When planning your earphone DIY project, the very first thing you shall look to is the type of drivers which is the most critical component to both sound quality and your budget – Earphones are made up of many parts, one of which is called the transducer or the driver unit.
Driver Unit Basics
The driver unit is made up of magnets, voice coils and a cone-like tiny diaphragm (measured in mm) and is one of the most essential pieces of the earphone. Its job is to convert the electrical signal into a sound wave that the ear can understand. However, there is more than one type of driver unit per their working methods, and there could be multiple heterogeneous drivers working together in an earphone (like dual or quad diver earphone hybrid different kinds of drivers), see an example below.
The simple answer is no. Although in general, the smaller the driver is, the better it can perform on high frequency (e.g., >15KHz) and worse on low frequency (e.g., <200Hz), it is not necessarily the case. Instead, it is the variation of technologies used to build the drivers which make the difference. It is worth noting that it is possible for earphones to have more than one driver to manage the different ranges of frequencies, like the example above.
Do the number of drivers matters?
It really depends the quality of the driver. There is few extremely Hi-End single driver having the capability to produce sound between 20Hz and 20kHz, and most have limitations. And that is why multiple drivers entering the equation. Where more than one drivers are involved, filtering is used to segregate the range of frequencies allowing each driver to focus on a frequency range. But, just like the driver size, an earphone with multiple drivers does not automatically makes it a great earphone. A poorly produced quad driver earphone will not rival a well-made single driver earphone.
Types of Driver
Lastly, there are drivers with different types of core mechanism. Each has their own unique ways of producing sound. In this section, we will be exploring five types of earphone drivers that you should know about. The five types of earphone drivers are:
- Dynamic or moving coil
- Balanced armature
- Planar magnetic
Magnetostriction or bone conduction
1. Dynamic or Moving Coil Driver
Dynamic drivers, or moving coil drivers, which are the most common drivers.
How does dynamic driver work?
The driver uses the physics of magnetism and electromagnetism to create movement, which leads to sound creation.
Mechanism of A Dynamic Driver
There is three mains part that makes up the core of a dynamic driver:
- a neodymium magnet
- voice coil
- a diaphragm that is attached to the voice coil
The magnet magnetizes the voice coil which makes it an electromagnet. Once the voice coil receives current, it creates a magnetic field that head in directions determined by the flow of the current. The voice coil is repelled and attracted towards this magnetic field. Subsequently, this moves the attached diaphragm and it displaces the air around it, creating sound. The large the air displacement, the higher the volume. To recreate realistic bass response in a driver, the driver must be able to displace air. This is why a dynamic driver is great at creating the bass response. Since the mechanism is simple, dynamic drivers are very effective and do not require much power to reach high volume. However, one of the biggest complaints about dynamic drivers is that the audio is susceptible to distortion, especially at high volume. This is also known as “non-linear distortion”. This effect can be attenuate by good engineering though. Hence, it is unfair to plainly associate dynamic driver with poor quality. In fact, you find that a lot of high-end earphones that use dynamic drivers such Sennheiser HD 800.
- Able to create a good amount of bass response without the need for excessive power
- Dynamic drivers are very cost-effective
Dynamic drivers that are of poorer quality are susceptible to audio distortion at higher volume
2. Balanced Armature Driver
Balanced armature (BA) drivers
Balanced armature (BA) drivers which are smaller than dynamic drivers and, because of their size, are only available in in-ear monitor (IEM). They are known to be more expensive than their dynamic driver counterparts.
How does Balanced Armature work?
Mechanism of A Balanced Armature Driver
The driver consists of a miniature arm (armature) inside a coil of wire surrounded by two magnets. The top and bottom magnets determine the movement of the armature. When there is no net force on the armature, meaning it is at equal distance from both magnets, we say that it is “balanced”. From the diagram, you can see that the armature is attached to the center of the diaphragm. When current flows through the coil, it magnetizes the armature, causing it to pivot towards either magnet. This pivoting movement will move the diaphragm and produce sound as a result.
Tune to specific frequency
This type of driver can be tuned to cover a specific frequency, although the range tends to be a little limited. You may find that one single set of IEMs can have as many as four different drivers to complete the sound.
Works hand in hand with Dynamic drivers
The difference between BA and dynamic drivers is that BA does not displace air to produce sound. This results in a lack of bass response. This is why you can find IEMs with multiple BA drivers in combination with one dynamic driver. The dynamic driver will make up for the lack of bass response.
There is an upside to the BA mechanism in relative with the Dynamic Driver. Since it does not need to displace air to produce sound, an IEM with BA driver will not have an additional air vent. This provides a better isolation which in turns gives you a more detailed sound.
- Drivers can be tuned for optimal quality in specific frequency
- Better performance in the treble frequency than dynamic driver
- Sounds are more detailed
- Balanced armature drivers are generally more costly than dynamic drivers
- Need additional drivers to get a better bass response
3. Planar Magnetic Driver
Planar magnetic driver and open-back over the ear earphones. The drivers are extremely thin and are usually located in high-end earphones.
How does planar magnetic driver work?
Mechanism of A Planar Magnetic Driver
The drivers are based on a similar principle to that found on the dynamic driver earphones – using magnetic fields to produce sounds. So instead of moving the voice coil like the dynamic drivers, the diaphragm (a thin flat film) is directly affected by the magnetic field to produce sound. And since the whole diaphragm has to be evenly vibrated, larger or more magnets are used and this adds on to the weight of the earphone. It also results in the need for more power from the audio source or purchasing an external amplifier. Hence, they are not as portable as the dynamic drivers and are generally purchased for home use. Earphones with planar drivers also have a higher price tag than dynamic drivers. The sound offered by planar magnetic drivers is of a high standard with relatively no distortion and has good transient response. The bass response for planar earphones is excellent. This is due to the combination of the large thin diaphragm and strong electromagnetic force leading to the ability to displace a large amount of air.
- Planar magnetic earphones provide excellent quality and low-distortion sound
- Excellent bass response
- Necessary to have a earphone amplifier
- Larger and heavier
4. Electrostatic Driver
Electrostatic drivers take advantage of static electricity – the basis of which lies in the fact that like charges repel while opposites attract. The vibrations occur as the diaphragm pushes and pulls against conductive plates (negatively and positively charged respectively) or electrodes, and the air is pushed through the perforations. This action, along with the continuously changing electrical signal, results in sound waves that are understood by the ear. As the driver is quite complex and requires special amplifiers known as energizers, they are usually found in the high-end open-back earphones. Electrostatic drivers are relatively uncommon and are more expensive. However, what they lack in portability and affordability, they definitely make up in the sound arena and the extremely life-like soundstage. The electrostatic driver can produce significantly better sound than any other earphone available and this is reflected in the sale price.
- Electrostatic drivers provide distortion-free sound
- They offer a life-like soundstage
- They are very expensive to buy
- Electrostatic driver-based earphones require an amplifier
- Large and bulky
5. Magnetostriction or Bone Conduction
Wireless Bone Conduction Earphones
Earphones and drivers, in particular, have come a long way thanks to modern invention and design. Bone conducting or magnetostriction earphones are an excellent example of this, as the drivers bypass the eardrum sending the vibrations directly to your inner ear via bone conduction. It sounds a bit like sci-fi, however, but they are particularly helpful in situations where the ears need to be left unobstructed. Joggers who need to hear the sound of oncoming traffic over the source of the music can find these useful. They are especially helpful for individuals who have hearing problems as well. You can even purchase bone conducting earphones which can be used underwater. Also known as “bonephones”, these unique earphones have limited capabilities when compared to other, more conventional, earphones.
- Able to hear external sounds while enjoying your music
- Can aid those with particular hearing loss
- Limitations to their fidelity
While the final choice may come down to cost and availability, it is still worth knowing all the facts before you make your final earphone choice. For the most part, the dynamic driver is a first-rate purchase for effectiveness and price, but there are circumstances where the other drivers may be more useful for your needs. A purist audiophile might consider an electrostatic pair is useful if portability is not required and a high price is not necessarily an obstacle. The planar magnetic earphones might fit your appetite if you have a bigger budget and want to try something aside from dynamic driver. Or maybe you need the bone phones with their unique capabilities? Whatever kind of earphone you are seeking, our recommendation is to do a bit of research before you buy and try them for yourself.
5 Types Of Headphone Drivers That You Should Know at https://www.earphonesty.com/2017/04/5-types-earphone-drivers-know/