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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