Download Audio

Audio Signal
sound waves of
compressed air molecules
diaphragm
permanent magnet
moving core
waves of electrical energy
coil
Microphone
coil and core
magnet
electrical signal
diaphragm
Speaker
sound waves
Microphones
Mics are classified by either:
 their generating element (transducer)
 dynamic
 condenser (electret)
 ribbon (velocity)
 their pickup pattern
 omnidirectional
 cardioid or unidirectional
Generating Elements Transducers
output voltage
polymer film diaphragm
diaphragm
impedance converter
spacer
output voltage
magnet
voice coil
permanently charged
electret coating
perforated back plate
magnetic
structure
Dynamic
Microphone Element
Condenser Microphone Element
Performance Characteristics of
Mic Transducers
 Dynamic mics
 durable, have good sound quality
 Condenser mics
 excellent sound (good frequency
response), require a power source, are
somewhat fragile
 Ribbon mics
 produce warm sound (excellent frequency
response), are extremely fragile
Dynamic and Condenser Mic
Pros and Cons
Dynamic Mic Advantages
Condenser Mic Advantages
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Rugged
Lower Cost
No Power Required
More Sensitive
Better Audio Quality
Can Be Extremely Small
Dynamic Mic Disadvantages
Condenser Mic Disadvantages
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Lower Sensitivity and Power
Output
Larger and Heavier
Slower Response Time
Not the Best Choice for
Maximum Audio Quality
Higher self-noise
More Fragile
More Expensive
Prone to Weather Problems and
RF Interference
Omnidirectional
Pickup Pattern
Omnidirectional
Pickup Pattern
Cardioid Pickup Pattern
Cardioid Pickup Pattern
Hypercardioid Pickup Pattern
Connectors
XLR connectors
phono plug
RCA phone plug
mini plug
Audio Mixer
Select and amplify the incoming sound
signals.
Control the volume of the various inputs.
Mix or combine and balance two or more
incoming sound signals.
Mixer Inputs
Each input module
requires that you select
either the mic or line
input.
Mixer Output/VU Meter
The mixed and qualityprocessed signal is then
routed to the output,
sometimes called line-out.
Volume Unit (VU) Meters
Analog VU Meters
VU meters measure the
volume units, the relative
loudness of amplified
sound.
Digital VU Meters
Calibration
An audio system is calibrated when all VU meters respond in the same
way to a specific audio signal—the control tone. Here the line-out of
the audio mixer is calibrated with the input (recording level) of the VTR.
Both VU meters show the same value.
Mixing Control—Analog Audio
100%
60%
Create proper
balance of sound.
Keep VU meter(s) in
range between 60100% (-5 to 0).
VU above 100%
distorts
VU below 60%
sounds weak and
may introduce noise
into the audio signal.
“Riding the gain”
means adjusting the
input faders to
maintain optimal
level and balance.
Digital Audio
Display
Stereo
meters
Calibration—Digital Audio
Stereo
meters
Display
Contrast
control
Left Tab
Scroll button
[F1]–[F4] buttons
Right Tab
Scroll button
Digital sound is
especially
susceptible to
overmodulation.
You should
therefore set the
audio levels
somewhat lower
than for analog
sound.
To calibrate our
digital console
feed a -12db tone.
That is the optimal
level for Final Cut
Pro.
Mixing Control—Digital Audio
Display
Left Tab
Scroll button
[F1]–[F4] buttons
Digital sound is
especially
susceptible to
overmodulation. You
should therefore set
Stereo
the audio levels
meters
somewhat lower
than for analog
sound.
Contrast
Set the input faders
control
at a maximum of -15
to -12db rather than
0db.
“Riding the gain”
means adjusting the
Right Tab
Scroll button
input faders to
maintain optimal
level and balance.