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Foldback (sound engineering)
Encyclopedia
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
s known as monitor speaker cabinets on stage
Stage (theatre)
In theatre or performance arts, the stage is a designated space for the performance productions. The stage serves as a space for actors or performers and a focal point for the members of the audience...
during live music
Live Music
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performances. The sound is amplified with power amplifiers or a public address
Public address
A public address system is an electronic amplification system with a mixer, amplifier and loudspeakers, used to reinforce a sound source, e.g., a person giving a speech, a DJ playing prerecorded music, and distributing the sound throughout a venue or building.Simple PA systems are often used in...
system and the speakers are aimed at the on-stage performers rather than the audience
Audience
An audience is a group of people who participate in a show or encounter a work of art, literature , theatre, music or academics in any medium...
. This sound signal may be produced on the same mixing console
Mixing console
In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...
as the main mix for the audience (called the 'front of house
Front of House
Front of house is primarily a theatrical term, referring to the portion of the building that is open to the public. In theatre and live music venues, it typically refers to the auditorium and foyer, as opposed to the stage and backstage areas...
' mix), or there may be a separate sound engineer and mixing console on or beside the stage creating a separate mix for the monitor system.
Without a foldback system, the sound that onstage performers would hear from front of house would be the reverberated reflections bouncing from the rear wall of the venue. The naturally reflected sound is delayed and distorted, which would cause the singer to sing out of time with the band. A separate mixed signal is often routed to the foldback speakers, because the performers may also need to hear a mix without electronic effects such as echo
Echo (phenomenon)
In audio signal processing and acoustics, an echo is a reflection of sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single...
and reverb (this is called a "dry mix") to stay in time and in tune
Pitch (music)
Pitch is an auditory perceptual property that allows the ordering of sounds on a frequency-related scale.Pitches are compared as "higher" and "lower" in the sense associated with musical melodies,...
with each other. In situations with poor or absent foldback mixes, vocalists may end up singing off-tune or out of time with the band.
Role
For live sound reproduction during popular music concerts there are typically two complete PA systems: the "main" system and the "monitor" system. Each system consists of a mixing board, sound processing equipment, amplifiers, and speakers. 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 (SR) systemsSound reinforcement system
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience...
or Public Address (PA) system
Public address
A public address system is an electronic amplification system with a mixer, amplifier and loudspeakers, used to reinforce a sound source, e.g., a person giving a speech, a DJ playing prerecorded music, and distributing the sound throughout a venue or building.Simple PA systems are often used in...
s. This distinction is important in some regions or markets, while in other regions or markets the terms are interchangeable.
The "main" system (also known as "Front of House
Front of House
Front of house is primarily a theatrical term, referring to the portion of the building that is open to the public. In theatre and live music venues, it typically refers to the auditorium and foyer, as opposed to the stage and backstage areas...
", commonly abbreviated FOH), which provides the amplified sound for the audience, will typically use a number of powerful amplifiers driving a range of large, heavy-duty loudspeakers including low-frequency speaker cabinets called subwoofer
Subwoofer
A subwoofer is a woofer, or a complete loudspeaker, which is dedicated to the reproduction of low-pitched audio frequencies known as the "bass". The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below...
s, full-range speaker cabinets, and high-range horns. A coffeehouse or small bar where singers perform while accompanying themselves on acoustic guitar may have a relatively small, low-powered PA system for the "mains", such as a pair of two 200 watt powered speakers. 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 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 onstage performers (typically using wedge-shaped monitor speaker cabinets), to help them hear the instruments and vocals. In British English, the monitor system is referred to as the "fold back". The monitor system in a coffeehouse or singer-songwriter stage for a small bar may be a single 100 watt powered monitor wedge. In the smallest PA systems, the performer may set their own "main" and "monitor" sound levels with a simple powered mixing board. 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.
In a large club where rock or metal bands play, the monitor system may use racks of power amplifiers and four to six monitor speakers to provide 500 to 1000 watts of power to the "monitor" speakers. In most clubs and larger venues, sound engineers and technicians control the mixing boards for the "main" and "monitor" systems, adjusting the tone, levels, and overall volume of the performance.
Larger clubs and concert venues typically use a more complex type of monitor system which has two or three different monitor mixes for the different performers. Each monitor mix contains a blend of different vocal and instruments, and an amplified speaker is placed in front of the performer. This way the lead vocalist can have a mix which forefronts their vocals, the backup singers can have a mix which emphasizes their backup vocals, and the rhythm section
Rhythm section
A rhythm section is a collection of musicians who make up a section of instruments which provides the accompaniment section of the music, giving the music its rhythmic texture and pulse, also serving as a rhythmic reference for the rest of the band...
members can have a mix which emphasizes the bass and drums. At an outdoor rock concert, there may be several thousand watts of power going to a complex monitor system that includes wedge-shaped cabinets for vocalists and larger cabinets called "sidefill" cabinets to help the musicians to hear their playing.
Without a foldback system, the sound that onstage performers would hear from front of house would be the reverberated reflections bouncing from the rear wall of the venue. The naturally reflected sound is delayed and distorted, which would cause the singer to sing out of time with the band. A separate mixed signal is often routed to the foldback speakers, because the performers may also need to hear a mix without electronic effects such as echo
Echo (phenomenon)
In audio signal processing and acoustics, an echo is a reflection of sound, arriving at the listener some time after the direct sound. Typical examples are the echo produced by the bottom of a well, by a building, or by the walls of an enclosed room and an empty room. A true echo is a single...
and reverb (this is called a "dry mix") to stay in time and in tune
Pitch (music)
Pitch is an auditory perceptual property that allows the ordering of sounds on a frequency-related scale.Pitches are compared as "higher" and "lower" in the sense associated with musical melodies,...
with each other. In situations with poor or absent foldback mixes, vocalists may end up singing off-tune or out of time with the band.
History
In the early 1960s, many professional live sound engineers were wrestling with the problem of giving the musical artist enough of their own voice to stay in tune during a performance. The employment of loudspeakers used for foldback may have been developed independently by sound engineers in different cities who were trying to resolve this problem during the 1960s. The first recorded time that a loudspeaker was used specifically for foldback was for Judy GarlandJudy Garland
Judy Garland was an American actress and singer. Through a career that spanned 45 of her 47 years and for her renowned contralto voice, she attained international stardom as an actress in musical and dramatic roles, as a recording artist and on the concert stage...
at the San Francisco Civic Auditorium
Bill Graham Civic Auditorium
The Bill Graham Civic Auditorium is a multi-purpose arena in San Francisco, California, currently named after promoter Bill Graham...
on September 13, 1961; provided by McCune Sound Service. Bob Cavin, then an engineer at McCune Sound, designed the first monitor mixer designed expressly for foldback duties. He also designed the first stage monitor loudspeaker that had two different listening angles, for performers standing at the loudspeaker and for performers further away.
From the 1960s to the 1980s, most monitor speaker cabinets used an external power amplifier. In the 1990s and 2000s, clubs increasingly used powered monitors, which contain an integrated power amplifier. Most monitor speakers include an L-pad for controlling the volume of the horn. Another trend of the 2000s was the blurring of the lines between monitor speaker cabinets and regular speaker cabinets; many companies began selling wedge-shaped full-range speakers intended to be used for either monitors or main public address purposes.
Related products
Headphones
Hardshell headphonesHeadphones
Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...
are typically used by the sound board operator to listen to specific channels or to listen to the entire mix. While an amplified monitor speaker can also be used for this purpose, the high sound volumes in many club settings make hardshell headphones a better choice, because the hard plastic shell and foam cushions help to block out the noise from the room. Some performers may use headphones as monitors as well, such as drummers in pop music bands.
In-ear monitors
In the 2000s, some bands and singers have begun using small "in ear"-style headphone monitors. In-ear monitors allow musicians to hear their voice and the other instruments with a clearer, more intelligible sound, because the molded in-ear headphone design blocks out on-stage noise. While some in-ear monitors are "universal fit" designs, some companies also sell custom-made in-ear monitors, which require a fitting by an audiologist. Custom-made in-ear monitors provide an exact fit for a performer's ear."Butt shakers"
Drummers typically use a monitor speaker that is capable of loud bass reproduction, so that they can monitor their bass drum. However, having a 15" or even 18" subwoofer producing a high sound pressure level can raise the overall stage volumes to uncomfortable levels for the drummer, since the drums are already very loud. Since much very low bass is felt, some drummers use tactile transducers called "bass shakers", "butt shakers" and "throne shakers" to monitor the timing of their bass drum. The tactile transducers are attached to the drummer's stool ("throne") and the vibrations of the driver are transmitted to the body then to the ear in a manner similar to bone conductionBone conduction
Bone conduction is the conduction of sound to the inner ear through the bones of the skull.Bone conduction is the reason why a person's voice sounds different to him/her when it is recorded and played back. Because the skull conducts lower frequencies better than air, people perceive their own...
. They connect to an amplifier like a normal subwoofer. They can be attached to a large flat surface (for instance a floor or platform) to create a large low frequency conduction area, although the transmission of low frequencies through the feet isn't as efficient as the seat. This helps the concert drummer to monitor his or her kick drum performance without "polluting" the stage with powerful low frequency waves from a subwoofer monitor.
Other meanings
The term "foldback" is sometimes applied to in-ear monitoring systems, also described as artist's cue-mixes, as they are generally set up for individual performers. "Foldback" may less frequently refer to current limitingCurrent limiting
Current limiting is the practice in electrical or electronic circuits of imposing an upper limit on the current that may be delivered to a load with the purpose of protecting the circuit generating or transmitting the current from harmful effects due to a short-circuit or similar problem in the load...
protection in audio electronic amplifier
Electronic amplifier
An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...
s.
The term foldback has been used when referring to one or more video monitors facing a stage, in the same manner as an audio foldback monitor. The video monitor allows a person on stage to see what is behind them on screen, to see distant parties during a video conference, or to read notes or sing lyrics to a song. Other terms for this usage are confidence monitor and kicker monitor.