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Acoustic Feedback
Audio feedback (also known as acoustic feedback, simply as feedback) is a positive feedback situation which may occur when an acoustic path exists between an audio input (for example, a microphone or guitar pickup) and an audio output (for example, a loudspeaker). In this example, a signal received by the microphone is amplified and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again. The frequency of the resulting howl is determined by resonance frequencies in the microphone, amplifier, and loudspeaker, the acoustics of the room, the directional pick-up and emission patterns of the microphone and loudspeaker, and the distance between them. The principles of audio feedback were first discovered by Danish scientist Søren Absalon Larsen, hence it is also known as the Larsen effect. Feedback is almost always considered undesirable when it occurs with a singe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feedback Loop Block Diagram
Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled carefully when applied to feedback systems: History Self-regulating mechanisms have existed since antiquity, and the idea of feedback had started to enter economic theory in Britain by the 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name. The first ever known artificial feedback device was a float valve, for maintaining water at a constant level, invented in 270 BC in Alexandria, Egypt. This device illustrated the principle of feedback: a low water level opens the valve, the rising water then provides feedback into the system, closing the valve when the required level is reached. This then reoccurs in a circular fashion as the water level fluctuates. Centrifugal governors were u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guitar Amplifier
A guitar amplifier (or amp) is an electronic device or system that strengthens the electrical signal from a pickup on an electric guitar, bass guitar, or acoustic guitar so that it can produce sound through one or more loudspeakers, which are typically housed in a wooden cabinet. A guitar amplifier may be a standalone wood or metal cabinet that contains only the power amplifier (and preamplifier) circuits, requiring the use of a separate speaker cabinet–or it may be a "combo" amplifier, which contains both the amplifier and one or more speakers in a wooden cabinet. There is a wide range of sizes and power ratings for guitar amplifiers, from small, lightweight "practice amplifiers" with a single 6-inch speaker and a 10-watt amp to heavy combo amps with four 10-inch or four 12-inch speakers and a 100-watt amplifier, which are loud enough to use in a nightclub or bar performance. Guitar amplifiers can also modify an instrument's tone by emphasizing or de-emphasizing certain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clipping (audio)
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 output power in excess of its power rating. In the frequency domain, clipping produces strong harmonics in the high-frequency range (as the clipped waveform comes closer to a squarewave). The extra high-frequency weighting of the signal could make tweeter damage more likely than if the signal was not clipped. In some cases, the distortion associated with clipping is unwanted, and is visible on an oscilloscope even if it is inaudible. However, clipping is often used in music for artistic effect, especially in heavier genres. Overview When an amplifier is pushed to create a signal with more power than its power supply can produce, it will amplify the signal only up to its maximum capacity, at which point the signal can be amplified no further. As the signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gain (electronics)
In electronics, gain is a measure of the ability of a two-port electrical network, circuit (often an amplifier) to increase the Electric power, power or amplitude of a Signal (electrical engineering), signal from the input to the output port by adding energy converted from some power supply to the signal. It is usually defined as the mean ratio of the Signalling (telecommunication), signal amplitude or power at the output port (circuit theory), port to the amplitude or power at the input port. It is often expressed using the logarithmic decibel (dB) units ("dB gain"). A gain greater than one (greater than zero dB), that is amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one. The term ''gain'' alone is ambiguous, and can refer to the ratio of output to input voltage (''voltage gain''), Electric current, current (''current gain'') or electric power (''power gain''). In the field of audio and general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree (angle)
A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol), is a measurement of a plane (mathematics), plane angle in which one Turn (geometry), full rotation is 360 degrees. It is not an SI unit—the SI unit of angular measure is the radian—but it is mentioned in the SI Brochure, SI brochure as an Non-SI units mentioned in the SI, accepted unit. Because a full rotation equals 2 radians, one degree is equivalent to radians. History 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 ecliptic path over the course of the year, seems to advance in its path by approximately one degree each day. Some ancient calendars, such as the Iranian calendar, Persian calendar and the Babylonian calendar, used 360 days for a year. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the language of mathematics, the set of integers is often denoted by the boldface or blackboard bold \mathbb. The set of natural numbers \mathbb is a subset of \mathbb, which in turn is a subset of the set of all rational numbers \mathbb, itself a subset of the real numbers \mathbb. Like the natural numbers, \mathbb is countably infinite. An integer may be regarded as a real number that can be written without a fractional component. For example, 21, 4, 0, and −2048 are integers, while 9.75, , and are not. The integers form the smallest group and the smallest ring containing the natural numbers. In algebraic number theory, the integers are sometimes qualified as rational integers to distinguish them from the more general algebraic integers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscillation
Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum and alternating current. Oscillations can be used in physics to approximate complex interactions, such as those between atoms. Oscillations occur not only in mechanical systems but also in dynamic systems in virtually every area of science: for example the beating of the human heart (for circulation), business cycles in economics, predator–prey population cycles in ecology, geothermal geysers in geology, vibration of strings in guitar and other string instruments, periodic firing of nerve cells in the brain, and the periodic swelling of Cepheid variable stars in astronomy. The term ''vibration'' is precisely used to describe a mechanical oscillation. Oscillation, especially rapid oscillation, may be an undesirable phenomenon in proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barkhausen Stability Criterion
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 (1881–1956). 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. Limitations Barkhausen's criterion applies to linear circuits with a feedback loop. It cannot be applied directly to active elements with negative resistance like tunnel diode oscillators. The kernel of the criterion is that a complex pole pair must be placed on the imaginary 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 in practice a steady-state oscillator is a non-linear circuit: * It needs to have positive feedback. * The loop gain is at unity (, \beta A, = 1\,). Cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guitar Solo
A guitar solo is a melodic passage, instrumental section, or entire piece of music, pre-written (or improvised) to be played on a classical guitar, electric guitar or an acoustic guitar. In 20th and 21st century traditional music and popular music such as blues, swing, jazz, jazz fusion, rock and metal, guitar solos often contain virtuoso techniques and varying degrees of improvisation. Guitar solos on classical guitar, which are typically written in musical notation, are also used in classical music forms such as chamber music and concertos. Guitar solos range from unaccompanied works for a single guitar to compositions with accompaniment from a few other instruments or a large ensemble. The accompaniment musicians for a guitar solo can range from a small ensemble such as a jazz quartet or a rock band, to a large ensemble such as an orchestra or big band. Unaccompanied acoustic guitar music is found in folk and classical music dating as far back as the instrument's fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jimi Hendrix
James Marshall "Jimi" Hendrix (born Johnny Allen Hendrix; November 27, 1942September 18, 1970) was an American guitarist, singer and songwriter. Although his mainstream career spanned only four years, he is widely regarded as one of the most influential electric guitarists in the history of popular music, and one of the most celebrated musicians of the 20th century. 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 US Army, but was discharged the following year. Soon afterward, he moved to Clarksville then Nashville, Tennessee, and began playing gigs on the chitlin' circuit, earning a place in the Isley Brothers' backing band and later with Little Richard, with whom he continued to work through mid-1965. He then played with Curtis Knight and the Squires before moving to England in late 1966 after bassis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grunge
Grunge (sometimes referred to as the Seattle sound) is an alternative rock genre and subculture that emerged during the in the American Pacific Northwest state of Washington, particularly in Seattle and nearby towns. Grunge fuses elements of punk rock and heavy metal, but without punk's structure and speed. The genre featured the distorted electric guitar sound 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, drums and vocals. Grunge also incorporates influences from indie rock bands such as Sonic Youth. Lyrics are typically angst-filled and introspective, often addressing themes such as social alienation, self-doubt, abuse, neglect, betrayal, social and emotional isolation, addiction, psychological trauma and a desire for freedom. The early grunge movement revolved around Seattle's independent record label Sub Pop and the region's underground music scene. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardcore Punk
Hardcore punk (also known as simply hardcore) 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. Its roots can be traced to earlier punk scenes in San Francisco and Punk rock in California, Southern California which arose as a reaction against the still predominant History of the hippie movement, hippie cultural climate of the time. It was also inspired by Washington D.C. and New York City, New York punk rock and early proto-punk. Hardcore punk generally disavows commercialism, the established music industry and "anything similar to the characteristics of Rock music, mainstream rock" and often addresses social and political topics with "confrontational, politically-charged lyrics." Hardcore sprouted underground scenes across the United States in the early 1980s, particularly in Los Angeles, San Francisco, Washington, D.C. hardcore, Washington, D.C., Boston, and New York h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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