Chapter 9 Flashcards
(22 cards)
Transducer
changes energy from one form to another
-in a microphone, changes sound waves to electrical
Dynamic Mics
- Moving coil microphone
- Mylar diaphragm attached to a voice coil
- movement within the magnetic field produces voltage in the coil which becomes the output signal
- Electromagnetism produces the signal
- do not require external power sources
- generally inexpensive
Ribbon Mic (Velocity)
Ribbon like metal placed between two poles of a magnet
- Ribbon vibrates between the magnetic poles when struck by sound waves creating a small amount of voltage in the ribbon - Voltage in the ribbon becomes the output signal - Sensitive to shock, fragile, large size
Condensor Mics
- Capacitor-electrical component with two electrodes (+and -)
- Variable Capacitance-diaphragm and backplate act as the electrodes of a capacitor
- Sound waves strike the diaphragm, distance between two electrodes changes producing a charge in the capacitance
- Requires power
- Electret Condenser- small microphone that does not respond well to high frequencies
- Phantom Power (+48V)-power supplied to the microphone along the same cable as the audio
- More fragile, expensive, more sensitive, have a better frequency response, and do not respond as well to sudden higher noises when compared to Dynamic microphones
Polar Response Charts
pickup patter of a particular microphone
- head of the microphone is at the center of the chart - sounds from top are on-axis - sounds from side are off-axis - Major polar patterns are
Frequency Response
omnidirectional: picks up sound equally from all directions
- More directional at higher frequencies(point at source)
- unidirectional-pickup sound from only one direction
- reduce background noise reverberation from off axis sounds and excessive reverberation
- cardioid patterns: super cardioid, hyper cardioid, cardioid
- bidirectional: picks up sound equally from two directions
- figure eight
- ribbon microphones usually have a bidirectional polar response
Impedance
amount of resistance a signal encounters in a microphone circuit
- more impedance = less signal - overload-too much signal, sound is distorted
Handheld Mics
dynamic or condenser
-can gather sounds quickly from multiple sources
Mounted Mics
studio or shotgun mics
- Studio: large microphones that are typically not moved - Shotgun: mounting the mic on the camera, boom stand, or fishpole
Lavaliere Mics
usually condenser
- acceptable appearance on camera - most use AA batteries - Omnidirectional pattern usually
Multiple Application Mics
change configuration using switches
Wireless Mics
AKA Radio frequency microphone
- prone to interference - they have two frequency ranges
UHF
Ultra High Frequency
- radio frequency electromagnetic waves: 300 mhz – 3 ghz - broader audio channels = higher fidelity (high quality)
VHF
very high frequency
-Radio frequency electromagnetic waves: 30 MHz – 300 MHz
Pop Screen
Helps with Plosives
Balanced Audio Lines
Mic signal is carried by two leads instead ofone
- Shield is the ground, conductor leads are isolated from other electrical component - Less susceptible to RF interference and hum
Unbalanced wires
Typically found on consumer level products
-Single conductor carrying the positive signal and a shield carrying the negative signal of the circuit
XLR inputs
Cannon connectors
male and female ends
- 1/4 inch and 1/8 inch - May lose audio frequencies on long wires - Amplification to the line level helps reduce the loss of signal
Filters
high pass filter: reduces bass and rumble by cutting out low frequencies
- low pass filter: reduces hiss by cutting out high frequencies - switchable attenuator pad-reduces impedance by 15, 20, 25, dB to avoid overload distortion - Line Adapter: reduces line level to mic level - Presence Adapter: slight boost in upper midrange frequencies to improve the intelligibility - Response Shaper-slight dip in midrange frequencies to reduce sibilance
NAt sound
background Audio natural sounds
Room tome
Natural sound of room - ambience
Mic Pre
amplifies low voltage, low impedance signal of mic to proper level for recording
