Stage monitor system
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.
The sound at popular music and rock music concerts is amplified with power amplifiers through a sound reinforcement system. With the exception of the smallest venues, such as coffeehouses, most mid- to large-sized venues use two sound systems. The main or front-of-house system amplifies the onstage sounds for the main audience. The monitor system is driven by a mix separate from the front-of-house system. This mix typically highlights the vocals and acoustic instruments so they can be heard over the electronic instruments and drums.
Monitor systems have a range of sizes and complexity. A small pub or nightclub may have a single monitor speaker on stage so that the lead vocalist can hear their singing and the signal for the monitor may be produced on the same mixing console and audio engineer as the front-of-house mix. A stadium rock concert may use a large number of monitor wedges and a separate mixing console and engineer on or beside the stage for the monitors. In the most sophisticated and expensive monitor set-ups, each onstage performer can ask the sound engineer for a separate monitor mix for separate monitors. For example, the lead singer can choose to hear mostly their voice in the monitor in front of them and the guitarist can choose to hear mostly the bassist and drummer in their monitor.
Role
For live sound reproduction during popular music concerts in mid- to large-size venues, there are typically two complete loudspeaker systems and PA systems : the main or front-of-house system and the monitor or foldback system. Each system consists of a mixing console, sound processing equipment, power amplifiers, and speakers.Without a foldback system, the sound that on-stage 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 could, for example, cause the singer to sing out of time with the band. In situations with poor or absent foldback mixes, vocalists may end up singing off-tune or out of time with the band.
The monitor system reproduces the sounds of the performance and directs them towards the onstage performers, to help them hear the instruments and vocals. A separately mixed signal is often routed to the foldback speaker to allow musicians to hear their performance as the audience hears it or in a way that helps improve their performance. More frequently, major professional bands and singers often use small in-ear monitors rather than onstage monitor speakers. The two systems usually share microphones and direct inputs using a splitter microphone snake.
The front-of-house system, which provides the amplified sound for the audience, will typically use a number of powerful amplifiers driving a range of large, heavy-duty loudspeaker cabinets including low-frequency speaker cabinets called subwoofers, 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, 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 large racks of a number of power amplifiers to provide 10,000 or more watts.
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 console. 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 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. 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 and singing.
Larger clubs and concert venues typically use a more complex type of monitor system which has two or three different monitor speakers and mixes for the different performers, e.g., vocalists and instrumentalists. 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 that forefronts their vocals, the backup singers can have a mix that emphasizes their backup vocals and the rhythm section members can have a mix which emphasizes the bass and drums. In most clubs and larger venues, sound engineers and technicians control the mixing consoles for the main and monitor systems, adjusting the tone, sound levels, and overall volume of the performance.
History
In the early 1960s, many pop and rock concerts were performed without monitor speakers. In the early 1960s, PA systems were typically low-powered units that could only be used for the vocals. The PA systems during this era were not used to amplify the electric instruments on stage; each performer was expected to bring a powerful amplifier and speaker system to make their electric guitar, electric bass, Hammond organ or electric piano loud enough to hear on stage and to fill the venue with sound.With these systems, singers could only hear their vocals by listening to the reflected sound from the audience-facing front-of-house speakers. This was not an effective way to hear one's vocals because of the associated delay which made it hard to sing in rhythm with the band and in tune.
The use of performer-facing loudspeakers for foldback or monitoring may have been developed independently by sound engineers in different cities who were trying to resolve this problem. The earliest recorded instance that a loudspeaker was used for foldback was for Judy Garland at the San Francisco Civic Auditorium on September 13, 1961; provided by McCune Sound Service.
File:Yes concert 2010-12-01.jpg|thumb|Stage monitors at a Yes concert in Paraguay in 2010
Early stage monitors were simply speakers on each side of the stage pointed at the performers driven by the same mix as the FOH; audio mixers used in PAs at the time rarely had auxiliary send mixes. Today these would be called sidefill monitors. F.B. "Duke" Mewborn of Atlanta's Baker Audio used left and right arrays of Altec loudspeakers to cover the audience and to serve sidefill duties for the Beatles at Atlanta Stadium on August 18, 1965. Bill Hanley working with Neil Young of Buffalo Springfield pioneered the concept of a speaker on the floor angled up at the performer with directional microphones to allow louder volumes with less feedback.
In the 1970s, Bob Cavin, chief engineer at McCune Sound, designed the first monitor mixer designed expressly for stage monitoring. He also designed the first stage monitor loudspeaker that had two different listening angles.
The introduction of monitor speakers made it much easier for performers to hear their singing and playing on stage, which helped to improve the quality of live performances. A singer who has a good monitor system does not have to strain their voice to try to be heard. Monitor systems also helped rhythm section instrumentalists hear each other and thus improve their playing together even on a huge stage with the musicians far apart.
From the late 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. 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.
The stage monitoring system
The monitor system consists of the monitor mixer, equalization or other signal processing, amplifiers, and monitor speakers on stage pointing at the performers. Microphones and direct inputs are shared with the front-of-house system.Front of house auxiliary speaker
The simplest monitor system is a speaker pointed at the performer fed from the FOH mix. This might be used by one or two performers in a coffee house, small club, or small house of worship. In this setting, a two-channel powered mixer might be used with one channel powering the main speakers and one channel powering the monitor speaker. The mixer would be on stage with the performers setting their own levels.Monitors mixed from front of house
A common monitor setup for smaller venues is one that uses one or more separate auxiliary mixes or sub-mixes on the FOH mixing console. These mixes are pre-fader so that changes to the FOH levels do not significantly affect what the performers hear on stage. The monitor mixes drive dedicated monitor equalizers and signal processors which in turn drive dedicated monitor amplifiers that power the monitor speakers. The FOH mixer is operated by an audio engineer who must mix for the audience and also tend to the needs of the musicians on stage.Separate monitor mixer
Larger venues will use a separate system for monitors with its own mixer and monitor sound engineer. In this case, a microphone splitter is used to split the signal from the microphones and direct inputs between the monitor mixer and the FOH mixer.This splitter may be part of the microphone snake or it may be built into the monitor mixer. With a separate monitor system, there may be 8, 12, or more separate monitor mixes, typically one per performer. Each monitor mix contains a blend of different vocals and instruments. This way the lead vocalist can have a mix that forefronts their vocals, the backup singers can have a mix that emphasizes their backup vocals and the rhythm section members can have a mix that emphasizes the bass and drums. In addition, there may be side-fill monitors to provide sound for areas on stage not covered by the floor wedges.