Classes Of Microphones

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  • 1. Microphone Sensitivity How far the pattern reaches out for the sound
  • 2. Three Basic Classes of Mics
    • Dynamic
    • Electret Condenser aka ENG
    • True Condenser or RF Condenser
  • 3. Dynamic
    • Least sensitive class of mic
    • Generates own electricity
    • Sound is AC electricity
    • VU meters measure voltage
  • 4. Dynamic
    • Magnetic diaphragm acts like sail and moves within a magnet, thus generating electricity (audio)
    • Due to relatively heavy mass and strong resistance, requires loud sounds to push this diaphragm in and out
    • Dynamic mics only react to strong sounds
  • 5. Advantages of Dynamic Mics
    • Short reach, low sensitivity
    • Low handling noise
    • Low feedback
    • Extremely rugged, few parts/electronics
    • No batteries or remote powering needed
    • Loud SPL less likely to cause damage
  • 6. Applications for Dynamic Mics
    • Live stage performance
    • Live Audience Question & Answer
    • Isolated Narration or Voice-over
    • On-site Reporting
    • Eliminating noisy backgrounds
    • Compressing loud sound effects
    • As a hand prop
  • 7. Examples of Dynamic Mics
    • Audio Technica AT804 omni
    • Audio Technica ATM63 cardioid
  • 8. Examples of Dynamic Mics
    • Shure SM57 cardioid
    • Shure SM58 omni
    • Shure VP64 omni
    • ElectroVoice RE50 omni
  • 9. Electret Condenser
    • No longer generates electricity from scratch, but releases existing electricity from battery
    • Diaphragm is much lighter and travels within less resistance
    • Diaphragm movement alters capacitance of a circuit, thus discharging electricity
    • Able to react to subtle sounds
  • 10. Electret Condenser
    • Requires nominal voltage (1 to 6 vDC)
    • Usually provided by internal battery, such as AA or button cell
    • Some mics able to take advantage of remote Phantom powering
    • Wireless bodypaks provide power to lavaliers
  • 11. Electret Condenser
    • Much better reach & sensitivity than dynamic mics
    • Includes ENG shotguns and most lavaliers, some other special app mics (PZM, peanut gooseneck mics, etc)
    • Some music mics, but noisy when handheld
    • Shotgun mics are nicknamed ENG type mics
  • 12. ENG Mics
    • ENG = Electronic News Gathering
    • Medium quality shotgun mics
    • Less expensive than condenser
    • Self-powered from internal battery
    • Camera-mounted shotguns are for general ambiance, not sync bites
  • 13. Applications for ENG shotguns
    • Overhead boom up to 3 feet
    • Plant mics
    • Interview mics
    • As a spare backup for condenser
    • Location music and sound effects
  • 14. Examples of Electret Condenser
    • AT835b short shotgun
    • K6/ME66 short shotgun
    • AT825 stereo mic
    • AT851a, AT841a plate mics
  • 15. Condenser Mics
    • Superlite diaphragm alters capacitance of circuit. Disturbs RF field.
    • Extremely sensitive to faint sound
    • Requires 12v to 48v external power
    • Best mics to use for dialogue
  • 16. Remote Powering
    • 12v or 48v DC
    • Travels along mic cable up to mic while audio travels AC down the cable
    • Potential for problems
    • Two types of powering:12v T (A-B) and 48v Phantom
    • Power supplied by recorder, mixing board, or in-line battery supply
  • 17. T or A-B Powering
    • 12v sent up Pins 2 & 3 of mic cable
    • Created for early Nagra because 48v was not practical for location recorders (only 18v from 12 D batteries)
    • Normal T power is Pin 2 POSITIVE and Pin 3 NEGATIVE. Pin 1 is not used.
  • 18. T or A-B Powering
    • Nagra uses Pin 2 for Negative and Pin 3 for Positive
    • Mics rewired for Nagra are known as RED DOT
    • If mic is not RED DOT, then use a PHASE REVERSING cable to change the electrical polarity. Pin 2 becomes Pin 3, and vice versa.
    • Presence of T power will reduce volume or mute mics that are not T-power condensers!
  • 19. Phantom Powering
    • 12v or 48v DC is sent up mic cable
    • Pins 2 and 3 are both POSITIVE
    • Pin 1 (shield) is NEGATIVE
    • Presence of Phantom power does not interfere with normal mics
    • 48v Phantom is industry standard today, but there are still some 12v T mics out there.
  • 20. Phantom Powering
    • Power can be provided by newer Nagras, some recorders & camcorders, mixing boards, or battery power supplies
  • 21. Mic Powering
    • T-power and A-B power are the same
    • RED DOT is a variation of T-power
    • T-power and Phantom are totally different
    • Make sure you know what type of power your microphones require
    • Never assume. Plug them in and test them!
  • 22. Examples of Condenser Mics
    • AT4050 studio mic
    • AT3035 studio mic
  • 23. Examples of Condenser Mics
    • AT4073a short shotgun
    • Good up to 5 feet above actors
    • Better for interior, nominal for exterior
  • 24. Examples of Condenser Mics
    • AT4071a long shotgun
    • Good up to 8 feet above actors
    • Best for exterior or very open interior
  • 25. Examples of Condenser Mics
    • AT4051a cardioid condenser
    • Good up to 2 feet above actors
    • Best for eliminating echo from tight interiors
  • 26. Examples of Condenser Mics
    • MKH416T short shotgun (T-power)
    • MKH60 short shotgun
    • MKH816T long shotgun (T-power)
    • MKH70 long shotgun
    • MKH40 cardioid
    • Schoeps MK41 cardioid
  • 27. Selecting Shotgun Mics
    • Choose for optimum reach and tight pattern
    • OR choose for mellow voice and reduction of interior echo
    • Interiors: echo is main problem
    • Exteriors: background ambiance is main problem
  • 28. Long Shotguns
    • Offer maximum reach and tightest pattern
    • Best for exteriors, where background noise is a problem
    • Tight pattern makes them difficult to use at short range (interiors)
    • Indoors, they tend to increase echo
  • 29. Short Shotguns
    • Offer medium reach and medium pattern
    • Excellent general purpose mic
    • Best for interior medium shots
    • Moderate echo indoors
    • Moderate background rejection
  • 30. Cardioid “shotguns”
    • Not actually shotguns, but very sensitive cardioid mics
    • Wider patterns reduce or eliminate interior echo problems
    • Not good for rejecting noise
    • Short range, best suited for close-ups
    • Amazingly rich dialogue at close range