THE WONDERFUL WORLD OF MICROPHONES:

By Mark James Seitz

How to Choose and How to Use

Objectives:

• Know the history• Know the basic types• Know how they work• Know the basic polar patterns• Know how to choose the right tool

for the job

What is a microphone?A microphone (or mic) is an electronic sensor used to convert acoustic wave forms into electrical impulses for use in recording or sound amplification.

Contrary to popular opinion, it is not a device used to make lead singers look cool.

Who invented this thing?Alexander Graham Bell was one of the first people to adapt the dynamic or moving coil concept invented by Ernst von Siemens. Bell used the idea to perfect his electrical telephone in 1876.

Emile Berliner (left) and Thomas A. Edison (right) were both independently pursuing the invention of the carbon transmitter (microphone) in 1877. Although Edison was eventually awarded the patent, both are generally credited as inventing the technology.

How many kinds are there anyway?• Condenser• Dynamic• Ribbon• Carbon• Liquid

• Piezoelectric• Fiber Optic• Laser• MEMS

More than you can shake a stick at but we’ll just focus on the three most common mics.

The Condenser Microphone

Acoustic waves

Front Plate Back Plate

BatteryOutput

• Uses two charged plates• When sound wave hits, the distance between the two plates varies

the electric charge• The electric charge is sent on to the rest of the signal chain.• Must be powered by battery or external source!• Extremely sensitive

+

-

The Dynamic Microphone

Acoustic waves

Diaphragm

Output

Mag

net +

-

• Diaphragm attached to coiled wire suspended between the field of a magnet

• Acoustic waves make diaphragm vibrate causing coils to move back and forth through magnetic field resulting in electrical impulses

• Very durable microphone• Exact opposite of how a loudspeaker works

Acoustic waves

Output

Magnet

+

-

• Corrugated metal “ribbon” suspended between poles of a magnet• As ribbon vibrates electrical impulses created• Weak signal must be “stepped-up” by a transformer before being

passed through signal chain• Extremely sensitive to loud sources• Like condenser mics, must be powered

The Ribbon Microphone

Corrugated Metal Strip

N S

Transformer

Microphones can also be sub-categorized by the shape of its “field of vision” known as its…

Polar Pattern

Omnidirectional Microphone

• Picks up sound equally behind as it does in front of the mic

Figure-8 Pattern Microphone

• Has more than one element• Perfect for more than one sound source• Sometimes selectable on condenser mics in particular

Cardioid Microphone

• Picks up sound only in front of the mic• Great for isolating particular voices or instruments without picking

up other sources• Often used on drums• Always used on President’s podium• Most common mic pattern

Hypercardioid Microphone

• Picks up sound better in front than behind the mic• Used for indiscriminate isolation of a source

Shotgun Microphone

• Has noise cancelling vents on sides of microphone• Used for precision isolation of sources• Mic of choice for recording sound for film• Very long and thin• Susceptible to wind noise so often used with windscreen, blimp

or “dead cat” to eliminate wind noise

Selecting the Right Mic

Ask Yourself Three Questions:

• What is the source I am capturing?

• What are the environmental conditions?

• What are my goals for this recording?

Consider the source!

Different instruments call for different types of microphones.

Drums

• Dynamic mic to handle loud instruments• Hypercardioid pattern• Larger diaphragm to pick up longer

sound waves

Electric Guitar

• Dynamic mic for amplified sound• Hypercardioid• Rugged enough to handle the high

decibels of an electric guitar

Acoustic Instruments

• Condenser or ribbon mic• Omni or perhaps cardioid to pick up

ambience of room• Sensitive enough to pick up subtlety in

performance

Vocals

• Dealer’s choice!• Condenser for delicate style

of singing• Dynamic for louder,

aggressive style of singing• Definitely use a pop filter or

windscreen to cut down on sibilance!

Consider the environment!Noisy crowd, need to isolate instrument from extra noise.

Quiet studio environment. Might wish to include ambience of the recording room.

What are your goals?

Podium micWhen the microphone doesn’t need to be hidden.

Lav micWhen you need a more discreet solution. Used often in video production.

The Rules of Selecting a Microphone…

There really aren’t any. Personal preference is everything here but when in doubt…ask those three questions again.

Summary• Three most common microphone technologies

• Dynamic microphone• Condenser microphone• Ribbon microphone

• Five common polar patterns• Omnidirectional• Figure-8• Cardioid• Hypercardioid• Shotgun

• Three questions to ask before choosing a microphone• What is your source?• What is the environment?• What are your goals?

• Rules for Microphone Use• There are no rules!

Let’s take a quiz!

The microphone was invented by Franz Ferdinand.

• True

• False

Right!

Even Frank is impressed!

Back to Quiz

Wrong!

Back to the garage, Slick!

Try again.

Let’s take a quiz!

A microphone that uses a moving coil like a loud speaker is a...• Condenser microphone

• Ribbon microphone

• Dynamic microphone

• Crystal microphone

Right!

Even Frank is impressed!

Back to Quiz

Wrong!

Back to the garage, Slick!

Try again.

Let’s take a quiz!

A microphone with a ________ polar pattern can pick up sound equally in all directions.

• Hypercardioid

• Omnidirectional

• North or South

• Shotgun

Right!

Even Frank is impressed!

Back to Quiz

Wrong!

Back to the garage, Slick!

Try again.

Let’s take a quiz!

What three questions should you ask yourself before selecting a microphone?• What is my source, environment

and goals?• Who am I recording, why and how

much am I getting paid?• What time does the gig start, who

will be there, can I come?• There are no questions to ask

yourself.

Right!

Even Frank is impressed!

Back to Quiz

Wrong!

Back to the garage, Slick!

Try again.

Let’s take a quiz!

How many rules are there in choosing a microphone for a job?• 7

• 4

• 6

• 0

Right!

Even Frank is impressed!

End Quiz

Wrong!

Back to the garage, Slick!

Try again.

Good luck recording your next big hit!

ADDITIONAL RESOURCES:

• http://blog.shure.com/shure-notes/• Shure has a great section on their site

about using their products. • http://www.akg.com/Recording-785.html

• AKG is another leading manufacturer of quality microphones. Their site is filled with great tips.

• http://www.audio-technica.com/world_map/• Leading manufacturer with extensive

support and “how to” materials.• http://www.sweetwater.com/sweetcare/articles/micr

ophones-frequently-asked-questions-faq/• With “out of this world customer

service” it is no wonder that Sweetwater is a retail industry leader. Great tips and FAQ section.