Microphone theory Flashcards
What are the 3 most important characteristics of microphones for live sound?
operating principle, frequency response and directionality
What are the secondary charateristics most important of microphones in live sound?
Their electrical output and actual physical design
What is meant by a microphones operating principle?
The type of transducer inside the microphone, that is, how the microphone picks up sound and converts it into an electrical signal.
What is a transducer?
a device that changes energy from one form into another, in this case, acoustic energy into electrical energy.
What are the two most common types of transducer?
Dynamic and Condenser
What components make up a dynamic microphone
diapragm, voicecoil and magnet which forms a miniature sound-driven electrical generator.
Describe how a dynamic microphone works
Sound waves strike a thin plastic membrane (diaphragm) which vibrates in response.
A small coil of wire (voice coil) is attached to the rear of the diaphragm and vibrates with it.
The voice coil itself is surrounded by a magnetic field created by a small permanent magnet.
It is the motion of the voice coil in this magnetic field which generates the electrical signal corresponding to the sound picked up by a dynamic microphone.
Which type of microphone requires phantom power?
Condenser micriophones
What is another name for a condenser microphone
Capacitor microphone
What is another name for a dynamic microphone?
Moving coil microphone
What is transient response?
Transient response refers to the ability of a microphone to respond to a rapidly changing soundwave.
What is the major factor in a microphones transient response?
Diaphragm weight. For instance, the diaphragm and voicecoil assembly of a dynamic microphone may weigh up to 1000 times more than the diaphragm of a condenser microphone.
What is a polar plot/polar pattern graph used for?
polar plots shows the variation in sensitivity as you move 360 degrees around the microphone. aka the pick up pattern
Describe the polar response pattern of a cardio microphone.
Cardioid (kar-dee-oid) has the highest sensitivity to sound coming in from directly in front of the microphone capsule (0º), practically no sensitivity to sound coming directly from behind (180º), and a reduced sensitivity to sound coming in from the sides (90º/270º)
Describe the polar response pattern of a omni-directional microphone.
An omnidirectional polar pattern picks up sound in a 360-degree radius – it is equally sensitive to sound at all angles. Imagine its pattern as a perfect sphere in three directions.