The type of driver being used in a headphone is certainly an important detail, but the majority of consumers have no real understanding of these mean in practical terms. Even among serious audio-enthusiasts there is sometimes some confusion as to the exact nature of different driver technology and how it affects the audio experience.
What is a Headphone Driver?
First of all, we need to be clear about what a headphone driver actually is. People may be familiar with software drivers on their PC, but what we‘re talking about here is hardware. Put simply, the driver is the part of a headphone that turns the electrical signal into sound waves. This can be achieved in all kinds of different ways, and the solution used has a big effect on the sound profile. It‘s important to keep in mind that one type of driver isn‘t necessarily “better” than another, it‘s more a case of different technologies providing different characteristics. Let‘s take a look at the main types of driver found in headphones today.
The most common type of driver found in headphones is a dynamic driver. This is basically the same technology used in full-sized speakers, only on a miniature scale. There are three main components to a dynamic driver; the magnet, the voice coil, and the diaphragm. The magnet is used to magnetize the voice coil, and when current is applied to this it becomes an electromagnet. This can create a magnetic field in a direction determined by the flow of the current, and this field moves the diaphragm in a specific way. It‘s this movement that creates the sound waves that make their way into your eardrums. The more the diaphragm moves, the greater the displacement of air and the louder the volume.
The fact that this technique involves the physical displacement of air makes it very suitable for reproducing bass. Good-quality dynamic driver headphones will produce a thumping bass your ears can really feel. Given that headphones are prone to lacking bass and sounding tinny, this is a significant characteristic, and is probably the main reason why you‘d want dynamic drivers in your earphones. The mechanism is cheap, easy to assemble, and doesn‘t require much power. This kind of technology has been around for a long time and the components required for it are very easy to source. Unfortunately, dynamic drivers are also often associated with a lack of clarity, especially when playing at a loud volume. This issue is known as non-linear distortion, and is caused by the diaphragm moving in ways that cannot be fully controlled. When a lot of force is being applied to the diaphragm, particularly when it reaches its maximum degree of movement (i.e. maximum volume), it vibrates beyond what can be controlled by the electromagnet. This won‘t create a buzz or a hiss but simply a lack of clarity, as the sound waves that are produced are slightly different from what was intended.
However, it would be an oversimplification to think of dynamic drivers as being “cheap” and only for budget headphones. Many high-end (and high-price) headphones use dynamic drivers, including offerings from the likes of Bose and Sennheiser. The pricey Beats range of headphones is also well-known for utilizing dynamic drivers to achieve the bass profile that brand is associated with. Dynamic drivers are certainly prone to distortion, but skilled engineering can keep this to minimum, and the impressive bass performance can often make up for that. AUKEY‘s T10 true wireless earbuds make use of dynamic drivers to produce the impressive bass performance they are renowned for.
• Physical movement of the diaphragm produces good bass response
• Relatively loud
• Relatively easy to manufacture
• Uses inexpensive components
• Can suffer from distortion at high volume
• Less clarity compared to other driver types, especially in the treble
Balanced Armature Drivers
Balanced armature drivers are a little more complex and are generally only used for in-ear headphones rather than larger audio equipment. An armature is the part of an electrical device that carries the current (and in this case vibrates and creates sound), and “balanced” refers to the fact that this is placed between two opposing magnets. Force is applied from these magnets to vibrate the armature and create sound. Modern designs usually use a “diving board” arrangement where the armature is fixed at one end.
One of the main advantages of balanced armature drivers is that they are so small and require very little physical movement. This makes them ideal for fitting into tiny in-ear headphones. It also means it‘s easily possible to include multiple drivers within each earbud, with individual drivers focusing on specific frequency ranges. The tiny size also means very little current is required, and so battery life is even better than with balanced drivers (which are themselves quite strong in this regard). The other main advantage is that because the physical movement is so low, it‘s easier to control the sound waves more tightly, resulting in crisp and clear sound. This is particularly noticeable in the treble when compared to dynamic drivers, and they tend to perform better at maximum volume too.
The relative lack of air displacement also means there is generally no need for an air vent, which improves noise isolation. The downside of not having much displacement of air is that the bass is often a bit underwhelming. They are also prone to resonance at high volumes, meaning some kind of damping is essential, adding complexity to the design and reducing the maximum volume. Although they need very little amplification, this also makes lower-quality balanced armature drivers prone to hiss, much more so than dynamic drivers.
• Noticeably better treble performance compared to dynamic drivers
• Overall more detailed sound
• Multiple drivers can be used at once and tuned to different frequencies
• Very small
• Requires very little power
• Weak bass compared to dynamic drivers
• Relatively complex and expensive
• Requires damping
• Prone to resonance and hissing unless well-engineered
As we‘ve seen above, the choice between balanced armature drivers and dynamic drivers is something of a trade-off between full bass and crisp highs. If you go with dynamic drivers, you sacrifice treble and clarity at high volumes, but if you go for balanced armature drivers, you missing out on bass.
It is possible, however, to combine both types of driver in a single headphone—a solution known as hybrid drivers. In such a setup, the balanced armature drivers provide high-quality mids and highs, while the dynamic drivers ensure there is a thumping bass. Because balanced armature drivers are so small, it‘s not too much of an issue to fit one (or several) alongside the dynamic driver in each speaker. As you might expect, this is a not a simple thing to achieve, and getting the different technologies to work together and produce a coherent sound requires a degree of expertise and engineering wizardry.
A hybrid-driver setup is quite common in high-end headphones popular with audiophiles, but you needn‘t break the bank to get your hands on such technology. AUKEY‘s EP-B80 wireless earbuds make use of hybrid drivers and offer impressive bang for buck.
• Combines the strong bass of dynamic drivers with the crisp treble of balanced armature drivers
• Complex to engineer and tune
• Generally more expensive than single-driver setups
There are other kinds of driver in existence, such as planar magnetic drivers, but the vast majority of earphones on the market use one of the three solutions outlined above. Next time you‘re looking for a pair of headphones, keep an eye out for the type of driver being used as it can give you a rough idea of the kind of sound profile you can expect.
You can browse AUKEY‘s full audio selection here.