We are familiar with different types of headphones, earphones, and headsets. But do you know what is a headphone driver?
According to experts, drivers, technically transducers are the heart of a headphone, and it is an electromagnetic device.
If you have ever checked the specification provided on the headphone or earphone box, the first thing would be driver size. Your headphone’s performance is directly related to the driver size and the quality of material used.
While shopping for headphones or earphones in online shopping sites such as Amazon or other offline shops, you might have noticed 6 mm, 15 mm, or 40 mm drivers. Do you know what are mm drivers in headphones?
Here we will clarify all your doubts about different types of headphone drivers and how to check them while selecting headphones.
What is a Headphone Driver?
A driver is a unit that contains the essential parts of a headphone for producing sound. The basic function of drivers is to convert electrical energy into a sound signal.
The electrical signals from the mobile phones coming through the cable will be converted into the corresponding sound energy by the driver unit.
Earphones and earbuds with smaller earpieces let the manufacturer use only smaller drivers of 6 to 15 mm, whereas headphones have bigger drivers ranging from 30 to 60 mm. Actually, does driver size matter in headphones? Yes, a big YES.
One of the most disputed facts among professionals is, what is a good driver size for headphones?
A bigger driver can deliver powerful and loud audio with broader frequency, and a smaller driver can offer only lower bass, frequency, and sound. But since the earphones and earbuds are inserted directly into the ear canal, it offers a better feel than the driver size.
Parts of a Headphone Driver Unit
- Voice Coil (Copper Coil)
We have already provided a detailed function of each of these parts in how do headphone drivers work. Anyway, the driver unit acts as a casing for all these components.
Now let us see what is a headphone driver and their classifications,
Types of Headphone Drivers
- Moving Coil Driver (Dynamic Driver)
- Electrostatic Drivers
- Orthodynamic Drivers (Planar Magnetic Drivers)
- Balanced Armature Driver (BA Drivers)
- Bone Conduction Drivers (Magnetostriction Drivers)
Moving Coil Driver (Dynamic Drivers)
In this type of driver setup, a structure, usually, a headphone frame, support the stationary magnet for producing a magnetic field.
The coil actuates the diaphragm for making audio based on the electrical signal moving through the copper coil. The vibration of the diaphragm moves the air around it and creates sound.
The amount of sound produced is directly proportional to the vibration of air by the driver.
Most of the moving coil drivers use Neodymium magnets, occasionally called rare earth magnets. They are an alloy (combination) of Neodymium, Boron, and Iron. It is considered the strongest permanent magnet in the world.
What makes them attractive among earphone manufacturers is their high magnetic energy storage capacity and the least possibility of demagnetization tendency.
Most of the headphones available in the market are neodymium drivers headphones.
Electrostatic Driver Headphones mainly consist of a diaphragm, two electrodes or plates, and a step-up transformer (amplifier). It consists of a thin, positively charged diaphragm instead of a cone-shaped one in the previous design.
It is then placed between perforated metallic electrodes. The audio signal (electrical sound signals) is amplified using an amplifier and then fed to the electrodes and forms a magnetic field.
It causes the diaphragm to move between the plates, vibrating the air around it and coming out through the perforated plates. This comes out as audio.
It can deliver a wide range of frequencies, usually beyond 20 Hz to 20 kHz, the standard audible limit of human ears. Unlike dynamic drivers, it does not have any moving parts, ensuring no distortions and maximum accuracy.
They are costly and affordable only in professional headphones and other high-end audiophile quality earphones.
Orthodynamic Drivers (planar Magnetic Drivers)
Their working principle is quite similar to electrostatic drivers, and the only difference is in the size of magnets used. It is equipped with a larger magnet and an ultra-thin diaphragm with thin wires are attached to it.
Here the magnetic field produced by the magnet directly vibrates the diaphragm without the aid of a moving coil. An additional amplifier for more power usually accompanies this kind of driver.
In order to ensure the uniform movement of the ultra-thin diaphragm, multiple magnets with bigger sizes are used.
The headphones with the planar magnetic drivers are more common in over-ear headphones with an open-back design. The diaphragm used in this driver is so thin in the range of nanometers (1 meter= 10^9 nanometer) and the conductor size in the range of microns (1 meter= 10^6 micrometre).
Balanced Armature Driver (BA Drivers)
Balanced Armature Drivers are the latest, smallest, and the best energy-efficient earphones. Because of their tiny size, they are used in canal earphones or IEMs (In-Ear Monitor) by professionals and audiophiles and hearing aids.
The technology used in this type of driver is entirely different from others. The main part of this driver is a coil wrapped around an armature that is balanced between two magnets.
While designing, extra care should be given for the perfect balancing of the magnet in the pivot. One tip of the armature is connected to the centre of a diaphragm using a rod.
When a current moves through the coil, it causes the magnet to move, resulting in vibration of the diaphragm through the rod connecting magnet and diaphragm. The vibrations of the diaphragm produce sound.
Usually, they offer only a narrow frequency response and medium bass. So they are integrated with dynamic types for better bass and broader frequency range. They are not found in headphones. They do not require the movement of air for sound generation.
The BA driver’s main advantage is that we can accommodate more drivers in a single earpiece due to its smaller size.
Bone Conduction Drivers (Magnetostriction Drivers)
As the name indicates, Bone Conduction drivers carry the vibration into the ear bones, stimulating our inner ear to hear the sound. Lack of diaphragm is the main difference between this type of driver from the rest. The piezoelectric property of the bones is used here.
These types of headphones are different in every aspect, from design to working principles. Instead of electromagnetism, it works on the piezoelectric effect.
It is the phenomenon of producing electricity by pressing a piezoelectric material by applying mechanical energy. This property of the material is widely used in the defense field, headphones, and so on.
Examples: bones, crystals, enamel, silk, etc.
Here the duty of the diaphragm is performed by a piezoelectric material. It means the electric signal is sent to a piezoelectric material.
Just like the electrostatic drivers, the piezoelectric material is suspended between two metallic sheets, and the audio signal is directly fed to that metal.
When the plates receive a current that carries an audio signal, it causes the piezoelectric material to expand and shrink accordingly. Then the movement of that material will be fed to your cochlea through face bones, and the vibration of the inner ear bones is finally heard as audio.
Classification of Headphones based on the Number of Drivers
The output of a headphone highly depends on the number of drivers and the size of the driver. Based on the number of drivers provided at each side of the earpiece, earphones are classified into,
Note: Equipment with more than three drivers is not included in this list because they are very rare. Such kinds are common among speakers.
Single Driver Earphones
In single driver headphones, you can hear only one range of frequencies. It has only one driver or speaker. Bass, treble, and other details of the music are integrated through this single driver. Most of the mid and low range headphones have a single driver.
Dual Driver Earphones
But in dual-driver earphones, it has two drivers or speakers of different sizes and different purposes. In most dual-driver headphones, one driver is meant for bass, and its size would be larger than the other.
The second smaller driver delivers treble and vocal sound. It means it ensures a double frequency. The output from both the drivers overlap and provides a more precise sound to the listener. High-end earphones are equipped with dual drivers.
Triple Driver Earphones
Triple drivers are the rarest of the rare in headphones. They are usually found in music studio speakers and earphones, where extreme precision is required.
As the name indicates, it has three drivers. Triple driver earphones are exclusively meant for professionals who must locate even minute errors in playing an instrument while recording a song. They are costly.
It is not mandatory that all the drivers should be of the same type. Usually, in Triple driver earphones, there are two Balanced Armature drivers and one dynamic driver.
Here we have provided a detailed description of all the major types of headphones drivers. For ordinary music lovers, single dynamic drivers are adequate.
Other technologies like Electrostatic and Planar drivers are recommended for professionals and are costly too. We hope this article helps you to understand what is a headphone driver. We believe now you have deep knowledge of what is the meaning of driver in headphones.