Electrostatic headphones are not new to the high-end IEM segment, but the FX15 is FiiO’s first attempt at such a product. When developing the FX15, FiiO’s R&D team spent a lot of time researching how best to use electrostatic drivers. Due to the low sensitivity of such drivers, special care must be taken to ensure that they are not overloaded by other dynamic and BA drivers in use. Otherwise, listeners will not be able to fully experience the unique sound that electrostatic drivers offer.
Electrostatic drivers are known for their high frequency detail reproduction, but such drivers are typically used in very expensive IEMs that are out of reach for most audiophiles. The FiiO FX15 uses 4 electrostatic drivers per channel, which not only provide exceptional ultra-high frequency extension, but are also extremely fast and capable of reproducing every last detail in your music, giving listeners a truly sophisticated audio experience at a high level.
The FX15 uses the proven Knowles ED-29689 balanced armature driver to reproduce the midrange and low frequencies, resulting in a soft, rich yet detailed sound. In addition, the research and development team reduced the sensitivity of this balanced armature driver through housing design and other techniques. This ensures that the balanced armature driver and electrostatic drivers output their respective frequency ranges without interference from each other – resulting in the two drivers working together in harmony with a smoothed overall frequency response curve.
The FX15 is equipped with a 10mm DLC-coated dynamic driver, which was chosen for its high stiffness, high damping ratio and other positive characteristics – this allows the driver to reproduce a solid, full sound that successfully combines high detail with a pleasant listening experience. And to achieve harmony between the dynamic, BA and electrostatic drivers, the research and development team specially redesigned the structure of the dynamic driver, resulting in a consistent sound from bass to ultra-high frequencies in the frequency response curve of the FX15.
A separate switch allows you to turn the electrostatic emitters on and off and get the sound of a regular hybrid headphone with a combination of dynamic and armature emitters.
The FX15 are tri-hybrid headphones with the patented S.Turbo acoustic design, designed to maximize bass performance. The core of S.Turbo’s design is an elongated bass sound tube that effectively filters the high-frequency sounds produced by the dynamic driver, so that the sound of the bass dynamic driver and the mid-high frequency balanced armature driver are smoothly connected and do not interact with each other to achieve optimal sound quality.
The FX15 have a design that embodies the philosophy of “sound and form” working together in harmony. The golden ginkgo leaves applied to the FX15’s body serve as a visual reminder of its brilliant and vibrant sound, fully allowing the listener to discover the stories encoded in the music.
FiiO collaborated with HeyGears to create a case that combines excellent comfort and durability to allow the listener to fully enjoy electrostatic headphones without the worry. The FX15 enclosure is manufactured using an advanced DLP 3D printing method with a printing accuracy of up to 0.0375mm, which ensures that each FX15 enclosure is precisely molded to ensure high sonic consistency between each manufactured unit. In addition, the FX15’s housing is made of photosensitive resin that is highly impact resistant, providing reliable protection for electrostatic and balanced armature drivers.
The FiiO FX15s come with a high purity silver cable that has 224 strands divided into 8 bundles of 28 wires each. Each wire has its own insulation and the cable has a Litz braid. The outer shell is made of environmentally friendly TPU, which not only gives the cable a transparent and bright appearance, but also better protects it from yellowing and loss of elasticity.