You may heard about those little shiny ‘boxes’ inside Hi-End monitor earphones, but what are they and how do they REALLY work? How does something so small produce a sound so amazing? It’s simply because they are balanced armatures which have some great advantages over dynamic drivers
If we look at a cut-away of a balanced armature driver and a brief technical explanation that we found on Wikipedia on how they work.
A balanced armature is a sound transducer design which is primarily intended to increase the electrical efficiency of the element by eliminating the stress on the diaphragm characteristic of many other magnetic transducer systems. As shown schematically in the diagram, it consists of a moving magnetic armature that is pivoted so it can move in the field of the permanent magnet. When precisely centered in the magnetic field there is no net force on the armature, hence the term ‘balanced.’
As illustrated in the diagram, when there is electric current through the coil, it magnetizes the armature, causing it to rotate slightly one way or the other about the pivot thus moving the diaphragm to make sound.
In simple terms, the coil is held in the middle by two magnets until it’s stimulated by an electrical current, causing the diaphragm to vibrate thus creating a sound wave. This sound wave then moves its way through the sound hole of the driver, through the earphone and into your eardrum… BAM! musical nirvana!