The driver is the most important component of Headphone. The driver converts electrical signals into the sound waves we hear. The headphone driver has 3 main components:
Magnet: Its purpose is to create a magnetic field, which is necessary to move the diaphragm between the magnetic field created by voice coils and magnet which in turn produces vibration in air which produces sound.
Voice coils: The electric signals are passed through the voice coil which magnetises it and diaphragm moves towards it and then when signal is no longer present diaphragm moves towards the magnet, this way diaphragm moves continuously displacing the air in controlled manner producing sound. The materials used to make voice coils are generally oxygen free copper (HI-OFC) and Pure Copper by Ohno Continuous Casting (PCOCC).
Diaphragm: This is a thin membrane which vibrates in accordance with the electric signals received. It displaces the air and produces sound waves, basically it converts mechanical vibrations into sound waves.
Impact of Headphone Driver on the Sound? Do Driver size matters?
Usually a larger driver produces more bass and people assume that having a larger driver means better sound but this is not always true. Sound quality and loudness depends on many things and not just driver size, sometimes even a small driver can be better than a large driver.
Headphone driver unit comes in varied sizes. They vary from 20mm to 50mm. The size do influence the bass response and loudness but does not always mean that will produce better sound. Big drivers produce better bass but lag behind when it comes to producing high frequencies.
To achieve good sound quality we need to focus on the variation of materials used and the quality of driver unit.
Factors on which sound Quality depends-
There are 3 main factors on which sound quality depends, they are tuning ie tuned for high frequencies or low frequencies, ear padding, with proper padding sound leakage can be prevented which enhances the experience and quality of materials used for the driver. With high quality materials used in driver the driver unit can produce high quality sound and with stand high power levels.
Usually these days most companies use good quality materials as cheaper materials easily distort or break on high power levels.
Types of Driver:
1. Dynamic Drivers (Moving Coil Drivers)
Most of the mid-range headphones ship with this type of driver. These are decent driver units which are easily available and produces good sound especially bass. They are very common and most of the headphones come with this.
Dynamic drivers have 3 main components, a voice coil, diaphragm and a magnet.
The magnet magnetises the voice coil and when the electric current flows it behaves as an electromagnet and in turn moves the diaphragm which displaces air to produce sound. It usually displaces large amounts of air producing good bass response.
However, it has one downside, at high volumes it tends to distort if good quality materials are not used. Choosing better materials can make this driver really good and some of the high-end headphones also use it.
2. Planar Magnetic Drivers
These drivers are usually used in open-back over the ear headphones. They are more expensive as compared to dynamic drivers and mostly used in high-end headphones.
The principle they use to produce sound is similar to dynamic drivers but instead of magnetising the voice coil, it directly magnetises the diaphragm to produce sound.
To obtain this more magnets and sometimes bigger magnets are used as we need to vibrate diaphragm evenly. Due to this the weight and power consumption of the headphone is increased and we need an amplifier to run the headphone to its full potential.
Headphones with this driver are generally more expensive but the sound they offer is of higher quality as well. They have good transient response and usually has no distortion.
3. Electrostatic Drivers
Electrostatic drivers work on the principle of static electricity. They are rarely used as they have complex mechanism and are found in very few open back headphones.
The diaphragm is located between to electrodes(conductive plates). When the electricity passes through the electrodes they produce electric field which in turn moves the diaphragm to and fro according to the supply of current, displacing the air and hence producing sound.
These drivers are very sophisticated and require a lot of power to run properly and hence cannot be used without an amplifier but that said they produce incredible sound which makes them worth for professionals and audiophiles.
4. Balanced Armature Drivers
These drivers are small in size and are usually used in in-ear earphones and earbuds. It comprises of a miniature arm (Armature) which is balanced between two magnets. The arm is connected with the diaphragm. When the current flows through the magnetic coils the arm moves towards either and according to the signal and with that the diaphragm moves and hence producing the sound. Since, the driver is small it does not produce very good bass response.
5. Hybrid Drivers
As dynamic drivers are good for Bass response but struggle in producing high frequency sounds and balanced Armature driver are good in producing high frequencies but struggle to produce good bass response, the combination of these two can provide us with best of both worlds. This is known as Hybrid Drivers. They are a combination of balanced armature and dynamic drivers.
Manufacturers use this type of driver to produce high quality sound in every frequency range. They sound they produce is vibrant, detailed and has warmth to it.