Microphones The Basics The microphone is your primary

Microphones The Basics

The microphone is your primary tool in the sound chain from sound source to audio storage medium.

Factors when capturing a sound with a microphone: § microphones location in relation to the sound source § the acoustic environment in which we choose to record the sound source

Types of Microphones There are three main types of microphones: � 1) Dynamic/Moving Coil � 2) Ribbon � 3) Condenser/Capacitor

1) Dynamic/Moving Coil microphones �They operate on a magnetic principle : movement of a copper coil around a magnet causes a changing flow of electrons that represent the sound wave. In dynamic microphones a physical cone acts like a lens to concentrate the incoming sound waves. The concentrated energy of these sound waves moves the cone and its attached coil of wire back and forth inside a magnetic field. The magnetic field induces electricity to flow through the wire to produce an electrical signal which is the microphone's output. The electrical signal is analogous to the original sound wave: the voltage and current are proportional to the original sound.

Dynamic/Moving Coil microphones Advantages: �durable and can withstand a lot of volume before they distort (within their own circuitry). �they don’t require phantom power to operate. �colours the sound in range between 5 -10 khz, this adds clarity, presence and understandability to many vocal and instrument sounds. � doesn’t feedback as easily as other mics

Dynamic/Moving Coil microphones typical uses: �mostly live situations, but they are also used a lot in the studio. �close mic applications (1 -12 inches) �snare drums, guitar amplifiers, kick drum, vocals and any instrument that can play loud.

Dynamic/Moving Coil microphones disadvantage: These microphones often miss the many subtle nuances of sounds because it takes a lot of sound pressure to move the coil.

2) Ribbon microphones �a metallic ribbon is suspended between two poles of a magnet. Sound waves vibrate the metallic ribbon which causes a varying flow of electrons to the different poles of the magnet. Sound waves cause the foil to vibrate, producing fluctuations in the electrical current, creating the audio signal. This extremely sensitive configuration picks up a wide range of frequencies and produces an extraordinarily rich representation of the original sound. The trade off for this sensitivity is the delicacy of the mechanism. These ribbon microphones are also sensitive to physical impacts and therefore are not considered portable and can be easily damaged by power overdrive.

Ribbon microphones advantages: �This extremely sensitive configuration picks up a wide range of frequencies and produces an extraordinarily rich representation of the original sound. �These microphones capture a warmer and smoother sound than dynamic/moving coil microphones. �Don’t feedback much in live situations. �Don’t require phantom power to operate.

Ribbon microphones typical uses: �Typically used in the studio because they are fragile �Used in close mic applications (1 -12 inches) �Often used for acoustic guitars. Also work well for vocals.

Ribbon microphones disadvantages: �colours the sound by adding a high frequency edge �fragile �will only pick up sounds that are very close.

3) Condenser/Capacitor microphones A charged electrical current is applied to a metal-coated piece of plastic. the coating vibrates sympathetically in response to a sound wave because it is very thin. The metal-coated piece of plastic is positioned close to a piece of metallic alloy. The changes in the space between the surfaces create a changing discharge of electrical current. It makes an electrical version of acoustic energy from the sound source.

Condenser/Capacitor microphones advantages: �they respond to fast attacks and transients more precisely than other mics and add little tonal colouration �they can be used to record sounds from a greater distance and capture a broader range of frequencies � big advantage: these mics record a sound while capturing natural ambience of a room.

Condenser/Capacitor microphones typical uses: �recording studios �can be used to record almost any sound…except very loud ones (ex. Kick drum) � extremely effective with quiet sounds �the perfect choice for capturing room ambience. �almost always used for vocals , acoustic guitars and drum overheads.

Condenser/Capacitor microphones disadvantages: �fairly fragile �feedback too easily in a live environment (although some have low frequency roll off switches to help alleviate feedback frequencies) �require phantom power to operate

Microphone Pickup Patterns: There are three main types of patterns: � 1) Cardioid (unidirectional) � 2) Bi-directional (figure-8) � 3) Omnidirectional (boundary)

Unidirectional or Cardioid Pickup Patterns They pick up sound primarily from one direction - the front of the microphone. This allows for the isolation of the signal source from other performance elements or background noise. The cardioid pickup pattern resembles the shape of a human heart, hence the name, cardioid. You point the mic towards the sound you want to record and away from the source you don’t want to record.

Bidirectional or Figure 8 Pickup Patterns The bidirectional or figure 8 pickup pattern is equally sensitive on the two opposing faces of the microphone which correspond to the front and rear of the diaphragm, while rejecting sounds from the sides. Very good for recording two voices or voice and instrument on the same track. Positioning is very important to get the correct blend and balance of the two sounds.

Omnidirectional or Boundary Pickup Patterns The omnidirectional pickup pattern collects sounds equally well from all directions and will deliver the most accurate representation of a total environment (usually condenser mics). They capture room resonance along with the source, thereby yielding a much more open sound than that of the focused cardioid microphone. A major drawback to omnidirectional mics is their sensitivity to feedback. Again placement is a key concern.

Conclusion �Effective sound miking requires lots of experimentation. �Most home studios should have at least one good moving coil and one good condenser mic.