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Contents 1 Transducers 1.1 Microphones 1.2 Microphone Comparison 1.3 Proximity Effect 1.4 Polar Patterns

Transducers

Transducer = a device that converts one type of energy to another. A microphone converts acoustic energy to electrical energy. A speaker converts electrical energy to acoustical energy. They are both transducers.

Microphones

Microphones

good reading Audio Technica Guide to Microphones

Types of microphones

1. Dynamic
2. Condenser
3. Ribbon
4. piezo electric (contact Mic)

other (Stereo, binaural, PZM- pressure zone microphone http://www.crownaudio.com/mics.htm)

Ribbon Mic

The first type of mic was a Ribbn Microphone. Basically a light wieght ribbon that conducts electricity the is suspened in between two magnets. Older ribbon mics usally have a reduced frequency response.

http://www.coutant.org/ribbons.html

Dynamic Mics

A light weight diaphragm is connected to a coil that is suspended between a magnet.

Condenser Microphone

A very light weight diaphragm is suspended in front of an electrically charged back plate. The two plates basically act as an open air capacitor. As the air pressure changed the distance between the plated the capacitance between the plates also changes.

Condenser microphones need Phantom Power to work.

Our stereo mic: Audio Technica AT825 [1]

Microphone Comparison

Parameter	Dynamic	Condenser	Ribbon
Frequency Response	Good	Best	Worst
Dynamic Range	Good	Good	Worst
Durability	Best	Good	Worst

Proximity Effect

The frequency response of a directional microphone changes as it it brought close to a source. The bass response increases.

http://en.wikipedia.org/wiki/Proximity_Effect#In_audio

http://www.csun.edu/~record/prox/prox.html

Polar Patterns

http://en.wikipedia.org/wiki/Microphones#Microphone_polar_patterns

• Omni-directional - all directions

• Bi-directional (figure 8)- front and back rejects on the side

• Uni-directional - one direction

• Cardioid - one direction with lobe

• Hypercardiod - really one direction with lobe

http://www.mikelights.com/micpolar.htmlALC Microphone Directionality Some pictures

http://www.csun.edu/~record/polar.html Some more Pictures

Stereo Mic Techniques

Spaced Omni's - two spaces Omni mics

XY - Coincident cardioids at 90 degrees

ORTF (Office de Radiodiffusion -- Television Francaise)110 degrees 17cm apart - Near Coincident Pair About.com Microphones Part 1

Dat Heads mic-FAQ.txt