Audio visual glossary
Every term you are likely to meet in a lighting, sound or display quotation, explained in plain language with the practical buying implication.
A
- Amplifier Bridging
- Amplifier bridging combines two channels of a stereo amplifier into one higher-power mono output, typically used to drive demanding loads like subwoofers. Bridging requires checking the amplifier's minimum impedance rating in bridged mode to avoid damage.See also: Impedance, Wattage RMS, Subwoofer
- Aspect Ratio
- Aspect ratio is the proportional relationship between the width and height of a screen or image, such as 16:9 for widescreen. Choosing the correct aspect ratio ensures content displays without unwanted cropping or black bars on an LED wall or projector screen.See also: Pixel Pitch, Projector Throw Ratio
B
- Backline
- Backline refers to the musical instrument amplifiers and equipment used by a live band, such as guitar amps, drum kits and keyboard stands. Backline is often hired separately from the main PA and lighting system for touring acts.See also: DI Box, Monitor Wedge
- Beam Angle
- Beam angle describes the width of the cone of light produced by a fixture, measured in degrees. A narrow beam angle produces a tight, focused spot while a wide beam angle creates a broad wash suited to lighting large areas.See also: Lumens, Moving Head, Gobo
- Blackout
- A blackout is the instantaneous cutting of all stage lighting to complete darkness, often used for dramatic scene changes or transitions. Lighting consoles have a dedicated blackout button for quick, precise control during a live show.See also: DMX512, Moving Head
C
- Chain Motor
- A chain motor (chain hoist) is a motorised device used to raise and lower truss, lighting and speakers safely to a required height. Chain motors are rated for specific safe working loads and are operated with dedicated control units.See also: Rigging, Truss
- CO2 Jet
- A CO2 jet fires a burst of compressed carbon dioxide gas to create a dramatic white plume, commonly used at nightclubs and concerts for visual impact. Unlike pyro, it doesn't involve flame but still requires ventilation and safety planning.See also: Pyro, Haze, Fog Fluid
- Colour Temperature
- Colour temperature, measured in Kelvin, describes whether a light source appears warm (orange, around 3000K) or cool (blue-white, around 6500K). Matching colour temperature across fixtures is important for consistent-looking video and photography.See also: CRI, RGBW
- Compressor
- A compressor automatically reduces the volume of an audio signal once it passes a set threshold, evening out loud peaks and quiet moments. It's commonly used on vocals and music to keep levels consistent and prevent clipping.See also: EQ, Gain Staging, SPL
- Confidence Monitor
- A confidence monitor is a screen placed facing a speaker or performer showing them the exact content being displayed to the audience, such as slides or their own camera feed. It helps presenters stay on track without turning to look at the main screen.See also: Media Server, HDMI
- CRI
- CRI (Colour Rendering Index) is a score out of 100 showing how accurately a light source reveals the true colours of objects compared to natural daylight. High CRI (90+) lighting is essential for video production and photography where accurate skin tones and colours matter.See also: Colour Temperature, Lumens
- Crossover
- A crossover splits an audio signal into separate frequency bands, sending low frequencies to subwoofers and higher frequencies to main speakers. This ensures each speaker only reproduces the range it's designed for, improving clarity and protecting drivers.See also: Subwoofer, Line Array, Impedance
D
- Dante
- Dante is a digital audio networking protocol that transmits multiple channels of high-quality audio over standard Ethernet cable. It has become an industry standard because it simplifies large-scale audio routing and reduces the need for bulky analogue cabling.See also: Stage Box, Mixing Console, Latency
- Delay Speaker
- A delay speaker is an additional speaker positioned further back in a large venue to reinforce sound for audience members far from the main system, with its timing electronically delayed to stay in sync with the main speakers. This prevents echo and keeps sound arriving consistently across a large space.See also: Line Array, SPL
- DI Box
- A DI (Direct Injection) box converts a high-impedance instrument or line signal into a balanced low-impedance signal suitable for a mixing console, while also eliminating hum caused by ground loops. It's commonly used for keyboards, laptops and acoustic instrument pickups.See also: XLR, Phantom Power, Patch Bay
- Dimmer Pack
- A dimmer pack controls the brightness of conventional (non-LED) lighting fixtures by regulating the electrical power sent to them, usually via DMX control. Dimmer packs are still used for tungsten fixtures like fresnels and profile spots.See also: DMX512, Par Can
- Diversity Receiver
- A diversity receiver uses two antennas to continuously select whichever signal path is stronger, reducing dropouts in wireless microphone and IEM systems. This makes wireless audio far more reliable in venues with reflective surfaces or interference.See also: Wireless Frequency Band, Squelch, IEM
- DMX512
- DMX512 is the standard digital protocol used to control stage lighting, moving heads and effects from a lighting console. It sends 512 channels of data down a single cable, with each fixture assigned an address so it responds to the correct commands.See also: Moving Head, Dimmer Pack, RDM
E
- EQ
- EQ (equalisation) is the adjustment of specific frequency ranges in an audio signal to shape tone, remove unwanted resonances or prevent feedback. Sound engineers use EQ on both individual microphones and the overall system to make speech and music sound clear.See also: Compressor, Crossover, Feedback
F
- Feedback
- Feedback is the loud squeal or howl that occurs when a microphone picks up sound from a speaker and re-amplifies it in a continuous loop. It's controlled through careful gain staging, EQ notching and speaker/microphone positioning.See also: EQ, Gain Staging, Monitor Wedge
- Fog Fluid
- Fog fluid is a water and glycol/glycerine-based liquid heated inside a fog machine to produce thick, visible clouds of atmospheric effect. Different fluid mixes produce fog that dissipates quickly or lingers longer, depending on the desired look.See also: Hazer, Haze, CO2 Jet
- Follow Spot
- A follow spot is a powerful manually operated light used to track a performer as they move across a stage, keeping them highlighted against the background. It's operated live by a technician and is standard for theatre, award shows and concerts.See also: Gobo, Beam Angle, Moving Head
G
- Gain Staging
- Gain staging is the process of setting appropriate signal levels at each stage of an audio chain, from microphone preamp through to the main output, to maximise clarity and headroom. Poor gain staging causes either noisy, weak signals or distorted, clipped audio.See also: Compressor, Feedback, EQ
- Generator
- A generator is a portable power source used at outdoor or off-grid events where mains electricity isn't available or sufficient. Generator sizing must account for the total wattage of all connected lighting, sound and video equipment plus a safety margin.See also: Power Distro, Watt
- Genlock
- Genlock synchronises the timing of multiple video sources or displays so they switch frames simultaneously, preventing tearing or glitches when mixing between cameras or screens. It's essential in professional live event video production with multiple camera feeds.See also: SDI, Latency
- Gobo
- A gobo is a small metal or glass stencil placed inside a light fixture to project a pattern, logo or texture onto a surface. Gobos are widely used at weddings and corporate events to project names, monograms or textured light effects onto walls and dance floors.See also: Moving Head, Follow Spot, Beam Angle
H
- Handheld Mic
- A handheld microphone is held directly by the speaker or performer and is available in both wired and wireless versions. It's the standard choice for MCs, singers and Q&A sessions due to its flexibility and consistent sound pickup.See also: Wireless Microphone, XLR
- Haze
- Haze is a very fine, low-density atmospheric effect used to make light beams visible in the air without the thick visual weight of fog. It's the preferred effect for concerts and theatre because it lingers evenly in a room without obscuring the stage.See also: Hazer, Fog Fluid, CO2 Jet
- Hazer
- A hazer is a machine that produces fine atmospheric haze, using either oil-based fluid or compressed air, to make light beams visible without heavy fog. Hazers are preferred over fog machines for events needing subtle, consistent beam visibility.See also: Haze, Fog Fluid
- HDMI
- HDMI is a consumer and professional connector that carries high-definition digital video and audio over a single cable. It's common for short runs between laptops, media players and screens, though longer distances usually require SDI or fibre extension.See also: SDI, Pixel Pitch, Latency
- House Lights
- House lights are the general illumination in the audience seating area, separate from the stage lighting rig. They are typically dimmed during performances and brought back up for breaks or the end of an event.See also: Dimmer Pack, Blackout
I
- IEM
- IEM (In-Ear Monitor) is a wireless earpiece system that gives performers a private, high-quality mix of the show directly in their ears instead of relying on floor wedges. It reduces stage volume and feedback risk while giving each performer a customised mix.See also: Monitor Wedge, Wireless Frequency Band, Diversity Receiver
- Impedance
- Impedance, measured in ohms, describes the electrical resistance a speaker presents to an amplifier. Matching speaker impedance to amplifier specifications is critical, as mismatches can damage equipment or reduce sound quality.See also: Wattage RMS, Amplifier Bridging, Crossover
- Intercom System
- An intercom system provides dedicated headset communication channels for the production crew, allowing the show caller, lighting, sound and video operators to coordinate in real time during an event. Wired and wireless intercom systems are both common depending on venue size.See also: Show Caller
L
- Laser Class
- Laser class is a safety rating (Class 1 to Class 4) indicating how powerful and potentially hazardous a laser is to eyes and skin. Event lasers are typically Class 3B or 4 and require a trained operator and safety zoning to comply with regulations.See also: Pyro, Haze
- Latency
- Latency is the delay between an audio or video signal being generated and it being heard or seen at the output. Low latency is critical for live sound and video where performers and audiences need synchronised timing.See also: Dante, Sample Rate, HDMI
- Lavalier Mic
- A lavalier (lapel) microphone is a small clip-on microphone worn on clothing, commonly used for presenters and panellists who need hands-free, discreet audio pickup. It's usually paired with a wireless bodypack transmitter.See also: Wireless Microphone, Diversity Receiver
- Line Array
- A line array is a vertically stacked set of loudspeaker cabinets designed to project sound evenly over long distances with consistent coverage. They are the standard choice for large events because they reduce hotspots and keep volume predictable throughout the audience.See also: Subwoofer, SPL, Amplifier Bridging
- Load-In
- Load-in is the process of delivering, unloading and setting up all equipment at a venue ahead of an event. Efficient load-in planning, including access routes and timing, is essential for tight event schedules.See also: Ground Support, Rigging
- Lumens
- Lumens measure the total visible light output of a fixture or projector. Higher lumen ratings mean a brighter image or wash, which matters when lighting large stages or projecting in rooms with ambient light.See also: Nits, Beam Angle, CRI
M
- Media Server
- A media server is a dedicated computer system that plays back and manages video content, graphics and effects across multiple screens or projectors at an event. It allows synchronised, programmable playback controlled from a single interface.See also: Scan Converter, Genlock
- Mixing Console
- A mixing console (or mixer) combines, balances and processes multiple audio signals from microphones and instruments into a single output for the PA system. Modern digital consoles also offer built-in EQ, compression and effects for every channel.See also: EQ, Compressor, Stage Box
- Monitor Wedge
- A monitor wedge is a floor-facing speaker placed on stage so performers can hear themselves and other instruments clearly. It runs on a separate mix from the main house sound, tailored to what each performer needs to hear.See also: IEM, Feedback, Mixing Console
- Moving Head
- A moving head is a motorised lighting fixture that can pan, tilt and change colour, gobo and beam shape automatically via DMX control. They allow lighting designers to create dynamic, changing looks throughout an event without repositioning fixtures manually.See also: DMX512, Gobo, Beam Angle
N
- Nits
- Nits measure the brightness of an LED screen or display. Outdoor screens need a high nit rating (often 4000+) to remain visible in daylight, while indoor screens can use much lower brightness.See also: Pixel Pitch, Lumens
P
- Par Can
- A par can is a simple, widely used lighting fixture that produces a fixed, round beam of light, often in LED form with colour-mixing capability. Pars are commonly used for stage washes, uplighting and general colour effects at events.See also: RGBW, Beam Angle, Strobe
- Patch Bay
- A patch bay is a panel of connection points that allows technicians to quickly route audio or video signals between different pieces of equipment using patch cables. It saves time during setup and troubleshooting by centralising all connections in one place.See also: DI Box, Stage Box, Snake
- Phantom Power
- Phantom power is a 48-volt DC current sent through a microphone cable to power condenser microphones and some DI boxes. It travels on the same XLR cable as the audio signal without affecting dynamic microphones, which don't require it.See also: XLR, DI Box, Mixing Console
- Pin Spot
- A pin spot produces a very tight, narrow beam of light used to highlight a specific small object, such as a centrepiece or cake, without spilling light onto surrounding areas. They are a popular finishing touch at weddings and gala dinners.See also: Beam Angle, Follow Spot
- Pixel Pitch
- Pixel pitch is the distance in millimetres between individual LED pixels on a video wall, and it determines how close viewers can stand before individual pixels become visible. A smaller pixel pitch gives a sharper image up close, while a larger pitch is fine for screens viewed from a distance.See also: Nits, HDMI, SDI
- Power Distro
- A power distro (distribution unit) splits a single high-capacity power feed into multiple outlets protected by circuit breakers, used to safely supply electricity to lighting, sound and video equipment. Distros are essential on larger events to prevent overloading a single circuit.See also: Watt, Generator
- Projector Throw Ratio
- Throw ratio describes the relationship between a projector's distance from the screen and the width of the image it produces. It determines how far back a projector needs to be positioned to achieve a given screen size.See also: Aspect Ratio, Lumens
R
- RDM
- RDM (Remote Device Management) is an extension of the DMX512 protocol that allows two-way communication, letting a lighting console remotely check fixture status and change settings like addressing. It saves time on large rigs by removing the need to manually check every fixture.See also: DMX512, Moving Head
- RGBW
- RGBW fixtures combine red, green, blue and white LEDs to produce a wide range of colours plus a true, clean white light. Adding a dedicated white LED avoids the slightly muddy white produced by RGB-only fixtures.See also: Colour Temperature, Par Can, Moving Head
S
- Sample Rate
- Sample rate is the number of times per second an analogue audio signal is measured when converted to digital, expressed in kHz (e.g. 48kHz). Higher sample rates can capture more detail but also require more processing power and bandwidth.See also: Latency, Dante
- Scan Converter
- A scan converter changes a video signal's resolution or format so it's compatible with a different display, projector or LED processor. It's often used to adapt a laptop's output to match the native resolution required by an LED wall.See also: Pixel Pitch, HDMI
- SDI
- SDI (Serial Digital Interface) is a professional broadcast-grade video connector that carries uncompressed video reliably over long cable runs using standard coaxial cable. It's the preferred choice for live event video production because it's more robust over distance than HDMI.See also: HDMI, Pixel Pitch, Latency
- Show Caller
- A show caller is the person who cues lighting, sound, video and stage crew via headset communication throughout a live event to keep every department synchronised. This role is essential for complex shows with tight timing between multiple technical elements.See also: Media Server, Blackout
- Site Survey
- A site survey is a pre-event visit or assessment of a venue to check power availability, rigging points, access and any technical constraints before equipment is confirmed. It helps avoid costly surprises on the day of the event.See also: Load-In, Power Distro
- Snake
- A snake is a multicore cable bundle that carries multiple audio channels between the stage and the mixing position in a single run. It simplifies cabling by replacing dozens of individual XLR cables with one manageable cable.See also: Stage Box, XLR, Mixing Console
- SPL
- SPL (Sound Pressure Level) is a measurement of how loud a sound is, expressed in decibels (dB). Event organisers often set maximum SPL limits to comply with noise regulations and protect audience hearing.See also: Line Array, Wattage RMS, Compressor
- Squelch
- Squelch is a setting on wireless microphone receivers that mutes the audio output when the received signal is too weak or noisy. It prevents bursts of static from reaching the PA system when a wireless mic is switched off or out of range.See also: Wireless Frequency Band, Diversity Receiver
- Stage Box
- A stage box is an input/output unit placed on stage that connects microphones and instruments, then sends the combined signal to the mixing console via a snake or digital network cable. Digital stage boxes reduce cable runs by converting audio to a network signal like Dante.See also: Snake, Dante, Mixing Console
- Strike
- Strike is the process of dismantling and removing all equipment from a venue after an event has finished. It's typically planned with the same care as load-in to ensure a safe, efficient turnaround.See also: Load-In, Rigging
- Strobe
- A strobe is a lighting effect that produces rapid, high-intensity flashes, commonly used to build energy during dance music drops or dramatic moments. Strobe effects should always come with an epilepsy warning at public events.See also: Moving Head, Par Can
- Subwoofer
- A subwoofer is a loudspeaker dedicated to reproducing low-frequency bass content, typically below 100Hz. Subwoofers add depth and impact to music and are usually positioned on the floor separately from the main line array.See also: Line Array, Crossover, Wattage RMS
T
- Truss
- Truss is a lightweight modular metal frame structure used to suspend lighting, speakers and video screens above a stage or event space. It is rated for specific load limits and assembled from aluminium sections to create spans, ground supports or roof structures.See also: Rigging, Moving Head, Line Array
U
W
- Watt
- A watt is the standard unit of electrical power, used to describe how much energy a piece of equipment consumes or an amplifier can output. Understanding wattage requirements is essential for planning safe power distribution at an event.See also: Wattage RMS, Power Distro
- Wattage RMS
- RMS wattage is the continuous power a speaker or amplifier can handle or produce under normal operating conditions, as opposed to brief peak power ratings. RMS figures give a more realistic picture of real-world loudness and system matching than peak wattage.See also: Impedance, Amplifier Bridging, SPL
- Wireless Frequency Band
- Wireless frequency band refers to the range of radio frequencies (such as UHF or 2.4GHz) that wireless microphones and IEMs operate on. Correct frequency coordination between multiple devices is essential to avoid interference at busy events with many wireless systems.See also: Squelch, Diversity Receiver, IEM
- Wireless Microphone
- A wireless microphone transmits audio via radio frequency to a receiver instead of using a cable, giving performers and speakers freedom of movement. Reliable operation depends on correct frequency coordination and receiver placement.See also: Diversity Receiver, Wireless Frequency Band, Squelch
X
- XLR
- XLR is a three-pin locking connector used for balanced audio connections between microphones, mixers and amplifiers. Its balanced design rejects electrical interference, making it reliable for long cable runs at live events.See also: Phantom Power, DI Box, Snake