FiiO’s JadeAudio has launched a new open-back planar magnetic headphone with a huge 95 x 86 mm driver, a 1-micron sapphire-coated diaphragm, and both 3.5 mm and 4.4 mm cables in the box. And it costs €399.
Planar magnetic headphones are no longer reserved exclusively for the expensive end of the market, and JadeAudio is pushing that idea even further with its new JT9. The FiiO-owned brand has introduced a full-size open-back headphone built around a custom planar magnetic driver and an unusually thin diaphragm, with sales beginning August 13, 2026.
The interesting part isn’t simply that the JT9 uses planar technology. It’s what JadeAudio has done with the driver.
A 1-Micron Diaphragm Is the Big Story
Inside each JT9 is a 95 x 86 mm planar magnetic driver using a PET diaphragm just 1 micron thick. JadeAudio then applies a patented double coating of sapphire and aluminum to the membrane.
That makes the diaphragm significantly thinner than the planar driver used in the company’s previous generation, with JadeAudio saying it is around three times thinner than the one introduced a year earlier.
A lighter diaphragm can respond more quickly to changes in the electrical signal, which is one of the reasons planar magnetic headphones are so appealing to listeners who care about transient detail and high-frequency clarity. The large driver also gives JadeAudio plenty of surface area to work with without relying on a conventional cone-style diaphragm.
The sapphire coating is another unusual touch at this price. Rather than simply using an ultra-thin membrane, JadeAudio is combining low mass with a stiffer coated structure.
JadeAudio Is Also Paying Attention to the Magnetic Field
The diaphragm is only half of the equation. The JT9 uses a uniform-field magnetic system, designed to keep the magnetic force more consistent across the driver’s surface.
That matters because planar diaphragms need to move evenly across a relatively large area. A more uniform magnetic field can help maintain consistent diaphragm movement and reduce unwanted distortion, particularly when the headphones are being pushed harder.
It’s a technical approach normally associated with more ambitious planar designs, which makes its appearance in a €399 headphone particularly interesting.
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You Don’t Need a Huge Amplifier to Run Them
Despite the JT9’s large planar driver, JadeAudio hasn’t made it especially difficult to drive.
The headphones have an impedance of 20 ohms and a sensitivity of 95 dB/mW. That puts them within reach of considerably more sources than some demanding planar headphones.
A desktop headphone amplifier will still make sense if you’re building a serious listening system, but the JT9 should also be comfortable with portable players, USB DACs, and other medium-power sources.
And JadeAudio has included both connections in the box.
Both 3.5 mm and 4.4 mm Cables Are Included
The JT9 comes with an unbalanced 3.5 mm cable and a balanced 4.4 mm cable.
That’s a useful inclusion because owners don’t immediately have to spend extra money on another cable just to connect the headphones to a balanced output on a portable player or desktop DAC.
The headphones themselves weigh 365 grams and use a foldable design. That’s not exactly lightweight, particularly compared with conventional dynamic-driver headphones, but a large planar magnetic driver and its magnetic structure inevitably add some weight.
The folding mechanism does make the JT9 somewhat more practical for listeners who want to move between a desktop system and a portable setup.
JadeAudio JT9 Specifications
| Specification | JadeAudio JT9 |
|---|---|
| Design | Open-back, over-ear |
| Driver | Custom planar magnetic |
| Driver size | 95 x 86 mm |
| Diaphragm | 1-micron PET |
| Diaphragm coating | Sapphire + aluminum |
| Magnetic system | Uniform-field design |
| Impedance | 20 ohms |
| Sensitivity | 95 dB/mW |
| Weight | 365 g |
| Cables | 3.5 mm + 4.4 mm balanced |
| Design | Foldable |
| Price | €399 |
The JT9 Could Be One of JadeAudio’s More Interesting Planar Headphones
At €399, the JadeAudio JT9 lands in a part of the headphone market where planar magnetic models have become increasingly competitive.
But the specification that immediately grabs attention is that 1-micron sapphire-and-aluminum-coated diaphragm. Pairing that with a 95 x 86 mm driver and a uniform magnetic field gives the JT9 a technical foundation that looks considerably more ambitious than its price suggests.
Whether that translates into a genuinely exceptional listening experience will ultimately come down to tuning, distortion performance, and how well JadeAudio has balanced detail with musicality. Those are things a specification sheet can’t tell us.
For now, though, the JT9 is an intriguing new option for anyone looking to step into full-size planar headphones without moving into four-figure territory.
At €399, JadeAudio is clearly betting that sophisticated planar technology doesn’t have to come with a sophisticated price tag.
