UNDERSTANDING MICROPHONES by wpr1947

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									UNDERSTANDING
 MICROPHONES
   This PowerPoint will
         cover: -
• Different microphones types
• Microphone positioning
          Microphones
• Are the first link in the audio chain
• Try to capture as closely as possible the
  sound of an instrument
• BUT their sound quality can be affected by
  - their construction
  - their sensitivity
  - where they are placed (EG close/ambient)
    Microphone construction
  There are 3 basic construction types:
• Dynamic – accentuates the middle freqs
• Ribbon – rolls off the high freqs
• Condenser – well-rounded frequency
  response
       Condenser microphones
• Most popular for recording purposes
• Sensitive, accurate but can be expensive
• Consist of a very thin diaphragm suspended
  parallel to a backplate. When sound hits the
  diaphragm it vibrates, into the space
  between it and the backplate. This produces
  a small signal that can then be amplified.
• Require a small amount of voltage 9 or 48
  volts to function properly. This voltage is
  called phantom power.
       Dynamic microphones
• Most popular for live sound
• Can handle high volume sound (EG drums.
  Amplifiers, and some rock vocalists)
• Colour the audio, imparting a ‘gritty’ or
  ‘dirty’ sound to the signal
• Use a magnetic field to convert the sound
  signal from the diaphragm into electrical
  energy
• Are also very durable, tough, inexpensive,
  and easy to maintain
        Ribbon microphones
• Produces sound similar to the dynamic
  microphone, but using different materials
  (aluminum rather than plastic or Mylar)
• Not used as much as before) as they are
  expensive, fragile and aren’t as transparent
  as a condenser mic
• Have a unique sound though – often called
  ‘silky’ or ‘smooth’.
           Polarity patterns
• Microphones pick-up sounds in different
  ways, known as polarity patterns.
• 3 main ones:
  - omni-directional capture sounds from all
  around them
  - cardioid pick up sounds just in front
  - figure 8 (or bi-directional) pick up sounds
  from both the front and back
     Omnidirectional pattern

• Useful for capturing the
  sound source and the
  sound of the room it’s
  coming from.
• Not used for close-miking (less than 30cm)
  as too much background sound is picked up
          Cardioid pattern

• Reject sounds that are from
  behind them
• Common for live use as you
  can control the sounds you
  pick up
• When used close-miking emphasizes bass
  frequencies. This is called the proximity
  effect and is found only on cardioid mics
            Figure-8 patterns

• Capture sounds from the front
  and back, but not from the sides
• Used in recording studios to
  record 2 sounds simultaneously
  (EG 2 horn players with mic perpendicular to
  the players)
• Most figure-8s have same freq response for
  front and back
      What mic should I use?
1. Think about the frequency response of the
   mic EG a dynamic mic used on a
   symphony orchestra will lack the high-
   freq response. Similarly a small condenser
   mic on tom-toms will make them sound
   thin.
2. It can be a subjective thing, but the
   following list contains typically used mics
• Vocals - most people prefer large diaphragm
  condensers, unless you want a dirtier sound and use a
  dynamic for this.
• El. Guitar amp – dynamic, or small condenser
• Bass amp – either large diaphragm condenser or
  dynamic
• Acoustic guitar/stringed instruments – large or small
  diaphragm condenser, or ribbon. Dynamic mic has
  too limited freq response.
• Drum set – toms, snare and kick sound good with
  dynamics, because they don’t have any high freqs
• Cymbals – on a drumset use a pair of small
  diaphragm condensers. Dynamics lack the high freq
  response.

								
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