Have you ever wondered how a microphone actually works? Understanding what goes into the construction of a microphone and what each component does can actually go a long way towards making sure that you are choosing the correct microphone. I’ve often struggled to wrap my head around how two microphones can have almost identical specifications yet differ in price by hundreds of dollars. It was not until I really understood what went into the construction of a microphone that this all made sense to me.
Microphones have been needed throughout history for two reasons: to record audio for the purpose of having historical records, and to amplify sound so that it can carry across a large distance or audience. The modern definition of a microphone is a transducer that can convert sound into an electronic signal, and this makes sense because microphones for recording and microphones for amplification are pretty much interchangeable. The first microphone however did not use any electronics whatsoever, and it is still used today.
History of the Microphone
If you’ve ever been to a college football game, you’ve probably seen this ancient technology. A megaphone amplifies a voice by allowing the sound to reflect several times off the interior of the cone before eventually leaving in an amplified directional pattern. There is evidence of these megaphones being used in ancient Greece as early as the 5th century BC.
The megaphone could no longer be considered a microphone as it does not have a transducer. In modern microphones, it is the transducer that converts sound energy into electric energy, but a transducer is any device that can convert energy from one form to another. The first example of a microphone with a transducer was invented by 1965 by Robert Hooke. Many of us have seen this type of microphone in pop culture. It is the “Lover’s Telephone.”
That’s right, two cans connected by a wire are transducer microphones. Sound waves enter one can, are converted to vibrations by the wire, and converted again back to sound by the next can. While this type of microphone would be highly ineffective for almost all modern applications of the microphone, it is a great example of how sound can be converted by a transducer into something else.
We moved one step closer to the modern microphone with the invention of the phonograph in 1877. A phonograph looks like a record player with a giant horn, but it works in reverse. A magnetically charged membrane called a diaphragm picks up sound, converts it to vibration and a needle etches that vibration into a record so that it can be replayed. This was a huge step towards modern microphones as that magnetically charged membrane is still used in almost all microphones today.
The diaphragm is a key component in a modern microphone. It simulates the diaphragm in our ears, more commonly referred to as our ear drums, by suspending a metal membrane using magnetic energy. As sound waves meet that membrane, its vibrations are measured and converted to electric signal by a transducer. Different types of microphones have different technologies when it comes to membranes and transducers and as we now dive deeper into naming the parts of the microphone, you’ll see some similarities between the primitive microphones listed above and the modern microphones we use today.
The most common microphone is the dynamic microphone. We’ll use this as our first example and explain other microphones by listing how they differ from the dynamic microphone. You can also read our microphone specifications article for more info on the terminology used by many microphone companies and users.
The parts of the dynamic microphone are as follows:
Different Parts of a Microphone
- Wind Screen: This is the part of the mic you speak into. Typically a microphone has a round protective barrier made of woven hard metal. Directly beneath this barrier lies the wind screen. Almost all microphones come with a built-in wind screen, but for studio use or even outdoor performances where wind could be an issue, it is wise to use an additional pop filter. The wind screen is a thin layer of foam designed to block out wind from entering the diaphragm and creating unnecessary noise in the signal.
- Diaphragm: This is the membrane of the microphone that is most similar to our ear drums. As sound waves enter the microphone, they meet the diaphragm and cause the diaphragm to vibrate. This vibration is turned into electric signal by the microphone. A diaphragm is probably the biggest factor of the entire microphone when it comes to quality of sound.
- Coil: The coil is unique to dynamic microphones. The coil is attached to the diaphragm so when the diaphragm begins to vibrate, so will the coil. As the coil vibrates, it will move back and forth between a magnet. The movement between the magnetically charged coil and the magnet create the electric energy in the signal.
- Magnetic Core: This is also unique to a dynamic microphone. The magnetic core creates a magnetic field for the coil so that the vibrations can create an electric signal.
- Capsule: On any microphone, the capsule is where sound is transformed from vibration to electric signal. On a dynamic microphone, the coil and the core are apart of the capsule. Some microphones require power for the capsule to do its job while others do not. Microphones can draw power from a mixer through a setting called “phantom power.” Be sure to be aware whether or not your microphones require phantom power.
- Body: The body of the microphone probably has the least to do with its quality of sound and the most to do with how long your microphone will last. The body of the microphone is like the chassis of a car. Great microphones have sturdy bodies with intelligently placed electronics on the inside so that they can handle bumps, drops, and other things that are sure to happen during the life of your microphone.
- Output: On any microphone, this is where you would plug a cable into the mic. The default cable type for microphones is XLR. This three-pronged cable sends stereo signal, and can be purchased in many lengths. Some microphones have outputs for 1/4” cables while some cheaper microphones come with the cable attached.
Almost all of these components can be purchased independently of the microphone, so when your microphone starts to give you trouble, this guide could help you determine what parts you might be able to buy so that you can fix your microphone instead of buying a new one.