The Microphones

The sound is a mechanical vibration transmit by the air to the membrane of a microphone. Audible frequencies by the ear vary between 20Hz and 20.000Hz .

On the technical plan there are two types of microphone . The dynamic microphone is constituted by a coil of wire fixed to a membrane and that bathes in a magnetic field .

The electret microphone is constituted of two thin membranes submit to a high tension . The professional version is called condenser microphone .

The dynamic microphone is autonomous. The electret microphone contains an electronic circuit that adapts features to obtain those from a dynamic microphone .

Dynamic Mike	No power supply	No overdrive ( good > drums )	Catch magnetic fields	No noise	Not light membrane
Electret Mike	Supply : battery , phantom	Electronic : can overdrive	Dont catch magnetic fields	Electronic = noise	Light membrane

On the utilization plan there are two types of microphones . Cardioids microphones ( directs ) take the sound in front of them . Omnidirectionnal microphones take all around.

The big problem with cardioids microphones is that they take less bass sounds by far but exaggerate them when taking sound of near ( example : singing ).

But with two identical cardioids microphones we can realize a stereophonic sound take. We place them together with an angle of 90 degrees .

The best result for the respect of the reply curve is to use two omnidirectionnal microphones (or better measure mikes ) but spaced one of the other .

1 2 3 4

1 : Dynamic mike for singing 2 : Electret mike for recording 3 : Professional condenser mike 4 : Electret mike for measuring

Most current microphones are destined to take the voice and are adapted to this function . They have a reply curve which is very particular .

Do not utilize them to make a take of sound or a recording . They exaggerate a lot some treble frequencies .

We recognize them because they are equipped by a large fenced sphere destiny to avoid take all the hummed that would be caused by the pronunciation .

A type of microphone is destined to make measures . It is omnidirectionnal and has a reply curve practically flat . This is the alone in this case .

The ideal connection for a microphone is called symmetrical . We use an armored wire with two internal wires .

Thereby we eliminate the hum and we can use long wire . This connection allows also to power the microphone by the same wire .

This possibility is called phantom power supply. It is in general 48 volts . The plug is a large plug with three spits .