How Does it Work?
Microphones
Choosing a microphone can be daunting. There are many different styles and brands on the market these days, from classic round-head dynamic mikes to the tiny, high-tech wireless models today’s pop stars use.
One way to know which mike is best for you is to understand a little about the differences between two common types found in music stores: dynamic and condenser mikes. Which type of microphone you choose will depend on what instrument you play and the purpose of the mike.
All microphones work by converting sound waves, or vibrating air, into an electrical signal, which can then be relayed to an amplifier and speaker. This is true of the common dynamic and condenser mikes, as well as for more exotic styles, such as ribbon, carbon, or laser microphones.
Dynamic Microphones
Uses of a Dynamic Mike
If you play rock and roll or travel with your equipment a lot, you probably want to go with a dynamic microphone. Dynamic mikes are a convenient choice because, unlike condenser mikes, they don’t need a power supply. Plus, their sturdy construction means they can withstand extreme levels of temperature and humidity. They can also handle high levels of sound, which creates a warmer, fuller, and smoother resonance, ideal for rock or jazz, drums, and amplifiers. They are not the best choice for amplifying acoustic instruments as their sensitivity is not as great as a condenser mike.
Inside a Dynamic Mike
Dynamic microphones work by employing an electromagnetic principle called induction, discovered by scientist Michael Faraday in 1831. When you sing into a dynamic mike, the sound waves generated by your voice cause a thin membrane called a diaphragm to vibrate. The vibrations of the diaphragm cause a small coil of wire (the “voice” coil or induction coil), attached to the end of the diaphragm, to vibrate as well. Also inside a dynamic mike is a small magnet, which casts a magnetic field around the coil. As the coil moves in the magnetic field, an electrical signal is generated (or induced) with an output frequency proportional to the input frequency, or the voice. That electrical signal is then sent by wire to an amplifier and loudspeaker through which the voice is magnified.
Condenser Microphones
Uses of a Condenser Mike
Condenser microphones are a good choice for vocalists and musicians who play acoustic instruments, such as acoustic guitars or cellos. Condenser mikes are more expensive, but they produce a crisp, sensitive, and uniform sound. They are a little more delicate than a dynamic mike and, unlike dynamic mikes, they require an independent power source. Some run on battery power, although they are usually plugged into a mixer or some other device that provides “phantom” power that runs into the mike from its jack plug input.
Inside a Condenser Mike
In a condenser microphone, a device called a capacitor or condenser converts sound waves into an electrical signal. A condenser is simply two plates that conduct electricity, separated by an insulator. If the electrical charge maintained across the plates is constant, any change in distance between the plates will produce a change in voltage, or electric force. In a condenser mike, one of the plates is a thin metal or metal-coated diaphragm and the other is a stationary back plate. Sound waves cause the diaphragm to move, creating variations in the space, and therefore, voltage between the plates. The change in voltage instantaneously reflects changes in the frequency of a voice or instrument. This electrical signal is then sent by wire to an amplifier and loudspeaker.
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What to Choose The Shure SM57 remains a popular dynamic mike for general use. It’s relatively inexpensive and is considered a good workhorse. Other dynamic mikes to check out include the Samson Q1U Handheld USB and the AKG 288S. |
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What to Choose Although typically more expensive than dynamic microphones, in recent years the price of condenser mikes has dropped. The Audio-Technica AT4040 is a good choice for a high-quality condenser mike. Other options include the AKG Perception 400 and the Rode NT1-A. |
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