to snap into position, for example in switches, out of control, it can cause bridges to collapse. Positive feedback in systems can cause boom-then-bust cycles. Positive feedback enhances or amplifies an effect by it having an influence on the process gave rise to it. For example, when part of an output signal returns to the input, and is in phase with it. The feedback from the outcome to the process can be direct. Such systems can give rich qualitative behaviors, but whether the feedback is positive or negative in sign has an extremely important influence on the results. Positive feedback reinforces and negative feedback moderates the original process, Positive and negative in this sense refer to loop gains greater than or less than zero, and do not imply any value judgements as to the desirability of the outcomes or effects. A key feature of positive feedback is thus that small disturbances get bigger, when a change occurs in a system, positive feedback causes further change, in the same direction. A simple feedback loop is shown in the diagram, if the loop gain AB is positive, then a condition of positive or regenerative feedback exists. If the functions A and B are linear and AB is smaller than unity, then the system gain from the input to output is finite
2.
Microphone
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A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal. Several different types of microphone are in use, which employ different methods to convert the air pressure variations of a wave to an electrical signal. Microphones typically need to be connected to a preamplifier before the signal can be recorded or reproduced, in order to speak to larger groups of people, a need arose to increase the volume of the human voice. The earliest devices used to achieve this were acoustic megaphones, some of the first examples, from fifth century BC Greece, were theater masks with horn-shaped mouth openings that acoustically amplified the voice of actors in amphitheatres. In 1665, the English physicist Robert Hooke was the first to experiment with an other than air with the invention of the lovers telephone made of stretched wire with a cup attached at each end. German inventor Johann Philipp Reis designed an early sound transmitter that used a strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved with the transmitter design in Scottish-American Alexander Graham Bells telephone of 1876 – the diaphragm was attached to a conductive rod in an acid solution. These systems, however, gave a poor sound quality. The first microphone that enabled proper voice telephony was the carbon microphone and this was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, the carbon microphone is the direct prototype of todays microphones and was critical in the development of telephony, broadcasting and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886 and this microphone was employed at the first ever radio broadcast, a performance at the New York Metropolitan Opera House in 1910. In 1916, E. C. Wente of Western Electric developed the next breakthrough with the first condenser microphone, in 1923, the first practical moving coil microphone was built. The Marconi Skykes or magnetophon, developed by Captain H. J. Round, was the standard for BBC studios in London and this was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day. Also in 1923, the microphone was introduced, another electromagnetic type, believed to have been developed by Harry F. Olson. Over the years these microphones were developed by companies, most notably RCA that made large advancements in pattern control. With television and film technology booming there was demand for high fidelity microphones, electro-Voice responded with their Academy Award-winning shotgun microphone in 1963. During the second half of 20th century development advanced quickly with the Shure Brothers bringing out the SM58, digital was pioneered by Milab in 1999 with the DM-1001. The latest research developments include the use of optics, lasers and interferometers
3.
Pickup (music technology)
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The signal from a pickup can also be recorded directly, using a DI box or broadcast on the radio or television. Most electric guitars and electric basses use magnetic pickups, acoustic guitars, upright basses and fiddles often use a piezoelectric pickup. A magnetic pickup consists of a permanent magnet with a core of such as alnico or ferrite. The pickup is most often mounted on the body of the instrument, Magnetic pickups used with string basses can be attached to the bridge. The permanent magnet creates a field, the motion of the vibrating steel strings disturbs the field, changing magnetic flux. The pickup is then connected with a cable to an amplifier which amplifies the signal to a sufficient magnitude of power to drive a loudspeaker. A pickup can also be connected to recording equipment via a patch cable, there may also be an internal preamplifier device mounted in an acoustic guitar or in an external box. When a preamp is used in way, it is between the pickup and cable and can significantly reduce the equivalent impedance of the pickup coil. The output voltage of magnetic pickups varies between 100 mV rms to over 1 V rms for some of the higher output types, some high-output pickups achieve this by employing very strong magnets, thus creating more flux and thereby more output. This can be detrimental to the sound because the magnets pull on the strings can cause problems with intonation as well as damp the strings. Other high-output pickups have more turns of wire to increase the voltage generated by the strings movement, however, this also increases the pickups output resistance/impedance, which can affect high frequencies if the pickup 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 and 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, the inductive source impedance inherent in this type of transducer makes it less linear than other forms of pickups, such as piezo-electric or optical. The tonal quality produced by this nonlinearity is, however, subject to taste, the external load usually consists of resistance and capacitance between the hot lead and shield in the guitar cable. The electric cable also has a capacitance, which can be a significant portion of the overall system capacitance and this arrangement of passive components forms a resistively-damped second-order low-pass filter. Single coil pickups act like an antenna and are prone to pick up mains hum along with the musical signal. Mains hum consists of a signal at a nominal 50 or 60 Hz, depending on local alternating current frequency. The changing magnetic flux caused by the mains current links with the windings of the pickup, the pickups also are sensitive to the electromagnetic field from nearby cathode ray tubes in video monitors or televisions
4.
Audio power amplifier
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This includes both amplifiers used in home audio systems and musical instrument amplifiers like guitar amplifiers. It is the electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers. The inputs can also be any number of sources like record players, CD players, digital audio players. Most audio power amplifiers require these low-level inputs, which are line level, the audio amplifier was invented in 1909 by Lee De Forest when he invented the triode vacuum tube. The triode was a three terminal device with a grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio, early audio power amplifiers were based on vacuum tubes and some of these achieved notably high audio quality. Audio power amplifiers based on transistors became practical with the availability of inexpensive transistors in the late 1960s. Since the 1970s, most modern audio amplifiers are based on solid state devices, transistor-based amplifiers are lighter in weight, more reliable and require less maintenance than tube amplifiers. In the 2010s, there are still audio enthusiasts, musicians, audio engineers and music producers who prefer tube-based amplifiers, key design parameters for audio power amplifiers are frequency response, gain, noise, and distortion. These are interdependent, increasing gain often leads to increases in noise. While negative feedback reduces the gain, it also reduces distortion. Most audio amplifiers are linear amplifiers operating in class AB, until the 1970s, most amplifiers were tube amplifiers which used vacuum tubes. During the 1970s, tube amps were increasingly replaced with transistor-based amplifiers, which were lighter in weight, more reliable, one alternative to a separate preamp is to simply use passive volume and switching controls, sometimes integrated into a power amplifier to form an integrated amplifier. The final stage of amplification, after preamplifiers, is the output stage, for this reason, the design choices made around the output device or devices, such as the Class of operation of the output devices is often taken as the description of the whole power amplifier. For example, a Class B amplifier will probably have just the power output devices operating cut off for half of each cycle, while the other devices operate in Class A. In a transformerless output stage, the devices are essentially in series with the supply and output load. For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers and this led audiophiles to believe that tube sound or valve sound had an intrinsic quality due to the vacuum tube technology itself. In 1970, Matti Otala published a paper on the origin of a previously unobserved form of distortion, transient intermodulation distortion, TIM distortion was found to occur during very rapid increases in amplifier output voltage
5.
Loudspeaker
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A loudspeaker is an electroacoustic transducer, which converts an electrical audio signal into a corresponding sound. The most widely used type of speaker in the 2010s is the speaker, invented in 1925 by Edward W. Kellogg. The dynamic speaker operates on the basic principle as a dynamic microphone. Besides this most common method, there are several technologies that can be used to convert an electrical signal into sound. The sound source must be amplified or strengthened with a power amplifier before the signal is sent to the speaker. Speakers are typically housed in an enclosure or speaker cabinet which is often a rectangular or square box made of wood or sometimes plastic. The enclosures materials and design play an important role in the quality of the sound, where high fidelity reproduction of sound is required, multiple loudspeaker transducers are often mounted in the same enclosure, each reproducing a part of the audible frequency range. In this case the individual speakers are referred to as drivers, drivers made for reproducing high audio frequencies are called tweeters, those for middle frequencies are called mid-range drivers, and those for low frequencies are called woofers. Smaller loudspeakers are found in such as radios, televisions, portable audio players, computers. Larger loudspeaker systems are used for music, sound reinforcement in theatres and concerts, the term loudspeaker may refer to individual transducers or to complete speaker systems consisting of an enclosure including one or more drivers. To adequately reproduce a range of frequencies with even coverage, most loudspeaker systems employ more than one driver. Individual drivers are used to different frequency ranges. The drivers are named subwoofers, woofers, mid-range speakers, tweeters, the terms for different speaker drivers differ, depending on the application. In two-way systems there is no mid-range driver, so the task of reproducing the mid-range sounds falls upon the woofer and tweeter, home stereos use the designation tweeter for the high frequency driver, while professional concert systems may designate them as HF or highs. When multiple drivers are used in a system, a network, called a crossover. Loudspeaker driver of the type pictured are termed dynamic to distinguish them from earlier drivers, or speakers using piezoelectric or electrostatic systems, or any of several other sorts. Johann Philipp Reis installed an electric loudspeaker in his telephone in 1861, it was capable of reproducing clear tones, alexander Graham Bell patented his first electric loudspeaker as part of his telephone in 1876, which was followed in 1877 by an improved version from Ernst Siemens. In 1898, Horace Short patented a design for a loudspeaker driven by compressed air, he sold the rights to Charles Parsons
6.
Amplifier
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An amplifier, electronic amplifier or amp is an electronic device that can increase the power of a signal. An amplifier functions by taking power from a supply and controlling the output to match the input signal shape. In this sense, an amplifier modulates the output of the power supply based upon the properties of the input signal, an amplifier is effectively the opposite of an attenuator, while an amplifier provides gain, an attenuator provides loss. An amplifier can either be a piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are used in almost all electronic equipment. Amplifiers can be categorized in different ways, another is which quantity, voltage or current is being amplified, amplifiers can be divided into voltage amplifiers, current amplifiers, transconductance amplifiers, and transresistance amplifiers. A further distinction is whether the output is a linear or nonlinear representation of the input, amplifiers can also be categorized by their physical placement in the signal chain. The first practical device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when the transistor, invented in 1947, today most amplifiers use transistors, but vacuum tubes continue to be used in some applications. Before the invention of electronic amplifiers, mechanically coupled carbon microphones were used as amplifiers in telephone repeaters. After the turn of the century it was found that negative resistance mercury lamps could amplify, the first practical electronic device that could amplify was the Audion vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. The terms amplifier and amplification were first used for this new capability around 1915 when triodes became widespread, the amplifying vacuum tube revolutionized electrical technology, creating the new field of electronics, the technology of active electrical devices. It made possible long distance lines, public address systems, radio broadcasting, talking motion pictures, practical audio recording, radar, television. For 50 years virtually all electronic devices used vacuum tubes. Early tube amplifiers often had positive feedback, which could increase gain but also make the amplifier unstable, much of the mathematical theory of amplifiers was developed at Bell Telephone Laboratories during the 1920s to 1940s. Other advances in the theory of amplification were made by Harry Nyquist, the vacuum tube was the only amplifying device for 40 years, and dominated electronics until 1947, when the first transistor, the BJT, was invented. Today most amplifiers use transistors, but vacuum tubes are used in some high power applications such as radio transmitters. All amplifiers have gain, a factor that relates the magnitude of some property of the output signal to a property of the input signal
7.
Frequency
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Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as frequency, which emphasizes the contrast to spatial frequency. The period is the duration of time of one cycle in a repeating event, for example, if a newborn babys heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as vibrations, audio signals, radio waves. For cyclical processes, such as rotation, oscillations, or waves, in physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter ν or ν. For a simple motion, the relation between the frequency and the period T is given by f =1 T. The SI unit of frequency is the hertz, named after the German physicist Heinrich Hertz, a previous name for this unit was cycles per second. The SI unit for period is the second, a traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. As a matter of convenience, longer and slower waves, such as ocean surface waves, short and fast waves, like audio and radio, are usually described by their frequency instead of period. Spatial frequency is analogous to temporal frequency, but the axis is replaced by one or more spatial displacement axes. Y = sin = sin d θ d x = k Wavenumber, in the case of more than one spatial dimension, wavenumber is a vector quantity. For periodic waves in nondispersive media, frequency has a relationship to the wavelength. Even in dispersive media, the frequency f of a wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave. In the special case of electromagnetic waves moving through a vacuum, then v = c, where c is the speed of light in a vacuum, and this expression becomes, f = c λ. When waves from a monochrome source travel from one medium to another, their remains the same—only their wavelength. For example, if 71 events occur within 15 seconds the frequency is, the latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an error in the calculated frequency of Δf = 1/, or a fractional error of Δf / f = 1/ where Tm is the timing interval. This error decreases with frequency, so it is a problem at low frequencies where the number of counts N is small, an older method of measuring the frequency of rotating or vibrating objects is to use a stroboscope
8.
Public address system
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Simple PA systems are often used in small venues such as school auditoriums, churches, and small bars. Intercom systems, installed in buildings, have both speakers throughout a building, and microphones in many rooms allowing the occupants to respond to announcements. Sound reinforcement systems and PA systems may use some similar components, Sound reinforcement systems are for live music or performance, whereas PA systems are primarily for reproduction of speech. A short time later the Automatic Enunciator Company was established in Chicago in order to market the new device, in August 1912 a large outdoor installation was made at a water carnival held in Chicago by the Associated Yacht and Power Boat Clubs of America. Seventy-two loudspeakers were strung in pairs at intervals along the docks. The system was used to announce race reports and descriptions, carry a series of speeches about The Chicago Plan, and provide music between races. Four years later, in 1915, they built a dynamic loudspeaker with a 1-inch voice coil, a 3-inch corrugated diaphragm, the electromagnet created a flux field of approximately 11,000 G. Their first experiment used a carbon microphone, when the 12 V battery was connected to the system, they experienced one of the first examples of acoustic feedback. They then placed the loudspeaker on the roof, and claims say that the amplified human voice could be heard 1 mile away. Jensen and Pridham refined the system and connected a phonograph to the loudspeaker to be able to broadcast recorded music and this demonstration was official presentation of the working system, and approximately 100,000 people gathered to hear Christmas music and speeches with absolute distinctness. The first outside broadcast was one week later, again supervised by Jensen. Jensen oversaw the governor using the microphone while Pridham operated the loudspeaker, the following year, Jensen and Pridham applied for a patent for what they called their Sound Magnifying Phonograph. Over the next two years developed their first valve amplifier. In 1919 this was standardized as a 3-stage 25 watt amplifier, wilsons speech was part of his nationwide tour to promote the establishment of the League of Nations. It was held on September 9,1919 at City Stadium, as with the San Francisco installation, Jensen supervised the microphone and Pridham the loudspeakers. Wilson spoke into two large horns mounted on his platform which channelled his voice into the microphone, similar systems were used in the following years by Warren G. Harding and Franklin D. Roosevelt. By the early 1920s, Marconi had established a department dedicated to public address, in 1925, George V used such a system at the British Empire Exhibition, addressing 90,000 via six long-range loudspeakers. This public use of loudspeakers brought attention to the possibilities of such technology, the 1925 Royal Air Force Pageant at Hendon Aerodrome used a Marconi system to allow the announcer to address the crowds, as well as amplify the band
9.
Sound reinforcement system
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In both cases, these systems reinforce sound to make it louder or distribute it to a wider audience. Some audio engineers and others in the audio industry disagree over whether these audio systems should be called sound reinforcement systems or PA systems. Distinguishing between the two terms by technology and capability is common, while others distinguish by intended use, in some regions or markets, the distinction between the two terms is important, though the terms are considered interchangeable in many professional circles. These primary parts involve varying amounts of components to achieve the desired goal of reinforcing and clarifying the sound to the audience, performers. These signal inputs are plugged into the input jacks of a thick multicore cable, the snake then routes the signals of all of the inputs to either one or two mixing consoles. In these cases, at least two audio engineers are required, one to do the FOH Main mix and one to do the Monitor mix, once the signal arrives at a channel on the mixing console, this signal can be adjusted in many ways by the sound engineer. A signal can be equalized, compressed, or panned before being routed to an output bus. The signal may also be routed into an effects processor, such as a reverb effect, which outputs a wet version of the signal. Many electronic effects units are used in sound reinforcement systems, including digital delay, some concerts use pitch correction effects, which electronically correct any out-of-tune singing. A group of signals may be routed through a bus before being sent to the main bus to allow the engineer to control the levels of several related signals at once. A bus can often be processed just like an input channel. The mix of all the different signals and channels to the master faders on the console. Mixing consoles also have additional sends, also referred to as auxes or aux sends, on each channel so that a different mix can be created. One usage for aux sends is to create a mix of the vocal, another use of an aux send is to select varying amounts of certain channels, and then route these signals to an effects processor. A common example of the use of aux sends is to send all of the vocal signals from a rock band through a reverb effect. While reverb is usually added to vocals in the mix, it is not usually added to electric bass. The next step in the path generally depends on the size of the system in place. In smaller systems, the outputs are often sent to an additional equalizer, or directly to a power amplifier
10.
Audio engineer
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An audio engineer works on the recording, manipulating the record using equalization and electronic effects, mixing, reproduction, and reinforcement of sound. Audio engineers work on the. technical aspect of recording—the placing of microphones, pre-amp knobs, the physical recording of any project is done by an engineer. Many audio engineers creatively use technologies to produce sound for film, radio, television, music, electronic products and computer games. Audio engineers also set up, sound check and do live sound mixing using an audio console, research and development audio engineers invent new technologies, equipment and techniques, to enhance the process and art of audio engineering. They might also be referred to as acoustic engineers, audio engineers in research and development usually possess a bachelors degree, masters degree or higher qualification in acoustics, physics, computer science or another engineering discipline. They might work in consultancy, specializing in architectural acoustics. Alternatively they might work in companies, or other industries that need audio expertise. Some positions, such as faculty require a Doctor of Philosophy, in Germany a Toningenieur is an audio engineer who designs, builds and repairs audio systems. The listed subdisciplines are based on PACS coding used by the Acoustical Society of America with some revision, audio engineers develop algorithms to allow the electronic manipulation of audio signals. These can be processed at the heart of audio production such as reverberation. Alternatively, the algorithms might carry out echo cancellation on Skype, or identify, architectural acoustics is the science and engineering of achieving a good sound within a room. For audio engineers, architectural acoustics can be about achieving good speech intelligibility in a stadium or enhancing the quality of music in a theatre, architectural Acoustic design is usually done by acoustic consultants. Electroacoustics is concerned with the design of headphones, microphones, loudspeakers, sound reproduction systems, examples of electroacoustic design include portable electronic devices, sound systems in architectural acoustics, surround sound in movie theater and vehicle audio. Musical acoustics is concerned with researching and describing the science of music, in audio engineering, this includes the design of electronic instruments such as synthesizers, the human voice, computer analysis of audio, music therapy, and the perception and cognition of music. Psychoacoustics is the study of how humans respond to what they hear. At the heart of audio engineering are listeners who are the final arbitrator as to whether a design is successful. The production, computer processing and perception of speech is an important part of audio engineering, ensuring speech is transmitted intelligibly, efficiently and with high quality, in rooms, through public address systems and through mobile telephone systems are important areas of study. Producer, engineer, and mixer Phil Ek has described audio engineering as the aspect of recording—the placing of microphones, the turning of pre-amp knobs
11.
Cardioid
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A cardioid is a plane curve traced by a point on the perimeter of a circle that is rolling around a fixed circle of the same radius. It can also be defined as an epicycloid having a single cusp and it is also a type of sinusoidal spiral, and an inverse curve of the parabola with the focus as the center of inversion. The name was coined by de Castillon in 1741 but had been the subject of study decades beforehand, named for its heart-like form, it is shaped more like the outline of the cross section of a round apple without the stalk. Let be a the common radius of the two generating circles with midpoints, φ the rolling angle and the origin the starting point. One gets the parametric representation, x =2 a ⋅ cos φ, y =2 a ⋅ sin φ,0 ≤ φ <2 π and the representation in polar coordinates, r =2 a. Proof for the parametric representation The proof can be done easily using complex numbers, the rolling movement of the black circle on the blue one can be split into two rotations. In the complex plane a rotation around point 0 by an angle φ can be performed by the multiplication of a point z by e i φ. Hence the rotation Φ + around point a is, z ↦ a + e i φ, rotation Φ − around point − a is, z ↦ − a + e i φ. Herefrom one gets the parametric representation above, x = a =2 a ⋅ cos φ y = a =2 a ⋅ sin φ. For the cardiod as defined above the following hold, area A =6 π a 2, arc length L =16 a. The proofs of these statement use in cases the polar representation of the cardioid. For the cardioid r =2 a =4 a sin 2 φ2 one gets ρ = ⋯ =3224 a 2 sin 2 φ2 =83 a sin φ2. C1, chords through the cusp of the cardioid have the same length 4 a, C2, The midpoints of the chords through the cusp lie on the perimeter of the fixed generator circle. Proof for C1 The points P, p, Q, p are on a chord through the cusp. Hence | P Q | = r + r =2 a +2 a = ⋯ =4 a. proof for C2 For the proof the representation in the plane is used. A cardioid is the curve of a parabola with its focus at the center of inversion For the example shown in the picture the generator circles have radius a =12. Hence the cardioid has the polar representation r =1 − cos φ and its inverse curve r =11 − cos φ, remark, Not every inverse curve of a parabola is a cardioid. For example, if a parabola is inverted across a circle whose center lies at the vertex of the parabola, in the previous section if one inverts additionally the tangents of the parabola one gets a pencil of circles through the center of inversion
12.
Electric guitar
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The vibrations of the strings are sensed by a pickup, of which the most common type is the magnetic pickup, which uses the principle of direct electromagnetic induction. The signal generated by a guitar is too weak to drive a loudspeaker, so it is plugged into a guitar amplifier before being sent to a loudspeaker. The output of a guitar is an electric signal. Invented in 1931, the electric guitar was adopted by jazz guitarists. Early proponents of the guitar on record included Les Paul, Lonnie Johnson, Sister Rosetta Tharpe, T-Bone Walker. During the 1950s and 1960s, the guitar became the most important instrument in pop music. It has evolved into an instrument that is capable of a multitude of sounds and styles in genres ranging from pop and rock to country music, blues and jazz. It served as a component in the development of electric blues, rock and roll, rock music, heavy metal music. Electric guitar design and construction vary greatly in the shape of the body and the configuration of the neck, bridge, Guitars may have a fixed bridge or a spring-loaded hinged bridge that lets players bend the pitch of notes or chords up or down or perform vibrato effects. The sound of a guitar can be modified by new playing techniques such as string bending, tapping, hammering on, using audio feedback, in a small group, such as a power trio, one guitarist switches between both roles. In larger rock and metal bands, there is often a rhythm guitarist, many experiments at electrically amplifying the vibrations of a string instrument were made dating back to the early part of the 20th century. Patents from the 1910s show telephone transmitters were adapted and placed inside violins, hobbyists in the 1920s used carbon button microphones attached to the bridge, however, these detected vibration from the bridge on top of the instrument, resulting in a weak signal. With numerous people experimenting with electrical instruments in the 1920s and early 1930s, Electric guitars were originally designed by acoustic guitar makers and instrument manufacturers. Some of the earliest electric guitars adapted hollow-bodied acoustic instruments and used tungsten pickups, the first electrically amplified guitar was designed in 1931 by George Beauchamp, the general manager of the National Guitar Corporation, with Paul Barth, who was vice president. The maple body prototype for the one-piece cast aluminum frying pan was built by Harry Watson, commercial production began in late summer of 1932 by the Ro-Pat-In Corporation, in Los Angeles, a partnership of Beauchamp, Adolph Rickenbacker, and Paul Barth. In 1934, the company was renamed the Rickenbacker Electro Stringed Instrument Company, in that year Beauchamp applied for a United States patent for an Electrical Stringed Musical Instrument and the patent was issued in 1937. The Electro-Spanish Ken Roberts provided players a full 25 scale, with 17 frets free of the fretboard and it is estimated that fewer than 50 Electro-Spanish Ken Roberts were constructed between 1933 and 1937, fewer than 10 are known to survive today. The need for the guitar became apparent during the big band era as orchestras increased in size, particularly when acoustic guitars had to compete with large
13.
Rock music
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It has its roots in 1940s and 1950s rock and roll, itself heavily influenced by blues, rhythm and blues and country music. Rock music also drew strongly on a number of genres such as electric blues and folk. Musically, rock has centered on the guitar, usually as part of a rock group with electric bass guitar. Typically, rock is song-based music usually with a 4/4 time signature using a verse-chorus form, like pop music, lyrics often stress romantic love but also address a wide variety of other themes that are frequently social or political in emphasis. Punk was an influence into the 1980s on the subsequent development of subgenres, including new wave, post-punk. From the 1990s alternative rock began to rock music and break through into the mainstream in the form of grunge, Britpop. Similarly, 1970s punk culture spawned the visually distinctive goth and emo subcultures and this trio of instruments has often been complemented by the inclusion of other instruments, particularly keyboards such as the piano, Hammond organ and synthesizers. The basic rock instrumentation was adapted from the blues band instrumentation. A group of musicians performing rock music is termed a rock band or rock group, Rock music is traditionally built on a foundation of simple unsyncopated rhythms in a 4/4 meter, with a repetitive snare drum back beat on beats two and four. Melodies are often derived from older musical modes, including the Dorian and Mixolydian, harmonies range from the common triad to parallel fourths and fifths and dissonant harmonic progressions. Critics have stressed the eclecticism and stylistic diversity of rock, because of its complex history and tendency to borrow from other musical and cultural forms, it has been argued that it is impossible to bind rock music to a rigidly delineated musical definition. These themes were inherited from a variety of sources, including the Tin Pan Alley pop tradition, folk music and rhythm, as a result, it has been seen as articulating the concerns of this group in both style and lyrics. Christgau, writing in 1972, said in spite of some exceptions, rock and roll usually implies an identification of male sexuality, according to Simon Frith rock was something more than pop, something more than rock and roll. Rock musicians combined an emphasis on skill and technique with the concept of art as artistic expression, original. The foundations of music are in rock and roll, which originated in the United States during the late 1940s and early 1950s. Its immediate origins lay in a melding of various musical genres of the time, including rhythm and blues and gospel music, with country. In 1951, Cleveland, Ohio disc jockey Alan Freed began playing rhythm and blues music for a multi-racial audience, debate surrounds which record should be considered the first rock and roll record. Other artists with rock and roll hits included Chuck Berry, Bo Diddley, Fats Domino, Little Richard, Jerry Lee Lewis
14.
Guitar amplifier
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The input of modern guitar amplifiers is a 1/4 jack, which is fed a signal from an electro-magnetic pickup or a piezoelectric pickup using a patch cord, or a wireless transmitter. For electric guitar players, their choice of guitar amp and the settings they use on the amplifier are a key part of their signature tone or sound, some guitar players are longtime users of a specific amp brand or model. Many electric guitar players use external effects pedals to alter the sound of their tone before the signal reaches the guitar amp, such as the wah wah pedal and this article focuses on electric guitar amps. For information on amps for guitar, a lower-pitched, similar instrument. More expensive amplifiers typically have controls for other frequency ranges. Some guitar amplifiers have a graphic equalizer, which uses vertical fader controls which can control many frequency bands, the first amplifier stage is a preamplifier stage, which amplifies the guitar signal to a level that can drive the power stage. The power amplifier or output stage produces a current signal to drive a loudspeaker to produce sound that the guitarist. Amplifiers may use vacuum tubes, solid-state devices, or both, a wide range of speaker configurations are available in guitar cabinets, ranging from cabinets with a single speaker or multiple speakers. Guitar amplifiers have a range in price and quality. Music equipment companies import small, low-powered practice amplifiers for students, other companies produce expensive custom-made amplifiers for professional musicians, which can cost thousands of dollars. Most combo amplifiers have a handle, and many combo amplifiers. Control knobs are typically mounted on the front of the cabinet or chassis, though in some cases, the most basic amps only have a few knobs, which typically control volume, bass and treble. More expensive amps may have a number of knobs that control pre-amp volume, distortion or overdrive, volume, bass, mid and treble, some older amps have a knob that controls a vibrato effect. The 1/4 input jack is typically mounted on the front of the amplifier, in the simplest, least expensive amplifiers, this 1/4 jack is the only jack on the amplifier. Some amps have a 1/4 jack for connecting a pedal to turn the amps onboard overdrive and reverb on, the cone speaker, widely used in 2000s-era amp cabinets, was not offered for sale until 1925. The first amplifiers and speakers could only be powered with large batteries, when engineers developed the first AC mains-powered amplifiers, they were soon used to make musical instruments louder. Engineers invented the first loud, powerful amplifier and speaker systems for public address systems and these large PA systems and movie theatre sound systems were very large and very expensive, and so they could not be used by most touring musicians. During the late 1920s to mid-1930s, small portable PA systems, in 1928, the Stromberg-Voisinet firm was the first company to sell an electric stringed instrument and amplifier package
15.
Loudspeaker enclosure
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As such, a loudspeaker cannot be used without installing it in a cabinet of some type, or mounting it into a wall or ceiling. The enclosure also plays a role in managing vibration induced by the frame and moving airmass within the enclosure, as well as heat generated by driver voice coils. 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. Speaker enclosures are used in homes in stereo systems, home cinema systems, televisions, boom boxes, small speaker enclosures are used in car stereo systems. Speaker cabinets are key components of a number of applications, including sound reinforcement systems, movie theatre sound systems. Electric musical instruments invented in the 20th century, such as the guitar, electric bass and synthesizer, among others, are amplified using instrument amplifiers. Early on, radio loudspeakers consisted of horns, often separately from the radio itself. When paper cone loudspeaker drivers were introduced in the mid 1920s and these cabinets were made largely for the sake of appearance, with the loudspeaker simply mounted behind a round hole in the cabinet. It was observed that the enclosure had an effect on the bass response of the speaker. This results in a loss of bass and comb filtering, before the 1950s many manufacturers did not fully enclose their loudspeaker cabinets, the back of the cabinet was typically left open. This was done for reasons, not least because electronics could be placed inside. In some respects, the 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 sound waves from interfering with the sound waves from the front. An open baffle loudspeaker is an approximation of this, since the driver is mounted on a panel, a speaker driver mounted on a finite baffle will display a physical phenomenon known as interference which can result in a perceivable frequency-dependent sound attenuation. This phenomenon is particularly noticeable at low frequencies where the wavelengths are large enough that interference will affect the entire listening area, the box 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, wharfedale, in some designs, reduced panel resonance by using two wooden cabinets with the space between filled with sand. Home experimenters have even designed speakers built from concrete, granite, many diffraction problems, above the lower frequencies, can be alleviated by the shape of the enclosure, such as by avoiding sharp corners on the front of the enclosure. Research experiments from the 1930s by Dr. Harry F. Olson showed that curved loudspeaker baffles reduce some response deviations due to sound wave diffraction and it was discovered later that careful placement of a speaker on a sharp-edged baffle can reduce diffraction-caused response problems
16.
Distortion (music)
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Distortion and overdrive are forms of audio signal processing used to alter the sound of amplified electric musical instruments, usually by increasing their gain. Distortion is most commonly used with the guitar, but may also be used with other electric instruments. Guitarists playing electric blues originally obtained an overdriven sound by turning up their vacuum tube-powered guitar amplifiers to high volumes, the terms distortion and overdrive are often used interchangeably, where a distinction is made, distortion is used to denote a more extreme version of the effect than overdrive. Fuzz is a used to describe a particular form of distortion originally created by guitarists using faulty equipment. Distortion, overdrive, and fuzz can be produced by effects pedals, rackmounts, pre-amplifiers, power amplifiers, speakers and by digital amplifier modeling devices and these effects are used with electric guitars, electric basses, electronic keyboards, and more rarely as a special effect with vocals. The first guitar amplifiers were relatively low-fidelity, and would often produce distortion when their volume was increased beyond their design limit or if they sustained minor damage. Around 1945, Western-swing guitarist Junior Barnard began experimenting with a rudimentary humbucker pick-up, in early rock music, Goree Carters Rock Awhile featured an over-driven electric guitar style similar to that of Chuck Berry several years later, as well as Joe Hill Louis Boogie in the Park. In the early 1950s, pioneering rock guitarist Willie Johnson of Howlin Wolf′s band began deliberately increasing gain beyond its intended levels to produce distorted sounds. Guitar Slim also experimented with distorted overtones, which can be heard in his hit electric blues song The Things That I Used to Do, Chuck Berrys 1955 classic Maybellene features a guitar solo with warm overtones created by his small valve amplifier. Rock guitarists began intentionally doctoring amplifiers and speakers in order to emulate this form of distortion, according to other sources Burlisons amp had a partially broken loudspeaker cone. In the late 1950s, Guitarist Link Wray began intentionally manipulating his amplifiers vacuum tubes to create a noisy and dirty sound for his solos after a similarly accidental discovery. Wray also poked holes in his speaker cones with pencils to further distort his tone, used electronic echo chambers, the recent powerful and fat Gibson humbucker pickups, the resultant sound can be heard on his highly influential 1958 instrumental, Rumble and Rawhide. In 1961, Grady Martin scored a hit with a fuzzy tone caused by a faulty preamplifier that distorted his guitar playing on the Marty Robbins song Dont Worry, later that year Martin recorded an instrumental tune under his own name, using the same faulty preamp. The song, on the Decca label, was called The Fuzz, Martin is generally credited as the discoverer of the fuzz effect. Rhodes offered The Ventures a fuzzbox he had made, which used to record 2000 Pound Bee in 1962. The best-known early commercial distortion circuit was the Maestro FZ-1 Fuzz-Tone, manufactured by Gibson, in May 1965 Keith Richards used a Gibson Maestro FZ-1 Fuzz-Tone to record Satisfaction. The songs success boosted sales of the device, and all available stock sold out by the end of 1965. In music the different forms of linear distortion have specific names describing them, in the context of music, the most common source of distortion is clipping in amplifier circuits and is most commonly known as overdrive
17.
Heavy metal music
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Heavy metal is a genre of rock music that developed in the late 1960s and early 1970s, largely in the United Kingdom and the United States. Heavy metal lyrics and performance styles are associated with aggression. The first heavy metal such as Led Zeppelin, Black Sabbath. During the mid-1970s, Judas Priest helped spur the evolution by discarding much of its blues influence, Motörhead introduced a punk rock sensibility. Beginning in the late 1970s, bands in the new wave of British heavy metal such as Iron Maiden, before the end of the decade, heavy metal fans became known as metalheads or headbangers. During the 1980s, glam metal became popular with such as Mötley Crüe. Since the mid-1990s popular styles have further expanded the definition of the genre and these include groove metal and nu metal, the latter of which often incorporates elements of grunge and hip hop. Heavy metal is characterized by loud distorted guitars, emphatic rhythms, dense bass-and-drum sound. Metal subgenres variously emphasize, alter, or omit one or more of these attributes, the typical band lineup includes a drummer, a bassist, a rhythm guitarist, a lead guitarist, and a singer, who may or may not be an instrumentalist. Keyboard instruments are used to enhance the fullness of the sound. Deep Purples Jon Lord played an overdriven Hammond organ, in 1970, John Paul Jones used a Moog synthesizer on Led Zeppelin III, by the 1990s, in. almost every subgenre of heavy metal synthesizers were used. The electric guitar and the power that it projects through amplification has historically been the key element in heavy metal. The heavy metal guitar sound comes from a use of high volumes. Guitar solos are an element of the heavy metal code. That underscores the significance of the guitar to the genre, most heavy metal songs featur at least one guitar solo, which is a primary means through which the heavy metal performer expresses virtuosity. One exception is nu metal bands, which tend to omit guitar solos, with rhythm guitar parts, the heavy crunch sound in heavy metal. Palm muting the strings with the hand and using distortion. Palm muting creates a tighter, more sound and it emphasizes the low end
18.
Hardcore punk
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Hardcore punk is a punk rock music genre and subculture that originated in the late 1970s. It is generally faster, harder, and more aggressive than other forms of punk rock, New York punk had a harder-edged sound than its San Francisco counterpart, featuring anti-art expressions of masculine anger, energy and subversive humor. Hardcore punk generally disavows commercialism, the music industry and anything similar to the characteristics of mainstream rock. Hardcore sprouted underground scenes across the United States in the early 1980s, particularly in Washington, New York, New Jersey, and Boston—as well as in Australia, Canada and the United Kingdom. Hardcore has spawned the straight movement and its associated submovements, hardline. Hardcore was heavily involved with the rise of the independent record labels in the 1980s and it has also influenced various music genres that have experienced widespread commercial success, including alternative rock, thrash metal, emo and metalcore. While traditional hardcore has never experienced mainstream success, some of its early pioneers have garnered appreciation over time. In 2011, Rolling Stone writer David Fricke placed Greg Ginn of Black Flag 99th place in his 100 Greatest Guitarists list, although the music genre started in English-speaking western countries, notable hardcore scenes have existed in Italy, Brazil, Japan, Europe and the Middle East. The origin of the hardcore punk is uncertain. The Vancouver-based band D. O. A. may have helped to popularize the term with the title of their 1981 album, Hardcore 81. C. Hardcore historian Steven Blush said that the term hardcore is also a reference to the sense of being fed up with the existing punk, Blush also states that the term refers to an extreme, the absolute most Punk. One definition of the genre is a form of exceptionally harsh punk rock, like the Oi. subgenre of the UK, hardcore punk can be considered an internal music reaction. According to one writer, distressed by the artificiality of much post-punk, lacking the art-school grace of post-punk, hardcore punk favor low key visual aesthetic over extravagance and breaking with original punk rock song patterns. One of the important philosophies in the scene is authenticity. The pejorative term poseur is applied to those who associate with punk and adopt its stylistic attributes but are deemed not to share or understand the underlying values and philosophy. Joe Keithley, the vocalist of D. O. A. said in an interview, in the vein of earlier punk rock, most hardcore punk bands have followed the traditional singer/guitar/bass/drum format. The songwriting has more emphasis on rather than melody. Critic Steven Blush writes The Sex Pistols were still rocknroll. like the craziest version of Chuck Berry, Hardcore was a radical departure from that
19.
Grunge
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Grunge is a subgenre of alternative rock and a subculture that emerged during the mid-1980s in the Pacific Northwest U. S. state of Washington, particularly in Seattle and nearby towns. The early grunge movement revolved around Seattles independent record label Sub Pop, the success of these bands boosted the popularity of alternative rock and made grunge the most popular form of rock music at the time. Grunge was also an influence on subsequent genres such as post-grunge, Grunge fuses elements of punk rock and heavy metal, such as the distorted electric guitar used in both genres, although some bands performed with more emphasis on one or the other. Like these genres, grunge typically uses electric guitar, bass guitar, a drummer, Grunge also incorporates influences from indie rock bands such as Sonic Youth. Lyrics are typically angst-filled and introspective, often addressing themes such as alienation, apathy, concerns about confinement. A number of factors contributed to decline in prominence. During the mid-late 1990s, many grunge bands broke up or became less visible, the word grunge was used in print in prior to the use of the term in mainstream publications to refer to the Seattle music genre. Rock has always been about it, Theres primal grunge. distortion. and fuzz. especially on the underground, a reference to distorted sounds in rock in a general sense. Mark Arm, the vocalist for the Seattle band Green River—and later Mudhoney—is generally credited as being the first to use the term grunge to describe the Seattle genre of music. Arm first used the term in 1981, when he wrote a letter under his given name Mark McLaughlin to the Seattle zine Desperate Times, criticizing his own band Mr. Epp and the Calculations as Pure grunge. Sub Pop called Green Rivers 1986 EP Dry as a Bone ultra-loose GRUNGE that destroyed the morals of a generation, Everett True states that when Arm stated that the streets of Seattle paved with grunge, he was using the term disparagingly. In this use of the word grunge, Arm was using it as an adjective, Arm said years later, Obviously, I didnt make grunge up. I got it from someone else, the term was already being thrown around in Australia in the mid-80s to describe bands like King Snake Roost, The Scientists, Salamander Jim, and Beasts of Bourbon. Arm used grunge as a descriptive rather than a genre term. When grunge first developed, music journalists called it rock, due to the genres focus on impossibly. Evergreen State was a college which did not use grading. Bands from Portland, Oregon, such as the Wipers, also influenced the genres pioneers. Some bands associated with the genre, such as Soundgarden, Pearl Jam and Alice in Chains, have not been receptive to the label, preferring instead to be referred to as rock and roll bands
20.
Jimi Hendrix
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James Marshall Jimi Hendrix was an American rock guitarist, singer, and songwriter. The Rock and Roll Hall of Fame describes him as arguably the greatest instrumentalist in the history of rock music, born in Seattle, Washington, Hendrix began playing guitar at the age of 15. In 1961, he enlisted in the U. S. Army and trained as a paratrooper in the 101st Airborne Division, within months, Hendrix had earned three UK top ten hits with the Jimi Hendrix Experience, Hey Joe, Purple Haze, and The Wind Cries Mary. Hendrix was inspired musically by American rock and roll and electric blues and he favored overdriven amplifiers with high volume and gain, and was instrumental in utilizing the previously undesirable sounds caused by guitar amplifier feedback. He helped to popularize the use of a pedal in mainstream rock. Holly George-Warren of Rolling Stone commented, Hendrix pioneered the use of the instrument as a sound source. Hendrix was the recipient of several awards during his lifetime. In 1967, readers of Melody Maker voted him the Pop Musician of the Year, disc and Music Echo honored him with the World Top Musician of 1969 and in 1970, Guitar Player named him the Rock Guitarist of the Year. The Jimi Hendrix Experience was inducted into the Rock and Roll Hall of Fame in 1992, Jimi Hendrix was of African American descent. Both his mother Lucille and father Al were African Americans and his paternal grandmother, Zenora Nora Rose Moore, was African American and one-quarter Cherokee. On June 10,1919, Hendrix and Moore had a son they named James Allen Ross Hendrix, in 1941, Al met Lucille Jeter at a dance in Seattle, they married on March 31,1942. Al, who had been drafted by the U. S. Army to serve in World War II, Johnny Allen Hendrix was born on November 27,1942, in Seattle, he was the first of Lucilles five children. In 1946, Johnnys parents changed his name to James Marshall Hendrix, in honor of Al and he spent two months locked up without trial, and while in the stockade received a telegram announcing his sons birth. During Als three-year absence, Lucille struggled to raise their son, when Al was away, Hendrix was mostly cared for by family members and friends, especially Lucilles sister Delores Hall and her friend Dorothy Harding. Al received a discharge from the U. S. Army on September 1,1945. After returning from service, Al reunited with Lucille, but his inability to find steady work left the family impoverished and they both struggled with alcohol, and often fought when intoxicated. The violence sometimes drove Hendrix to withdraw and hide in a closet in their home and his relationship with his brother Leon was close but precarious, with Leon in and out of foster care, they lived with an almost constant threat of fraternal separation. In addition to Leon, Hendrix had three siblings, Joseph, born in 1949, Kathy in 1950, and Pamela,1951, all of whom Al and Lucille gave up to foster care
21.
Effects unit
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An effects unit or pedal is an electronic or digital device that alters how a musical instrument or other audio source sounds. In the 2010s, most effects use solid state electronics and/or computer chips, some vintage effects units from the 1930s to the 1970s and modern reissues of these effects use mechanical components as well or vacuum tubes. Musicians, audio engineers and record producers use effects units during live performances or in the studio, typically with electric guitar, electronic keyboard, while guitar effects are most frequently used with electric or electronic instruments, effects can also be used with acoustic instruments, drums and vocals. Rackmounted or audio console-integrated reverb effects are used with vocals in live sound and sound recording. Examples of common units include wah-wah pedals, fuzzboxes and reverb units. A stompbox or pedal is a metal or plastic box placed on the floor in front of the musician and connected to the instrument. Pedals are usually the least expensive format, a rackmount device mounts on a standard 19-inch equipment rack and usually contains several types of effects. Rackmount effects typically have buttons and/or knobs on the face of the chassis for controlling the effects, an effects unit is also called an effect box, effects device, effects processor or simply effects. In audio engineer parlance, a signal without effects is dry, the abbreviation F/X or FX is sometimes used. A pedal-style unit may be called a box, stompbox. When a musician has multiple effects in a rack mounted road case, Effects units are available in a variety of formats or form factors. Stompboxes are usually the smallest, least expensive, and most rugged effects units, rackmount devices are generally more expensive and offer a wider range of functions. An effects unit can consist of analog or digital circuitry or a combination of the two, during a live performance, the effect is plugged into the electrical signal path of the instrument. In the studio, the instrument or other sound-sources auxiliary output is patched into the effect, form factors are part of a studio or musicians outboard gear. Stompboxes are small plastic or metal chassis which usually lie on the floor or in a pedalboard to be operated by the users feet, pedals are often rectangle-shaped, but there are a range of other shapes. Typical simple stompboxes have a single footswitch, one to three potentiometers for controlling the effect, and a single LED that indicates if the effect is on, depending on the type of pedal, the potentiometers may control different parameters of the effect. For a chorus effect, for example, the knobs may control the depth, some pedals have two knobs stacked on top of each other, enabling the unit to provide two knobs per single knob space. An effects chain or signal chain is formed by connecting two or more stompboxes, effect chains are typically created between the guitar and the amp or between the preamplifier and the power amp
22.
Uni-Vibe
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The Uni-Vibe is a footpedal-operated phaser or phase shifter for creating chorus and vibrato simulations for electric organ or guitar. It was introduced in the 1960s by Shin-ei, and was intended to emulate the Doppler sound of a Leslie speaker. The effect, though associated with chorus, is in fact created through a staggered series of phasing filters. Unlike most other phaser pedals, this is achieved without the use of op-amps, the Shin-ei Uni-Vibe was also sold as a Univox product. Uni-Vibe is now a trademark of Dunlop Manufacturing, Inc. Notable users of the Uni-Vibe are Jimi Hendrix, Robin Trower, Trey Anastasio and David Gilmour of Pink Floyd
23.
Wah-wah pedal
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The pedal sweeps the peak response of a frequency filter up and down in frequency to create the sound, a spectral glide, also known as the wah effect. The wah-wah effect originated in the 1920s, with trumpet or trombone players finding they could produce an expressive crying tone by moving a mute in and this was later simulated with electronic circuitry for the electric guitar when the wah-wah pedal was invented. It is controlled by movement of the foot on a rocking pedal connected to a potentiometer. Wah-wah effects are used when a guitarist is soloing, or creating a wacka-wacka funk-styled rhythm for rhythm guitar playing, an envelope filter or envelope follower is often referred to as an auto-wah. The first wah pedal was created by Bradley J. Plunkett at Warwick Electronics Inc. /Thomas Organ Company in November 1966 and this pedal is the original prototype made from a transistorized MRB potentiometer bread-boarded circuit and the housing of a Vox Continental Organ volume pedal. The concept, however, was not new, country guitar virtuoso Chet Atkins had used a similar, self-designed device on his late 1950s recordings of Hot Toddy and Slinkey. A DeArmond Tone and Volume pedal was used in the early 1960s by Big Jim Sullivan, notably in some Krew Cats instrumental tracks, the creation of the modern wah pedal was actually an accident which stemmed from the redesign of the Vox Super Beatle guitar amplifier in 1966. In addition to distributing the British-made Vox amplifiers, the Thomas Organ Company also designed and manufactured much of the Vox equipment sold in the US, the US-made Vox product line development was headed by musician and bandleader Bill Page. Plunkett had lifted and bread-boarded a transistorized tone-circuit from the Thomas Organ to duplicate the Jennings 3-position circuit, after adjusting and testing the amplifier with an electronic oscillator and oscilloscope, Plunkett connected the output to the speaker and tested the circuit audibly. At that point, several engineers and technical consultants, including Bill Page and Del Casher, Page insisted on testing this bread-boarded circuit while he played his saxophone through an amplifier. After the installation, Page began playing his saxophone through the pedal and had asked Joe Banaron, CEO of Warwick Electronics Inc. /Thomas Organ Company, to listen to the effect. Banaron, being a fan of the big band style of music, was interested in marketing the wah pedal for wind instruments as suggested by Page rather than for the guitar as suggested by Casher. After the initial invention of the wah pedal, the pedal was then modified by Casher. The un-modified version of the Vox wah pedal was released to the public in February 1967 with an image of Clyde McCoy on the bottom of the pedal. Warwick Electronics Inc. assigned Lester L. Kushner, an engineer with the Thomas Organ Company, the patent application was submitted on February 24,1967 which included technical diagrams of the pedal being connected to a four-stringed guitar. Warwick Electronics Inc. was granted US patent 3530224 on September 22,1970, early versions of the Clyde McCoy featured an image of McCoy on the bottom panel, which soon gave way to only his signature. Thomas Organ then wanted the effect branded as their own for the American market, Jen, who had been responsible for the manufacture of Thomas Organ and Vox wah pedals, also made rebranded pedals for companies such as Fender and Gretsch and under their own Jen brand. When Thomas Organ moved production completely to Sepulveda, California and Chicago, some of the most famous electric guitarists of the day were keen to adopt the wah-wah pedal soon after its release
24.
Barkhausen stability criterion
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In electronics, the Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit will oscillate. It was put forth in 1921 by German physicist Heinrich Georg Barkhausen and it is widely used in the design of electronic oscillators, and also in the design of general negative feedback circuits such as op amps, to prevent them from oscillating. Barkhausens criterion applies to linear circuits with a feedback loop, therefore, it cannot be applied directly to one port negative resistance active elements like tunnel diode oscillators. The kernel of the criterion is that a complex pole pair must be placed on the axis of the complex frequency plane if steady state oscillations should take place. In the real world, it is impossible to balance on the imaginary axis so a steady-state oscillator must be a nonlinear circuit, barkhausens criterion is a necessary condition for oscillation but not a sufficient condition, some circuits satisfy the criterion but do not oscillate. Similarly, the Nyquist stability criterion also indicates instability but is silent about oscillation, apparently there is not a compact formulation of an oscillation criterion that is both necessary and sufficient. Barkhausens original formula for self-excitation, intended for determining the oscillation frequencies of the loop, involved an equality sign. However, stable oscillations only occur at frequencies for which equality holds
25.
Oscillation
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Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. The term vibration is used to describe mechanical oscillation. Familiar examples of oscillation include a swinging pendulum and alternating current power, the simplest mechanical oscillating system is a weight attached to a linear spring subject to only weight and tension. Such a system may be approximated on an air table or ice surface, the system is in an equilibrium state when the spring is static. If the system is displaced from the equilibrium, there is a net restoring force on the mass, tending to bring it back to equilibrium. However, in moving the back to the equilibrium position, it has acquired momentum which keeps it moving beyond that position. If a constant force such as gravity is added to the system, the time taken for an oscillation to occur is often referred to as the oscillatory period. All real-world oscillator systems are thermodynamically irreversible and this means there are dissipative processes such as friction or electrical resistance which continually convert some of the energy stored in the oscillator into heat in the environment. Thus, oscillations tend to decay with time there is some net source of energy into the system. The simplest description of this process can be illustrated by oscillation decay of the harmonic oscillator. In addition, a system may be subject to some external force. In this case the oscillation is said to be driven, some systems can be excited by energy transfer from the environment. This transfer typically occurs where systems are embedded in some fluid flow, at sufficiently large displacements, the stiffness of the wing dominates to provide the restoring force that enables an oscillation. The harmonic oscillator and the systems it models have a degree of freedom. More complicated systems have more degrees of freedom, for two masses and three springs. In such cases, the behavior of each variable influences that of the others and this leads to a coupling of the oscillations of the individual degrees of freedom. For example, two pendulum clocks mounted on a wall will tend to synchronise. This phenomenon was first observed by Christiaan Huygens in 1665, more special cases are the coupled oscillators where energy alternates between two forms of oscillation
26.
Integer
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An integer is a number that can be written without a fractional component. For example,21,4,0, and −2048 are integers, while 9.75, 5 1⁄2, the set of integers consists of zero, the positive natural numbers, also called whole numbers or counting numbers, and their additive inverses. This is often denoted by a boldface Z or blackboard bold Z standing for the German word Zahlen, ℤ is a subset of the sets of rational and real numbers and, like the natural numbers, is countably infinite. The integers form the smallest group and the smallest ring containing the natural numbers, in algebraic number theory, the integers are sometimes called rational integers to distinguish them from the more general algebraic integers. In fact, the integers are the integers that are also rational numbers. Like the natural numbers, Z is closed under the operations of addition and multiplication, that is, however, with the inclusion of the negative natural numbers, and, importantly,0, Z is also closed under subtraction. The integers form a ring which is the most basic one, in the following sense, for any unital ring. This universal property, namely to be an object in the category of rings. Z is not closed under division, since the quotient of two integers, need not be an integer, although the natural numbers are closed under exponentiation, the integers are not. The following lists some of the properties of addition and multiplication for any integers a, b and c. In the language of algebra, the first five properties listed above for addition say that Z under addition is an abelian group. As a group under addition, Z is a cyclic group, in fact, Z under addition is the only infinite cyclic group, in the sense that any infinite cyclic group is isomorphic to Z. The first four properties listed above for multiplication say that Z under multiplication is a commutative monoid. However, not every integer has an inverse, e. g. there is no integer x such that 2x =1, because the left hand side is even. This means that Z under multiplication is not a group, all the rules from the above property table, except for the last, taken together say that Z together with addition and multiplication is a commutative ring with unity. It is the prototype of all objects of algebraic structure. Only those equalities of expressions are true in Z for all values of variables, note that certain non-zero integers map to zero in certain rings. The lack of zero-divisors in the means that the commutative ring Z is an integral domain
27.
Degree (angle)
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A degree, usually denoted by °, is a measurement of a plane angle, defined so that a full rotation is 360 degrees. It is not an SI unit, as the SI unit of measure is the radian. Because a full rotation equals 2π radians, one degree is equivalent to π/180 radians, the original motivation for choosing the degree as a unit of rotations and angles is unknown. One theory states that it is related to the fact that 360 is approximately the number of days in a year. Ancient astronomers noticed that the sun, which follows through the path over the course of the year. Some ancient calendars, such as the Persian calendar, used 360 days for a year, the use of a calendar with 360 days may be related to the use of sexagesimal numbers. The earliest trigonometry, used by the Babylonian astronomers and their Greek successors, was based on chords of a circle, a chord of length equal to the radius made a natural base quantity. One sixtieth of this, using their standard sexagesimal divisions, was a degree, Aristarchus of Samos and Hipparchus seem to have been among the first Greek scientists to exploit Babylonian astronomical knowledge and techniques systematically. Timocharis, Aristarchus, Aristillus, Archimedes, and Hipparchus were the first Greeks known to divide the circle in 360 degrees of 60 arc minutes, eratosthenes used a simpler sexagesimal system dividing a circle into 60 parts. Furthermore, it is divisible by every number from 1 to 10 except 7 and this property has many useful applications, such as dividing the world into 24 time zones, each of which is nominally 15° of longitude, to correlate with the established 24-hour day convention. Finally, it may be the case more than one of these factors has come into play. For many practical purposes, a degree is a small enough angle that whole degrees provide sufficient precision. When this is not the case, as in astronomy or for geographic coordinates, degree measurements may be written using decimal degrees, with the symbol behind the decimals. Alternatively, the sexagesimal unit subdivisions can be used. One degree is divided into 60 minutes, and one minute into 60 seconds, use of degrees-minutes-seconds is also called DMS notation. These subdivisions, also called the arcminute and arcsecond, are represented by a single and double prime. For example,40. 1875° = 40° 11′ 15″, or, using quotation mark characters, additional precision can be provided using decimals for the arcseconds component. The older system of thirds, fourths, etc. which continues the sexagesimal unit subdivision, was used by al-Kashi and other ancient astronomers, but is rarely used today
28.
Clipping (audio)
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Clipping is a form of waveform distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to power in excess of its power rating. As the signal simply cuts or clips at the capacity of the amplifier. The extra signal which is beyond the capability of the amplifier is simply cut off, many electric guitar players intentionally overdrive their guitar amplifiers to cause clipping and other distortion in order to get a desired sound. Amplifiers have voltage, current and thermal limits, clipping may occur due to limitations in the power supply or the output stage. Some amplifiers are able to peak power without clipping for short durations before energy stored in the power supply is depleted or the amplifier begins to overheat. This extra power can cause damage to components, including the woofer, tweeter, or crossover. In the frequency domain, clipping produces harmonics at higher frequencies than the unclipped signal and this additional high frequency energy has the potential to damage a loudspeaker via overheating. As a result, many designers have incorporated circuits to prevent clipping. Such circuits compare the signal to the output signal to detect the presence of extra power caused by distortion. The simplest circuits act like a fast limiter, which engages after about one decibel of clipping is detected, a more complex circuit, called soft-clip, was used from the 1980s onward to limit the signal at the input stage. The soft-clip feature begins to engage prior to clipping, for starting at 10 dB below maximum output power. The output waveform retains a rounded characteristic even in the presence of an input signal as much as 10 dB higher than maximum specified. In digital signal processing, clipping occurs when the signal is restricted by the range of a chosen representation, as seen on the oscilloscope, the wave resulting from the clipping is not a full sine wave. To avoid this, the level of a mix can be lowered. It is not simple to eliminate all clipping, as filtering can align various frequencies in such a way as to create excessive peak outputs, the excessive peaks may become clipped even though the amplifier can play any single sine wave without clipping. As such, some audiophiles will use amplifiers that are rated for power outputs over twice the speakers ratings and it is preferable to avoid clipping, but if a recording has clipped, and cannot be re-recorded, repair is an option. The goal of repair is to make up a replacement for the clipped part of the signal
29.
Electronic oscillator
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An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current from a supply to an alternating current signal. They are widely used in electronic devices. Oscillators are often characterized by the frequency of their output signal and this term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator. An audio oscillator produces frequencies in the range, about 16 Hz to 20 kHz. An RF oscillator produces signals in the frequency range of about 100 kHz to 100 GHz. Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters, there are two main types of electronic oscillator, the linear or harmonic oscillator and the nonlinear or relaxation oscillator. The harmonic, or linear, oscillator produces a sinusoidal output, when the power supply to the amplifier is first switched on, electronic noise in the circuit provides a non-zero signal to get oscillations started. The noise travels around the loop and is amplified and filtered until very quickly it converges on a wave at a single frequency. RC oscillators are used to generate lower frequencies, for example in the audio range. Common types of RC oscillator circuits are the phase shift oscillator, in an LC oscillator circuit, the filter is a tuned circuit consisting of an inductor and capacitor connected together. Charge flows back and forth between the plates through the inductor, so the tuned circuit can store electrical energy oscillating at its resonant frequency. There are small losses in the circuit, but the amplifier compensates for those losses and supplies the power for the output signal. Typical LC oscillator circuits are the Hartley, Colpitts and Clapp circuits, in a crystal oscillator circuit the filter is a piezoelectric crystal. The crystal mechanically vibrates as a resonator, and its frequency of vibration determines the oscillation frequency, crystals have very high Q-factor and also better temperature stability than tuned circuits, so crystal oscillators have much better frequency stability than LC or RC oscillators. Crystal oscillators are the most common type of linear oscillator, used to stabilize the frequency of most radio transmitters, crystal oscillators often use the same circuits as LC oscillators, with the crystal replacing the tuned circuit, the Pierce oscillator circuit is also commonly used. Quartz crystals are generally limited to frequencies of 30 MHz or below, other types of resonator, dielectric resonators and surface acoustic wave devices, are used to control higher frequency oscillators, up into the microwave range. For example, SAW oscillators are used to generate the signal in cell phones
30.
Band-stop filter
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In signal processing, a band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels. It is the opposite of a band-pass filter, a notch filter is a band-stop filter with a narrow stopband. Other names include band limit filter, T-notch filter, band-elimination filter, typically, the width of the stopband is 1 to 2 decades. However, in the band, a notch filter has high. Anti-hum filter For countries using 60 Hz power lines, Low Freq,59 Hz Middle Freq 60 Hz High Freq,61 Hz This means that the filter passes all frequencies, except for the range of 59–61 Hz. This would be used to out the mains hum from the 60 Hz power line. For countries where power transmission is at 50 Hz, the filter would have a 49–51 Hz range, non-linearities of power amplifiers When measuring the non-linearities of power amplifiers, a very narrow notch filter can be very useful to avoid the carrier frequency. Use of the filter may ensure that the input power of a spectrum analyser used to detect spurious content will not be exceeded. Wave trap A notch filter, usually a simple LC circuit, is used to remove a specific interfering frequency and this is a technique used with radio receivers that are so close to a transmitter that it swamps all other signals. The wave trap is used to remove, or greatly reduce, optical notch filters rely on destructive interference
31.
Directivity
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In electromagnetics, directivity is a parameter of an antenna or optical system which measures the degree to which the radiation emitted is concentrated in a single direction. It measures the density the antenna radiates in the direction of its strongest emission. An antennas directivity is a component of its gain, the component is its efficiency. Directivity is an important measure because many antennas and optical systems are designed to radiate electromagnetic waves in a direction or over a narrow angle. Directivity is also defined for an antenna receiving electromagnetic waves, the directivity of an actual antenna can vary from 1.76 dBi for a short dipole, to as much as 50 dBi for a large dish antenna. The directivity, D, of an antenna is the value of its directive gain. Directive gain is represented as D and compares the radiant intensity U that an antenna creates in a particular direction against the value over all directions. Here θ and ϕ are the spherical coordinate angles, U is the radiation intensity, which is the power density per unit solid angle. Since there are 4π steradians on the surface of a sphere, the quantity P tot / represents the average power per unit solid angle. Directivity, then, is the directive gain value found among all possible solid angles. The word directivity is also used as a synonym for directive gain. This usage is readily understood, as the direction will be specified, later editions of the IEEE Dictionary specifically endorse this usage, nevertheless it has yet to be universally adopted. The beam solid angle, represented as Ω A, is defined as the angle which all power would flow through if the antenna radiation intensity were constant at its maximal value. If the beam angle is known, then directivity can be calculated as D =4 π Ω A. The beam solid angle can be approximated for antennas with one major lobe. The half-power beamwidth is simply the angle in which the intensity is at least half of the peak radiation intensity. In planar arrays, an approximation is D ≈32400 Θ1 d Θ2 d. The directivity is rarely expressed as the unitless number D but rather as a comparison to a reference antenna
32.
Energy conversion efficiency
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Energy conversion efficiency is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the output may be electric power, mechanical work, light. Energy conversion efficiency is not defined uniquely, but instead depends on the usefulness of the output, all or part of the heat produced from burning a fuel may become rejected waste heat if, for example, work is the desired output from a thermodynamic cycle. Energy converter is an example of an energy transformation, for example a light bulb falls into the categories energy converter. η = P o u t P i n Even though the definition includes the notion of usefulness, goal or mission oriented terms include effectiveness and efficacy. Generally, energy efficiency is a dimensionless number between 0 and 1.0, or 0% to 100%. Efficiencies may not exceed 100%, e. g. for a perpetual motion machine, however, other effectiveness measures that can exceed 1.0 are used for heat pumps and other devices that move heat rather than convert it. When talking about the efficiency of engines and power stations the convention should be stated, i. e. HHV or LCV. The two are separate but both must be stated, failure to do so causes endless confusion. g. for cogeneration, useful electric power and heat output per fuel energy consumed. Luminous efficiency, that portion of the electromagnetic radiation is usable for human vision. Using the LHV, a boiler can achieve a heating efficiency in excess of 100%. This is because the apparatus recovers part of the heat of vaporization, cited General The Intelligent Energy - Europe programme, the EUs tool for funding action towards a more energy intelligent Europe Does it make sense to switch to LED
33.
Foldback (sound engineering)
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Monitor speakers often include a single full-range loudspeaker and a horn in a cabinet. The sound at popular music and rock concerts is amplified with power amplifiers through a PA system or sound reinforcement system. With the exception of the smallest venues, such as coffeehouses, the main or front of house system is a PA system/sound reinforcement system which amplifies the onstage sounds for the main audience. The monitor system consists of monitor speakers aimed at the performers rather than the audience. Monitor systems have a range of sizes and complexity. In most mid- to large-size venues, there is a sound engineer. The monitor mix is different from the front of house mix. In the most sophisticated and expensive monitor set-ups, each onstage performer can ask the engineer for a separate monitor mix for separate monitors. For example, the singer can ask to hear mostly her/his voice in the monitor in front of her/him. Without a foldback system, the sound that on-stage performers would hear from front of house would be the reverberated reflections bouncing from the wall of the venue. The naturally reflected sound is delayed and distorted, which could, for example, in situations with poor or absent foldback mixes, vocalists may end up singing off-tune or out of time with the band. Each system consists of a board, sound processing equipment, power amplifiers. The two systems usually share microphones and direct inputs using a splitter microphone snake, there is disagreement over when to call these audio systems Sound Reinforcement systems or Public Address systems. This distinction is important in regions or markets, while in other regions or markets the terms are interchangeable. A large club may use several power amplifiers to provide 1000 to 2000 watts of power to the main speakers, an outdoor rock concert may use large racks of a number of power amplifiers to provide 10,000 or more watts. The monitor system reproduces the sounds of the performance and directs them towards the performers, to help them hear the instruments. The monitor system in a coffeehouse or singer-songwriter stage for a bar may be a single 100 watt powered monitor wedge. In the smallest PA systems, the performer may set their own main, the simplest monitor systems consist of a single monitor speaker for the lead vocalist which amplifies their singing voice, so that they can hear it clearly
34.
Resonance
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In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency. Frequencies at which the amplitude is a relative maximum are known as the systems resonant frequencies or resonance frequencies. At resonant frequencies, small periodic driving forces have the ability to produce large amplitude oscillations, Resonance occurs when a system is able to store and easily transfer energy between two or more different storage modes. However, there are some losses from cycle to cycle, called damping, when damping is small, the resonant frequency is approximately equal to the natural frequency of the system, which is a frequency of unforced vibrations. Some systems have multiple, distinct, resonant frequencies, resonant systems can be used to generate vibrations of a specific frequency, or pick out specific frequencies from a complex vibration containing many frequencies. Resonance occurs widely in nature, and is exploited in many manmade devices and it is the mechanism by which virtually all sine waves and vibrations are generated. Many sounds we hear, such as when hard objects of metal, glass, light and other short wavelength electromagnetic radiation is produced by resonance on an atomic scale, such as electrons in atoms. A familiar example is a swing, which acts as a pendulum. Pushing a person in a swing in time with the interval of the swing makes the swing go higher and higher. This is because the energy the swing absorbs is maximized when the match the swings natural oscillations. It may cause violent swaying motions and even catastrophic failure in improperly constructed structures including bridges, buildings, trains, avoiding resonance disasters is a major concern in every building, tower, and bridge construction project. As a countermeasure, shock mounts can be installed to absorb resonant frequencies, the Taipei 101 building relies on a 660-tonne pendulum —a tuned mass damper—to cancel resonance. Furthermore, the structure is designed to resonate at a frequency that does not typically occur, buildings in seismic zones are often constructed to take into account the oscillating frequencies of expected ground motion. Clocks keep time by mechanical resonance in a wheel, pendulum. The cadence of runners has been hypothesized to be energetically favorable due to resonance between the energy stored in the lower limb and the mass of the runner. Acoustic resonance is a branch of mechanical resonance that is concerned with the mechanical vibrations across the range of human hearing. Like mechanical resonance, acoustic resonance can result in failure of the object at resonance. The classic example of this is breaking a glass with sound at the precise resonant frequency of the glass
35.
Equalization (audio)
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Equalization is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in recording and reproduction but there are many other applications in electronics. The circuit or equipment used to achieve equalization is called an equalizer and these devices strengthen or weaken the energy of specific frequency bands or frequency ranges. In sound recording and reproduction, equalization is the commonly used to alter the frequency response of an audio system using linear filters. Most hi-fi equipment uses relatively simple filters to make bass and treble adjustments, graphic and parametric equalizers have much more flexibility in tailoring the frequency content of an audio signal. An equalizer is the circuit or equipment used to achieve equalization, since equalizers, adjust the amplitude of audio signals at particular frequencies, they are, in other words, frequency-specific volume knobs. The term EQ specifically refers to this variant of the term, stereos and basic guitar amplifiers typically have adjustable equalizers which boost or cut bass or treble frequencies. Mid- to high-priced guitar and bass amplifiers usually have more bands of frequency control, such as bass, mid-range and treble or bass, low-mid, high-mid, some amps have an additional knob for controlling very high frequencies. Broadcast and recording studios use sophisticated equalizers capable of more detailed adjustments. The most common equalizers in music production are parametric, semi-parametric, graphic, peak, graphic equalizers are often included in consumer audio equipment and software which plays music on home computers. Parametric equalizers require more expertise than graphic equalizers, and they can provide more specific compensation or alteration around a chosen frequency and this may be used in order to remove unwanted resonances or boost certain frequencies. An acoustic guitarist who finds that her instrument sounds too boomy may ask the engineer to reduce the low frequency range response. A guitarist who finds that the instrument sound in the PA has too much finger noise may ask the engineer to reduce the frequency range response. The concept of equalization was first applied in correcting the frequency response of telephone lines using passive networks, a plot of the systems net frequency response would be flat, as its response to all frequencies would literally be equal. Much later the concept was applied in engineering to adjust the frequency response in recording, reproduction. Audio amplifiers have long had filters or controls to modify their frequency response and these are most often in the form of variable bass and treble controls, and switches to apply low-cut or high-cut filters for elimination of low frequency rumble and high frequency hiss respectively. Graphic equalizers and other equipment developed for improving fidelity have since used by recording engineers to modify frequency responses for aesthetic reasons. Hence in the field of audio electronics the term equalization is now used to describe the application of such filters regardless of intent
36.
Blues
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Blues is a genre and musical form originated by African Americans in the Deep South of the United States around the end of the 19th century. The genre developed from roots in African musical traditions, African-American work songs, spirituals, Blues incorporated spirituals, work songs, field hollers, shouts, chants, and rhymed simple narrative ballads. Blue notes, usually thirds or fifths flattened in pitch, are also a part of the sound. Blues shuffles or walking bass reinforce the trance-like rhythm and form a repetitive effect known as the groove, Blues as a genre is also characterized by its lyrics, bass lines, and instrumentation. Early traditional blues verses consisted of a single line repeated four times, Early blues frequently took the form of a loose narrative, often relating the troubles experienced in African-American society. Many elements, such as the format and the use of blue notes. The origins of the blues are closely related to the religious music of the Afro-American community. The first appearance of the blues is often dated to after the ending of slavery and, later and it is associated with the newly acquired freedom of the former slaves. Chroniclers began to report about blues music at the dawn of the 20th century, the first publication of blues sheet music was in 1908. Blues has since evolved from unaccompanied vocal music and oral traditions of slaves into a variety of styles and subgenres. Blues subgenres include country blues, such as Delta blues and Piedmont blues, as well as urban blues styles such as Chicago blues, World War II marked the transition from acoustic to electric blues and the progressive opening of blues music to a wider audience, especially white listeners. In the 1960s and 1970s, a form called blues rock evolved. The term blues may have come from blue devils, meaning melancholy and sadness, the phrase blue devils may also have been derived from Britain in the 1600s, when the term referred to the intense visual hallucinations that can accompany severe alcohol withdrawal. As time went on, the phrase lost the reference to devils, by the 1800s in the United States, the term blues was associated with drinking alcohol, a meaning which survives in the phrase blue law, which prohibits the sale of alcohol on Sunday. Though the use of the phrase in African-American music may be older, it has been attested to in print since 1912, in lyrics the phrase is often used to describe a depressed mood. The lyrics of traditional blues verses probably often consisted of a single line repeated four times. Two of the first published songs, Dallas Blues and Saint Louis Blues, were 12-bar blues with the AAB lyric structure. Handy wrote that he adopted this convention to avoid the monotony of lines repeated three times, the lines are often sung following a pattern closer to rhythmic talk than to a melody
37.
Rock and roll
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While elements of rock and roll can be heard in blues records from the 1920s and in country records of the 1930s, the genre did not acquire its name until the 1950s. For the purpose of differentiation, this deals with the first definition. The beat is essentially a blues rhythm with an accentuated backbeat, classic rock and roll is usually played with one or two electric guitars, a double bass or string bass or an electric bass guitar, and a drum kit. Beyond simply a style, rock and roll, as seen in movies and on television, influenced lifestyles, fashion, attitudes. In addition, rock and roll may have contributed to the civil rights movement because both African-American and white American teens enjoyed the music and it went on to spawn various genres, often without the initially characteristic backbeat, that are now more commonly called simply rock music or rock. The term rock and roll now has at least two different meanings, both in common usage, the American Heritage Dictionary and the Merriam-Webster Dictionary both define rock and roll as synonymous with rock music. Encyclopædia Britannica, on the hand, regards it as the music that originated in the mid-1950s. In 1934, the song Rock and Roll by the Boswell Sisters appeared in the film Transatlantic Merry-Go-Round, in 1942, Billboard magazine columnist Maurie Orodenker started to use the term rock-and-roll to describe upbeat recordings such as Rock Me by Sister Rosetta Tharpe. By 1943, the Rock and Roll Inn in South Merchantville, in 1951, Cleveland, Ohio disc jockey Alan Freed began playing this music style while popularizing the phrase to describe it. The origins of rock and roll have been debated by commentators. The migration of former slaves and their descendants to major urban centers such as St. The immediate roots of rock and roll lay in the rhythm and blues, then called race music, particularly significant influences were jazz, blues, gospel, country, and folk. The 1940s saw the use of blaring horns, shouted lyrics. In the same period, particularly on the West Coast and in the Midwest, similarly, country boogie and Chicago electric blues supplied many of the elements that would be seen as characteristic of rock and roll. Rock and roll arrived at a time of technological change, soon after the development of the electric guitar, amplifier and microphone. It was the realization that relatively affluent white teenagers were listening to music that led to the development of what was to be defined as rock. Because the development of rock and roll was a process, no single record can be identified as unambiguously the first rock. Other artists with rock and roll hits included Chuck Berry, Bo Diddley, Little Richard, Jerry Lee Lewis
38.
Johnny "Guitar" Watson
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John Watson, Jr. known professionally as Johnny Guitar Watson, was an American blues, soul, and funk musician and singer-songwriter. A flamboyant showman and electric guitarist in the style of T-Bone Walker and his creative reinvention in the 1970s with disco and funk overtones, saw Watson have hits with Aint That a Bitch, I Need It and Superman Lover. His successful recording career spanned forty years, with his highest chart appearance being the 1977 song A Real Mother For Ya, Watson was born in Houston, Texas. His father John Sr. was a pianist, and taught his son the instrument, but young Watson was immediately attracted to the sound of the guitar, in particular the electric guitar as played by T-Bone Walker and Clarence Gatemouth Brown. His grandfather, a preacher, was also musical and my grandfather used to sing while hed play guitar in church, man, Watson reflected many years later. When Johnny was 11, his grandfather offered to him a guitar if, and only if. Watson agreed, but that was the first thing I did, a musical prodigy, Watson played with Texas bluesmen Albert Collins and Johnny Copeland. His parents separated in 1950, when he was 15 and his mother moved to Los Angeles, and took Watson with her. In his new city, Watson won several talent shows. This led to his employment, while still a teenager, with jump blues-style bands such as Chuck Higginss Mellotones and he worked as a vocalist, pianist, and guitarist. He quickly made a name for himself in the African-American juke joints of the West Coast and he was billed as Young John Watson until 1954. That year, he saw the Joan Crawford film Johnny Guitar, Watson affected a swaggering, yet humorous personality, indulging a taste for flashy clothes and wild showmanship on stage. His attacking style of playing, without a plectrum, resulted in him needing to change the strings on his guitar once or twice a show, because he stressified on them so much. Watsons ferocious Space Guitar single of 1954 pioneered guitar feedback and reverb, Watson would later influence a subsequent generation of guitarists. His song Gangster of Love was first released on Keen Records in 1957 and it did not appear in the charts at the time, but was later re-recorded and became a hit in 1978, becoming Watsons most famous song. He toured and recorded with his friend Larry Williams, as well as Little Richard, Don and Dewey, The Olympics, Johnny Otis and, in 1975 he is a guest performer on two tracks on the Frank Zappa album One Size Fits All. He also played with Sam Cooke, Herb Alpert and George Duke, but as the popularity of blues declined and the era of soul music dawned in the 1960s, Watson transformed himself from southern blues singer with pompadour into urban soul singer in a pimp hat. His albums Aint That a Bitch and Real Mother For Ya were landmark recordings of 1970s funk, Telephone Bill, from the 1980 album Love Jones, featured Watson rapping
39.
Link Wray
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Fred Lincoln Link Wray, Jr. was an American rock and roll guitarist, songwriter and vocalist who became popular in the late 1950s. Rolling Stone placed Wray at No.45 of the 100 greatest guitarists of all time, in 2013 he was a nominee for the Rock and Roll Hall of Fame. Though he began in music, his musical style went on to consist primarily of rock and roll, rockabilly. Wray was born on May 2,1929 in Dunn, North Carolina, to Fred Lincoln Wray, Sr. and his wife, three songs he performed were named for American Indian tribes, Shawnee, Apache, and Comanche. Apache was an instrumental composed by Jerry Lordan, it was originally a hit in the United Kingdom for The Shadows in 1960, Wray recorded a cover version 30 years later, when it was also associated with The Ventures and the Incredible Bongo Band. Wray served in the US Army during the Korean War, and contracted tuberculosis and his stay concluded with the removal of a lung, which doctors predicted would mean he would never be able to sing again. In 1958, Wrays first hit, Rumble, was banned in New York, the record was first released on Cadence Records as Cat #1347. Before, during and after his stints with major labels Epic and Swan, tiring of the corporate music machine, he began recording albums using a three-track studio he converted from an outbuilding on his brothers property that his father used to raise chickens. While living in the San Francisco Bay Area in the early 1970s and he subsequently formed a band initially featuring special guest Cipollina along with the rhythm section from Cipollinas band Copperhead, bassist Hutch Hutchinson, and drummer David Weber. They opened for the band Lighthouse at The Whisky a Go Go in Los Angeles from May 15–19,1974 and he later did numerous concerts and radio broadcasts in the Bay Area including KSAN and the Bill Graham venue Winterland Ballroom, with Les Lizama later replacing Hutchinson on bass. He toured and recorded two albums with retro-rockabilly artist Robert Gordon in the late 1970s, the 1980s to the present day saw a large number of reissues as well as new material. One member of his band in the 1980s, drummer Anton Fig, in 1994, he played on four songs of the album Chatterton by French rocker Alain Bashung. Wrays first three marriages—to Elizabeth Canady Wray, Katherine Tidwell Wray, and Sharon Wray—each ended in divorce, although Wray had eight children with his first three wives, he had little contact with any of them after relocating to Denmark in the early 1980s. He died of heart failure, aged 76, in 2005, survivors included his fourth wife, Olive Julie Povlsen Wray, and their son. He was buried in the crypt of the Christians Church, Copenhagen, jack Rose cited Wray as an influence, as did Iggy Pop and Neil Young. Jimmy Page says that Link Wray had a real rebel attitude, according to Rolling Stone, Pete Townshend of The Who once said, If it hadnt been for Link Wray and Rumble, I never would have picked up a guitar. The only people I ever really looked up to were Link Wray and Iggy Pop, Link Wray. are very special to me. On October 16,2013, the Rock and Roll Hall of Fame announced that Link Wray was a nominee for inclusion in 2014, Wray was a featured collaborator on Robert Gordons 1977 single Red Hot
40.
AllMusic
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AllMusic is an online music guide service website. It was launched in 1991 by All Media Guide which later became All Media Network, AllMusic was launched in 1991 by Michael Erlewine of All Media Guide. The aim was to discographic information on every artist whos made a record since Enrico Caruso gave the industry its first big boost and its first reference book was published the following year. When first released onto the Internet, AMG predated the World Wide Web and was first available as a Gopher site, the AMG consumer web properties AllMusic. com, AllMovie. com and AllGame. com were sold by Rovi in July 2013 to All Media Network, LLC. All Media Network, LLC. was formed by the founders of SideReel. com. The following are contributors to AllMusic, as of this date, All Media Network also produced the AllMusic guide series that includes the AllMusic Guide to Rock, the All Music Guide to Jazz and the All Music Guide to the Blues. Vladimir Bogdanov is the president of the series, in August 2007, PC Magazine included AllMusic in its Top 100 Classic Websites list. All Media Network AllGame AllMovie SideReel All Music Guide to the Blues All Music Guide to Jazz Stephen Thomas Erlewine Official website
41.
Richie Unterberger
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Richie Unterberger is an American author and journalist whose focus is popular music and travel writing. Having worked as a DJ at WXPN in Philadelphia, Unterberger started reviewing records for Op magazine in 1983, from 1985 to 1991, he was an editor for Option. Since 1993, he has been a contributor to allmusic. Unterberger contributes to local and national publications, including Mojo, Record Collector, Rolling Stone, Oxford American. He has written liner notes for dozens of CD reissues from labels like Rhino, Collectors Choice, unterbergers books draw extensively on first-hand interviews with musicians and their associates. Unterberger has given talks on music and popular culture at public libraries in San Francisco, Berkeley. He is also a speaker at area bookstores, including The Booksmith in the Haight Ashbury neighborhood of San Francisco and he has traveled to more than thirty countries and is an advocate of independent travel and alternative culture. His nephew, Andrew, formerly wrote for Stylusmagazine. com and he has been a staff writer or featured contributor on a number of music or sports blogs. His books include,1998, Unknown Legends of RocknRoll, profiles of 60 underappreciated cult rock artists of all styles and eras 1999, The Rough Guide to Music USA. Another look at underappreciated cult rock artists 2002, Turn, the first part of a history of folk rock 2003, Eight Miles High, Folk-Rocks Flight from Haight-Ashbury to Woodstock. // Eight Miles High // The Unreleased Beatles
42.
I Feel Fine
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I Feel Fine is a song written by John Lennon and released in 1964 by the Beatles as the A-side of their eighth British single. The song has one of the first uses of guitar feedback in popular music, Lennon wrote the guitar riff while in the studio recording Eight Days a Week. I wrote I Feel Fine around that riff going on in the background, I told them Id write a song specially for the riff. You go away and do that, knowing that wed almost finished the album Beatles for Sale, anyway, going into the studio one morning, I said to Ringo, Ive written this song but its lousy. But we tried it, complete with riff, and it sounded like an A-side, paul McCartney said the drums on I Feel Fine were inspired by Ray Charless Whatd I Say. At the time of the recording, the Beatles, having mastered the studio basics, had begun to explore new sources of inspiration in noises previously eliminated as mistakes. I Feel Fine marks one of the earliest examples of the use of feedback as an effect in popular music. Artists such as the Kinks and the Who had already used feedback live, I Feel Fine is written in 4/4 time with drummer Ringo Starrs R&B-influenced beat featured through most of the song except for the bridge, which has a more conventional backbeat. The melody, unusually, uses a third and a minor seventh. Just before the coda, Lennons intro riff is repeated with a sound by George Harrison on electric guitar. The song ends with a fadeout of the G major portion of the opening riff repeated several times, I Feel Fine starts with a single, percussive feedback note produced by plucking the A string on Lennons guitar. This was the first use of feedback on a rock record, according to McCartney, John had a semi-acoustic Gibson guitar. It had a pickup on it so it could be amplified and we were just about to walk away to listen to a take when John leaned his guitar against the amp. I can still see him doing it. it went, Nnnnnnwahhhhh, George Martin was there so we said, Can we have that on the record. Well, I suppose we could, we could edit it on the front and it was a found object, an accident caused by leaning the guitar against the amp. Although it sounded much like an electric guitar, Lennon actually played the riff on an acoustic-electric guitar. Later, Lennon was very proud of this sonic experimentation, in one of his last interviews, he said, I defy anybody to find a record—unless its some old blues record in 1922—that uses feedback that way. Two different music videos directed by Joe McGrath were filmed on 23 November 1965, both feature various bits of gym equipment
