Microphones

What are the 3 main types of microphones?

• Condensers

• Dynamic

• Ribbon

How do condenser microphones work?

• Contains 2 fixed plates and a diaphragm that moves. Both can conduct electricity.

•Its parts move very fast meaning they have very high frequency responses.

• Condensor microphones require external power (phantom power)

What can affect performance of a condenser microphone?

• Humidity

• Temperature

Are all dynamic microphones cardioids?

Yes

What is the proximity effect?

•The closer you place a cardioid microphone to an sound source, the bigger the bass boost. This produces an unnatural boosted bass. This usually requires EQ to reduces the bass.

• You can also change the polar pattern from cardioid to omnidirectional for example to reduce the boost of low frequencies are cardioids are more susceptible to the proximity effect.

How does a dynamic microphone work?

• Consists of a diaphragm, coil and magnet. The diaphragm and coil are attached to one another and the coil is wrapped around the magnet. Sound waves cause the diaphragm and to move within the magnetic field, which produces an electrical current.

Qualities of Dynamic microphones.

• Usually very durable

• The greater the mass of microphone, greater inputs (HSPL) can be handled.

• Less sensitive than condenser microphones

• Less linear frequency response.

• Less expensive

Qualities of Condensers microphones.

• More delicate than dynamics.

• Large inputs can damage them

• More sensitive to sound than dynamic

• Expensive condenser mics have a built in function, which allows them to change polar patterns for a different situation.

• More linear frequency response.

• Better transient response (can pick up sudden sound pressure level changes (lower mass, quicker transient)

• Usually more expensive

What are the types of polar pattens? (6 marks)

• Omnidirectional - Sensitive to sound from all angles.

• Cardioid - most sensitive at front/top and rejects sounds at the back. Useful to reject noise from the back, and prevents feedback.

• Hypercardioid - Large frontal pickup, smaller rear pickup. Use pop filters when using as they pickup plosives well.

• Supercardioid - Reduce pickup from sides and increase pickup from front/top. This however does pickup sound slightly more from rear than cardioid. Requires precise angle pointing. Very good in sound isolation.

• Figure of 8 (Bi-directional) - Picks up audio equally in 2 directions (usually front and rear). Great for vocal and instrument recordings when side rejection is heavily needed.

• Shotgun - Very focused at front, maximum rejection at sides and small pick up at rear. Often just hyper or supercarioid just in a tube. Often used in TV sets as they clearly capture sound at a distance without pickup up sound on sides.

What are polar patterns?

• Describes how sensitive a microphone is to sound waves from any direction.

How do ribbon microphones work?

• A type of dynamic microphone (transducers). Thin strip of aluminium is suspended in a magnetic field. When sound waves enter the mic, it causes the ribbon to vibrate, producing electrical current. RIbbon mics produce natural sound quality.

• The aluminium is usually 1/25 the thickness of a human hair!

What does HSPL stand for?

• High sound pressure level.

Qualities of Ribbon microphones.

• Very delicate. HSPL’s can easily break them.

• Don’t require phantom power (providing power will break the microphone)

• Great high frequency capability

• Even, flat frequency/transient response.

• Entirely rejects sound from sides.

• More expensive than dynamic microphones