midterm
What are the controls or a PEQ
Frequency select, bandwidth, cut/boost
What does RT60 determine
Reverb decay time
What is a direct box used for
High impedance to low impedance / Unbalanced to balanced
What is the amount of latency that some people will start to be able to hear
3-5ms
Describe side-chaining comp, give example
sidecahining comp is where a signal from one input channel engages comp on another channel when played. E.g music track is compressed when a DJ talks.
What is three octaves above and below 400hz
3200hz, 50hz
What are three ways that you can use a compressor
sidechain, inserting, parallel comp
2 speakers in series If a speaker was 8Ω what would the total impedance be
16Ω
Explain the basic operation of how piezo transducers work
a crystal is attached to a small diaphragm that moves and deforms the crystal which creates voltage.
TRUE OR FALSE: David Hughes coined the phrase “Rock and Roll”
false
What is another term for boundary mic
PZM - pressure zone mic
If frequency increases, what happens to wavelength (given constant speed)
wavelength decreases
What is the speed of sound in ft/sec and in meters/sec
1130ft/sec, 344m/sec
What is Dynamic range?
The difference in db between the loudest and quietest portion of a program
If frequency doubles, what happens to period
cut in half
What is the inverse square law
When the distance from a sound source by a factor of 2 there will be a change of +/-6dbSPL
What do the perforations in the backplate of a condenser diaphragm do
attenuates freq response from 8-12k
If you have an amp that is rated for 4Ω and four speakers that were 16Ω how would you wire them?
parallel
If you are 100ft from a wall and you clap your hands how long will it take you to hear the reflection from that wall?
v=D/T —- T=176ms
How much gain does phantom power add to a condenser microphone?
Phantom power does not add gain!
If you are 50ft from a sound source that is producing 100dbspl what would the level be at 75ft
20Log(d1/d2)-----20Log(50/75)= 97dbspl
What is an inductor?
An electrical compnet that is resistive to changes in current
What are three common weightings for SPL meters? Describe each one
A weighted - simulates human hearing at low levels
B weighted - less rolloff than A. Not as much roll off as C
C weighted - Flatter response
Linear/Z Weighted - FLAT response
Name 4 uses of a transformer
Voltage conversion
Current conversion
Isolation
Impedance conversion
If a 300W amp produces an SPL of 95db @ 1m, what would a 750W amp produce
db=10Log(750/300)=3.98db —- 95+3.98= 98.98dbSPL