The 7 Types Of Headphone Drivers that You May Have Heard Of
Headphone drivers. They matter more than you’d think.
These days you can find various headphones with different drivers. The drivers impact the sound output and sound signature of the headphones greatly. When picking a headphone, you must be aware of and understand the kind of driver it has. So that you get exactly what you’re looking for. And the headphone sounds the way you want them to.
It isn’t just about looks but also what’s on the inside. The transducer or the driver unit (simply called the ‘driver’) is the part that sits inside the earpieces of every headphone.
What are Headphone Drivers
A headphone driver is responsible for converting the electrical signal into a soundwave. The soundwave is what you hear in turn. The drivers reside in the earpieces of every headphone. They’re constructed from magnets, voice coils, and a piece called the diaphragm. Since they’re essential for producing sound, they are an important part.
Some headphones have a combination of drivers in them (more on that later). The size of the drivers for In-ear headphones (earbuds/earphones) can range from 8mm to 15mm. And for On-ear and Over-ear headphones, from 20mm to 50mm.
Types of Drivers
The Seven types of headphone drivers are:
- Balanced Armature
- Dynamic (Moving Coil)
- Planar Magnetic
- Bone Conduction (Magnetostriction)
Every driver adds a different colouration to the sound. Below we will go in-depth on how these drivers perform and how they differ from each other. From the list of drivers mentioned above, you may have most likely heard of some of them like the dynamic drivers.
Balanced Armature Driver
The Balanced Armature (BA) drivers are pretty small in size. This is why you’ll only find them in In-Ear Monitors (IEMs). Even compared to Dynamic drivers, they’re still quite small. Also opposed to Dynamic drivers, they’re more expensive to produce.
How does the Balanced Armature driver work?
The driver construction includes a coil of wire surrounded by two magnets inside of which you’ll find the miniature arm (armature). The magnets at the top and the bottom manage the movement of the armature. It is considered to be in a “balanced” state when there is an equal distance from both magnets.
As shown in the picture, the armature is connected to the middle of the diaphragm. When an electric current passes through the coil, it magnetizes the armature which causes it to turn towards either magnet. This action moves the diaphragm and produces sound.
Focus on a particular frequency range
The Balanced Armature driver can be attuned to cover a particular frequency range. Though, you’ll find the range to be fairly limited. A single pair of IEMs may require as many as four such drivers to cover the entire sound spectrum.
Aids Passive Noise Isolation
The way the Balanced Armature mechanism is built, it doesn’t require the movement of air to produce sound. An IEM (in-ear monitor) with a BA (Balanced Armature) driver does not need extra air vents. This results in better passive noise isolation.
Dynamic (also known as Moving Coil) driver is the most commonly found driver. The reason behind this is that they’re pretty inexpensive to manufacture compared to all the other drivers.
How does the Dynamic driver work?
The movement within the driver is caused using the physical principles of magnetism and electromagnetism. This in turn leads to sound production.
The centre of a dynamic driver is made of 3 parts – a neodymium magnet, a voice coil, and a diaphragm which is connected to the voice coil.
The voice coil turns into an electromagnet as it is connected to the neodymium-magnet. The flow of the electric current passing through the coil makes it move in either direction. Finally, this moves the connected diaphragm, which in turn moves the air around it. And that’s what creates sound.
Higher volume requires more air to be moved. To produce a strong low-end, the driver must have the ability to shift air. This is what makes a dynamic driver better than a balanced armature driver at producing a vivid low-end.
Due to the simplicity of the mechanism, dynamic drivers can reach higher volumes efficiently and effectively. Nevertheless, dynamic drivers face criticism for causing audio distortion at high volumes. In technical terms, this is called ‘non-linear distortion’. Though, this does not mean the dynamic driver is of poor quality as this effect can be negated by sound engineering.
Dynamic drivers are used in low, mid and high-end headphones as well.
A hybrid driver uses two drivers – dynamic and balanced armature to produce sound. Hybrid drivers generally use two, sometimes more drivers to produce an appealing and complete sound signature. Using multiple drivers ensures that the sound produced is vivid and precise with the right amount of low-end.
Since BA drivers are weak at producing bass they’re paired with Dynamic drivers to make up for the lack of bass. This is why you’ll find IEMs with various BA drivers coupled with one dynamic driver.
The 1More Triple Driver is a perfect example of this.
Planar magnetic or orthodynamic driver is found more in open-back style, over-ear headphones. These drivers are remarkably thin.
How does the Planar Magnetic driver work?
The Planar Magnetic drivers use magnetic fields to create sound, similar to the Dynamic driver. But instead of using the voice coil, they directly strike the diaphragm using the magnetic field. Multiple or large magnets are used to generate an even vibration throughout the diaphragm. This also adds to the weight of the headphone. Which also requires greater power.
This is where an external amplifier comes into play. This reduces their portability and is usually bought for casual home use. Compared to Dynamic drivers, headphones with Planar Magnetic drivers also cost a lot more.
Companies like HIFIMAN manufacture planar magnetic headphones that are fairly lightweight and have a low impedance. The HIFIMAN HE-400I is one example that weighs 370g and has an impedance level of 35 Ohm. The sound reproduction of Planar Magnetic drivers is phenomenal with nearly zero distortion.
Bone conducting, also called magnetostriction headphones are a great example of technological innovation. Unlike traditional drivers that send the sound directly into the eardrum, bone conduction uses the bones to transmit these sounds.
This type of headphones is especially useful when people need to stay aware of their surroundings. For example, joggers and commuters. People who suffer from hearing problems would also find these useful. Swimmers can look for bone-conducting headphones that can be worn underwater.
Sometimes called ‘bonephones’, they have a distinct look but also make some sacrifices in terms of features.
Electrostatic drivers use the principle of static electricity. Among all headphone driver technologies, this is the most expensive. Electrostatic drivers are quite rare to find, that’s partly due to their high prices. And they also need special amplification called energizers to function as intended. They also have the best sound reproduction.
How does the Electrostatic driver work?
When an electrical signal passes through the electrodes which are positively and negatively charged, it creates an electrical field. This makes the diaphragm (located between the two electrodes) to be drawn to one or the other electrode. This diaphragm movement causes the displacement of air. The working of this mechanism coupled with continuously shifting electrical signals results in sound generation.
Ribbon drivers or ‘tweeters’ is one headphone driver that you may have never heard of. Their construction makes use of thin grooved metal such as aluminium and magnets. The magnets determine the movement of the metal. This enables the ribbon to serve as both a voice coil and a diaphragm when the signal passes through it.
Ribbon drivers don’t use diaphragms, due to this they maintain quick impulse response and top-notch transients.
Their unique design allows them to cover a greater surface area which in turn helps them move more air. This gives a feeling of spaciousness and a better soundstage. They also shine in highs (treble) and micro-dynamics performance. Similar to Electrostatic drivers, they are challenging and very expensive to manufacture.
One such manufacturer of Ribbon driver headphones is Raal-Requisite with their SR1a headphones. They have a super low impedance of 0.018 ohms. They do necessitate using a speaker amplifier and impedance interface box (comes included with the headphones) to push the ribbon headphones to their peak performance.
Does the Size of a Driver matter?
It does matter but not in the sense you may think. The quality of sound is not determined by the size of the driver/s. Rather, it depends on the technology that the driver uses. Usually, the size of the driver is a sign of how spacious the audio sounds. It must be noted that headphones can possess several drivers (Hybrid driver headphones) to handle the different frequencies ranges.
Does the Quantity of Drivers matter?
Even a single driver is capable of producing sounds between 20Hz and 20kHz. That said, it does possess flaws. Using multiple drivers is one solution to tackle this problem. As seen in Hybrid drivers, each driver has to manage a particular range of frequencies. The result is overall better and more detailed sound output.
Just as the size of the driver doesn’t automatically make the headphones sound better, so too is the case with having multiple drivers.
Most often you’ll find the dynamic driver to be the best in terms of price to performance. They are also readily available as most headphones use them. An audiophile may go for an electrostatic pair if he’s willing to sacrifice portability and doesn’t mind the price tag.
You may want to try something different by going for the planar magnetic headphones. Maybe you want to give bone conduction headphones a shot. As with everything, when deciding on buying something, it is crucial to know what your needs are and how much you’re willing to spend.