VID102 DAY 3
Schedule Change Viewing Examples Audio Principles
Class Schedule
Electromagnetic Electrostatic/capacitance Ribbon
Methods of Transduction
Microphone Weaker signal, requires a pre-amp Mic level 2 mV to 1.2V
Professional Line +4dBu 1.23 V
Consumer Line -10dBu .316V
Speaker 4V
Signal Level Types
XLR Balanced 3 conductor
¼ Inch 2 or 3 conductor Balanced or unbalanced
Balanced Minimizes noise and rf interference, uses phase inversion,
helps with longer cable runs Unbalanced
No shielding
Connectors and Cables
The amount of give between your average level and the point of distortion
Clipping is the point at which you exceed your headroom and the limitation of the medium, resulting in distortion
Headroom
You want to have more signal then noise Noise is inherent in the environment and in
the equipment
Signal to Noise Ratio
Way in which a microphone will pick up the sound
This is influenced by the type of transduction Choosing the right polar pattern for the right
situation
Polar Patterns
Omni
Cardioid
Hyper-cardioid
Super-cardioid
Bi-directional
Sound Theory
Types of Transduction (Microphones) Describes the way in which the microphone
converts a sound source into an electrical signal.
Speakers do the reverse, an electrical signal is turned into an acoustic amplified sound Electromagnetic Electrostatic/Capacitance Ribbon
Sound Theory
Types of Transduction (Microphones) Electromagnetic
Dynamic microphone uses electromagnetic induction A small movable induction coil, positioned in the magnetic
field of a permanent magnet, is attached to the diaphragm. When sound enters through the windscreen of the microphone, the sound wave moves the diaphragm. When the diaphragm vibrates, the coil moves in the magnetic field, producing a varying current in the coil through electromagnetic induction.
Commonly used to capture loud percussive sounds with very strong transients.
Does not require an external power source
Sound Theory
Types of Transduction (Microphones) Electrostatic/Capacitance
Require 48v Phantom Power The diaphragm acts as one plate of a capacitor, and the vibrations
produce changes in the distance between the plates. variety of polar patterns Good at capturing full frequency sounds, captures subtle dynamics of a
performance Frequency Response is better
Ribbon use a thin, usually corrugated metal ribbon suspended in a magnetic
field. The ribbon is electrically connected to the microphone's output, and its vibration within the magnetic field generates the electrical signal. Ribbon microphones are similar to moving coil microphones in the sense that both produce sound by means of magnetic induction.
Microphone Specifications
Usually they are categorized by type of transduction and polar pattern
Polar patterns describe how a microphone will pick up a sound source.
Omni Cardioid Hyper-Cardioid Figure-8 MS
Omnidirectonal
low coloration; they add very little to the original sound. Being pressure-sensitive they can also have a very flat low-frequency response down to 20 Hz or below. Pressure-sensitive microphones also respond much less to wind noise and plosives than directional (velocity sensitive) microphones
Pick up sounds equally from all sides
Cardioid
named because the sensitivity pattern is heart-shaped.
Good rejection 180 degrees off axis (rear)
Pickup equally from the front and the sides
Subject to the proximity effect (closer you are to the source, the lower frequencies will be emphasized)
Fairly directional
Super-Cardioid/Hyper-Cardioid
Good rejection from the sides But some pickup from the rear Fairly directional
Shotgun
Good rejection from the sides
Narrower pickup from the rear
Highly directional Most Boom Microphones
Usually have interference tubing to phase cancel the sides and make more directional
Figure 8
Picks up from the front and rear
Hole in the center Commonly used for M/S
miking technique M/S or Mid Side is a
stereo miking technique which combines a figure 8 with a cardioid microphone, it provides a wide stereo image and when listening on headphones you get a sense of panning better then traditional stereo miking techniques.
Process of recording audio on set Starts in pre-production Specific crew positions Goal is to capture the cleanest possible
recording of set dialogue
Intro to Production Audio
The process of evaluating a location based upon the sound What will prevent you from capturing clean
dialogue What can be done to help you capture clean
dialogue What microphones should you use?
Location Scouting
Analysis of the script with a specific focus on sound Consider possible miking approaches Start thinking about post production Number of actors What equipment will be needed What are possible problems for sound?
Script Break Down
Production Mixer Boom Operator Video Assist Utility
Production Audio Crew
Request Gear Package Goes on the Scouting of locations Is responsible for running the mixer, the
recorder, and taking sound reports
Production Mixer
Is the on set Ninja Places microphones Responsible for positioning them selves
optimally for capturing dialogue without being seen in the frame.
Boom Operator
Utility is responsible for cable wrangling, batteries, helping the mixer, sometimes being a second boom op
Video Assist helps set up monitor feeds for the mixer
Utility and Video Assist
Read Chapters 3 and 4 Assignment #1
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