Selection and placement of microphones ppt

Learn how microphones should be placed and which microphones should be use for different purposes.
Key words :-
- What is microphone
- Selection of Microphones
- Types of microphones
- PICK UP PATTERNS MICROPHONE
- Placement of Microphone
- Summary

1. Selection and placement of microphones

2. What is microphone ? Microphones converts sound into an electrical signal. Microphones are used in many applications such as telephones, tape recorders, hearing aids, motion picture production, live and recorded audio engineering, megaphones , in radio and television broadcasting and in computers for recording voice, speech recognition. Most microphones today use dynamic microphone, condenser microphone, or light modulation to produce an electrical voltage signal from mechanical vibration.

3. Selection of Microphones

4. Selection of microphone is very important because the microphone is the piece of gear closest to the source, it stands to reason that selecting the right tool for the job can make all the work easy. There are basically three types of microphones . Dynamic microphone Condenser microphone Pick up patterns

5. DYNAMIC MICROPHONE

6. Dynamic microphones are versatile and ideal for general-purpose use. They use a simple design with few moving parts. They are also better suited to handling high volume levels, such as from certain musical instruments or amplifiers. They have no internal amplifier and do not require batteries or external power. The advantages of dynamic microphones are their relatively low cost, high durability, and lack of need of power supply. The main element commonly consists of a plastic-film diaphragm connected to a coil of wire that is suspended in a permanent magnetic field. Once sound hits the diaphragm, the whole assembly moves to create a small electrical current.

7. CONDENSER MICROPHONE

8. Condenser means capacitor, an electronic component which stores energy in the form of an electrostatic field. The term condenser is actually obsolete but has stuck as the name for this type of microphone, which uses a capacitor to convert acoustical energy into electrical energy. Condenser microphones require power from a battery or external source. The resulting audio signal is stronger signal than that from a dynamic. Condensers also tend to be more sensitive and responsive than dynamics, making them well-suited to capturing subtle noises in a sound. They are not ideal for high-volume work, as their sensitivity makes them prone to distort.

9. PICK UP PATTERNS MICROPHONE

10. Unidirectional Microphone It picks up sound directly in front of the mics. Useful when the sound source is at some distance from the camcorder.

11. Bidirectional Microphone It picks up the sound to the side and in front of the mics’s head. Mostly use in interviews , talk shows , live shows etc.

12. Omnidirectional Microphones Omnidirectional mic picks up sound waves approaching the microphone from all directions . While this is the most basic pattern of the three, and the “purest” sound, it is the least commonly used in the studio. Consider this pattern when capturing choral groups choirs, and the like, or when natural room ambience is the goal.

13. Placement of Microphone

14. The golden rule of microphone placement is Get the right distance . In general, place the microphone as close as practical to the sound source without getting so close that you introduce unwanted effects .

15. . Proximity Effect As you move a microphone closer to the source, bass frequencies increase as distance decreases. This is least apparent with omnidirectional mics, but must be considered carefully with directional mics. Make sure you place of your mics far enough away from the source to avoid “howling” or excessive bass response. There are some points to be considered while placing the microphone which are given below

16. Mic-Stand Noise and Floor Rumble Any vibrations traveling through a mic stand will transfer through the microphone and into your signal path. Keep cables attached or wrapped to prevent them rattling against the mic stand. Position your mic stand so it won’t transfer vibrations traveling through the floor (foot stomps, kick drums, bass amps, etc.). Due to their increased sensitivity, use shock mounts when recording with condenser microphone. Low cut can be useful for these situations as well.

17. Phase Issues This is a topic that will be covered more closely in following topics , but here is an important tip: When using multiple mics on the same source (acoustic guitars, drum kits ) roughly translated, if Microphone A is 7 inches from the source, then Microphone B should be at least 3 times that distance, or 21 inches, away from Microphone A. This will help prevent phase issues created by the time delay between the microphones.

18. Selection and placement of microphones for specific purposes :- NEWS – Unidirectional microphones / stand microphone. NEWS REEL – Unidirectional microphone. DRAMA – Bidirectional / hanging microphone. COMMENTARY – Hand held microphone. DOCUMENTARY – Bidirectional microphone. PHONE – IN PROGRAM – Hand held / bidirectional microphone. INTERVIEW – Bidirectional / hand held microphone. FIELD BASED PROGRAM - Condenser or dynamic microphone TALK – Bidirectional microphone. SUMMARY