All the wireless earbuds in our guide produce their sound using dynamic drivers, so that's one tech element you don't have to thing about. This is the most common kind of speaker technology in everything from big loudspeakers to over-ear headphones to earbuds. To explain how dynamic drivers work, and why they’re so dominant in wireless earbuds, we spoke to Andy Kerr, Director of Product Marketing and Communications at Bowers & Wilkins, which has over 60 years of experience creating these kinds of drivers in both headphones and loudspeakers.
“Dynamic drivers use a magnet, a voice coil (typically made from winds of copper wire wound around a circular form), and a diaphragm/drive unit (a thin cone of material that makes the sound). The narrow end of the diaphragm's cone is attached to the voice coil; the wide end of the diaphragm is held in place by a rubber surround, also called ‘suspension’. When electrical current is supplied to the voice coil, it becomes electromagnetic. This creates a push-pull interaction between the coil and the magnet, which it is coiled around, causing the coil to move up and down over the magnet rapidly. Since the coil is attached to the bottom of the drive unit, its movement pushes the drive unit up and down in response, creating sound pressure waves that your ears and brain translate into sound,” explains Kerr.
“A single dynamic driver can be made very compact, is light, and is highly efficient in terms of battery life, which is of course hugely relevant in the age of wireless earbuds. Dynamic drivers are also very popular in headphone designs essentially because they give companies like Bowers & Wilkins a way to use our knowledge and experience from designing and manufacturing them – for both loudspeakers and headphones – while customizing and continually improving the technology over time. For example, our approach to drive unit design combines stiffness in the material (for accuracy and fast response) plus good excursion (meaning how far the diaphragm is capable of moving, for deeper bass performance) that's equally important for both earbuds and loudspeakers."
Dynamic drivers are not the only earbuds driver technology available: planar magnetic is the most common other type, and we’re about to see the launch of more earbuds using a new solid-state driver. Some earbuds also combine a dynamic driver with a smaller solid-state driver to create a wider sound range, which is often known as dual-driver technology. It’s possible to have more than two drivers in earbuds, but it’s very uncommon in wireless earbuds.