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Audio Signal

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. Microphones. Mics are classified by either:

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Audio Signal

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  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 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 Dynamic and Condenser Mic Pros and Cons

  6. Omnidirectional Pickup Pattern

  7. Omnidirectional Pickup Pattern

  8. Cardioid Pickup Pattern

  9. Cardioid Pickup Pattern

  10. Hypercardioid Pickup Pattern

  11. XLR connectors phono plug RCA phone plug mini plug 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 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.

  17. 100% 60% Mixing Control—Analog 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.

  18. Display Stereo meters Digital Audio

  19. Calibration—Digital 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 Left Tab Scroll button Right Tab Scroll button [F1]–[F4] buttons

  20. Mixing Control—Digital 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 Left Tab Scroll button Right Tab Scroll button [F1]–[F4] buttons

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