Best microphones pick-up sound waves and convert those waves into an electrical signal to be utilized by audio equipment in one of two ways.
A dynamic (or moving coil) microphone operates simply by using a wire coil as well as a magnet to produce the audio signal. The interaction of the wire coil and magnet is known as electromagnetic induction and accounts for generating an output signal voltage. A diaphragm is attached to the coil, and is also mounted inside the mic so it can move in reaction to a solid wave. Once the diaphragm vibrates, the attached coil moves forward and backward in the magnetic field. This motion in the field generates an electric powered current (induction), which is often converted by audio equipment into sound waves. The strength of the electrical current is directly associated with the motion in the coil.
Dynamic mics are great general-purpose microphones. They have got less moving parts than condenser mics, and for that reason they’re typically more rugged and sturdy. In addition, since they generate their own current, no external source of energy is necessary.
The physics behind the moving coil can bring about limitations in frequency response. Most of the time, dynamic microphones are less sensitive than condenser mics.
In a condenser microphone a voltage charge is applied for the diaphragm by either a battery or phantom power. The diaphragm is mounted not far from a stationary back plate. Sound waves hitting the diaphragm causes it to go closer and farther away from the back plate which in turn causes electrical charge fluctuations to take place. The interaction involving the diaphragm and back plate creates an electrical component known as a capacitor (or condenser), and the resulting variations in voltage may be reinterpreted as sound waves by the receiving audio equipment.
Condenser microphones are very responsive and make up a much stronger signal than dynamic mics. This will make them a perfect selection for professional settings such as studio work, where it’s important to pick up vocal subtleties.
Typically Condenser Microphones have more moving parts than their dynamic counterparts and therefore are less durable. Also, since they usually do not generate their own current they might require another power source. (Battery or phantom power)
Precisely what is phantom power? Phantom power is a direct current (typically between 12 and 48 volts) that supplies microphones with power through audio cables. 48 volt phantom power is regarded as the common and is also often tihdsy by microphone preamps and audio mixers.
The pickup pattern is most likely just about the most key elements in choosing a mic. The pattern determines which directions will and won’t pick-up sounds. Pickup patterns for vocal microphones typically fall into these categories: omnidirectional, unidirectional and bidirectional.
Omnidirectional mics pick up sounds coming from all directions equally while a unidirectional mic is designed to only get sound in one direction. Bidirectional mics are rarer, and are designed to pick up from two sides – good for a two person podcast when sharing just one mic. “Cardioid” is an additional term often used when describing the pickup patterns of microphones. A cardioid mic picks up sounds from your front, there is however some limited pickup through the sides. This helps to supply some tolerance for sideways movement of the speaker while recording.
Accessibility to power is an additional consideration for podcasting microphones. Most studio vocal microphones (condenser type) require phantom power – which means external power must be provided to the machine. This is most often accomplished through mixers and mic preamps. USB microphones on the contrary, are able to connect right to a pc without requiring another source of energy. Dynamic mics are usually less sensitive but tend not to require a source of energy.