Classes Of Microphones


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Classes Of Microphones

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