Sound Reinforcement Midterm
When using an 31 band graphic EQ, the frequency band filters adjust ____.
1/3 of an octave only when placed at maximum boost.
Why is a condenser microphone so much more sensitive than a dynamic microphone?
A condenser mic's diaphragm has a very low mass, therefore it can move a lot faster than a dynamic mic, which has a much greater mass.
The two rules to microphone selection and placement are: There are no hard and fast rules, but never use a mic for anything other than it's manufactures intended use. If it sounds good then it is good.
False
When a compressor has a high ratio and long release time you may hear the level of the audio rise and fall. This effect is called breathing.
False
When considering stereo microphone techniques you must remember that coincident miking techniques are more likely to cause phase problems.
False
The sensitivity rating of a microphone is related to the...
Max SPL setting of a microphone
Digital processing is a serial process of several discrete steps where each step takes a small amount of time to complete. This amount of time is known as _____.
Latency
This amplifier type uses pulse wave modulation (PWM) to amplify signals.
Class D
Select the answer below that places the following items in order to complete a basic signal flow for a sound reinforcement system.
Microphone, Mixer/Console, Effects Processors, Power Amplifier, Speaker
If I were to place a microphone 20 cm away from a sound source, this this would be considered...
Mid-miking
Which of the following are the primary functions of a mixer?
Mix audio signals, route audio signals, process audio signals, and amplify signals to line level
No routing to subgroups or main L/R Bus
Monitor Mixer
Offer extensive talkback features to communicate with the performers.
Monitor Mixer
Takes the idea of a Mix Matrix and expands it out to the entire mixer.
Monitor Mixer
A line level, and typically pre-fader output used to feed headphones and/or a speaker on the stage for the band.
Monitor Outputs
When miking a sound source near a reflective surface, such as miking a person at a podium, the sound can reflect off of the surface an create phase interference known as comb filtering. An approach to solve this problem is...
To move the microphone as close to the sound source as practically possible, and to replace the microphone with a boundary micophone
It is generally agreed that most humans cannot hear Total Harmonic Distortion below 0.5%
True
___________ is used to prevent dropouts caused by radio cancelations at the antennas when using wireless microphones. Additionally, it is best practice to separate the antenna by a minimum of __________ wavelength.
Multiple antennae, one half
The Amplifier's output wattage should be twice as high as the power handling capability of the loudspeaker.
True
The Class A Amplifier is biased so that the output devices are always conducting electricity, even if there is no input signal present.
True
The inverse square law states: "For every doubling of distance from a sound source, the intensity of a sound is reduced by four times it's strength."
True
A mid-side microphone technique uses...
One cardioid microphone facing the instrument and one bi-directional microphone facing to the side.
When choosing a microphone for any application, you should consider the SPL of the source, distance from the source, coverage area and need for isolation, feedback control, tone, and cost.
True
A fader that controls signal levels at multiple channels with a voltage, but never actually combines the audio onto one shared electrical conductor.
VCA
sound system is more likely to have reflection issues when...
The room has a lot of hard materials in it such as wood or stone
When operating an amplifier in bridge mode...
You will hook up the + terminal of channel 1 and the - terminal of channel 2 to your speaker Both channels of the amplifier operate together to double the output voltage
Dampening factor is only an issue for...
Your low frequency audio content.
A compressor set to have "brick wall" limiting will have a ratio of...
∞:1
When phantom power is turned on at the mixer, +48v is supplied to pin(s) ___ of the XLR plug of a microphone.
2 and 3
Allows the engineer to listen to the audio from a channel with relative mix and panning levels in his/her headphones.
AFL
Select all of the following attributes of a parametric equalizer.
Adjustable Q, Adjustable Frequency, and Adjustable Gain
What is one of the easiest ways to reduce the effects of early reflections from side walls when placing loudspeakers in a room?
Aim the speakers inward
A ___ is an EQ that leaves all frequencies in tact but allows us to manipulate the phase of our audio signal.
All-pass filter
To place an EQ, compressor, or other external audio device onto a channel on my mixer I need to use a...
An Insert cable consisting of one TRS to two TS cables
An output that sends various combinations of the input signals to off-board processing equipment.
Auxiliary Sends
A typical mono channel input will have all of the following input jacks.
Balanced Microphone Input (XLR), Balanced Line Level (TRS), Insert Jack (TRS)
A shared electrical conductor for multiple audio signals to be mixed together, then accessed and processed from a single channel.
Busses or Subgroups
It is easier to absorb low frequency sounds than it is to absorb high frequency sounds.
False
What mic(s) best rejects sound from the back?
Cardioid
What mic(s) take advantage of a "port" to create their polar pattern?
Cardioid, Super cardioid
What Mic(s) are subject to proximity effect?
Cardioid, Super cardioid, Bidirectional
Since vocal ensembles are spread out over a larger area it is typically best to use two _____ microphones because of their sensitivity.
Condenser
Which microphone type requires a small built-in amplifier to amplify the voltage fluctuations from a sound source before it is sent to the mixer?
Condenser
___ is a graphic EQ where the bandwidth of each filter does not change when the slider is moved.
Constant-Q
The change of direction of travel of sound waves caused by the interaction with an object.
Defraction
When the energy of a sound is propagated in many directions by an irregularly shaped object.
Diffusion
What are the most common types of microphones in live sound reinforcement?
Dynamic and condenser
When referring to reverberation, _________ are sounds that arrive within the first 80ms of the direct sound and add to the perceived loudness of the sound.
Early Reflections
_________________ is important because it measure the noise created at each channel's preamp. If it is too high the console will have a large amount of noise when adding each channel together at the main outputs.
Equivalent input noise
Post-Fader sends are always used for monitors and Pre Fader sends are always used for effects.
False
A chorus effect needs to do two crucial things, delay a copy of the signal and add a flanging effect into that copy.
False
A good way to quickly assess the early reflective properties of a room is to excite the acoustics of the room by whistling.
False
In order to split an audio signal to two mixers, a passive or Y splitter is used to prevent noise from increasing on our microphone signal.
False
______ is the term used to refer to the equipment or resources whose primary function is to provide audio coverage to the main audience area.
Front of House (FOH)
Combines multiple input signals into one or more output signals, but it's primary focus is on mixing for the audience.
Front of House Mixer
Shares Aux Sends for both Monitor and Effects uses
Front of House Mixer
In general when frequency ________, wave length ________.
Goes up, decreases
Energy absorbed by acoustic panels is released as...
Heat
When considering an Amplifier's signal to noise ratio, an engineer must take note of the weighting system used to measure the noise. If a ______ is used, the midrange frequency content will be emphasized more than any other weighting system.
ITU-R-468
___________ is the total opposition that an electronic device gives to alternating current.
Impedance
The ____ of a room gives us information about the intensity of reflections, or reverberation, inside the space.
Impulse response
moving a microphone closer to the outside of a guitar amplifier will _____
Increase the bass response of the microphone
What Mic(s) will equally respond to sound from all directions?
Omni directional
_______ is a stereo near coincident technique using two cardioid microphones placed at a 110 degree angle.
ORTF
What are the connections and/or switches found on a DI box?
Parallel output / amplifier output, balanced XLR output, pad switch, ground lift
What effect does the audience have on the perception of sound in a space?
People absorb high frequencies, the type of clothing will affect how much is absorbed, and the sound can change based on if the audience is standing or sitting
What type of noise signal, that is equal energy per octave, is most commonly used to assess speaker performance?
Pink Noise
Which of the following items are not a primary requirement for a sound system?
Portability
A ___________ is a mixer with the speaker's amplifier built into it.
Powered mixer
The striking of a sound against a large flat object that propagates the energy at an angle equal to the angle of incidence.
Reflection
The best way to prevent plosives in a microphone is to...
Remove frequencies below 80 hz with a high pass filter, move the microphone out of the direct path of the plosive, move the mic back by at least 8 cm, and use an omni-directional microphone to reduce proximity effect and, therefore, the plosives.
Two mono channels that typically only accept line level inputs, and are managed by one set of controls.
Stereo Channel
What is the likely result of a person cupping a microphone like in the image below?
The Microphone will be much more likely to feedback
A class B amplifier will more than likely never be used in live sound because...
The amplifier creates a crossover distortion.
What happens if you exceed the maximum output voltage of a power amplifier?
The output signal will clip
A linear phase filter preserves the time relationship of a complex waveform and, therefore, eliminates the distortion of transients in dynamic music.
True
A room that has too much absorption will sound dead, and a room with too little absorption can make it difficult to hear.
True
