What is a headphone driver?
Drivers are used in all headphones and earbuds, even noise cancelling headphones, and produce the sound that you hear when listening to music. The basic principle of operation is similar across all types of drivers. Magnets create a magnetic field, and electrical signals pass through a conductor, which reacts electromagnetically with the magnet. This creates movement that vibrates a diaphragm, creating sound waves. The various types of drivers are constructed differently but usually feature magnets, conductors, and diaphragms.
Different types of drivers
Dynamic drivers
Dynamic drivers, also known as moving coil drivers, are by far the most common type in over-the-head headphones, using a magnet and voice coil to create sound waves. The basic form of this kind of driver hasn’t changed much in the last century, but technological advances have made great improvements in their efficiency, power, and accuracy.
When an electrical current is passed through a copper voice coil, the attraction and repulsion of this electromagnetic interaction with the magnet causes the voice coil to move. The voice coil is in physical contact with a diaphragm, or cone, making it move, producing the sound waves you hear when listening to a song.
Dynamic drivers are a relatively inexpensive type of headphone driver. Sound quality can vary due to design compromises, or the materials used in their construction, but they are good at reproducing bass frequencies and offer sound quality that is more than enough for most listeners. At high volumes there can be unwanted distortion from the movement of the voice coil causing secondary vibrations to other components, but this can be eliminated by good engineering.
Balanced armature drivers
Balanced armature drivers are mostly used for in-ear monitors, due to their smaller size compared to other drivers. They work by having a balanced armature resting on a pivot between two magnets, with a coil wrapped around the armature. When a current passes through the coil, the electromagnetic interaction moves the armature, in turn moving the attached diaphragm.