Every pair of headphones here uses a speaker tech called 'dynamic' drivers to recreate sound, and this is by far the most common option for all headphones, earbuds and loudpseakers. It's the classic cone-shaped design you might be familiar with from bigger speakers, but in these headphones the drivers tend to be between 30mm and 40mm in diameter.
To explain how these dynamic speakers work, and what it is that makes them so popular with manufacturers, we spoke to Andy Kerr, Director of Product Marketing and Communications at Bowers & Wilkins, which has been creating these types of drivers for headphones and speakers for over 60 years.
“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."
For noise-cancelling over-ear headphones, dynamic drivers are effectively the only option for the speaker tech. While alternatives exist ('planar magnetic' and 'electrostatic' headphones drivers, for example, while 'solid-state' earbuds are also arriving), these are not used for ANC headphones, so dynamic driver tech powers everything in this list.