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 .   





No power supply


No overdrive ( good > drums )


Catch magnetic fields


No noise


Not light membrane




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 .