Headphone Driver Units

headphone driver type

Let’s face it.

Choosing a new headphones pair is not easy even if you’re not a first-time buyer.

Should I pickup over ear headphones or over-ears? Earphones or earbuds?

Which one would be better: wireless or wired headphones?

These are just some of the questions we ask to ourselves while looking for new headphones. But these aren’t the only areas where headphones differ from each other.

Headphone drivers units are another factor that you should take note of while shortlisting new headphones. These units comes in different types with each type having its own pros and cons.

In this post, we’ll discuss all of these driver unit types: Dynamic drivers, Planar magnetic drivers, Electrostatic drivers, Balanced armature drivers, and Magnetostriction drivers.

What is a headphone driver unit?

 

headphone driver unit

Before discussing each of these driver unit types, we’ll talk about what is a headphone driver unit.

A headphone driver is an element inside headphones that converts an electric signal into the audible sound which goes into our ear canals. You can think of it as a mini loud speaker inside your headphones.

It consists of a magnet, voice coils, and a diaphragm (measured in mm). Every headphones pair, no matter what type, comes with a headphone driver unit but there are some headphones that feature more than one driver.

While multiple drivers help each one of them to concentrate on a particular frequency range, they don’t guarantee good sound.

Driver size ranges from 8mm to 20mm in earphones, and 20mm to 50m in headphones. Although bigger driver size means bigger sound production, but that doesn’t necessarily mean better sound quality either.

It’s because of the different techniques used to built a driver which affects in how a headphones pair sounds at the end of the day.

Dynamic or Moving Coil Driver

Dynamic driver is the most common drive type and is found in most of headphones in the market. One of major reasons for that is because it’s cheaper to produce than all other driver types.

It usually features a neodymium magnet which magnetizes the voice coil to make it act as an electromagnet and create a magnetic field when current passes through it.

After this, the voice coil attracts or repel towards the magnetic field, depending on the flow of current. This movement of the voice coil moves the attached diaphragm as a result. The diaphragm vibrates and displaces the air around it, which produces the sound we hear.

Due to simplicity of the working mechanism, these drivers are cheaper to produce, are small/lightweight, can produce good bass response, and don’t require much power to reach higher volumes.

One downside noted in these drivers however, is that your audio can distort at high volume. But that effect can be reduced to a large extent by good engineering – something which all popular headphones brands do.

Planar Magnetic Drivers

Planar magnetic drivers, also called orthodynamic drivers by Yamaha, are slightly similar to the dynamic drivers because both of them require magnetic fields to produce sound.

But instead of using a voice coil, planar magnetic drivers have their diaphragms directly affected by those magnetic fields through snake-shaped wires embedded on it. 

Since the whole diaphragm has be to vibrated in this case, larger magnets (which make the headphones heavier) as well as more power from the audio source is required. If your source is not powerful enough, you would have to buy an external amplifier.

Yes, there are headphones like Oppo PM-1, which feature low impedance and less weight, but they are exception rather than the norm.

Due to all these reasons, planar magnetic drivers are usually found in high-end over ear headphones designed for home usage. Most of the times, these headphones feature rectangular earcups from the inside, and are open-back in nature (they are some in-ear model too, however).

As far as the advantages are concerned, these drivers offer a superb bass response due to their large-sized thin diaphragm and strong electromagnetic field in order to displace that diaphragm.

And since the vibrations of the diaphragm are evenly distributed across all the surface, you get very low harmonic distortion and more accurate sound. Lastly, these drivers make the headphones last longer when compared to dynamic drivers.

Electrostatic Drivers

Electrostatic drivers are called so because they use static electricity to produce sound. An electrically charged diaphragm is placed under two conductive (negatively and positively) metal plates, aka. electrodes. After this, it’s the diaphragm that push and pulls towards either of those perforated electrodes.

The air (that pass through these perforations) and the diaphragm’s vibrations produce the sound waves.

These drivers are complex, much more expensive to produce, and require special amplifiers (to amplify sound) to work which adds to the overall cost of the headphones. This is the reason why these drives are found only in very high-end open-back models.

They’re usually paired with dynamic drivers to produce bass response. The electrostatic headphones also tend to be really bulky and lack any portability whatsoever.

On the other hand, the absence of any moving metal pieces makes these drivers produce distortion-free sound. Moreover, the sound quality is better than what any other drivers offer and you get a true soundstage. 

Balanced Armature Drivers

Balanced armature drivers are smaller as compared to others. That’s why they’re used only in in-ear headphones.

These drivers consist of an armature wrapped by a coil and surrounded by two magnets. This armature rests on a pivot, rotates between the two surrounding magnets, and is attached to the centre of the diaphragm.

The reason why they’re called balanced armature drivers is because, in the case of no current, the armature is equally distant from both magnets, or you can say ‘balanced’. 

When current passes through the coil, it magnetizes the armature and causes it to move towards either of those side magnets. This movement of armature moves the diaphragm (because they’re connected) and produces sound as a result.

These drivers can be tuned to a specific frequency range but that range is limited. Therefore, many in-ear headphones come with multiple balanced armature drivers.

In order to make up for the lack of bass response, a dynamic driver is usually paired with these multiple BA drivers (like in 1more Quad-driver headphones). These drivers are expensive than dynamic drivers which adds to the overall cost of headphones.

Since these drivers don’t need to lot of air to displace, they don’t come with additional air vent. This, in turn, gives you a better sound isolation and more detailed sound as compared to dynamic drivers. These drivers also offer more treble than dynamic drivers.

Magnetostriction or bone conduction

Like in all other gadgets, there’s been a huge technological advancement in how headphones drivers are made – of which bone conduction drivers are an excellent example.

Instead of sending sound waves into your eardrum, as all other drivers do, they send vibrations directly into your inner ear through bone conduction.

Despite looking like some sci-fi gadgets, their working principle is fairly simple and you can learn more about it here.

These bone conduction headphones, also called bonephones, are especially helpful for those with hearing problem, but are limited in terms of sound quality, as compared to the headphones having any other driver unit.  

Conclusion

So these were all the headphones driver units we discussed. As for which of these drivers is best, that would depend on your needs. Dynamic drivers are sufficient for most people because they offer a perfect balance between budget and versatility. 

But in case you have both money and passion to find more accurate sound, then an upgrade to other driver types is definitely worth it.

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