mics: the sonic lens
DESCRIPTION
Mics: The Sonic Lens. Recording Chain. A system or “ecosystem” for recording and playback. 3 Main Considerations for Mic Choice. 1) Transduction: how a mic turns sound to audio 2) Polar pattern: the directivity of a mic or the direction at which it picks up sound - PowerPoint PPT PresentationTRANSCRIPT
Mics: The Sonic Lens
Recording Chain
• A system or “ecosystem” for recording and playback
3 Main Considerations for Mic Choice
• 1) Transduction: how a mic turns sound to audio
• 2) Polar pattern: the directivity of a mic or the direction at which it picks up sound
• 3) Type: the shape of the body of the mic
Transduction
• Transduction w/ mic= turning sound to audio; vibrations to electricity
– Speaker is a transducer, but works in opposite way
• 2 main mic types:
– 1) dynamic
– 2) condenser
– 3) also ribbon (for string instruments; super sensitive, figure 8 polar pattern...don't worry about these)
Dynamic
• Do not require external power
• Rugged: drums, explosions
• Can handle loud noises with less distortion
• Does not pick up sound, esp. high frequencies as accurately because diaphragm moves slowly
• Great for beginning recordists, news reporting, etc.
Condenser
• Always require phantom power (+48 volts or some rarely want +24v/+12v)
• More “faithful” sound reproduction
• Cannot handle loud sounds for a long time
• Most used in sfx, Foley, broadcast/reality TV/film production recording (of mainly dialog), and studio
Phantom Power
• All condenser mics require power
• Some you can put a battery in (i.e. NTG-2)
• Many you cannot, thus they require Phantom Power, usually +48v
• This uses the power on your camcorder, audio recorder, or mixing board and will use such a device's battery
Polar Patterns
• Pickup pattern
• How a capsule (the sensitive transducer part of mic) “sees” sound from the front of a microphone
Omnidirectional
• Picks up sound at 360 degrees equally
– Except high frequencies (short wavelengths)
• Have nice natural sound
• Good for recording atmos (if a room/atmos has a nice tone)
• Least susceptible to wind induced noise
• Can also be good for the voice if you want natural reverb
Cardiod
• Unidirectional, heart-shaped pattern
• Rejects some sound on sides / back of mic
• Susceptible to wind-induced noise
• Point at sound source
• Used for dialog, sfx, and specific sounds to add to atmos (good for most applications)
Hypercardiod
• Unidirectional
• Some sensitivity in the back of the mic
• Susceptible to wind-induced noise
• Mostly used in sfx, music, and Foley
Supercardiod
• Rejects most side sound and ALL on the back of mic (Rode NTG-2)
• Unidirectional
• Use when sound source is far from mic or lots of ambient noise
• Susceptible to wind-induced noise
• Mostly used in tv/film dialog, but fine for sfx/Foley
Shotgun
• Aka “boom” mic
• Focus on sound in front of mic
• Pulls sound closer like zoom lens
• Best mic dialog on TV/film captured with this, SFX that you have to capture from a long distance (i.e. bird sound in a tree)
Spaced Pair Stereo
• 3:1 rule (place the mics 3 times as far from each other as they are from the sound source).
XY Stereo Recording
Type
• Shotgun
• Handheld
• Lav
• Binaural
Accessories
• Air diffusion
• Vibration dampening
• Why?
Cables and Connectors
• Balanced vs. Unbalanced
• Unbalanced: more susceptible to hum
– Most consumer audio: RCA, 1/4”, 1/8”
– Work at short distance
Cables and Connectors Cont’d
• Balanced: rejects hum, AC and RFI noise and other low frequency interference
– Can only use phantom power (+48v)
– ALWAYS use in professional audio production
– Can work at long and short distances
– Avoid using unbalanced outputs w/ balanced inputs
– 1/4” and 1/8”, but must be TRS to be balanced
Line Level vs. Mic Level
• Line Level=a higher level signal
– Line input for: audio mixer, iPod, computer, CD player, etc.
• Mic Level=lower level signal
– Mic input: has a mic preamplifier to boost the signal (some mics also require +48v)
– If you plug a line device into the mic input will get a loud, distorted signal
Other Factors
• SPL= sound pressure level
• Frequency response: range of frequency a mic can reproduce accurately
• Flat frequency: preferred as it doesn't “color” sound. You “equalize” this in post.
– Look for a mic that is 20Hz-20KHz for flat frequency
Other Factors Cont’d
• If hiding a mic under actors' clothing, find a mic that responds/emphasizes high frequencies. Why?
• HPF: high pass aka low cut filter. Reduces low frequencies (i.e. AC/fridge/traffic rumble.)
– Don't use usually
Proximity Effect
• When mic is too close to sound source
• Increases low frequencies
• Make voice, sound, instrument sound more bassy or booming
• Move mic away a bit to correct this