Most effective microphones pick up sound waves and convert those waves into an electrical signal to be used 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 create the audio signal. The interaction in the wire coil and magnet is called electromagnetic induction and is mainly responsible for generating an output signal voltage. A diaphragm is attached to the coil, and is also mounted within the mic so that it can move around in reply to a sound wave. When the diaphragm vibrates, the attached coil moves forward and backward in the magnetic field. This motion in the field generates an electric current (induction), which is often converted by audio equipment into sound waves. The effectiveness of the electrical current is directly linked to the motion from the coil.
Dynamic mics are excellent general-purpose microphones. They have less moving parts than condenser mics, and as a result they’re typically more rugged and sturdy. Furthermore, because they generate their particular current, no external source of energy is needed.
The physics behind the moving coil can play a role in limitations in frequency response. In most cases, dynamic microphones are less sensitive than condenser mics.
In a condenser microphone a voltage charge is applied to the diaphragm by either battery power or phantom power. The diaphragm is mounted very close to a stationary back plate. Sound waves striking the diaphragm causes it to move closer and farther away from the back plate that causes electrical charge fluctuations to occur. The interaction between the diaphragm and back plate creates an electric component called a capacitor (or condenser), and also the resulting variations in voltage could be reinterpreted as sound waves through the receiving audio equipment.
Condenser microphones are very responsive and make a much stronger signal than dynamic mics. This makes them an ideal selection for professional settings such as studio work, where it’s important to pick up vocal subtleties.
Typically Vocal Microphones get more moving parts than their dynamic counterparts and are less durable. Also, since they usually do not generate their particular current they require an outside power source. (Battery or phantom power)
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 often tihdsy by microphone preamps and audio mixers.
The pickup pattern is most likely one of 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 under the following categories: omnidirectional, unidirectional and bidirectional.
Omnidirectional mics get sounds coming from all directions equally while a unidirectional mic was created to only get sound from a single direction. Bidirectional mics are rarer, and are designed to pick-up from two sides – beneficial to a two person podcast when sharing a single mic. “Cardioid” is an additional term often used when describing the pickup patterns of microphones. A cardioid mic picks up sounds through the front, however, there is some limited pickup from the sides. It will help to offer some tolerance for sideways movement in the speaker while recording.
Accessibility of power is yet another consideration for podcasting microphones. Most studio vocal microphones (condenser type) require phantom power – which suggests external power needs to be given to the gear. This is most often accomplished by the use of mixers and mic preamps. USB microphones on the contrary, are able to connect straight to a pc without requiring an external power source. Dynamic mics are typically less sensitive but usually do not need a power source.