Headphones

Hardware devices that allow users to listen to their favorite tracks and creating the illusion that they are in the moment without annoying others. They typically consist of a set of two drivers that displace air in such a way so as to resonate the inner ear, creating what is perceived as sound. The three main types of headphone drivers are dynamic, planar and electrostatic, with each producing their own distinct flavor of sound. Headphones can also be open-back, semi-open or closed-back.

Headphone Drivers

Dynamic Drivers

The most common transducer in headphones is the dynamic driver. Dynamic drivers typically require less power to drive, allowing them to be powered by mobile devices such as phones (as long as it isn't an iphone), tablets and laptops. A dynamic driver converts an electrical signal that represents the music into mechanical energy expressed in movement of the driver diaphragm, moving the air in front of it and creating the sound you hear.

How Do They Work?

There are three main parts that make up the core of a dynamic driver: - a neodymium magnet - voice coil - a diaphragm that is attached to the voice coil

Inside a dynamic driver there is a voice coil or electromagnet connected to a diaphragm. The electrical signal sent to the electromagnet will cause the magnet to move in a pistonic motion at the same frequency as the audio signal. The diaphragms are typically make of laminates in the lower end and thin membranes coated in titanium, beryllium, magnesium, ect. in the mid-range to higer-end. Dynamic Drivers also come in different sizes, usually 40mm but it is not uncommon to see dynamic drivers that are 45mm, 50mm or even 60mm in diameter. A larger driver will be able to move more air and thus higher volume. To recreate a realistic bass response in a driver, the driver must be able to displace air, so if your looking for a bass heavy pair of headphones a dynamic driver headphone with a large diaphragm is recommended.

Balanced armature

Balanced armature (BA) drivers are much smaller than dynamic drivers and hence are only available in in-ear monitors (IEMs). Hearing aids and early loudspeakers for radio receivers were the first devices to use the technology. Balanced armature drivers are generally only capable of accurately producing frequencies in a small range. This does not pose an issue for hearing aids since they only need to reproduce frequencies between 250hz and 6khz, but IEMS need to produce a range of 20hz to 20khz. This is why you typically will see IEMs with 3 or even 4 BA drivers, each tuned for a specific portion of this range.

How Do They Work?

The BA driver consists of a miniature arm called an armature which is 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 and it is at an equal distance from both magnets, it is said to be “balanced”. The armature is attached to the center of the diaphragm and when current flows through the coil, it will magnetize the armature, causing it to pivot towards either magnet depending on the audio signal. This pivoting movement will then move the diaphragm and produce the sound you hear. As a result of this design, there is no need for an air vent meaning the IEM is completely sealed, creating more detail in the sound and offering the same effect as a pair of noise cancelling headphones with no sound being able to leak in provided the tips used also form a good seal.

Planar Drivers

The Planar Magnetic Driver or orthodynamic driver, is less common driver found mainly in open-back headphones. They require significantly more power to drive and cannot be reasonably powered by mobile devices or even a motherboard. Planar drivers require a high power desktop amplifier with tube amplifiers being the general recommendation. The drivers are extremely thin, often nano-meters and are usually in high-end headphones typically in the $1200+ range. The sound fidelity found in a good pair of planars is unmatched by dynamic drivers, making them extremely popular in the audiophile community.

How Do They Work?

Planar drivers are much like dynamic drivers in that they use magnetic fields to produce sounds. However, instead of moving a voice coil, the thin diaphragm is directly affected by the magnetic field, producing the sound you hear. As the whole diaphragm has to be evenly vibrated, larger or more magnets are used, adding onto the weight of the headphone. The drivers are typically at least 100mm, meaning planar headphones have significantly larger ear cups, adding to their comfort.

Electrostatic Drivers

// sound generated by force exerted on membrane in electrostatic field

Open and Closed Back

Open Back

// sound leakage both in and out, susceptible to dust, better soundstage, keeps ears cooler

Semi Open

// tries to strike balance between open back and closed, generally has a couple vents around the headphone

Closed Back

// complete seal, almost no sound leakage, no soundstage, music focused inside head, allows for an active noise cancelling design.