Drivers

Dynamic

Most of the time drivers are dynamic.
This is the moving coil speaker we know for decades.

 

Sennheiser HD 800

 

Balanced armature

This is a very small driver.

Therefore it is used in IEMs (In Ear Monitor)

 

Etymotic ER3SE IEM with balanced armature

 

 

 

Planar magnetic

This is known as ribbons in the speaker world.


Instead of a coil there is a thin foil hanging close to magnets.
The magnetic field created by the current flowing through the foil makes it move towards or away of the magnets.
As there is quite a gap between foil and magnets, efficiency is in general low.
The magnets make them heavy as well.

 

Audeze LCD X planar magnetic headphone

Electrostatic

Quad ELS was the first commercially successful speaker using the electrostatic principle.


A static loaded foil is moved between two stationary stators depending on the polarity of the stators.
As the foil is loaded, it requires a special amp supplying the bias load ( 300V most of the time)

Stax electrostatic headphone and amp.

References
  1. 5 Types Of Headphone Drivers That You Should Know - headphonesty
  2. How Headphone Dynamic Drivers Work - Tyll Hertsens
  3. How Planar Magnetic Headphone Drivers Work - Tyll Hertsens