It is said that music is every person's best friend. This is true for you, only with a slight difference. For you, music is life! One day, your favorite headphones suddenly stop working. You are so disappointed, and decide to get a new pair of headphones. Then, you notice something different; every beat, every sound, all so crystal clear and distinct. You mention this to your 'tech-savvy' friend who tells you that the reason is that you are using Dynamic Headphones and so your interest is piqued.
1. What are Dynamic Headphones?
When it comes to sound and audio, the term ‘dynamic’ is frequently used, and it simply refers to the loudness or amount of intensity of a sound, i.e., how quiet or how the audio turns out and the difference between this quiet and loud range. However, with headphones, it is slightly different as ‘dynamic’ describes the way the headphones work in transmitting sound. Dynamic headphones use the principle of electromagnetism to transmit audio into sound.
Let me break it down a little more. Dynamic headphones have an element called a ‘Driver’ that is electromagnetic and converts audio signals into sound using electromagnetic induction. This driver is basically a conductive wire that is connected to a movable diaphragm, suspended in a magnetic field. When an audio signal passes through the driver, the diaphragm vibrates, thus creating sound. The driver is the most important part of dynamic headphones as the headphones can come in many forms, such as open-back or closed-back, on-ear or over-ear, wired or wireless, stereo or mono or even as headphones or earbuds.
2. History of Dynamic Headphones
Dynamic headphones have flooded the market today such that it is only a tiny fraction of headphones that are not dynamic, and they will be labeled if otherwise. So, it is easy to assume that headphones have always been dynamic. This is not quite the case, though.
The first dynamic headphones were produced in 1937, and it was the Beyer Dynamic DT-48 model, which is still being produced today, although in modern versions. The main advantages of this early design were;
- They were easy to produce.
- Inexpensive models were made, as they were produced through a simple technical process, with readily available materials.
Nowadays, quality drivers make excellent sound, but they are quite expensive.
Electromagnetism was discovered by Sir Michael Faraday in 1831. It is a principle where an electrical signal moves across a changing magnetic field to cause an effect in a magnetic field. Electromagnetic induction using magnets and conductive material will cause relative movement between them to ensure equilibrium. This can occur with a fixed conductor and a varying magnetic field or fixed magnetic field and a moving conductor. The movement between a conductor and its magnetic field varies constantly.
This principle of electromagnetism will help understand the way dynamic headphones produce both high and low sounds. Some people think that the diaphragm moves forward, and this is what produces high sound. Then it comes back and emits a low note. Electromagnetism helps us understand what happens in reality. In dynamic headphones, the driver moves and simultaneously performing thousands of micro oscillations back and forth, producing a microsecond of both high and low notes.
All of this happens so fast that the listener might think it is happening at the same time. This is why the quality of material used in making the headphones are extremely important as they can affect the fluctuations of sounds. Therefore, the driver (the most important element in the headphones) must be light enough to move quickly, yet strong enough to not deform when moving, as there will be distortions in sound. The distortion of sound is the most significant in the sound chain of headphones as the distortion of a driver is measured in tens of percent. In contrast, the distortion of an amplifier or audio card is measured in tenths and hundredths of a percent.
This difference is quite large and is quite noticeable because the Amplitude-Frequency Characteristic (AFC) of the speaker, which humps in one part of the spectrum and dips in the other, can leave much to be desired. This factor is most important, and this is why sound engineers are constantly trying to get a variety of options of materials to create an ideal ‘driver’ as well as more advanced types of sound emitters that can be found in modern headphones.
There is no ideal material for such purpose, but there is a wide variety of options, from Bitumen Paper to Kevlar. Manufacturers have to choose their distinguishing feature, e.g., some headphones play better bass, while others capture sounds in the middle flawlessly.
3. Classification of Dynamic Headphones
Most dynamic headphones are classified based on how they work and the kind of drivers each type of use. With this, they are classified into 3 main groups
3.1 Moving-Coil Dynamic Headphone Driver (Electrostatic Headphones)
Electrostatic Headphones are one of the most popular headphones in the market today. They were first produced in 1959 by the Japanese Company Stax as the model SR-1. The emitter/diaphragm of this headphone is basically an ultrathin membrane (measuring a few microns thick) made of composite material. The driver of this headphone has a moving coil of conductive wire attached to the emitter. This driver conducts electric current and is located between a magnetic structure (composed of magnets and pole pieces which act as electrodes).
The electrodes are supplied with static electricity as the audio signal passes through the pole pieces. The magnetic field surrounding it causes the membrane to push and pull air around the driver, which then creates sound.
There are advantages of electrostatic headphones, some of which include;
- The diaphragm’s weight is a lot less and, therefore, moves faster, producing more detailed sounds, playing the most delicate parts of a soundtrack.
- There are little or no sound distortions in electrostatic headphones.
- The frequency response of electrostatic headphones is much more even than the frequency response of conventional speakers.
Some of the disadvantages of the electrostatic headphones include;
- Price: There is a complexity in the production of electrostatic headphones, as entry-level models cost as high as a thousand dollars and above. For example, Sennheiser recently released the Orpheus HE-1 electrostatic headphones, which can be purchased for $59,000.
- Need for Amplifiers: Dynamic headphones still need amplifiers for them to be used regularly. The amplifiers needed to work with a moving-coil headphone will also cost a couple of thousand dollars.
- Bass: Electrostatic headphones do not produce the ultra-low frequencies that produce bass sounds. This is a primary design flaw in Electrostatic headphones.
3.2 Magnetic Planar Dynamic Drivers
Magnetic Planar headphones also work using the principle of electromagnetism, but the conductive element in a planar magnetic headphone is transmitted directly into the diaphragm itself, put between 2 permanent magnets, rather than being attached to the diaphragm in Electrostatic headphones. The driver of the magnetic planar headphones is quite similar to the electrostatic driver design, due to its structure of a very thin diaphragm placed between 2 space slotted magnets.
The diaphragm is made of a thin film that has a flattened wire within. This structure of flat thin diaphragm and flat magnetic discs give the name ‘Magnetic Planar’ as the magnets work on a plane. There are different designs of this type of headphones, with varying sizes and numbers of magnets.
Here’s a list of famous Magnetic Planar Headphones: Audeze LCD4, Hifiman HE-400s, Audeze El-8, Oppo PM-1, Audeze LCD-24 Special Edition Planar Headphone, HIFIMAN SUNDARA Open-back Planar Magnetic Headphones, Audeze iSine 10
Some of the advantages of the Magnetic Planar Headphones include;
- Magnetic Planar headphones are not as expensive as Electrostatic ones. For example, the cost of Audeze Mobius is cheaper compared to other dynamic headphones in its range.
- This class of headphones yields a greater precision of transmitting sound.
- The Magnetic Planar headphones are produced in a way that the signal vibrates the diaphragm directly, and this produces a greater range of sounds, and thus, an overall sound quality.
Some disadvantages of the Magnetic Planar headphones include;
- The magnetic planar headphones are not as fast as the electrostatic headphones in producing sounds.
- Magnetic Planar headphones require large permanent magnets to work, which negatively affect their weight and overall comfort.
3.3 Balanced Armature Dynamic Headphones (Drivers)
They are a little bit more technical in their workings but still use the electromagnetic induction principle. The headphones use balanced armatures, which are basically U-shaped in a way that the top part is fixed, and the bottom part is bendable. This armature can conduct electrical signals, but there is a wire coil wrapped around it that is directly connected to the audio source. This source cases a magnetic flow in the armature, making the lower movable part move towards one of the magnets’ poles.
To create sound, a drive pin connects the bottom of the armature to the diaphragm, making it move up to push air and create high sounds. To create low sounds, the pin makes the armature pull the diaphragm downwards, pulling air too. In the balanced armature system, the audio signal causes sound waves by the movement of the diaphragm.
Here are some great example of the Balanced Armature Dynamic Headphones: Shure SE846-CL, Shure SE535-CL, 1 More Quad Driver, Westone W40, Mee Audio Pinnacle P1, KZ AS10 In-Ear Monitors, Optoma NuForce HEM8
Some of the advantages of this class of headphones include:
- They are highly efficient in producing sounds of high and low ranges.
- The armature is usually balanced and relatively unstable, so it can capture low-level audio signals.
- They are small in size and are used generally as In-Ear Monitors (IEM).
However, the disadvantages of this type of Headphones include;
- It is not very effective and requires extensive tuning and dampening due to high resonances.
- They usually fail in reproducing an entire audible spectrum, and as such, many drivers are needed in a single IEM to produce a wide range of sound.
I am sure you’ve become more enlightened than I was many years ago when I first learned about headphones’ classification. Newer versions of headphones are being produced as dynamic headphones are ever-increasing in popularity, so now you have a wide range of products to choose from.
Just ensure you have these tips to help you choose the best product that fits your purpose!