Live Sound Flashcards
What is a PA system?
Public address system
Made up of high freq drivers, mid freq drivers, low freq drivers and sub drivers
How do you estimate the power required for a PA system?
You allocate an average of 5 watts of total PA power per audience member.
e.g, a small pub of 100 people, should have about 500-watts PA
What is the PA wattage allocation?
Subs 50%
Mids 35%
Highs 15%
What is point source?
a point source system is where the audience member is supposed to be able to hear a pure sound from each speaker (not blurred).
A point source loudspeaker is just what its name suggests: a single speaker, or multiple speakers placed far apart, broadcasting a full range of sound from a single point. (Actually, a true point source speaker is impossible, but we’ll retain this description for simplicity’s sake.)
What is a line array?
A line array system, the listener gets a blurred sound from all speakers.
A line array PA system features a number of identical (or nearly identical) loudspeakers arranged in a vertical line: hence the name.
What size are high frequency drivers usually?
Between 0.5 - 2 inches
What size are low frequency drivers usually?
Between 12 inches or more
What is the difference between hazard and risk
Hazard is anything that may cause harm
Risk is the likelihood of harm being caused
What is a risk assessment sheet?
A sheet that lists all potential hazards, their danger rating and the likelihood rating
What is the linkwitz-riley curve
in a typical linkwitz-riley curve (or filter) the idea is to reduce the level at the crossover frequency enough that we don’t hear a change in level near that frequency
What is a passive crossover?
passive crossovers are typically built into speaker enclosures.
they receive amp level signals and are usually fixe frequency - meaning you cant change them
What are active crossovers?
active crossovers have transistors and require AC mains to work. They receive line level straight from the mixing console and then send line level to the amps
Which type of crossover are you more likely to see at smaller shows?
Passive crossovers
What are main safety considerations in live sound
Clamp all cables and never disconnect the earth ground
Never exceed 140 dB
What is a risk assessment sheet
a sheet that lists all potential hazards, their danger rating and likelihood rating
