Stage monitor systems are speakers 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...

 pointing towards the performers to help them hear themselves. Monitor speakers are useful when amplified instruments are used with acoustic instruments

Acoustic music

Acoustic music comprises music that solely or primarily uses instruments which produce sound through entirely acoustic means, as opposed to electric or electronic means...

 and voice

Vocal music

Vocal music is a genre of music performed by one or more singers, with or without instrumental accompaniment, in which singing provides the main focus of the piece. Music which employs singing but does not feature it prominently is generally considered instrumental music Vocal music is a genre of...

. Monitor speakers typically have their own power amplifier(s) and equalizers

Equalization

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...

. They are driven by a separate mix

Live sound mixing

Live sound mixing is the art of combining and processing a number of audio signals together to create a "mix" that the audience or performers at a live show hear. There can be a variety of different mixes required, depending on the performance requirements...

 from the main or 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...

 system. This mix typically highlights the vocals and acoustic instruments so they can be heard over the electronic instruments

Electronic musical instrument

An electronic musical instrument is a musical instrument that produces its sounds using electronics. Such an instrument sounds by outputting an electrical audio signal that ultimately drives a loudspeaker....

 and drum

Drum

The drum is a member of the percussion group of musical instruments, which is technically classified as the membranophones. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a shell and struck, either directly with the player's hands, or with a...

s. The collection of monitor speakers, amplifiers, equalizers and monitor mixer if used is called the stage monitor system or simply monitors. The British use the term foldback or foldback speakers.

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. Using monitor loudspeakers 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 as a stage monitor was for Judy Garland

Judy 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. It was provided by McCune Sound Service.

Early stage monitors were simply speakers on each side of the stage pointed at the performers driven by the same mix as the FOH because PA mixers rarely had auxiliary send mixes. Today these would be called "side fill" monitors. Bill Hanley

Bill Hanley

William "Bill" Hanley was an ice hockey administrator in the province of Ontario in Canada, best known for his lifetime of service to the Ontario Hockey Association. He was inducted into the Hockey Hall of Fame in 1986...

 working with Neil Young

Neil Young

Neil Percival Young, OC, OM is a Canadian singer-songwriter who is widely regarded as one of the most influential musicians of his generation...

 of the Buffalo Springfield

Buffalo Springfield

Buffalo Springfield is a North American folk rock band renown both for its music and as a springboard for the careers of Neil Young, Stephen Stills, Richie Furay and Jim Messina. Among the first wave of North American bands to become popular in the wake of the British invasion, the group combined...

 was the first person to combine putting the speaker on the floor angled up at the performer with directional microphones to allow louder volumes with less feedback.

Bob Cavin, a former 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 stage monitoring system

The monitor system consists of the monitor mix, equalization or other signal processing

Signal processor

A signal processor is an electronic circuit that removes information from an analog signal as quantifiable units for further analysis. Most modern signal processors are either dedicated microprocessor integrated circuits or general-purpose programmable microprocessors. A DSP is an electronic...

, amplifiers, and monitor speakers on stage pointing at the performers. Microphones and direct inputs are shared with the front of house or "FOH" system.

Front of House Auxiliary Speaker

The simplest monitor system is a speaker pointed at the performer powered by 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

The more common monitor system is one that uses one or more separate auxiliary mixes or sub-mixes on the FOH mixing board. These mixes are pre-fader

Fade (audio engineering)

In audio engineering, a fade is a gradual increase or decrease in the level of an audio signal. The term can also be used for film cinematography or theater lighting, in much the same way ....

 and pre-input equalization so that changes to the FOH levels and equalization do not affect what the performers hear on stage. These mixes then drive dedicated monitor equalizers and signal processors which in turn drive dedicated monitor amplifiers which power the monitor speakers. The FOH mixer is operated by a sound engineer

Audio engineering

An audio engineer, also called audio technician, audio technologist or sound technician, is a specialist in a skilled trade that deals with the use of machinery and equipment for the recording, mixing and reproduction of sounds. The field draws on many artistic and vocational areas, including...

 located in the audience who also adjusts the monitor mix for the performers.

Separate Monitor Mixer

Larger clubs, concerts and houses of worship will use a completely separate system for monitors with its own mixer and monitor sound engineer. In this case a splitter is used to split the signal from the microphone

Microphone

A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...

s and direct inputs

DI unit

A DI unit, DI box, Direct Box, or simply DI , is a device typically used in recording studios to connect a high-impedance, line level, unbalanced output signal to a low-impedance microphone level balanced input, usually via XLR connector...

 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 vocal and instruments, and a floor monitor speaker or "wedge" 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. In addition there may be "side-fill" monitors to provide sound for areas on stage not covered by the floor wedges.

Distributed monitoring

A recent innovation first used in recording studios is to use small mixers placed next to the performer so that they can adjust their own mix. The simplest of these are four-channel mini-mixers like the Furman HR-6 Personal Mixing Station The mixers are driven by four sub-mixes on the FOH console with each sub-mix having a subset of the inputs on stage. For example, mix 1 vocals, mix 2 guitars, mix 3 keyboards, and mix 4 drums and bass. The performers could then adjust these four groups to their own preference. If the balance between several vocals or the balance between bass and drums needed to be changed, the sound engineer would have to change it at the main mixing board.

A recent variation on this is to add an additional input to each mixer which is the performer's instrument or vocal microphone so that each performer can add more of their performance to the other sub-mixes. This approach has been called "more me" in the monitors. A simple example of this is the Rolls PM50s Personal Monitor Amplifier, which combines a monitor mix with a local input to drive a headphone amplifier. A more sophisticated example is the "hear back" system by Hear Technologies.

With advances in digital technology, it is now possible to transmit multiple audio channels over a single Ethernet

Ethernet

Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

 cable. This allows the distribution of most or all of the input sources to each performer's mixer, giving them complete control over their mix. An example of this is the Aviom

Aviom

Aviom is a pro audio equipment manufacturer of personal monitoring systems. Headquartered in West Chester, Pennsylvania, Aviom produces distributed audio networking gear which uses a proprietary digital audio transport system called A-Net, based on the physical layer of Ethernet and carried over...

 A-16II personal mixer.

Distributed monitor mixers are most successful with headphones

Headphones

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...

 or in-ear monitor

In-ear monitor

In-ear monitors are devices used by musicians, audio engineers and audiophiles to listen to music or to hear a custom crafted mix of vocals and stage instrumentation for live performance or recording studio mixing...

s. If monitor speakers are used, feedback

Feedback

Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...

 problems are common when the performer turns their microphone up too loud.

Monitor speakers

Monitor speakers come in two types: floor monitors and side fill monitors. Monitor speakers are normally heavy duty speakers that can accept high input power to create high volumes and withstand extreme electrical and physical abuse.

Floor monitors

Floor monitors are compact speakers with an angled back that is laid on the floor. This angled shape gives the floor monitor its other name of wedge. The angle is typically 30 degrees which points the speaker back and up towards the performer. These speakers may be single small speakers such as the "hot spot" monitor by Galaxy Audio which are sometimes mounted on a microphone stand to get them closer to the performers ears. More often they are heavy duty two way systems with a woofer

Woofer

Woofer is the term commonly used for a loudspeaker driver designed to produce low frequency sounds, typically from around 40 hertz up to about a kilohertz or higher. The name is from the onomatopoeic English word for a dog's bark, "woof"...

 and a high frequency horn. A small floor monitor might use a 12" woofer with an integrated high frequency horn/driver combination such as the JBL

JBL

JBL is an American audio electronics company currently owned by Harman International. It was founded in 1946 by James Bullough Lansing. Their primary products are loudspeakers and associated electronics. There are two independent divisions within the company — JBL Consumer and JBL Professional...

 4602A floor monitor. A large floor monitor might use one or two 15" woofers and a high frequency driver

Compression driver

A compression driver is a type of loudspeaker driver which uses the technique of "compression" to achieve high efficiencies. In this context compression refers to the fact that the area of the loudspeaker diaphragm is significantly larger than the aperture through which the sound is radiated....

 attached to a high frequency horn

Horn speaker

A horn loudspeaker is a complete loudspeaker or loudspeaker element which uses a horn to increase the overall efficiency of the driving element, typically a diaphragm driven by an electromagnet. The horn itself is a passive component and does not amplify the sound from the driving element as such,...

 such as the EAW SM159zi stage monitor The speaker might use a passive crossover

Audio crossover

Audio crossovers are a class of electronic filter used in audio applications. Most individual loudspeaker drivers are incapable of covering the entire audio spectrum from low frequencies to high frequencies with acceptable relative volume and lack of distortion so most hi-fi speaker systems use a...

 or might be bi-amped

Bi-amping

Bi-amping is the practice of using two audio amplifier channels to power a loudspeaker with multiple drivers.-Description:Bi-amping is the act of using a single loud-speaker system, that is one channel of a speaker pair, with one channel handling only low frequency information and the other channel...

 with an active crossover

Audio crossover

Audio crossovers are a class of electronic filter used in audio applications. Most individual loudspeaker drivers are incapable of covering the entire audio spectrum from low frequencies to high frequencies with acceptable relative volume and lack of distortion so most hi-fi speaker systems use a...

 and separate amplifiers for the woofer and high frequency driver.

Active monitors

A recent trend has been to build the amplifier and associated sound processing equipment into the monitor itself. These monitors are called "active" or "powered" monitors. This design allows amplifiers with the right amount of power to be custom made for the speakers. Active monitors are typically bi-amped and have an active crossover with custom equalization to tune the monitor to have a flat frequency response. One of the first examples of this type of monitor is the Meyer Sound Laboratories

Meyer Sound Laboratories

Meyer Sound Laboratories is an American company based in Berkeley, California that manufactures self-powered loudspeakers, multichannel audio show control systems, electroacoustic architecture, and audio analysis tools for the professional sound reinforcement, fixed installation, and sound...

 UM-1P

Side-fill monitors

Side fill monitors are monitors that sit upright on the side of the stage and are used to provide sound to the areas of the stage not covered by the floor monitors. Side fill monitors are typically standard FOH speakers. A special case of a sidefill monitor is a "drum monitor". Drum monitors are typically large 2 or 3 way speakers with one or more large woofers capable of extremely high volumes.

Monitor amplifiers

Monitor amplifiers are heavy duty amplifiers, typically 200 watts

Watts

-People:*Watts , the surname of several people*Watts S. Humphrey , American software engineer often called the father of software quality*Watts , a Canadian record producer-Fictional characters:*Watts family in EastEnders...

 per channel or more. If the monitor speakers are using passive crossovers then each channel is connected to one or more monitor speakers. In simple monitor configurations a single monitor mix might drive both channels of the amplifier so that the single mix can be heard by most of the band by using multiple speakers. In more complex monitor configurations where each performer has a separate mix, each mix will drive a separate channel on the amplifier. If the monitors are bi-amped then two or more amplifier channels are needed for each speaker. This may be a single channel of two different amplifiers, a high power amp for the woofer and a medium power amp for the high frequency driver, or it may be two channels of a high power amp. A key criteria of a monitor amp is reliability. They must be able to survive the abuse of their output being shorted or speakers being plugged and un-plugged while the amp is turned on. They must continue to function while being overloaded for extended periods of time.

Equalization and signal processing

Monitor speakers need their own equalization primarily to reduce or eliminate acoustic feedback. One of the main problems affecting monitors is acoustic feedback or "ringing". Acoustic feedback occurs when the time delay between the acoustic input of a microphone and the output of a monitor speaker is a multiple of the period of a frequency. When this occurs the acoustic output of the speaker is picked up by the microphone and amplified again by the monitor speaker. This is a positive feedback loop that reinforces the specific frequency causing the speaker to howl or squeal. Equalization is used to attenuate the specific frequency that is feeding back.

Eliminating feedback

The process of eliminating feedback in the monitor is called ringing out

Ringing out

Ringing out is a process in audio engineering used to prevent audio feedback and maximize volume. It involves a sound technician raising the slider controls on a mixing desk to cause an audio system to feedback. Once feedback occurs, the technician uses the graphic equalizer to pull back the...

 the monitors. To eliminate feed back, the monitor's level is increased until it starts to feedback. The feedback frequency is identified either by ear or by a frequency analyzer. Equalization is used to reduce that frequency. The monitor level is again increased until the next frequency starts to feed back and that frequency is eliminated. Normally eliminating the first 4 or 5 feedback frequencies is all that is needed. If multiple monitor mixes are being used, the process has to be repeated for each separate monitor mix.

Graphic equalizer

The most common equalizer used in monitor systems are graphic equalizers

Equalization

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...

. They get their name from the slide potentiometers or "sliders" used to adjust the level of each frequency band. Graphic equalizers are fixed frequency equalizers. The center frequency of each band can not be adjusted. The bandwidth or Q of each band can either be 1/3, 2/3 or one octave giving you a 31 band, 15 band, or 10 band graphic equalizer. The narrower the band the more precisely the feedback frequency can be isolated. Normally 31 band equalizers are used such a Klark Teknik

Klark Teknik

1971 saw the start of Klark Teknik when brothers Phillip and Terence Clarke formed “Klark Equipment” a company that produced garage forecourt equipment; vending style vacuum cleaners, space heaters and other similar products....

 DN360 or a DBX

Dbx

dbx or DBX may refer to:* dbx , a Unix source-level debugger* dbx, Inc., a professional audio recording equipment company** dbx , a noise reduction system invented by dbx, Inc....

 1231. Taller units are preferred since the longer slider length gives you more precise control over level adjustments.

A variation on the graphic equalizer is a "cut only" graphic equalizer. Since most of the time monitor equalization involves the removing of frequencies a cut only equalizer can give you more precise level adjustments since the entire travel of the slider is used for reducing the level rather than wasting half the travel for boost. An example of this is the UREI 539

One of the advantages of graphic equalizers is their simplicity of use. As you are ringing the monitors you can boost then restore each frequency band until the ringing starts.
This helps you identify the feedback frequency. A drawback of graphic equalizers is the fixed frequency bands. Feedback rarely occurs on the exact center of the frequency band so two adjacent frequency bands may have to be reduced in parallel to eliminate the feedback.

1/3 octave RTA

Peavey LEDs

Parametric equalizer

A second type of equalizer used in monitor systems are parametric equalizers

Equalization

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...

. A parametric equalizer does not use fixed frequency bands. Instead each frequency band can be adjusted. The center frequency can be adjusted over a several octave range. The bandwidth of each band can be adjusted from a wide Q affecting several octaves to a narrow Q affecting 1/3rd, 1/6th, or less of an octave, and the level of the band can be adjusted. Each band may have a different frequency sweep range with the left or lower bands sweeping the lower octaves, the middle bands sweeping the middle octaves, and the right or higher bands sweeping the higher octaves. There is normally a lot of overlap between bands. Parametric equalizers typically have 3 to 5 filtering bands per channel. Examples of parametric equalizers are Rane

Rane Corp.

Rane Corporation is a pro audio equipment manufacturer. Located in Mukilteo, Washington, it was made up of former employees of Phase Linear Corporation, and started out with products aimed at small live bands...

 PE 55 and Klark Teknik DN410.

The advantage of using parametric equalizers in a monitor system is that the filter can be exactly adjusted to the specific feedback frequency and the bandwidth of the filter can be set to be very narrow so the adjustment affects as little of the frequency band as possible. This leads to more precise feedback elimination with less coloring of the sound. For this reason many professionals recommend using parametric equalizers over graphic equalizers for monitors..

The process of using a parametric equalizer is different than a graphic equalizer. When using a parametric equalizer the first step is to choose the band to use. Normally the first feedback frequency is in the lower mid-range so the second band would be a good choice. If the feedback frequency is in the upper mid-range then the 3rd or 4th band would be a good choice. Next adjust the Q of the filter to be as narrow as possible and boost the frequency by 6 to 9 db

DB

DB may refer to:In science and technology:*Decibel , a logarithmic unit of measurement in acoustics and electronics*Dubnium , a chemical element*DB connector, a size of D-subminiature electrical connector...

. Raise the level of the monitor until it just begins to feedback, lower by 3 db or so. Now sweep the frequency of the filter until the monitor feeds back. Sweep it back and forth over the feedback frequency to find the center frequency by finding the lower and upper frequency of the ring and setting it to the middle between these two frequencies. You may need to drop the gain on the frequency if the feedback is to loud. You repeat the process for the next and the next feedback frequencies. You may discover that the order of the frequencies does not increase left to right. For example the sequence might be 250 Hz, 800 Hz, 500 Hz, 2.6 kHz, and 1.7 kHz. While this may look confusing, it is OK. You can reorder them if you like at the cost of extra work on your part.

Notch filter

A notch filter is a semi-parametric equalizer where the bandwidth is set very narrow, a 1/6 of an octave or less and is a cut only filter. An example is a UREI 562 Feedback Suppressor and the Ashly SC-68 Parametric Notch Filter.

Speaker processors

Digital signal processing has allowed the integration of a graphic equalizer, a parametric equalizer, automatic notch filter and active crossover into a single unit called a digital signal processor or a speaker processor.

DBX, BSS

Monitor Mixer

May not have faders

Cue mix for engineer

Monitor mixes may be mono or stereo

Built-in splitter

Placement of the monitor mixer

Monitorland

Headphones

Hardshell headphones

Headphones

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" 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...

 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 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 conduction

Bone 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 15" 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 limiting

Current 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.