Ringing out is a process in audio engineering technique used to prevent audio feedback between on-stage microphones and loudspeakers, and to maximize gain before feedback. Depending on the acoustics of a venue, certain frequencies may be resonant and thus will be more prone to feedback.
To ring out a room, a sound technician will raise the gain or fader controls on a mixing desk to induce an audio system to feedback. Once feedback occurs, the technician uses an equalizer, usually a graphic equalizer to reduce the gain at the frequency of the feedback. The frequency of the feedback can be identified using a spectrum analyzer. This is repeated until feedback is sufficiently reduced without compromising the quality of the sound.
Ringing out is particularly important for the stage monitor system. While the performer or musician is usually behind the main PA system, the monitors are so they can hear themselves. As such, a microphone is much more likely to feedback through the monitor loudspeakers than the main PA.
Ringing out can become quite complex when working with a large number of microphones and monitors. Indeed, with larger touring acts, one of the major advantages of using in-ear monitors is the minimal ringing out that needs to be done.
A subwoofer is a loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be (optimally) generated by a woofer. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-certified systems. Subwoofers are never used alone, as they are intended to augment the low-frequency range of loudspeakers that cover the higher frequency bands. While the term "subwoofer" technically only refers to the speaker driver, in common parlance, the term often refers to a subwoofer driver mounted in a speaker enclosure (cabinet), often with a built-in amplifier.
An audio power amplifier is an electronic amplifier that amplifies low-power electronic audio signals such as the signal from radio receiver or electric guitar pickup to a level that is high enough for driving loudspeakers or headphones. Audio power amplifiers are found in all manner of sound systems including sound reinforcement, public address and home audio systems and musical instrument amplifiers like guitar amplifiers. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.
Audio crossovers are a type of electronic filter circuitry used in a range of audio applications. They split up an audio signal into two or more frequency ranges, so that the signals can be sent to loudspeaker drivers that are designed to operate within different frequency ranges. Crossovers are often described as "two-way" or "three-way", which indicate, respectively, that the crossover splits a given signal into two frequency ranges or three frequency ranges. Crossovers are used in loudspeaker cabinets, power amplifiers in consumer electronics and pro audio and musical instrument amplifier products. For the latter two markets, crossovers are used in bass amplifiers, keyboard amplifiers, bass and keyboard speaker enclosures and sound reinforcement system equipment.
Audio feedback is a special kind of positive loop gain which occurs when a sound loop exists between an audio input and an audio output. 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 sound 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. For small PA systems the sound is readily recognized as a loud squeal or screech. The principles of audio feedback were first discovered by Danish scientist Søren Absalon Larsen, hence the name Larsen effect.
A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 Hz up to 1000 Hz. The name is from the onomatopoeic English word for a dog's bark, "woof". The most common design for a woofer is the electrodynamic driver, which typically uses a stiff paper cone, driven by a voice coil surrounded by a magnetic field.
In sound recording and reproduction, and sound reinforcement systems, a mixing console is an electronic device for combining sounds of many different audio signals. Inputs to the console include microphones being used by singers and for picking up acoustic instruments, signals from electric or electronic instruments, or recorded music. Depending on the type, a mixer is able to control analog or digital signals. The modified signals are summed to produce the combined output signals, which can then be broadcast, amplified through a sound reinforcement system or recorded.
Positive feedback is a process that occurs in a feedback loop which exacerbates the effects of a small disturbance. That is, the effects of a perturbation on a system include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A. In contrast, a system in which the results of a change act to reduce or counteract it has negative feedback. Both concepts play an important role in science and engineering, including biology, chemistry, and cybernetics.
An instrument amplifier is an electronic device that converts the often barely audible or purely electronic signal of a musical instrument into a larger electronic signal to feed to a loudspeaker. An instrument amplifier is used with musical instruments such as an electric guitar, an electric bass, electric organ, synthesizers and drum machine to convert the signal from the pickup or other sound source into an electronic signal that has enough power, due to being routed through a power amplifier, capable of driving one or more loudspeaker that can be heard by the performers and audience.
A DI unit is an electronic device typically used in recording studios and in sound reinforcement systems to connect a high-output impedance, line level, unbalanced output signal to a low-impedance, microphone level, balanced input, usually via an XLR connector and XLR cable. DIs are frequently used to connect an electric guitar or electric bass to a mixing console's microphone input jack. The DI performs level matching, balancing, and either active buffering or passive impedance matching/impedance bridging to minimize unwanted noise, distortion, and ground loops. DI units are typically metal boxes with input and output jacks and, for more expensive units, “ground lift” and attenuator switches.
A public address system is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound source or recorded sound or music. PA systems are used in any public venue that requires that an announcer, performer, etc. be sufficiently audible at a distance or over a large area. Typical applications include sports stadiums, public transportation vehicles and facilities, and live or recorded music venues and events. A PA system may include multiple microphones or other sound sources, a mixing console to combine and modify multiple sources, and multiple amplifiers and loudspeakers for louder volume or wider distribution.
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience. In many situations, a sound reinforcement system is also used to enhance or alter the sound of the sources on the stage, typically by using electronic effects, such as reverb, as opposed to simply amplifying the sources unaltered.
Powered speakers, also known as self-powered speakers and active speakers, are loudspeakers that have built-in amplifiers. Powered speakers are used in a range of settings, including in sound reinforcement systems, both for the main speakers facing the audience and the monitor speakers facing the performers; by DJs performing at dance events and raves; in private homes as part of hi-fi or home cinema audio systems and as computer speakers. They can be connected directly to a mixing console or other low-level audio signal source without the need for an external amplifier. Some active speakers designed for sound reinforcement system use have an onboard mixing console and microphone preamplifier, which enables microphones to be connected directly to the speaker.
Loudspeaker measurement is the practice of determining the behaviour of loudspeakers by measuring various aspects of performance. This measurement is especially important because loudspeakers, being transducers, have a higher level of distortion than other audio system components used in playback or sound reinforcement.
A bass amplifier or "bass amp" is a musical instrument electronic device that uses electrical power to make lower-pitched instruments such as the bass guitar or double bass loud enough to be heard by the performers and audience. Bass amps typically consist of a preamplifier, tone controls, a power amplifier and one or more loudspeakers ("drivers") in a cabinet.
Live sound mixing is the blending of multiple sound sources by an audio engineer using a mixing console or software. Sounds that are mixed include those from instruments and voices which are picked up by microphones and pre-recorded material, such as songs on CD or a digital audio player. Individual sources are typically equalised to adjust the bass and treble response and routed to effect processors to ultimately be amplified and reproduced via a loudspeaker system. The live sound engineer listens and balances the various audio sources in a way that best suits the needs of the event.
Audio signal flow is the path an audio signal takes from source to output. The concept of audio signal flow is closely related to the concept of audio gain staging; each component in the signal flow can be thought of as a gain stage.
A stage monitor system is a set of performer-facing loudspeakers called monitor speakers, stage monitors, floor monitors, wedges, or foldbacks on stage during live music performances in which a sound reinforcement system is used to amplify a performance for the audience. The monitor system allows musicians to hear themselves and fellow band members clearly.
Equalization is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in sound recording and reproduction but there are many other applications in electronics and telecommunications. The circuit or equipment used to achieve equalization is called an equalizer. These devices strengthen or weaken the energy of specific frequency bands or "frequency ranges".
In live sound mixing, gain before feedback (GBF) is a practical measure of how much a microphone can be amplified in a sound reinforcement system before causing audio feedback. In audiology, GBF is a measure of hearing aid performance. In both fields the amount of gain is measured in decibels at or just below the point at which the sound from the speaker driver re-enters the microphone and the system begins to ring or feed back. Potential acoustic gain (PAG) is a calculated figure representing gain that a system can support without feeding back.
A professional audio store is a retail business that sells, and in many cases rents, sound reinforcement system equipment and PA system components used in music concerts, live shows, dance parties and speaking events. This equipment typically includes microphones, power amplifiers, electronic effects units, speaker enclosures, monitor speakers, subwoofers and audio consoles (mixers). Some professional audio stores also sell sound recording equipment, DJ equipment, lighting equipment used in nightclubs and concerts and video equipment used in events, such as video projectors and screens. Some professional audio stores rent "backline" equipment used in rock and pop shows, such as stage pianos and bass amplifiers. While professional audio stores typically focus on selling new merchandise, some stores also sell used equipment, which is often the equipment that the company has previously rented out for shows and events.
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