Microphones!

This week we are learning the different types of microphones and their technical aspects. The 3 types of mics are dynamic, condenser, and ribbon. Dynamic mics work based on a magnetic moving coil (electro-magnetic). a copper coil moves around a magnet when sound pressure waves come in contact with the diaphragm (top of coil). Diaphragms can be large or small. This acts as a TRANSDUCER, which is converting the spw's into an electric current that goes down the mic cable into the board. Dynamic mics are less sensitive than condenser mics and can handle close micing better. Condenser mics need an additional power source, phantom power. This powers 48 volts to the mic, because these mics operate electro-statically. Ribbon mics use the electro-magnetic principle as well, and are very sensitive. Polar patterns are another important part of the anatomy of a mic. Some mics have varying patterns, in which case you can switch the polar lattern depending on the room. This is a way of picking up the sound, and there are different spherical shapes that respond differently. Cardioid is a very common pattern, and it is shaped like an upsidedown heart. A mic with this polar pattern will pick up noise best from the front and reject noise from the back. Figure-8 is another pattern, which will pick up sound from the front and back of the mic, and the null points are located on the sides of the mic. An omnidirectional pattern picks up sound from all sides, except the very back of the mic, because it is theoretically impossible to pick up with the body of the mic in the way. Super or Hypercardioid picks up like a cardioid, and has rejection at about 120 and 240 degrees. The rejection of sound from the mics is really just an attenuation of certain frequencies down a certain number of decibels. Frequency Response is how a mic picks up frequencies. Each mic has specific boosts and attenuations in frequency. Each microphone has an SPL or sound pressure level. Sound waves are the movement of air, so if sound hits a mic too hard it can cause the moving coil or ribbon to break, incapacitating the mic.