Narnarayan Shastri Institute Of Technology SUBJECT:- AVS FACULTY:- Malhar Chauhan FIELD:- E.C SEM-5 TH TOPIC:- Types Of Microphones Prepared By, PATEL TIRTHAL D{ } JOSHI PARSHAD C{ } MANIRATNAM MUDALIAR P{ }

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. Introduction

 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.  Principle working of microphone:-  Electrical circuit is used to change these detected vibrations into an electrical signal that “images” the sound with an output voltage or current. Overview of a Microphone Transducer: device that changes one form of energy into another Mics and speakers: sound to electrical signal

Types of microphone 1.Moving coil microphone. 2.Ribbon microphone. 3.Crystal microphone. 4.Carbon microphone. 5.Capacitor microphone. 6.Piezoelectric Microphone. 7.Laser Microphone. 8.Fiber Optic Microphone. 9.Microelectromechanical Microphone. 10.Electret Microphone.

Dynamic Microphone

Overview Of Dynamic Microphone The moving coil microphones uses the principle of the electromagnetic induction. when a coil is laced in the magnetic field is moved with the sound pressure variations, there is change in the magnetic flux through the coil. Microphone consists of the permanent magnet, a diaphragm and a coil. The mass of the diaphragm is negligible. Sound pressure varies, the diaphragm moves in response to the changing force applied by the moving air.

sound moves the cone and the attached coil of wire moves in the field of a magnet. The generator produces a voltage which "images" the sound pressure variation - characterized as a pressure microphone.  Principle Working:-

Frequency Response hz DirectivityOmni directional Resonant Frequency3 to 4 KHz Sensitivity0.1 Pascal Distance Of Speakers25 to 30 cm Distortion5% Characteristics Of Dynamic Microphone

 Advantages Of Dynamic Microphone:- They are robust inexpensive and resistant to the moisture. Ideal for the on stage use. Good for line vocals, which improves speech intelligibility. Used for capacitor speaker cabinets and drum kits.  Disadvantages Of Dynamic Microphone:- Does not respond linearly to all the audio frequency. Combining the multiple signals correctly is difficult and design that do this are rare and tend to be expensive.

Condenser Microphone

Overview Of Condenser Microphone Sometimes called capacitor microphone. 2 parts: conductive diaphragm and metal back plate, spaced very close together Both charged with static electricity When sound waves strike diaphragm, it vibrates, varying the spacing between the plates This variation generates a similar signal to incoming sound wave Diaphragm mass is lower, responds faster to rapidly changing sound waves (transients)

sound pressure changes the spacing between a thin metallic membrane and the stationary back plate. The plates are charged to a total charge q.  Principle Working:-

Characteristics Of Condenser Microphone Impedance600 to 10,000 ohms DirectivityOmni-directional Distortion<1% Sensitivity0.1 Pascal Frequency Response 500 to 1100 Hz Resonant Frequency 2 to 5 KHz

 Advantages Of Condenser Microphone:- When the ultra thin diaphragm response to the sound pressure level, it changes the static electricity between the conductors into electric signal directly. Due to the material of the diaphragm is very thin and light, and can transform the sound into electric signal directly; the range of the frequency response can reach to the ultra-low frequency. The diaphragm of the electret condenser microphone works without any load.  Disadvantages Of Condenser Microphone:- They are Expensive. May pop and crack when close mic. Requires a battery or external power supply to bias the plates.

Ribbon Microphone

Overview Of Ribbon Microphone A thin ribbon is placed in the magnetic field, it moves at right angle to the magnetic field due to the sound pressure. This produces change in the magnetic flux through the ribbon conductor, inducing an emf across the conductor. The ribbon microphone is call as the pressure gradient microphone because the driving mechanical force is proportional to the difference of the pressure acting on the two sides of the conductor.

The air movement associated with the sound moves the metallic ribbon in the magnetic field, generating an imagining voltage between the ends of the ribbon which is proportional to the velocity of the ribbon - characterized as a "velocity" microphone.  Principle Working:-

Frequency Response20 to hz DirectivityBidirectional Impedance0.25 ohm Sensitivity0.1 Pascal Distortion<1 % Signal To Noise Ratio(SNR)50 db. Characteristics OF the Ribbon Microphone

 Advantages Of ribbon Microphone:- Good response for musical instrument. Ideal for dramas. Does not require an external bias. Ideal for stereo recording.  Disadvantages Of Ribbon Microphone:- It is very fragile and dielectric. Continuity and the resistance of the ribbon cannot be measured using metallic. Any mechanical shock can displace the ribbon.

Microphone Selection Criteria Natural, smooth tone qualityFlat frequency response Bright, present tone qualityPresence peak (5kHz) Extended lowsOmni condenser dynamic with extended low frequency response. Extended highscondenser Reduced leakage, reduced room acousticsDirectional Coincident or near-coincidentStereo mic Extra ruggednessDynamic Distortion-free pick-up of loud soundsCondenser with high SPL spec or dynamic Low self-noise, high sensitivity, noise-free pickup of quiet sounds Large-diaphragm condenser mic

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