Audio Signal

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Audio Signal
sound waves of compressed air molecules
diaphragm
permanent magnet
moving core
waves of electrical energy
coil
Microphone
magnet
coil and core
electrical signal
diaphragm
sound waves
Speaker
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Microphones

• Mics are classified by either
• their generating element (transducer)
• dynamic
• condenser (electret)
• ribbon (velocity)
• their pickup pattern
• omnidirectional
• cardioid or unidirectional

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Generating Elements -Transducers
output voltage
polymer film diaphragm
impedance converter
diaphragm
spacer
output voltage
magnet
voice coil
permanently charged electret coating
perforated back plate
magnetic structure
Dynamic Microphone Element
Condenser Microphone Element
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Performance Characteristics ofMic 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

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Dynamic and Condenser Mic Pros and Cons

• Dynamic Mic Advantages
• Rugged
• Lower Cost
• No Power Required
• Dynamic Mic Disadvantages
• Lower Sensitivity and Power Output
• Larger and Heavier
• Slower Response Time
• Not the Best Choice for Maximum Audio Quality

• Condenser Mic Advantages
• More Sensitive
• Better Audio Quality
• Can Be Extremely Small
• Condenser Mic Disadvantages
• Higher self-noise
• More Fragile
• More Expensive
• Prone to Weather Problems and RF Interference

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Omnidirectional Pickup Pattern
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Omnidirectional Pickup Pattern
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Cardioid Pickup Pattern
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Cardioid Pickup Pattern
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Hypercardioid Pickup Pattern
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Connectors
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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.

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Mixer Inputs
Each input module requires that you select either
the mic or line input.
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Mixer Output/VU Meter
The mixed and quality-processed signal is then
routed to the output, sometimes called line-out.
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Volume Unit (VU) Meters
Analog VU Meters
VU meters measure the volume units, the relative
loudness of amplified sound.
Digital VU Meters
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Calibration
To make all VU meters (usually of the audio
console and the record VTR) respond in the same
way to a specific audio signal.
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Calibration
An audio system is calibrated when all VU meters
respond in the same way to a specific audio
signalthe 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.
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Mixing ControlAnalog Audio

• Create proper balance of sound.
• Keep VU meter(s) in range between 60-100 (-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.

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Digital Audio
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CalibrationDigital Audio

• 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.

Stereo meters
Display
Contrast control
Right Tab Scroll button
Left Tab Scroll button
F1F4 buttons
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Mixing ControlDigital Audio

• Digital sound is especially susceptible to
  overmodulation. You should therefore set the
  audio levels somewhat lower than for analog
  sound.
• Set the input faders at a maximum of -15 to -12db
  rather than 0db.
• Riding the gain means adjusting the input
  faders to maintain optimal level and balance.

Stereo meters
Display
Contrast control
Right Tab Scroll button
Left Tab Scroll button
F1F4 buttons