AV JARGON BUSTER
How often have you been left scratching your head after a technician has just explained something in what appears to be a rare dialect of a language spoken by a near extinct tribe from a little known corner of a distant continent?
The old “blind them with science” and “BS baffles brains” techniques of confusing people into thinking they’re out of their depth and should leave you alone is way past its time. You as an event manager should have a broad knowledge of what happens in the technical world; not necessarily detail, leave that to the experts, but at least an understanding of what is going on.
Here’s an AV Jargon Buster – a list of some terms that you will regularly hear on site during an event production and their meanings. You may be even able to impress a technician with some of the trivia here. I’ve included hyperlinks (underlined) for some more in-depth definitions if you want to learn more. I’ve deliberately not included equipment brands and model numbers, these are widely used in the techie world but they are too numerous to list in this article and besides they regularly change as new technology and models are released.
DMX – Digital Multiplex – this is the name of the standard means of controlling lights: dimming, moving or changing colours/shapes. A lighting console will have a DMX interface to which the technician will connect lighting fixtures and effects which also have a DMX interface. They can be daisychained and then each one can be individually controlled from the console by giving them specific addresses in the form of a unique number. Wireless DMX is becoming ever more widely used.
LED – Light Emitting Diode – until recently LED’s were simply a small light on your TV screen to indicate on or standby. Now they have developed in to powerful bright lights and are rapidly replacing traditional “light bulbs”. Being very low on power consumption and very small they are becoming popular since an enormous number of colours and effects can be achieved from a small cluster or strip of LED’s using DMX control (qv).
Splash – Wash – Spot – technical terms used regularly in a laundry but in lighting terms ways of describing what a lighting fixture does. A wash will light a large area without creating hard beam edges whereas a spot will do exactly that, create a spot of light.
LX – “Elecs” or “Electrics” – the term often given to the lighting technician (Lampie) or electrician. Often a lighting tech will look after power distribution since lighting traditionally uses the most power and the discipline requires a greater electrical knowledge.
Socapex – this is in fact a genericised trademark of a company called Amphenol Socapex which created this large connector to run multiple electrical signals along a single thick (15-24mm diameter) cable. Most commonly used in lighting, sometimes sound too, a “breakout” adapts the cable to multiple sockets to which fixtures are connected and powered up.
Halogen Lamps – often called Tungsten Halogen, these are light bulbs that use a tungsten (rare metal with a very high melting point) filament with a small amount of iodine or bromine sealed inside a glass bulb. They are efficient, bright and can be made very small, commonly used in theatrical lamps, floodlights and car headlamps.
XLR – see Sound (qv) for explanation, this type of connector is also used for DMX control cables that run from a lighting console to lamps/fixtures.
Gel Filter – coloured translucent film used to tint lamps to a desired shade or colour
XLR – this is a type of connector most commonly used in the sound industry for connecting microphone cables to mixing desks. They are also used for lighting control and other low voltage applications. More senior technicians may refer to them as “Cannon” connectors – they were invented in 1950 by James Cannon, the “Canon X series with Locking mechanism and Rubber insulation, hence XLR.
Decibel – dB – one tenth of a Bel (after Alexander Graham Bell), commonly mistaken as “how loud it is” this is a measurement of how MUCH louder it is than [whatever you had at first]. It’s a logarithmic unit and let’s just say it’s complex! Even experienced techies will still say “this sound system goes up to 120dB”. Feel free to tell him/her that they are talking nonsense and that the Decibel is an expression of ratio and not an absolute quantity. That should keep them quiet for at least 2 minutes!
White Noise – it sounds a bit like a huge waterfall and can drive you mad. It has actually been used in torture techniques. It’s a noise that includes the whole audio frequency spectrum, ie every conceivable note all at once, and is used to measure the acoustic properties of a room when setting up a sound system. In fact “pink noise” is most commonly used since it allows for the characteristics of the human ear. It’s still annoying!
Feedback – as well as the noun used for telling the sound tech how great the sound was it’s the term for when you hear the howling or squeaking on a PA system. It happens when a microphone picks up its own sound and amplifies itself then picks up that amplified sound and amplifies that and so on until you’re holding your ears lest they start bleeding. The sound technician will be working to avoid feedback throughout the event but mainly during the set up where all the nasty howls can be identified and eliminated.
EQ – equalisation – how to “shape” the sound, give it more clarity, deal with room acoustics, feedback different types of voice, different microphones, or just make it more pleasing to the ear.
Delay – unlike light, sound moves very slowly. in fact it can take over a quarter of a second to travel 100 metres which, if you’re at the back of a room near a loudspeaker will mean you hear the voice on stage twice: first from the loudspeaker near you then more softly the original sound of the voice arriving at your ears. Not a lot of fun and difficult for your brain to decipher, especially after a few minutes. So the sound tech has to “delay” the back-of-room loudspeaker, often using a built in gadget on the mixing desk, so that all the sound arrives at you at the same time. Now imagine a music festival without the delay being used….
Aspect Ratio – this refers to the shape of your screen. If you’re looking at this on a mobile phone it will be different to an iPad and different again to your desktop screen. 16:9 is the most common presentation format. It used to be 4:3 so less elongated. It means 16 across by 9 up so your screen might be 16 feet across by 9 feet high, 8 feet across by 4.5 feet high and so on. It’s important that content destined for the screen is the same shape as the screen otherwise you’ll encounter black lines or blank areas at the sides or top and bottom.
Resolution – this is a measurement of the amount of detail in the image on the screen (or indeed print). The higher the numbers the better image quality and detail you’ll get. Sometimes it’s referred to as definition; High Definition (HD) means the image is made up of 1920 dots or “pixels” across by 1080 up, often referred to as “1080p”. If you’re mathematically minded you’ll have noticed that this is extremely close to a 16:9 ratio. In fact it’s so close that it’s the standard resolution for 16×9 TV’s and screens. 4K and 8K TV screens are now available which are much higher resolutions and you can see extreme detail (as long as the video is actually recorded in 4K or 8K resolution!). The bigger the projection screen or video wall the more you’ll notice the pixels if the resolution is low. From here on in you should leave it to your esteemed video tech and a calculator!
Format – video and sound files can be recorded in many different formats. From a grooved PVC disc to a digital mp3 file each format is suited to different applications (and different eras). For example VHS was the preferred and most widely used format for storing video on a cassette tape, m4V is the format developed by Apple for storing video on iPods, iPads and iPhones. Here’s a list of digital video formats and their respective uses, from Wikipedia, quite technical but worth a glance to understand a bit more. Here’s a more comprehensive list if you need a reference guide to digital formats.
HDMI - High Definition Media Interface – it’s a modern type of digital video connector for joining, say, media players to TV screens. It’s a domestic connector but widely used in professional applications. As an aside, the more money you spend on an HDMI cable does not mean the better the quality will be. One of my longstanding bug bears against Hi-Fi shops that will remain nameless. Here’s an article if this tickles your interest!
VGA - Video Graphics Array – less commonly known as the D-Sub connector. Not so widely used nowadays it’s an analogue connector that hooks up a PC graphics card to a monitor, so used to connect laptops to projectors and video switchers. It’s being replaced with digital signal connectors such as SDI and HDMI.
Serial Digital Interface – this is another way of connecting video devices (camera to screen, video mixer to projector), it is widely used in the broadcast industry and is gradually being adopted in the AV industry. It allows very high quality transmission over long distances without interference.
Some terms you may hear which are meant to sound technical but are in fact meaningless:
DFA or DDA – Does F All or Doesn’t Do Anything. Listen out for a sound tech saying he’s just adjusting the DFA control. Magically it often fixes things. Call it a placebo…
Flux Capacitor – from the movie “Back to the Future”, the invention that made time travel possible. It doesn’t exist in any AV discipline but sounds very convincing so may be used in the same context as the DFA button.