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Microphone Types and Designs
John Lewis Kilgore
9/19/2012
PHY3091
Introduction
A microphone is a type of transducer.
Early microphones were invented for
communication purposes.
Later modifications were made to design as
the microphone was used more in
entertainment industry.
Introduction
Different situations call for the need of
different microphone designs as well
different pickup patterns.
Need to consider factors such as the source,
the location of the source and the
environment of the source.
Overview of a Microphone
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Diaphragm—part of microphone which receives
the vibration from sound waves.
Thickness and material of diaphragm are changed
depending on the sound waves you wish to pick
up.
How it works?
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Electrical circuit is used to change these
detected vibrations into an electrical signal
that “images” the sound with an output
voltage or current.
Different Types of Microphones
Microphone types we will discuss today:
Carbon Button
Ribbon
Dynamic
Condenser
Carbon Button Microphone—
Historical Design
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Thomas Alva Edison and
Sir Emile Berliner filled
patents for Carbon Button
Microphone in 1877.
Edison's design became
the accepted design and
patent.
This is a popular
microphone for telephones
as well as early radio and
speeches.
Carbon Button Microphone
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Diaphragm: Thin Metal Plate
The diaphragm is connected to a button full of
carbon power.
A voltage is applied across the button.
Sound pressure changes the resistance through
the button by compressing/decompressing the
carbon by pushing the plate.
Carbon Button—Design Diagram
Ribbon Microphone
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Diaphragm: Thin piece of metal foil
suspended in a magnetic field.
Vibrations in ribbon produce a small voltage
which is then stepped up by a transformer.
Diaphragm is very easily damaged by wind
or loud incoming sounds.
Ribbon Microphone—
Design Diagram
Dynamic Microphone
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Diaphragm: Plastic
Diaphragm pushes a coil of wire suspended
in a magnetic field.
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Durable design and versatile use.
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A reverse of a loudspeaker.
Dynamic Microphone—
Design Diagram
Condenser Microphone
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Diaphragm: Thin metal strip suspended next to a
charged electric plate.
This creates a capacitor.
Diaphragm moves in and out and changes
electrical capacitance.
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Requires a power source for the charged plate.
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Distorts easily and has a flat frequency response.
Condenser Microphone-Design Diagram
Frequency Response
Microphone Pickup Patterns
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Pickup patterns help to reduce unwanted
signal from getting pickups
Popular patterns: Monodirectional,
Bidirectional, Cardioid, and Omnidirectional
Sources
http://www.mediacollege.com/audio/microphones/dynamic.htm
lhttp://www.cybergeo.com/music/microphones/
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/mic.html
http://lloydmicrophoneclassics.com/mic_history.html
http://en.wikipedia.org/wiki/Microphone
http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/David_BonifaceJones/Page2.htm