Microphones Flashcards
What are microphones?
Transducers which convert acoustical energy (sound waves) into electrical energy (the audio signal).
What do all microphones have in common?
They all have a diaphragm which vibrates when sound waves hit it; the vibrations are converted into electrical energy.
What is a transducer?
A device which converts energy from one form to another.
The four most common microphone types are…
Dynamic, condenser, ribbon, crystal
What are dynamic microphones?
Versatile microphones for general-purpose. They use a magnetic and a coil of wire to act as an electromagnet.
What are condenser microphones?
Microphones which use a capacitor ( 2 plates with a current) to convert acoustical energy to electrical energy. For this reason, they require external power (battery or phantom power)
What is phantom power?
A 44V current used to power condenser microphones.
What is the directionality of a microphone?
The sensitivity to sound from various directions this can also be known as the polar pickup pattern
What are the three categories of directionality?
Omnidirectional, unidirectional (cardiod, hyper cardiod), bidirectional.
What does omnidirectional mean?
The sound is captured evenly from every direction.
Uses of omnidirectional mics:
Ambient noise, moving sound source, sound from multiple directions.
What is a cardioid mic?
Unidirectional mic where the polar pattern is heartshaped. It picks up noise mostly from the front but some also from the sides.
Uses of cardioid mics:
Emphasizing sound from the direction the mic is pointed in but also some ambient noise.
What is a hypercardioid mic?
Exaggerate cardioid, eliminates most side sound and focuses on one subject. They are often called shotgun mics and have increased rear sensitivity.
Uses of a hypercardioid mic:
Isolating the sound from a subject when there is a lot of ambient noise, picking up a sound from a distance.
What is a bidirectional mic?
A figure-of-eight pattern, pics up sound evenly from two opposite directions.
Uses of a bidirectional mic:
Interviews.
What is microphone impedance?
The resistance against an AC current in a device.
What are the three impedance classifications?
Low (less than 600 ohms)
Medium (600-10000 ohms)
High (greater than 10,000 ohms)
Which is the best impedance?
High= cheap but produce poor quality over long distances. Low= more expensive but generally better.
What is microphone frequency response?
How a microphone responds to different frequencies, which are exaggerated or attenuated.
How is frequency response shown?
In a frequency response chart.
What does the x-axis of a frequency response chart show?
Frequency in Hertz
What does the y-axis of a frequency response chart show?
Response in decibels.
What is the difference between an XLR and a jack lead?
An XLR is low impedance and balanced, a jack leade is un-balanced and high impedance.
What is a balanced lead?
Carries the original and inverted version of the signal which combine to remove any spikes caused by interference.
Pros of a condenser mic:
Sensitive
Fast
Flatter frequency response
Cons of a condenser mic:
More expensive than dynamic
Needs external power
Not very robust
Pros of a dynamic mic:
No external power need
Durable- good for live performances
Cheaper than condenser
Cons of a dynamic mic:
Not as accurate/ sensitive
Lower sound quality
Examples of condenser mics:
AKG C451B
AKG C1000S
Examples of dynamic mics:
AKG D112
SHURE SM57
SENNHEISER e835
What is the proximity effect?
In dynamic microphones, lower frequencies are boosted as you get closer to a sound source.
What is coloration?
In dynamic microphones, the sound is not high fidelity but a certain tone is added.
What is SPL?
SPL is sound pressure level and condensor microphones are very sensitive to it
