Darshan Institute of Eng. & Tech. Subject:- Audio Video System Topic:- Types of microphones Prepared By: Pruthvirajsihn Jadeja (130540111013)

Introduction A microphone is a type of transducer. Early microphones were invented for communication purposes. Later modifications were made to design as the microphone was used more in entertainment industry. Different situations call for the need of different microphone designs as well different pickup patterns. Need to consider factors such as the source, the location of the source and the environment of the source.

Overview of a Microphone Diaphragm—part of microphone which receives the vibration from sound waves. Thickness and material of diaphragm are changed depending on the sound waves you wish to pick up. How it works? Electrical circuit is used to change these detected vibrations into an electrical signal that “images” the sound with an output voltage or current.

Different Types of Microphones Carbon Button Microphone Ribbon Microphone Dynamic Microphone Condenser Microphone

Carbon Button Microphone Thomas Alva Edison and Sir Emile Berliner filled patents for Carbon Button Microphone in 1877. Edison's design became the accepted design and patent. This is a popular microphone for telephones as well as early radio and speeches. Diaphragm: Thin Metal Plate The diaphragm is connected to a button full of carbon power. A voltage is applied across the button. Sound pressure changes the resistance through the button by compressing/decompressing the carbon by pushing the plate.

Carbon Button—Design Diagram

Advantages: Disadvantages: Low cost High output Considerable background noise fold has carbon that can not be eliminated. Frequency response is not good for high feudality work.

Ribbon Microphone Diaphragm: Thin piece of metal foil suspended in a magnetic field. Vibrations in ribbon produce a small voltage which is then stepped up by a transformer. Diaphragm is very easily damaged by wind or loud incoming sounds. 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 The lightness of the ribbon guarantees a flat frequency response for mid and high frequencies up to 14kHz. It resonates at very low frequencies (around 40Hz)

Ribbon Microphone—Design Diagram

Advantages: Disadvantages: 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. Disadvantages: Diaphragm: Plastic Diaphragm pushes a coil of wire suspended in a magnetic field. Durable design and versatile use. A reverse of a loudspeaker.

Dynamic Microphone Movement of a copper coil around a magnet causes a changing flow of electrons that represent the sound wave. Dynamic mics consist of a diaphragm suspended in front of a magnet to which a coil of wire is attached. The coil sits in the gaps of the magnet. Vibrations of the diaphragm make the coil move in the gap causing an AC to flow Coils of wire are used to increase the magnitude of the induced voltage and current

Dynamic Microphone—Design Diagram

Advantages: Disadvantage: Durable and can withstand a lot of volume before they distort (within their own circuitry). They don’t require phantom power to operate. Colors 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 microphones Disadvantage: These microphones often miss the many subtle nuances of sounds because it takes a lot of sound pressure to move the coil.

Condenser Microphone Diaphragm: Thin metal strip suspended next to a charged electric plate. This creates a capacitor. Diaphragm moves in and out and changes electrical capacitance. Requires a power source for the charged plate. Distorts easily and has a flat frequency response. 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.

Condenser Microphone-Design Diagram

Advantages: Disadvantages: 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. Disadvantages: 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 Pickup patterns help to reduce unwanted signal from getting pickups Popular patterns: Monodirectional, Bidirectional, Cardioid, and Omnidirectional