Microphones come in all shapes and sizes, and we’ll be going over what they are, how they work, and the 3 main types of microphones.
Microphones are transducers, and transducers are anything that convert one type of energy into another. In this case, a microphone turns acoustic energy into electrical energy. I think this goes without saying, but the usefulness of a microphone is that we can turn audio into electricity so that we can easily change and manipulate it, whether it be for music, movies, or enjoyment.
There are 3 main types of microphones: Dynamic, Condenser, and Ribbon. They serve the same purpose, but function and sound differently. The most common ones are dynamic and condenser, so let’s go over how they work.
A dynamic mic has a diaphragm at the front of the microphone. The diaphragm is a small disc made from metal, and attached to a metal coil that lies behind it. Sound waves will hit the diaphragm and cause it to vibrate sympathetically. The metal coil will also vibrate with the diaphragm. A magnet is placed within the metal coil, so an electrical current will flow through the coil as it’s vibrated forwards and backwards around the magnet. This current will then flow down the wire of the microphone to whatever equipment you have it attached to. These microphones are very common and can withstand high SPL (sound pressure level), such as drums and singers. The most common dynamic microphone you will likely encounter is the Shure SM58, the workhorse of the audio industry. These mics are built to last and can literally be tossed, kicked, drowned, run over, and shot and will still work. Albeit, it probably won’t sound great after being shot, but it’ll still work. The diaphragms of dynamic microphones are larger and heavier than the diaphragms of the other microphone types, and they need a louder sound wave to cause it to vibrate. So, they’re good for loud noises, and not so much for quiet noises. Let’s move on to our second microphone type.
Condenser microphones also have a diaphragm, but instead of coil, it’s placed in front of a backing plate. The backing plate requires an electrical charge known as phantom power, or 48 voltz. Either the attached sound equipment will send phantom power to the microphone or the microphone will require a battery to be plugged into it. When sound waves hit the diaphragm, it vibrates and varies the distance between it and the backing plate. This changing distance causes fluctuations in the charge, which is then sent down the wire to your sound equipment. These microphones are very sensitive and good for quieter sounds, like string instruments. Condenser microphones can also be made very small, and are great for headsets and lapel placements. Now let’s explore our third type of microphone.
Ribbon microphones are unusual in that the diaphragms are ribbons of metal, cut very thinly and corrugated. The ribbon is suspended inside a magnet. As sound waves hit the ribbon, it vibrates and causes fluctuations in the surrounding magnetic field. Then this signal is sent down the cable to your sound equipment. These microphones are not as common as the previous two and are much more fragile, but can lend more warmth smoothness to your recordings. Very loud sources can actually cause the ribbon to tear, rendering the mic useless.
Microphones come in different sizes and casings. The casings are an important part of the microphone because not only does it protect the innards and look cool, it can prevent self-noise. We should also get into the specifications you’ll come across when observing microphones, which we will discuss in the next article.
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