I mentioned condenser microphones and dynamic microphones but did not explain them (I will also explain polar patterns…how a microphone hears).  I will explain them in detail now.

“A condenser, or capacitor (same thing), Mic capsule has a conductive diaphragm and a metal backplate placed very close to the diaphragm. They are charged with static electricity to form two plates of a capacitor. When sound waves strike the diaphragm, it vibrates, varying the spacing between the plates. In turn, this varies the capacitance and makes a signal analogous to the incoming sound waves. There are two types of condenser Mic’s: the true condenser and the electret condenser. In the true condenser, the diaphragm and backplate are charged with a voltage from a circuit (The 48V phantom power). In the electret, the diaphragm and backplate are charged by an electret material, which is in the diaphragm or on the backplate. All true condenser Mic’s need a power supply to operate, such as a battery or phantom power. In general, condensers have a smooth, detailed sound with a wide, flat frequency response – usually up to 15kHz – 20kHz (15,000-20,000 Hz), useful for cymbals or instruments that need a detailed sound, such as an acoustic guitar, strings, piano, or voices. Condenser Mic’s tend to be more expensive and fragile than dynamic microphones. Note that omnidirectional condenser Mic’s have deeper lows than cardioid (polar pattern) condensers, making the omnidirectional (polar pattern) condenser a good choice for pipe organs and bass drums”.

“The membrane part of a microphone’s capsule or cone of a loudspeaker that moves in response to sound waves or an incoming signal, respectively”.

“If two metal plates have molten wax poured between them and a high DC voltage is sent across the two plates, this assembly yields a permanent electric field, in the same way that a magnet produces a permanent magnetic field. It is hypothesized that the polar molecules in the wax align, then producing the electric field. An assembly of this type is used to provide a polarization voltage for small condenser microphones so that they do not require phantom power at 48V, but operate instead at a small pre-amplified voltage of 5V – 12V. Microphones constructed in this way are called electret microphones”.

“In a dynamic microphone there is a moving coil in a magnetic field which generates electricity. Two types of dynamic microphones are the moving coil (dynamic mics) and ribbon. (moving coil mics are typically referred to as dynamic mics, while ribbon mics seem to be called ribbon mics). Dynamic mics have a rougher response than condensers or ribbons, and can be used to soften fine detail in the recorded sound. A well-designed moving-coil dynamic mic can handle very loud sound without distortion, and so is preferred for Mic’ing guitar amps and drums. Dynamic mics also have a pronounced presence peak that gives the sound an edge or punch”.

“In a moving coil mic, a coil of wire is attached to a diaphragm and is suspended in a magnetic field. When sound waves vibrate the diaphragm, the coil vibrates in the magnetic field and generates an electrical signal similar to the incoming sound wave. For some reason, moving coil mics are called dynamic microphones, but not ribbon microphones”.

“A type of dynamic microphone which has a thin metal foil, or ribbon, suspended in a magnetic field. Sound waves vibrate the ribbon in the field and generate an electrical signal. Ribbon mics are usually quite fragile, but are used for their warm, smooth tone quality. They work well with digital recording and on brass instruments to mellow the tone. Ribbon mics are either figure-eight (polar pattern) or cardioid (polar pattern)”.

CARDIOID	SUPERCARDIOID	HYPERCARDIOID
• Cardioid: “Heart-shaped” pattern that offers maximum rejection (null) at the rear of the microphone.	• Supercardioid: Has a narrower pickup pattern than cardioid, but also has some rear pickup. Note that there are two nulls of maximum sound rejection.	• Hypercardioid: Has a narrower pickup pattern than supercardioid, but also has more rear pickup than supercardioid. Note that there are two nulls.
OMNIDIRECTIONAL	HALF-OMNIDIRECTIONAL	BI-DIRECTIONAL (FIGURE 8 )
• Omnidirectional: Picks up equally in all directions.	• Half-omnidirectional or hemispherical: Picks up equally over a 180° spherical angle. This is the pickup pattern of PZMs.	• Bi-directional (figure-eight or cosine): Picks up mainly in two directions (in front of and behind the mic) and rejects sound from the sides.

Microphone Pickup Angles
Omnidirectional	-	360°
Cardioid	-	131°
Supercardioid	-	115°
Hypercardioid	-	105°

Answer: 2 feet.

Suppose you have set up several microphones to pick up sound sources. Each sound source has its own close-placed mic. You are mixing the mic signals through a mixer.

The figure above shows a poor way to mic a person at a lecture. The microphone is too far away from the mouth, resulting in pickup of reflected sound from the lecturer’s surface. This will result in an audible comb-filter effect, which sounds hollow or tonally colored.
The figure below shows a better way to mic a person at a lecture. The microphone is close to the mouth (about 8 inches). The sound reflected from the lecturer arrives toward the rear of the mic, where sound is rejected (null point). This will greatly reduce the audible comb-filter effect.

The figure below shows an effective way to mic an actor on a stage. Use a boundary mic, which is designed with the mic capsule on or very near the reflected surface. In a boundary mic, the reflected path is nearly equal to the direct-sound path length, so the direct and reflected sounds are in phase. This will greatly reduce the audible comb-filter effect. To reduce feedback, use a Crown PCC-160 boundary mic (example), which is directional. For maximum clarity and gain-before-feedback, use a wireless lavalier mic on the actor.