Balanced armature how does it work

BA drivers are very small and have size limitations. The main point is that we cannot understand balanced armature IEMs and earphones without comprehending how their drivers function. The design of the balanced armature earphone driver is pretty involved. In the above diagram, we see 7 different noteworthy components of the balanced armature driver design:.

In this example, the diaphragm is a stiff solid material much like the armature. It is connected to the inner case via a thin, flexible membrane. This membrane allows the diaphragm to move while keeping the two air volumes on either side of the diaphragm separated.

The working principle is the same in both general designs. So how does the balanced armature driver work? It begins with connecting the headphones to the audio source. When properly connected, the audio signal is passed through a circuit that includes the conductive coil. The coil is wrapped around a conductive armature, and the AC electrical signal and accompanying varying magnetic field are extended to the armature.

The varying magnetic field within the armature interacts with these two permanent magnets. Therefore, as the current flows in one direction, the armature will be attracted to the top magnet and repelled by the bottom magnet. This moving armature is mechanically coupled to a thin diaphragm via the drive pin. As the armature vibrates up and down, it causes the relatively large surface area of the diaphragm to push and pull air.

This pushing and pulling of air produce sound waves. The components within the balanced armature are rather fragile, and a protective case is required. The sound waves are produced within this case and escape through a sound outlet. The frequencies at which the armature and diaphragm vibrate should be consistent with the waveforms of the applied audio signals. Unfortunately, balanced armature drivers have notoriously poor frequency responses.

This means that, although the audible range of human hearing is between 20 Hz — 20, Hz and quality audio signals have the potential to cover this entire range, balanced armature drivers cannot reproduce all these frequencies. This is partly due to the inherent resonance frequencies that come with a balanced armature. The armature will be more easily moved at some frequencies compared to others.

On top of that, the volume of air inside the case has its own resonances due to the dimensions of the case. Extensive damping is often required to level out the frequency response. Even still, many BA transducers require multiple drivers to produce a wide frequency response effectively.

There are many factors that manufacturers tune or are at least aware of that affect the sound of the BA drivers, units, and ultimately the hearing aid, earphone or in-ear monitor. Larger volumes allow larger diaphragms and greater diaphragm movement, which results in higher sound pressure levels. Increasing the mass of the armature permits greater magnetic flux and improves low-end frequencies. Reducing the mass and increasing the armature stiffness increases the bandwidth of the system while worsening the low-end response.

Getting an extended frequency response with decent bass is difficult in a BA driver. Some balanced armature earphones designed even include a moving-coil dynamic driver to produce the low-end to avoid relying on a BA driver to do so. All else being equal, larger diaphragms push more air, but their higher mass limits their ability to produce high frequencies.

Adjusting the stiffness and mass is, therefore, a way to tune the BA driver. The placement of the diaphragm also plays a role in determining the overall loudness of the driver.

No surprises here, considering that it is the cheapest transducer on the list. The driver uses the physics of magnetism and electromagnetism to create movement, which leads to sound creation.

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 effect can be attenuate by good engineering though. Hence, it is unfair to plainly associate dynamic driver with poor quality. Balanced armature BA drivers are smaller than dynamic drivers and, because of their size, are only available in in-ear monitor IEM.

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 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. 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.

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. 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. Planar magnetic driver, also referred to as orthodynamic driver by Yamaha, is featured more in open-back, over the ear headphones. These drivers, originally developed for hearing aids and other critical listening applications, offer improved fidelity, realism and detail over traditional dynamic drivers. They are incredibly small and lightweight, and provide greater output with less power.

Balanced armature drivers use an electronic signal to vibrate a tiny reed that is balanced between two magnets inside a tiny enclosure. Audiophile Earphones Perfect for music lovers, audiophiles and travelers. Accessories Replacement cables, cases, and other accessories for your IEMs. Heritage Trusted on every stage in the world for over 25 years. Can you explain a little bit about the difference between Balanced Armature BA and Diaphragm sound reproduction?

So BA is a bit like a reed where a diaphragm is a more like a drum head or a speaker? The BA diaphragm is hinged at one end while the dynamic diaphragm moves axially.

Balanced Armatures were developed for hearing aids first and then applied to earphones, is that correct? What are some of the advantages to Balanced Armatures versus small dynamic speakers? So am I correct in thinking that BA has a higher or more efficient output than small dynamic speakers?

You see that in the output graph for same input power. So if I am understanding this correctly BA can be used in a smaller space than small dynamic speakers, how is this an advantage in In-Ear Monitors? Can you explain a little about what we're are seeing in the attached screenshot?