sound reinforcement Flashcards
with respect to cabling, magnetic fields are only canceled by two things. what are they
shielding, twisting
condenser microphone
voltage 9 and 48 volts applied to diaphragm
responsive and quality sound
slightly more sensitive to environmental factors
what causes hum
leakage of AC power:
- poorly isolated power transformer
- power supply issue
a loudspeakers sensitivity rating denotes what
efficiency of speaker. power in to energy out
what type of cables should be kept to 10 ft or less in length
high impedance cable
common cause of noise
improper:
grounding
ground loops
shielding
ACTIVE crossovers are inserted __________ the power amplifier
before
compressor
compress signals from a high and low frequencies
what is the overall frequency band of the human voice
100hz to 6Khz
when you need to measure loudness use a
sound pressure level meter.
multiband equalizer
boost and cut signals. last step
how does humidity affect sound
dry air absorbs more acoustical energy
an active crossover is also known as a _______ level crossoer
low
real time analyzer
used to obtain an instantaneous display of the frequency response
what two things is a passive crossover sensitive to?
load impedance
source impedance
how does temp affect sound
sound passes through hot air faster
outdoor audio systems are affected by what 3 environmental factors
temp
wind
humidity
what audio component can directly drive a loudspeaker
power amp
what is the best shielding you can use in a permanent install or within a rack or piece of equipment
foil because it has no penetrable points like a braid.
when you want to record the physical wave form
osilloscope
each time you double the number of microphones the system gain must be ____________ to avoid feedback
dropped 3 dB
low pass filter
cuts out high frequencies
when you need to know a signal source use
sine wave oscillator
what is special about a lavalier microphone
small and cab be worn on clothing maintaining a consistent distance from voice
three parts of a sound system
input transducer - signal processing - output transducer
what is the common name for a pin connector and who invented it
phono pin
RCA radio corporation America
when you need to test the polarity of a circuit use a
phase tester
what is the speed of sound
1130 feet per second at sea level at 59 degrees
oscilloscope
displays a visual representation of an electrical signal
passive crossovers are inserted __________ the power amplifier
after
phase testor
test polarity of a circuit
noise gate
shuts off mic when not in use
any piece of equipment used for sound reinforcement should cover what frequency range
20hz to 20khz
high pass filter
cuts out low frequencies
what is the function of a mixer
combine multiple inputs and create one output
dynamic mics
is like a miniature loud speaker
most common
durable]
reasonable insensitive to environmental factors
a passive cross over is also known as a ______ level crossover
high
sine wave oscillator
signal generator that produces a sine wave
when you have a pink noise generator as your test signal
real time analyzer
best connections for avoiding ground loops and noise
tin and tighten
limiters
limits either the high or the low frequencies not both
what is the typical impedance of a balanced low impedance line input
600 ohlm
define compression ratio as applied to audio systems
relationship between input and output transducers (2:1)
