Foldable portable open-back headphones

The JadeAudio JT9 open-back planar headphones combine a large proprietary 3.74 x 3.39 in (95 x 86 mm) planar magnetic driver with an ultra-thin 0.000039 in (1 μm) diaphragm, sapphire and aluminum dual-coating technology, and a patented uniform magnetic field design. With 95dB/mW sensitivity, a lightweight foldable structure, and both 3.5mm single-ended and 4.4mm balanced cables included, the JT9 brings planar magnetic performance to a wider range of portable and desktop sources. :contentReference[oaicite:0]{index=0}

Large proprietary planar driver

The JT9 uses a proprietary 3.74 x 3.39 in (95 x 86 mm) planar magnetic driver developed by FIIO's acoustic engineering team. Its large diaphragm supports deep bass extension, broad dynamic range, and a spacious presentation. Refinements to the manufacturing process lower the driver's resonant frequency, while a redesigned ear cup structure helps expand the vertical soundstage and create a more natural sense of space.

Ultra-thin diaphragm

An ultra-thin 0.000039 in (1 μm) diaphragm keeps moving mass exceptionally low, allowing the JT9 driver to respond rapidly to changes in the audio signal. This fast transient behavior helps reproduce fine harmonic information, sustained high-frequency decay, and subtle dynamic changes with precision.

Sapphire and aluminum dual coating

FIIO's patented dual-coating technology applies natural sapphire and aluminum to a high-performance PET diaphragm substrate. Lightweight aluminum supports voice-coil conductivity, lowers impedance, and contributes to wide dynamic range. Sapphire adds rigidity to the diaphragm, supporting high-frequency clarity and resolution. Patent number: ZL2024205488218.

Semiconductor-grade manufacturing precision

The JT9's conductive voice coil is produced using a 28nm-grade fabrication process adapted from semiconductor manufacturing. Processing takes place in a 6.6×10⁻³ Pa high-vacuum environment and at 248°F (120°C), allowing ionized metal particles to be deposited evenly across the diaphragm. This controlled process supports consistent coating thickness, durability, and long-term voice-coil reliability.

Uniform magnetic field design

FIIO's patented uniform magnetic field technology uses an optimized magnetic circuit and custom-shaped high-strength magnets to distribute magnetic force more evenly across the driver. Consistent force helps the diaphragm move with controlled excursion across its surface, reducing diaphragm break-up and associated distortion while preserving fine detail. Patent number: ZL202420884963.1.

High sensitivity for easier driving

With sensitivity rated at 95dB/mW at 1kHz and 112dB/Vrms at 1kHz, the JT9 requires less power than many conventional planar headphones. Its low 20Ω impedance and optimized magnetic circuit allow it to work with portable DAC and amplifier dongles as well as desktop headphone amplifiers. FIIO recommends an output power of 300mW or higher to fully drive the headphones.

Lightweight foldable construction

At approximately 12.9 oz (365 g) without the cable, the JT9 is designed to reduce wearing fatigue during extended listening. Rotating and folding ear cups make the headphones more compact for storage and transport, while the multi-axis headband and three-axis ear cup structure allow the fit to adapt naturally to different head and facial contours.

Ergonomic fit

The JT9 uses a contoured 3D structure designed around the natural shape of the face. Adjustable ear cup rotation and extension help distribute clamping force evenly, supporting a secure and comfortable fit during longer listening sessions.

Custom-tuned oxygen-free copper cable

The supplied cable uses high-purity oxygen-free copper with 0.0024 in, 0.0031 in, and 0.0047 in (0.06 mm, 0.08 mm, and 0.12 mm) strands arranged as a substantial 22AWG conductor. The cable was tuned specifically for the JT9 planar driver to support body through the mids and bass, bass impact, and a spacious presentation.

Single-ended and balanced cables included

The JT9 includes separate 3.5mm single-ended and 4.4mm balanced headphone cables, both terminating at dual 3.5mm TS connectors on the headphones. A 6.35mm male to 3.5mm female adapter is also included, providing compatibility with a broad range of portable and desktop audio sources.

Water-resistant storage case

A fitted storage case made from water-resistant, moisture-resistant woven fabric is included for transport and storage. Its dimensions are tailored to the folding JT9 chassis for convenient protection between listening sessions.

Hi-Res Audio certification

The JT9 has received Hi-Res Audio certification from the Japan Audio Society, reflecting its extended 7Hz–40kHz rated frequency response.

Black and deep brown finishes

The JT9 is offered in black and deep brown finishes. The deep brown version is expected to launch in September 2026.

Product highlights

• Proprietary 3.74 x 3.39 in (95 x 86 mm) planar magnetic driver
  
• Ultra-thin 0.000039 in (1 μm) diaphragm
  
• Patented sapphire and aluminum dual-coating technology
  
• Patented uniform magnetic field design
  
• 28nm-grade conductive voice-coil manufacturing process
  
• 95dB/mW sensitivity at 1kHz
  
• 20Ω impedance at 1kHz
  
• Approximately 12.9 oz (365 g) without cable
  
• Foldable multi-axis ergonomic design
  
• 22AWG high-purity oxygen-free copper cable
  
• 3.5mm single-ended and 4.4mm balanced cables included
  
• Hi-Res Audio certified

Specs

• Headphone type: Open-back planar headphones
  
• Frequency response: 7Hz–40kHz
  
• Driver: 3.74 x 3.39 in (95 x 86 mm) planar magnetic driver
  
• Impedance: 20Ω at 1kHz
  
• Sensitivity: 95dB/mW at 1kHz
  
• Sensitivity: 112dB/Vrms at 1kHz
  
• Weight: Approximately 12.9 oz (365 g), excluding cable
  
• Cable material: 22AWG high-purity oxygen-free copper
  
• Cable length: Approximately 4.9 ft (1.5 m)
  
• Headphone connector: Dual 3.5mm TS
  
• Audio plugs: 3.5mm and 4.4mm
  
• Colors: Black and deep brown

What’s included

• JadeAudio JT9 headphones
  
• Storage case
  
• 3.5mm single-ended headphone cable
  
• 4.4mm balanced headphone cable
  
• 6.35mm male to 3.5mm female adapter
  
• Quick start guide