Understand what a microphone is, in the audio-signal chain.
Discuss the three main categories of microphones and define the Advantages and Disadvantages of these types.
Explain some of the leading brands of microphones and illustrate when and where these are used.
Classify all the Polar Patterns for microphones .
Be able to recognise the three main microphone categories used in studios: Dynamic, Condenser, Ribbon.
Relate to when and where these three microphone types can and should be used in recording.
Indentify common types of microphones brands and explain what category of microphone they are.
Able to list five other types of microphone categories.
Distinguish all varieties of Polar Patterns and identify what microphones from the three main categories they relate to.
What is a microphone?
A microphone is an example of a transducer, a device that changes information from one form to another.
Sound information exists as patterns of air pressure (sound-waves) the microphone changes this information into patterns of electric current.
The purpose of the microphone is to convert the sound-wave into an electrical audio-signal
Converts sound into an electrical signal:
(air pressure -> movement of conductor/coil -> magnetic field -> signal)
Can you name 4 types of microphone?
What are the most common microphones in a studio?
I ain’t getting on no plane!
I ain’t getting on no plane!
Based around the electromagnet principle. Very much like a speaker, but in reverse.
Dynamic microphone use a wire-coiland a magnet to create an audio signal.
Sound-waves hit the diaphragm, this connected to the moving wire-coil into (or around) the magnet producing an electric current.
“Velocity Sensitive” – determined by the speed of the sound-waves.
Polar Patterns can alter, but usually that of ‘Cardioid’ or ‘Hyper-Cardioid’.
Moving Coil wire
Early example of a microphone, used in old phones
Small Diaphragm Dynamic
Vocals, Snare, Kick-Drum, hi-hat, guitar amplifiers
Large Diaphragm Dynamic
Tom-Drums, kick-Drum, Amplifiers
SHURE SM57 + SM58, Sennhesiser MD441
AKG D112, SHURE SM7, Sennhesiser MD421
Advantages of Dynamic Microphones:
Rugged (strong, durable)
Good for High SPL and Sudden SPL
Easily produced (maybe not so good for the customer?)
Resistant to Moisture
Disadvantages of Dynamic Microphones:
Normally tailored frequency response; i.e. Primarily for vocals (SM58)
Reduced of high frequencies
Generally FIXED Polar Patterns
Cab have a lack of clarity
Condenser microphones, also known as a Capacitor or Electrostatic microphone.
Sound-waves change the spacing between a thin metallic membrane (Diaphragm) and the stationary back plate.
They require a power source, provided either via microphone outputs as Phantom Power (48v from desk) or from a small battery.
Power is necessary for establishing the capacitor plate voltage, and is also needed to power the microphone electronics.
The voltage across the resistor is amplified for performance or recording.
Front Plate (Diaphragm)
Power to charge the plate
Open Condenser Microphone
Small Condenser Microphones
Snare, hi-hat, guitar amplifiers, possibly Live vocals
Large Condenser Microphones
Studio vocal, Tom-Drums, kick-Drum, ambient recordings
RODE NT1, AKG 414, sE 3300A
AKG C1000,RODE M3, AKG C451
Advantages of Condenser Microphones:
High Out-Put level
Excellent frequency response
Quite common to have Variable Polar Patterns
Disadvantages of Condenser Microphones:
Requires external power source
Not resistant to moisture (new models are better)
Ribbon microphones use a thin, 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.
Known as "velocity" microphones.
Basic ribbon microphones detect sound in a bidirectional (figure-eight) pattern, because the ribbon is open to sound both front and back.
Crossed figure 8 (Blumlein pair), stereo recording and the figure 8 response of a ribbon microphone is ideal for that application.
Sounds arriving from the back will produce polarity oppositeto those arriving from the front.
RCA “44” - Produced in 1931, it was a breakthrough technology in sound, and revolutionized the audio recording.
Common to see artists of the 50’s with these microphones.
Advantages of Ribbon Microphones:
Relatively flat frequency response
Needs no external or internal power
Many believe it adds “warmth” to the recording sound, this could be due to a swell at low/mid frequencies.
Disadvantages of Ribbon Microphones:
Liable to lose quality from wind noise (not for outside recording)
Often demonstrate the ‘Proximity Effect’
The proximity effect in audio refers to a change in the frequency response of a directional microphone as the sound source is brought close to the microphone. The result of the change is a disproportionate increase in the bass response of the microphone.
Examples of Ribbon Microphones:
Example of Ribbon Microphones - Stereo recording “Blumlein Pair”
1. Shotgun Microphones
Highly directional microphone, name comes from the Polar Pattern.
Sound arriving from the side is reduced
Used normally for news reports, wildlife recording and TV/Movie sets.
2. Lapel Microphones
Usually condenser microphones with a omnidirectional Polar Pattern, due to the small sound shadow.
Can have problem with handling noise, placement important.
3. PZM Microphone
‘Pressure Zone Microphone’
Designed to decrease the amount of reverb when recording in a large room
Placed against a flat surface, record reflected sound-waves hitting from all angles.
4. Wireless Microphones
Consist of three main elements Input (Mic.), transmitter and receiver.
Common in live performances
Work within VHF (Very High Frequencies) and UHF (Ultra High Frequencies). Transmit between 300 MHz and 3 GHz
5. Parabolic Microphones
Similar to a radio telescope, essentially a ominidirectional microphone. However the dish focuses all the sound into one point.
Microphone faces the dish, the sound is then focused into it.
Used for sports broadcasting, eavesdropping, law enforcement, and even espionage.
Microphone Polar Patterns
A microphone's directional response (Polar Pattern) indicates how sensitive it is to sounds arriving at different angles about its central axis.
Some microphone designs combine several principles in creating the required polar pattern, allowing you change the pattern.
Example of a Cardioid Pattern in 3D
Important Phrases to Remember:
Area in Polar Pattern that is decreased in supremacy and signal strength. Example, standing at 180° to the front of a CardioidMicrophone, weak signal level.
Area in Polar Pattern where signal strength is strong. Example, the front of a Shotgunpattern or at the very back of a Hyper-Cardioid.
The decrease of amplitude in a signal as it passes from one point to another. Example, the slow loss of signal strength as you move around a Cardioid Pattern.