Transducers

1
Transducers

• A transducer is a device that converts kinetic
  energy to electrical energy or electrical energy
  to kinetic energy.
• The most common types of transducers that we
  encounter in the studio are microphones, speakers
  and guitar pickups.

2
How a Speaker Works

• An electrical signal from a power amplifier flows
  through the coil, the resulting magnetic field
  interacts with the field of the permanent magnet.
  
• This causes the coil to move back and forth
  according to the variations in the electrical
  current.
• The flexible speaker cone attached to the coil
  moves with it and thus creates fluctuations in
  physical air pressure.

A speaker is essentially a dynamic microphone in
reverse
3
Types of Microphones

• Dynamic Microphones
• Relatively Cheap, Sturdy, Reliable
• Examples Shure SM57, SM58 EV RE-20
• OK for sound reinforcement, some recording
• Better for some things e.g., loud electric
  guitar
• Less sensitive, dont tend to pick up as much
  ambient sound
• Do not require power for pre-amplification

4
Types of Microphones

• Uses a movable plate called a diaphragm to detect
  fluctuations in air pressure
• Translates those fluctuations to electrical
  current using a voice coil and stationary magnet.

5
Types of Microphones

• Condensor (Capacitor) Microphones
• Expensive, Delicate, Sensitive
• Require power for pre-amplification
• Modern microphones use Phantom Power
• Examples AT 4033 Neumann U87, KM 84
• Usually best for professional recording
• Many types with different characteristics

6
Types of Microphones

• contains a flexible diaphragm as well as a
  stationary backplate
• The fluctuation of the diaphragm causes a change
  in electrical charge between the two plates.

7
Microphone Characteristics

• Basic types
• Omnidirectional (360 degree response)
• Directional (limited response field)
• Cardioid (most common)
• Supercardioid
• Hypercardioid
• Figure 8 (bi-directional)

8
Microphone Polar Patterns
9
Microphone Polar Patterns
10
Frequency Response

• Ideally, a flat frequency response
• No coloration accurate across spectrum
• WYHIWYG (audio equivalent of WYSIWYG)
• Closest to flat response directly in front, at
  optimal distance from microphone
• Proximity Effect
• Coloration enhanced bass response when close