Backstage Technical Services | Stage Management Guide | Basic Sound

Basic Sound - Microphones

Tutorials & Info --> Sound Guide --> Microphones

Microphones come in a huge range of different makes, types and prices but they are usually one of two types. For more detailed information on particular microphones, see the Backstage Sound Guide.

Dynamic

This is the most common, cheapest and the most reliable type of microphone available. It works like a speaker but in reverse; sound in, moving a diaphragm, giving electricity out.

Sound waves hit the diaphragm, moving the coiled wires attached to it.
The wires move in relation to the fixed magnet, causing an electrical current to be produced in the wire.
This current is sent down a cable to your other equipment (mixer, amplifier, tape recorder etc.)

Dynamic microphones are generally built to last, their diaphragms being protected by a metal grill. They can handle pretty much any conditions and produce a good sound quality, even coping with very high sound levels. If in doubt, use a dynamic!

Condenser

These microphones employ a different method of changing sound in electricity. It is built like a capacitor, with two electrically-charged plates, one large and thick, the other paper-thin.

When sound waves cause the thin plate (diaphragm) to move, the gap between the two plates changes and so the capacitance between them changes. This property is detected by the microphone and translated into a signal which is sent down the cable to the mixing desk.

One important feature of condenser microphones is that they require the plates to be electrically charged and so a power source must be provided, this is done in one of three ways:

The microphone has a special piezo material which provides a constant voltage all by itself
The microphone uses a battery
Power is sent down the output cable from a desk to power the microphone. This is most commonly used by Backstage due to it being cheap and reliable. It does however rely on the use of 3-core balanced cables (see our sound guide for more details).

Condensor microphones use a very, very thin diaphragm which can therefore move extremely fast. They are consequently very sensitive and can pick up very quiet sounds. Condensors tend to have better high frequency responses than dynamic mics and can be made smaller. The downside is that they can’t cope with very high sound levels, are more expensive and less reliable.

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