Clipping is a form of waveform distortion that occurs when an amplifier is overdriven, which happens through attempts to increase the voltage or current beyond its threshold of power. waveformogg|right|a sine square and sawtooth wave at 440 hz]] Waveform means the shape and form of a signal such as a Wave moving in a solid liquid or gaseous A distortion is the alteration of the original shape (or other characteristic of an object image sound waveform or other form of information or representation Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal.
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Overview of clipping
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 will be amplified no further. As the signal simply "cuts" or "clips" at the maximum capacity of the amplifier, the signal is said to be "clipping". The extra signal which is beyond the capability of the amplifier is simply cut off, resulting in a distorted waveform.
Many electric guitar players will intentionally overdrive their guitar amplifiers to cause clipping in order to get a desired sound (see guitar distortion). An electric guitar is a type of Guitar that uses pickups to convert the vibration of its steel-cored strings into an electrical current which is made louder A guitarist is a Musician who plays the Guitar. Guitarists may perform solo pieces or play with ensembles and bands of a wide variety of genres A guitar amplifier is an Electronic amplifier designed for use with an electric or electronic Musical instrument, such as an Electric guitar. A distortion is the alteration of the original shape (or other characteristic of an object image sound waveform or other form of information or representation
All amplifiers have voltage and current limits. Some amplifiers will use creative techniques to increase these limits or decrease them as needed. If an amplifier needs to output 20 V, but is limited to +10 V to -10 V, then the amplifier will output +10 V. It is best not to speak of a power limit outside of specific applications where the amplifier has an output impedance nearly equal to the load. For instance, a modern solid state amplifier may achieve maximum power output into a load that is ten times smaller than it can thermally handle over a long period of time.
Effects of clipping
In power amplifiers, the signal from an amplifier operating in clipping has two characteristics that could damage a connected loudspeaker:
- Because the clipped waveform has more area underneath it than the smaller unclipped waveform, the amplifier produces more power. For the Marty Friedman album see Loudspeaker (album A loudspeaker, speaker, or speaker system is an electroacoustical Electric power is defined as the rate at which Electrical energy is transferred by an Electric circuit. This extra power can cause damage to any part of the loudspeaker, including the woofer, tweeter, or crossover, via overheating or overexcursion. A tweeter is a Loudspeaker designed to produce high frequencies typically from around 2000 Hertz to 20000 hertz (20000 Hz generally considered to be the upper Audio crossovers are a class of Electronic filters designed specifically for use in audio applications especially Hi-fi.
- In the frequency domain, clipping produces strong harmonics in the high-frequency range. Frequency domain is a term used to describe the analysis of Mathematical functions or signals with respect to frequency In Acoustics and Telecommunication, the harmonic of a Wave is a component Frequency of the signal that is an Integer Extra high-frequency weighting of a signal is more likely to damage a tweeter than a signal that was not clipped. However most loudspeakers are designed to handle signals with abundant high frequencies, like cymbal crashes, which have a greater high-pitch frequency weighting than amplifier clipping could produce. Cymbals are a modern percussion instrument Cymbals consist of thin normally round plates of various Cymbal alloys; see Cymbal making for a discussion of their Therefore damage attributable to this characteristic is rare.
Other effects of clipping include:
- When applied to a musical signal, the clipping may prevent a note from decaying in a normal amount of time. This can cause rapidly played notes to blend together.
- Music which is clipped experiences amplitude compression, whereby all notes begin to sound equally loud because loud notes are being clipped to the same output level as softer notes.
Digital clipping
In digital signal processing, clipping occurs when the signal is restricted by the range of a chosen representation. Saturation arithmetic is a version of Arithmetic in which all operations such as addition and multiplication are limited to a fixed range between a minimum and maximum value Digital signal processing ( DSP) is concerned with the representation of the signals by a sequence of numbers or symbols and the processing of these signals For example in a system using 16-bit signed integers, 32767 is the largest positive value that can be represented, and if during processing the amplitude of the signal is doubled, sample values of 32000 should become 64000, but instead they are truncated to the maximum, 32767. Signed-digit representation of numbers indicates that digits can be prefixed with a &minus (minus sign to indicate that they are negative In Signal processing, sampling is the reduction of a Continuous signal to a Discrete signal. Clipping is preferable to the alternative in digital systems — wrapping — which occurs if the digital hardware is allowed to "overflow", ignoring the most significant bits of the magnitude, and sometimes even the sign of the sample value, resulting in gross distortion of the signal. The term arithmetic overflow or simply overflow has the following meanings In Computing, the most significant bit ( msb) is the Bit position in a binary number having the greatest value
Avoiding clipping
As seen on the oscilloscope, the wave resulting from the clipping is not a full sine wave. To avoid this, the overall level of a mix can be lowered, or a limiter can be used to dynamically bring the levels of the loud parts down (for example, bass and snare drums). In Electronics, a limiter is a circuit that allows signals below a specified input power to pass unaffected while attenuating the peaks of stronger signals that exceed this input A bass drum is a large Drum that produces a note of low definite or indefinite pitch. The snare drum is a Drum with strands of snares made of curled metal wire metal cable plastic cable or gut cords stretched across the a drumhead typically
It is not simple to eliminate all clipping, as filtering can align various frequencies in such a way as to create excessive peak outputs. A high-pass filter is one type of filter that can do this. A high-pass filter is a filter that passes high frequencies well but attenuates (reduces the amplitude of frequencies lower than the Cutoff frequency 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 speaker's ratings. They will then set the amplifier up with low gain, so that the amplifier does not overpower the speaker in the long run.
Repairing a clipped signal
It is impossible to restore a clipped signal to its original state because part of the original signal was lost. 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 plausible replacement for the clipped part of the signal.
There are several methods of which partial restoration can be achieved. Once the clipped portion is known, one can attempt partial recovery. One such method is interpolation or extrapolation of known samples. In the mathematical subfield of Numerical analysis, interpolation is a method of constructing new data points within the range of a Discrete set of In Mathematics, extrapolation is the process of constructing new data points outside a Discrete set of known data points While this approximation is rarely close to the original, the subjective quality may be improved.
Other methods may also be used. One of the methods in CuteStudio Declip, for example, works by copying the signal directly from one stereo channel to another, as it may be the case that only one channel is clipped.
Several software solutions of varying results and methods exist to counteract this problem: Sony Sound Forge, Adobe Audition, Nero Wave Editor, and a plugin in the Audacity LADSPA package come with clip restoration software. Sony Sound Forge, formerly known as Sonic Foundry Sound Forge, is a digital Audio editing and creation suite aimed at the professional as well as the Adobe Audition (formerly Cool Edit Pro) is a Digital audio editor Computer program from Adobe Systems featuring both a multitrack Audacity is a Digital audio editor application Audacity is Cross-platform, using the WxWidgets software library to provide a similar Graphical There is also a Nyquist plugin called Clipfix for Audacity.
Sources of clipping
In analogue audio equipment, there are three general causes of clipping:
- An integrated circuit or discrete solid state amplifier cannot give an output voltage larger than the voltage it is powered by (commonly a 24- or 30-volt spread for operational amplifiers used in line level equipment). An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside
- If the power supply capacitor is no longer able to keep the voltage "flat" due to a massive current draw, the positive and negative voltage supply of the amplifier will fluctuate resulting in sort of a clipped signal (AC line frequency harmonics). Power supply is a reference to a source of Electrical power. A device or system that supplies Electrical or other types of Energy to an output load
- A vacuum tube can only move a limited number of electrons in an amount of time, dependent on its size, temperature, and metals. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J
- A transformer (most commonly used between stages in tube equipment) will clip when its ferromagnetic core becomes electromagnetically saturated. Ferromagnetism is the basic mechanism by which certain materials (such as Iron) form Permanent magnets and/or exhibit strong interactions with Magnets it
- While less common, an amplifier can limit the current output for a variety of reasons both intentional or not. The result of this form of clipping may not create a flat top to the Voltage wavefrom, but rather a flat top to the current waveform.
- Certain signal processing elements can produce a unique form of phase-inverted clipping when the input signal exceeds the common-mode input range of an opamp. The result is that the voltage waveform clips, but in the wrong direction. This form of clipping should be limited to DIY electronics.
Some audiophiles believe that the clipping behavior of vacuum tubes is superior to that of transistors, in that vacuum tubes clip more gradually than transistors, resulting in harmonic distortion that is generally less objectionable. An audiophile, from Latin audio "I hear" and Greek philos "loving" is an audio reproduction enthusiast who typically listens This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals
Length clipping
The term clipping may also refer to the shortening of voice snippets due to failures in voice activity detection equipment. Voice activity detection (also known as speech activity detection or more simply speech detection is an algorithm used in Speech processing wherein the presence or absence It is unrelated to amplifier saturation.
See also
The phrase loudness war (or loudness race) refers to the Music industry 's tendency to record produce and broadcast music at progressively increasing levels of Tube sound (or valve sound) is the characteristic sound associated with a Vacuum tube -based Audio amplifiers Some Audiophiles In Electronics, a clipper is a device designed to prevent the output of a circuit from exceeding a predetermined voltage level without distorting the remaining part of the Dynamic range compression, also called DRC (often seen in DVD player settings or simply compression, is a process that reduces the Dynamic range ofDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic