AUDIO VIDEO SYSTEM E.C Engg. 5 th Sem. Anurag Pandey ( ) Guided by :- Prof. Parth Patel (E.C Department)

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  Example: Shure SM 57  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

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 5-10khz, 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  Example: Beyer M 160  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

Ribbon microphones advantages:  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  Example: Audio Technica AT 4033  How do condenser microphones work?  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 ovreheads.

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 polar patterns:  A polar pattern is the pickup pattern of the microphone.  There are three main types of patterns:  1) Cardiod  2) Bi-directional  3) Omnidirectional

Frequency Response  Most microphones respond to frequencies within and beyond the human range of hearing.  Our ears have the ability to hear frequencies from hertz.  All microphone manufacturers provide specifications for the frequency range of their products.

Frequency response curve  The frequency response curve of a microphone shows how the microphone responds to different frequencies across the audible spectrum.  A mic with a flat response adds little colouration to the sound. Many mics drop off sharply in the frequencies below 300 hz. Yet boast frequencies in the area of 4000 hz.

Pre-amplifiers  Although a microphone can be plugged directly into a mixing board, better results are often achieved by using a pre-amplifier.  Example: Universal Audio 2-610

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

Thank You