FiiO FT15 Open-Back Planar-Magnetic Headphones

FiiO FT15 Open-Back Planar Headphones

• 800 nm ultra-thin diaphragm

• Diamond-coated diaphragm

• Proprietary planar technology

• Large 101 mm planar driver

• Patented uniform magnetic field design

• 28 nm chip-grade manufacturing process

• 95 dB/mW high-sensitivity, easy-to-drive design

• Lightweight 425 g construction

• Premium North American walnut wood ear cups

• Liquid-nitrogen-treated 6N monocrystalline copper cable

• 2 pairs of tuning ear pads included

• Custom Yaoli linen headphone storage case included

Proprietary Planar Technology

Building on the foundation established by the pioneering FT5, the FT15 introduces a new evolution in planar design.

It features a groundbreaking 800 nm ultra-thin diaphragm and FIIO's first diamond-coating process, capable of reproducing even the finest nuances in music. A specially optimized patented magnetic circuit applies force to the diaphragm more evenly and powerfully, reducing vibration-induced distortion. The result is deep and solid bass, refined and easy-to-listen-to mid-to-high frequencies, and an overall warm, natural sound.

At the same time, the FT15 combines high sensitivity and easy drivability with a lightweight construction, delivering not only outstanding sound performance but also a more relaxed and comfortable experience during extended listening sessions.

Large 101 mm Driver

The effective vibrating area of a diaphragm directly determines bass energy density and soundstage scale. Equipped with a massive 101 mm full-size driver, the FT15 boasts an effective vibrating area of 6,443.5 mm², an impressive 35% increase over the previous-generation FT5.

This large energy reserve gives the FT15 exceptional dynamic impact and remarkable sub-bass extension. When reproducing highly dynamic pieces such as full-scale symphonies, it delivers a wider and more natural horizontal soundstage while effortlessly handling rapid dynamic variations.

800-Nanometer Ultra-Thin Diaphragm

The FT15's diaphragm thickness has been reduced from the previous generation's 6 microns to just 800 nanometers, making it 86.7% thinner than its predecessor. This nanometer-scale thinness approaches the physical limits of the material and represents the current state of the art in the industry. A thinner diaphragm means better sound performance in every respect.

Thanks to nanometer-level diaphragm precision, the FT15 delivers a faster transient response. Even the most subtle signals in the high and ultra-high frequencies can be reproduced with greater precision and accuracy.

The diaphragm follows the signal closely and moves with precision, starting and stopping in sync with the signal, with minimal residual ringing. The result is an exceptionally clean and refined sonic character.

The ultra-thin diaphragm provides greater compliance and lower distortion, producing smooth and refined highs that remain comfortable even during extended listening sessions.

Innovative Diamond Coating

The FT15 incorporates a patented multi-layer coating technology developed in-house by FIIO (patent no. ZL2024205488218). The voice coil features a silver-aluminum alloy coating to improve its mechanical performance and conductivity, while the diaphragm uses an innovative full-surface diamond coating.

Through a highly sophisticated manufacturing process, this design brings the unique physical properties of diamond into the field of acoustics.

The diamond material used in the FT15's coating offers greater hardness and structural stability, the same characteristics that make it a common choice for diaphragms in high-end loudspeaker tweeters.

Applied through a vapor deposition process, the coating forms a stable reinforcing layer on the diaphragm, reducing high-frequency breakup and improving response speed, extending the frequency response up to 40 kHz.

Because the coating resists decomposition and fatigue even under prolonged vibration, it maintains consistent acoustic performance over time.

An additional vacuum high-temperature treatment optimizes the substrate's natural frequency, lowering its resonance point to achieve deep and powerful bass extension.

Patented Uniform Magnetic Field Design

Traditional rectangular magnet designs generate an uneven magnetic field distribution, which can cause diaphragm breakup vibration and distortion, compromising sound quality.

The FT15 uses a patented uniform magnetic field technology specially developed by FIIO (patent no. ZL202420884963.1), combining custom-shaped high-strength magnets with an extremely precise and optimized magnetic circuit alignment to create a highly uniform magnetic field.

By applying uniform and synchronized force across the entire surface of the diaphragm, this design helps suppress breakup vibration and distortion at the source, faithfully preserving the details of the original sound.

The FT15's magnets have been precisely optimized using finite element analysis. Magnetic flux is distributed more evenly, the effective field covers a larger area, and the coil driving area is significantly increased.

The diaphragm is therefore driven more fully, increasing driver sensitivity. Along the direction of diaphragm movement, the magnetic field remains highly uniform. At different excursion levels, the force applied to every part of the coil remains even.

Nonlinear diaphragm breakup is suppressed at the source, and harmonic distortion is significantly reduced.

28 nm Chip-Grade Manufacturing Process

Conductive coils have always had one weakness: over time, they can deteriorate and break. The FT15 addresses this issue by adopting a precision process directly from the semiconductor industry.

Through a vacuum electroplating process, the voice coil is uniformly formed on the diaphragm, significantly strengthening the bond between the conductive layer and the diaphragm substrate.

The structure remains firmly bonded and stable even after prolonged vibration, improving the synchronization of diaphragm movement while maintaining greater consistency and stability in sound performance over time.

Already successfully used in several products, this process brings the likelihood of vibration-induced coil damage close to zero.

95 dB/mW High-Sensitivity, Easy-to-Drive Design

The FT15 incorporates a dual-sided heterogeneous magnetic array, using finite element analysis to optimize magnetic field distribution.

This keeps the voice coil positioned within the strongest region of the magnetic field, ensuring high driving force.

The FT15 can be easily driven by portable players and dongle DACs, delivering full and solid sound wherever and whenever you listen to music.

425 g Lightweight Design

To overcome the traditionally heavy weight of planar headphones, the engineers carefully optimized the material selection, structural design, magnetic circuit, and other aspects of the FT15, reducing its total weight to 425 g, significantly lighter than comparable planar headphones.

Less weight, without compromising quality.

The FT15 uses high-quality carbon fiber for the headband, a material that is costly and difficult to process, taking advantage of its light weight, high rigidity, and strength. Combined with an optimized structural design, it helps address the problems of excessive weight and unwanted twisting or deformation.

The high-end modified specialty plastic magnet bracket offers rigidity comparable to aluminum alloy while weighing only two-thirds as much at the same volume, providing all the magnetic-circuit strength required by the FT15 at a fraction of the weight.

The dual-sided heterogeneous magnetic circuit also reduces magnet weight compared with conventional designs while maintaining sufficient magnetic driving force.

Premium North American Walnut Wood Ear Cups

The central frame of the FT15's ear cups is made from FAS-grade North American black walnut, a wood commonly used for luxury car interiors, fine furniture, and high-end musical instruments.

Each pair is carefully finished and polished to preserve the wood's natural grain, resulting in a product that is as much a collectible as it is a pair of headphones, where musical craftsmanship meets fine woodworking.

FAS (Firsts and Seconds) is a high-level grading standard used in the North American hardwood industry and identifies timber that has passed rigorous quality controls.

Compared with standard-grade wood, FAS-grade black walnut offers more consistent grain patterns, fewer natural imperfections, and greater ease of processing.

Liquid-Nitrogen-Treated 6N Monocrystalline Copper Cable

The FT15 uses 6N OCC monocrystalline copper with a purity of up to 99.99998%, free of grain boundaries, with low resistance and high electrical conductivity.

These characteristics help reduce interference caused by oxygen and hydrogen impurities during signal transmission.

Each conductor undergoes more than 100 hours of cryogenic treatment with liquid nitrogen at -192 °C, reducing internal stresses in the metal and optimizing its microscopic structure.

This allows the signal to travel with exceptional smoothness, revealing clearer and more distinct sound.

The FPA insulation also provides subtle tuning of the mid-low frequencies, adding just the right amount of character so that the timbre remains transparent, open, and relaxed.

The cryogenic treatment applies exclusively to the copper core conductor and not to the cable's outer protective jacket.

A Comprehensive Set of Premium Accessories

Two pairs of ear pads are included.

The suede ear pads are extremely durable, enhance the bass, and add warmth to vocals while providing a smooth and non-fatiguing treble response, making them ideal for pop music and vocal-focused tracks.

The protein leather ear pads enhance high-frequency resolution and vocal clarity, making them particularly suitable for classical instrumental music and female vocal tracks.

Included as standard are a 4.4 mm balanced headphone cable, a 4.4 mm-to-6.35 mm adapter, and a 4.4 mm-to-XLR-4 balanced adapter, providing more options for connecting, upgrading, and enjoying the FT15.

The FT15 comes with a premium custom Yaoli storage case, made with the same materials and craftsmanship typically found in high-end French luxury products.

Durable and elegant, it provides optimal protection for the headphones wherever you take them.

Hi-Res Audio Certification

The FIIO FT15 is certified by the Japan Audio Society (JAS) for high-quality audio and accurately reproduces high-fidelity sound, delivering an authentic and realistic listening experience.

Specifications

Headphone type: Full-size open-back planar headphones

Frequency response: 7 Hz – 40 kHz

Driver type: 101 mm proprietary planar driver

Impedance: 24 Ω @ 1 kHz

Sensitivity: 95 dB/mW @ 1 kHz, 111 dB/Vrms @ 1 kHz

Weight: approx. 425 g (excluding cable)

Clamping force: 3.8 N ± 0.3 N

Cable material: Liquid-nitrogen-treated 6N monocrystalline copper cable

Cable length: approx. 1.5 m

Headphone connectors: Dual 3.5 mm TS

Audio connector: 4.4 mm balanced

In the Box

• Headphones ×1

• Fabric storage case ×1

• 4.4 mm headphone cable ×1

• XLR-4 (male) to 4.4 mm (female) balanced adapter ×1

• 4.4 mm (female) to 6.35 mm (male) adapter ×1

• Suede ear pads ×1 (pre-installed)

• Protein leather ear pads ×1

• FT15 packaging box ×1

• Quick start guide ×1