Zeddicus Zu'l Zorander
Perth Australia
Ultra Senior Member - over at anythingbutipod.com/forum
provides a nice synopsis:
Dynamic Drivers & Balanced Armature Drivers
In all speakers there is a U-shaped permanent magnet, which produces a constant magnetic field between its two poles. Between these two poles is located a coil, which doesn't touch the magnet. When an electric current is placed into the coil it creates another magnetic field around the coil. Since these two magnetic fields are sharing the same space and the current which causes a temporary field to be established is constantly changing, so to will the temporary magnetic field. This will result in a force which will cause anything which isn’t held in place to vibrate.
Dynamic Driver:
The part of a dynamic driver which is not in a fixed position is the coil itself. It is held by a flexible support so the vibrations it carries are transferred directly into a diaphragm (very basically put, a thin disc) from where the circumference of the coil’s end makes contact. The diaphragm carries the vibrations over a greater surface area so that the sound which is passed into the air in front of the diaphragm has enough amplification.
Balanced Armature Driver:
Unlike the above arrangement, the coil does have a fixed position in a balanced armature driver.
Instead a long arm, the armature, is placed through the centre of the coil, but does not come in contact with it.
The arm is only held in place in its centre, so it can still move and become the source of the driver’s vibration.
As the diagram shows, one end of the armature is connected to a small connecting rod (also called a drive rod, or drive pin) which carries the vibration to the very centre of the diaphragm.
Once again the diaphragm in turn passes the sound ahead with a sufficient sound pressure level.
--click on image to enlarge:
Attachment 19237
