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Audio Signal

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An audio system is calibrated when all VU meters respond in the same way to a ... Here the line-out of the audio mixer is calibrated with the input (recording ... – PowerPoint PPT presentation

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Title: Audio Signal


1
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
2
Microphones
  • Mics are classified by either
  • their generating element (transducer)
  • dynamic
  • condenser (electret)
  • ribbon (velocity)
  • their pickup pattern
  • omnidirectional
  • cardioid or unidirectional

3
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
4
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

5
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

6
Omnidirectional Pickup Pattern
7
Omnidirectional Pickup Pattern
8
Cardioid Pickup Pattern
9
Cardioid Pickup Pattern
10
Hypercardioid Pickup Pattern
11
Connectors
12
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.

13
Mixer Inputs
Each input module requires that you select either
the mic or line input.
14
Mixer Output/VU Meter
The mixed and quality-processed signal is then
routed to the output, sometimes called line-out.
15
Volume Unit (VU) Meters
Analog VU Meters
VU meters measure the volume units, the relative
loudness of amplified sound.
Digital VU Meters
16
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.
17
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.
18
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.

19
Digital Audio
20
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
21
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
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