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Decoding Headphone Driver Units & its Types

What Does a Driver Unit Mean?

First, let’s understand what music is, in this context. It’ll help us better understand what a driver is. Music or any sound that you hear is basically air molecules that move in a particular pattern in rapid succession.

This pattern, when it reaches you is “understood” by the brain (via feedback from your ears) as sound.

Now to create sound, a body must vibrate in a particular manner that it asses this vibration to the air around it, which then becomes sound, as humans perceive it.

Now for or a speaker, any kind of speaker, to produce music, it needs to a unit within it that makes the air molecules vibrate in a particular manner.



Ali Pardiwala, NDTV
"Headphones come with different driver technologies The most common and affordable technology is dynamic drivers, which exists on the vast majority of headsets available. As you go up the price range, you can also get balanced armature drivers, planar magnetic drivers, electrostatic drivers or hybrids, which make use of two different kinds of drivers in the same headset."


This unit inside a headphone, in this case, whose movement or vibration causes air to move and thus help create music is known as a Driver.

The driver unit takes in electrical signals and converts them into sound waves that reach your ears.

A standard driver unit is made up of a magnet, voice coils and a diaphragm. The diameter of a driver is an important aspect.

Usually measured in millimeters, it determines the kind of music a headphone can produce or is capable of.

 

How Does it Impact the Sound?

The short answer - yes it does. Different drivers (different by virtue of technology used or size and other factors) provide unique outputs.

These can be tuned as per the requirements of a user by a brand that is particular on the kind of output it wants their users to experience.

Do note that it’s usually thought that the bigger the driver, the louder the sound it produces because it can push more volume of air at the same time. This is not entirely true.

The reason being that every headphone design, from micro-sized earphones to huge headphones with varying sizes of the driver unit, the loudest volume at which you would hear them, stays the same.

This is because loudness is defined by what your ears perceive. Whether a small or large driver produces say 80dB, it won’t be different in terms of loudness because the ear sense loudness as 80dB and that’s about that.

There can be other discerning factors like sensitivity, soundstage, clarity among others that will be different for different drivers, but not loudness.

You might also think that headphones ought to be louder than earphones due to bigger drivers.

Not true because headphone driver units are at a further away from your eardrums compared to that of earphones which are comparatively closer to your eardrums.




Left to Right: 14.33mm, 9mm and 7mm. Typically, in-ear drivers are smaller.

What Makes a Driver Unit Good?

Bigger the driver unit, larger the speaker, and more powerful is the output - that’s the basic mantra.

This doesn't necessarily mean better output though. The quality of the driver unit - it’s make, the material used, the tech involved, design and so on - is what makes a huge difference to the sound.

The size of the driver unit for earphones falls in the range of 8mm to 15mm and 20mm to 50mm for headphones.

Earbud style earphones have bigger driver units as compared to canalphones (commonly known as in-ears) because of their ability to house bigger units.

Same is the case with headphones, an over-ear headphone will have bigger drivers as compared to on-ears.


Types of Driver Units

Dynamic Drivers


This is the most common driver type used. The dynamic driver uses larger diaphragms. It is the most preferred one as they’re efficient at producing powerful bass and achieve the right amount of sound pressure without using a lot of power.

However the concept of ‘ a bigger driver unit hence a better bass response’ doesn't apply to dynamic drivers.


 

Balanced Armature Drivers


These are very well suited for In Ear Monitors because they are quite small in size.

But why would you want to have a small driver that displaces more air?

Simply because you can have more number of them at a relatively tiny space!

How this translates to better audio is that each armature can then be assigned to generate one particular frequency (such as bass, mids or highs).

This helps in producing an output that is well-defined and clear. Most IEMs have anywhere between 1-4 balanced armature drivers per earpiece & Custom IEMs can have up to 20.

How this helps is that you by adding more armatures, you can even assign drivers to focus on frequencies like mid-bass, mid-highs and so on. Balancing them all out can result in a truly impressive output from a very tiny unit, i.e. an IEM. 

 

Planar Magnetic Drivers

Most high-end headphones these days have planar magnetic drivers in them. In this pioneering technology, a very thin diaphragm (thinner than the width of a human hair! No kidding!) is sandwiched between two very powerful magnets.

A wire is made to go through the diaphragm in a serpentine pattern creating an electromagnetic field that can interact with the magnetic field which thus creates sound waves.

Audeze headphones are a remarkable example. The benefits of such technology are many. Simply put, the audio reproduction is truly phenomenal and Audeze as a brand is still untouchable when it comes to providing with the best rage of headphones in this category.



Electrostatic Drivers



Most headphones use a moving-coil or dynamic driver. Electrostatic drivers are extremely expensive & uncommon.

The reason - these headphones use a thin, electrically-charged diaphragm that is placed between two conductive plates or electrodes.

This needs heavy duty power and that too of a very particular kind to function. But, the performance received is worth the effort.

For example, STAX is one of the pioneering headphone brand in this category. However, to run a STAX headphone, you’ll need a special amplifier to enjoy music. Audiophiles and purists swear by this technology and for very solid and irrefutable reasons.

 

Hybrid Drivers

Hybrid Drivers are a relatively new technology. It is a combination of dynamic and balanced armature drivers.

This means audiophiles can enjoy a balance of both, deep dynamic bass and bright treble. These earphones tend to be on the costlier side but then again, they’re revered for their performance and sought out for their unique output.

 

 


Dynamic drivers or balanced armature, Planar magnetic or Electrostatic - the driver technology that goes into powering music from a headphone are many. Each one, as you can see has a specific output and thus, a unique following or fanbase. Take your time and look at the various factors (including what’s in your wallet!) while considering a headphone or earphone. Ideally, we suggest first understanding the kind of Sound Signature you’re looking from your headphones. Then consider what kind of driver technology you should be looking at.

Happy Listening!