Microphone Basics: Transducer Type
Whenever you want to reinforce the sound of a voice or an instrument you use a microphone. This can be done when performing on stage, while rehearsing, giving a presentation or when you are recording at home or in the studio. Three technical charateristics distinguish microphones from each other. It is important to understand these so that you can make the best choice for your needs:
- Transducer type: How does the microphone physically pick up the sound and convert it into an electrical signal?
- Polar pattern / directionality: From which direction does a microphone pick up the sound?
- Frequency response: Is the output level or sensitivity of all frequencies the same?
In this post we will explain the Transducer type of a microphone.
Transducer Types (Dynamic, Condenser, Ribbon)
The type of transducer inside the microphone, that is, how the microphone picks up sound and converts it into an electrical signal.
A transducer is a device that changes energy from one form into another, in this case, acoustic energy into electrical energy. The operating principle determines some of the basic capabilities of the microphone. The two most
common types are Dynamic and Condenser. Another more special type is the ribbon microphone.
Dynamic microphones employ a diaphragm, a voice coil and a magnet. The voice coil is surrounded by a magnetic field and is attached to the rear of the diaphragm, therefore moving in correlation with the diaphragm’s movements. The motion of the voice coil in this magnetic field generates the electrical signal corresponding to the picked up sound.
Dynamic microphones have a relatively simple construction and are therefore economical and rugged. They can handle extremely high sound pressure levels and are largely unaffected by extreme temperatures or humidity.
Condenser microphones are based on an electrically-charged diaphragm/backplate assembly which forms a soundsensitive capacitor. When the diaphragm is set in motion through sound, the space between the diaphragm and the backplate changes, which in turn alters the capacity of the capacitor. This variation in spacing produces the electrical signal.
All condenser microphones need to be powered: either by batteries in the microphone or by phantom power provided by a mixer for example. Condensers are more sensitive and can provide a smoother, more natural sound, particularly at higher frequencies.
A ribbon microphone is a type of dynamic microphone that uses a thin electrically conducting ribbon placed between the poles of a magnet. Ribbon microphones are typically bidirectional. They pick up sounds from in front of the microphone and from the rear but not the side (90 degree angle).
Traditionally, ribbon microphones have been appreciated for their distinct sound quality, although they tend to be very fragile due to the nature of the ribbon’s material. Shure’s KSM313/NE and KSM353/ED microphones utilise Roswellite® proprietary ribbon material, which replaces traditional foil ribbons with high tensile strength, toughness, and shape memory that provides superior resilience at extreme sound pressure levels.