Microphones and Level

audio transducers

Convert between changing pressure (sound) and changing voltage (audio signal)

three building blocks

housing, membrane, element

membrane

transfer between acoustic to mechanical energy

what part of the mic is the membrane

diaphragm and speaker cone

the element

transfer between mechanical and electrical energy

dynamic

a voice coil suspended in a magnetic field

condenser

capacitor tied to an amplifier circuit

the housing

determines directionality of microphone

faradays law

a conductor moving through a magnetic field forces the current to move through the conductor

the dynamic element

pressure changes move diaphragm, voice coil moves through the magnetic field, current is forced back and forth, output voltage goes up and down

the condenser element

made up of two conductors, needs external power (phantom power 48 volts)

how condenser elements work

Pressure changes move the diaphragm, changes the distance between the diaphragm and the backplate, "storage capacity" of the element changes with the change in distance, output voltage rises and falls.

microphone attributes

-Frequency response
-transient response
-sensitivity or efficiency
-directivity or directionality

signal level too high vs too low

distortion vs distortion and noise

peak level

actual instantaneous level

VU/RMS

represent loudness of a signal

nominal level

-15dBFS