AET 2560 - Sound Reinforcement Final Exam 2023 Guide
with complete solution
illegal frequency bands
100 - 799 mHz
squelch
a circuit for preventing a radio receiver from producing audio-frequency output in the
absence of a signal having predetermined characteristics
diversity receiving
two antennas switching systems to pick up strongest signal from antenna
difference between limiting and compressing
compressor: a signal processor that for a given input amplitude range produces a
smaller output range
limiter: a signal processor in which some characteristic of the output is automatically
prevented from exceeding a predetermined value
side-chain input on a compressor
input to the gain reduction stage of circuit
allows external audio source to control gain reduction
gate
attenuates signals that register below the threshold; the gate opens when signals pass
the threshold
downward expander
when the signal level drops below the threshold, the signal gain is decreased
notch filter
a band-stop filter with a narrow stop band (high Q factor)
advantage of using stereo input channel over a reverb return
...
parametric EQ
provides both sweepable center frequencies and adjustable Q, as well as boost / cut
controls
semi-parametric EQ
provides control of the amplitude and frequency, but uses a pre-set bandwidth of the
center frequency
non-parametric EQ
...
graphic EQ
multi-frequency, band reject filter, or a band-pass / reject filter
LPF
low-pass filter; passes low-frequency signals and attenuates signals with frequencies
higher than the cutoff frequency
BPF
band-pass filter; passes frequencies within a certain range and attenuates frequencies
outside that range
, HPF
high-pass filter; passes high-frequency signals but attenuates signals with frequencies
lower than the cutoff frequency
threshold
certain dB point at which a compressor reduces the level of an audio signal if its
amplitude exceeds that point
ratio
amount of gain reduction
4:1 means that if input level is 4 dB over the threshold, the output signal level will be 1
dB over the threshold; the gain (level) has been reduced by 3 dB
attack
period when the compressor is decreasing gain to reach the level that is determined by
the ratio
release
period when the compressor is increasing gain to the level determined by the ratio, or,
to zero dB, once the level has fallen below the threshold
make-up gain
the gain for after a signal undergoes the gain reduction process of compression
personal PA
...
fixed installation
permanent, consistent, ready
inflexible, costly
distributed system
multiple sections of speakers, point source
headroom
the amount by which the signal-handling capabilities of an audio system exceed a
designated level
distortion
any kind of deformation of an output waveform compared to its input
usually clipping, harmonic distortion, or intermodulation distortion (mixing phenomena)
caused by non-linear behavior of electronic components and power supply limitations
crest factor
measure of a waveform, such as alternating current or sound, showing the ratio of peak
values to the average value
gain before feedback
a measure of how much a microphone can be amplified in a sound reinforcement
system before causing audio feedback
NL2, NL4, NL8
speakon connectors
NL2: 1+, 1-
with complete solution
illegal frequency bands
100 - 799 mHz
squelch
a circuit for preventing a radio receiver from producing audio-frequency output in the
absence of a signal having predetermined characteristics
diversity receiving
two antennas switching systems to pick up strongest signal from antenna
difference between limiting and compressing
compressor: a signal processor that for a given input amplitude range produces a
smaller output range
limiter: a signal processor in which some characteristic of the output is automatically
prevented from exceeding a predetermined value
side-chain input on a compressor
input to the gain reduction stage of circuit
allows external audio source to control gain reduction
gate
attenuates signals that register below the threshold; the gate opens when signals pass
the threshold
downward expander
when the signal level drops below the threshold, the signal gain is decreased
notch filter
a band-stop filter with a narrow stop band (high Q factor)
advantage of using stereo input channel over a reverb return
...
parametric EQ
provides both sweepable center frequencies and adjustable Q, as well as boost / cut
controls
semi-parametric EQ
provides control of the amplitude and frequency, but uses a pre-set bandwidth of the
center frequency
non-parametric EQ
...
graphic EQ
multi-frequency, band reject filter, or a band-pass / reject filter
LPF
low-pass filter; passes low-frequency signals and attenuates signals with frequencies
higher than the cutoff frequency
BPF
band-pass filter; passes frequencies within a certain range and attenuates frequencies
outside that range
, HPF
high-pass filter; passes high-frequency signals but attenuates signals with frequencies
lower than the cutoff frequency
threshold
certain dB point at which a compressor reduces the level of an audio signal if its
amplitude exceeds that point
ratio
amount of gain reduction
4:1 means that if input level is 4 dB over the threshold, the output signal level will be 1
dB over the threshold; the gain (level) has been reduced by 3 dB
attack
period when the compressor is decreasing gain to reach the level that is determined by
the ratio
release
period when the compressor is increasing gain to the level determined by the ratio, or,
to zero dB, once the level has fallen below the threshold
make-up gain
the gain for after a signal undergoes the gain reduction process of compression
personal PA
...
fixed installation
permanent, consistent, ready
inflexible, costly
distributed system
multiple sections of speakers, point source
headroom
the amount by which the signal-handling capabilities of an audio system exceed a
designated level
distortion
any kind of deformation of an output waveform compared to its input
usually clipping, harmonic distortion, or intermodulation distortion (mixing phenomena)
caused by non-linear behavior of electronic components and power supply limitations
crest factor
measure of a waveform, such as alternating current or sound, showing the ratio of peak
values to the average value
gain before feedback
a measure of how much a microphone can be amplified in a sound reinforcement
system before causing audio feedback
NL2, NL4, NL8
speakon connectors
NL2: 1+, 1-
