Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
69 Cards in this Set
- Front
- Back
define the dynamic range of a system
|
Difference in decibel between noise floor and the system's maximum output before distortion
|
|
define the noise floor of a live sound system
|
The amount of noise surrounding a system (i.e. planes, trains, automobiles) when there is no sound going through
|
|
define a live sound headroom
|
The difference between the softest and the loudest mix before distortion
|
|
Why do your master outputs have to be set to unity gain?
|
It prevents the amps from being underloaded
|
|
What is white noise?
|
The sound of the electrons moving within a system
|
|
What is the difference between white noise and pink noise?
|
White noise contains a 3dB increase of energy per octave.
Pink noise has equal energy at every frequency |
|
What causes popcorn noise?
|
Dirt, debris, and poor system maintenance
|
|
What causes harmonic distortion?
|
Excessive EQ on a weak passive system
|
|
What are the 4 kinds of noise that can be caused by a live sound system?
|
White noise
pink noise popcorn noise harmonic distortion |
|
What is a transducer?
|
anything that changes one type of energy to another
|
|
What is the speed of sound?
|
1130 ft/second or 740 mph
|
|
What is the speed of light?
|
186,242 miles per second
|
|
What advantage does a horn have over a direct radiator?
|
The throat of a horn produces a natural compression
the horn gives total control over the directional pattern |
|
Why would you place the horn below a direct radiator in a speaker?
|
to stop the bass from traveling too far
|
|
What is a common name for a direct radiator?
|
Woofer
|
|
What happens when natural elements hit the rear of a driver?
|
the voice coil goes into extra movements causing distortion
|
|
What happens when resonating frequencies escape the rear of a driver?
|
They move to the front and cause frequency cancellation
|
|
Why would you put a port on a speaker enclosure?
|
to re-enforce the sound of the low end frequencies
|
|
What does the diameter of a port determine?
|
which frequencies will be allowed to escape.. dependent on wavelength
|
|
What does the length of a port determine?
|
The sound delay. Prevents phase cancellation
|
|
What method of transduction do all speakers use?
|
Electromagnetic
|
|
what causes the stationary magnetic field in a speaker?
|
the voice coil surrounded by the magnet
|
|
What causes the secondary magnetic field in a speaker?
|
amplifier output through the voice coil
|
|
What determines the polarity of the speaker's secondary magnetic field?
|
The amplifier output
|
|
What causes the actual transduction of a speaker?
|
The interaction between the stationary and secondary magnetic fields
|
|
What are the 9 components of a speaker?
|
Pole piece
magnet gap basket spider former voice coil cone dome |
|
Define Voice Coil
|
A flat cable wrapped around the former
|
|
What does the former consist of?
|
Chemically treated heat resistant cardboard
|
|
Describe a stationary speaker magnet
|
donut shaped
fitted top to bottom with two steel plates |
|
What is the pole piece?
|
A steel rod inserted in the donut shaped magnet
|
|
What is the home of the voice coil?
|
The gap between the magnet and the pole piece
|
|
What is the dome?
|
The dust cover over the gap
|
|
What two things does the spider do?
|
Attaches the voice coil to the cone and the dome
Allows easy suspension to the voice coil |
|
Where does the speaker cone attach to?
|
The basket
|
|
What is the speaker basket?
|
The actual physical shape of the driver
|
|
what are the 4 speaker specifications?
|
Frequency response
Power handling Sensitivity Impedance |
|
Define a frequency response
|
A component's ability to produce an output signal with the same frequency range as the input signal
|
|
What is a typical speaker margin of error?
|
+/- 3dB
|
|
What is a typical amplifier margin of error?
|
+/- 1dB
|
|
What is a speaker or amp's state of tolerance?
|
The ability to produce an intended frequency response within a margin of error
|
|
What are the three ratings that determine a speaker's power handling capabilities?
|
Continuous rating
Program rating Peak rating |
|
How do you test the continuous rating of a speaker?
|
send a continuous low level sound through it to see how well the voice coil can handle the heat
|
|
What is the program rating of a speaker used for?
|
matching the power to the amplifier
|
|
How is a speaker's peak rating determined?
|
put a very loud signal to the speaker for 1/10th of a second
|
|
What are the three test levels that determine a speaker's sensitivity?
|
1 watt @ meter
1 watt @ 4 feet 1 milliwatt @ 30 feet |
|
What is the difference between impedance and resistance?
|
Impedance is the opposition to electrons in an AC circuit
Resistance is the opposition to electrons in a DC circuit |
|
What are the three types of impedance?
|
Source Impedance
Load Impedance Nominal Impedance |
|
What is the source impedance?
|
Impedance of the amplifier
|
|
What is the load impedance?
|
Impedance of the speaker
|
|
What is the nominal impedance?
|
The lowest amount of impedance the speaker will present to the amp
|
|
when doing a show, are speakers hooked up in series or parallel?
|
parallel ALWAYS!!
|
|
What is the measurement for current?
|
amps (i)
|
|
What is the measurement for impedance?
|
ohms (z)
|
|
What is the measurement for power?
|
Watts (p)
|
|
What is the measurement for pressure?
|
Volts (v)
|
|
What is the ohm's law formula for current?
|
I=v/z
|
|
What is the ohm's law formula for power?
|
P=i*v
|
|
What are the steps for calculating net impedance from a parallel setup?
|
1) invert each speaker's impedance (i.e. 8 ohms speaker becomes 1/8)
2) add the fractions for all speakers 3) invert the sum of the fractions 4) divide the denominator into the numerator The total is your net impedance |
|
how do you calculate net impedance for a series setup?
|
add the speaker impedances together
|
|
What happens when you cut the impedance in half?
|
You double the wattage
|
|
Why can't you connect an 8 ohm amp to a 4 ohm speaker?
|
load impedance cannot be lower than the source impedance
|
|
Under the insertion laws how many watts does one dB equal?
|
1dB=21 Watts
|
|
What is the insertion law?
|
Loss of no more than 1dB of signal in a passive crossover due to the heat of the fundamental electronic components.
|
|
What is the difference between a crossover cutoff point and the flat range of signal?
|
-3dB
|
|
What is a crossover slope?
|
The rate at which the frequency to its own intended driver will start to gradually fall off after the cutoff frequency point
|
|
What is the rate of a professional crossover's slope?
|
24dB/octave
|
|
What is the rate of a semi-professional crossover's slope?
|
18dB/octave
|
|
What is the rate of a first order consumer crossover's slope?
|
6dB/octave
|
|
What is the rate of a second order consumer crossover's slope?
|
12dB/octave
|