FiiO FX15 adopts a 4-electrostatic hybrid driver acoustic architecture – this is the first time FiiO has launched tribrid drivers earphones (Electrostatic Driver + 10mm DLC Dynamic Driver + Knowles Armature Driver).
FiiO FX15 specs and features:
- 4 electrostatic + 1 dynamic +1 armature driver
- High-precision DLP-3D printed shell
- 224 wires 8 strands sliver cable
- MMCX detachable cable
- Interchangeable audio plugs
- $749 – Check latest price on AliExpress, Amazon US or other Amazon countries
Appearance Design, Comfort and Accessories
FiiO has released a lot of new products this year – the FiiO FD11 and FiiO FW3 that I have recently experienced left a good impression on me. However, I didn’t expect FiiO to launch a hybrid electrostatic headphones – FiiO FX15.
FiiO FX15 uses 3D printing technology to create the earbud shell. The shell material is made of engineering resin and is colored to give the earbuds a black semi-transparency effect.
The comfortable of FX15 is quite good, and the earbud-shape is close to the ears. I didn’t feel any obvious fatigue in my ears when I wore FiiO FX15 for a long time. Sure enough, resin materials are less likely to cause a foreign body sensation in the ears than metal. But, what surprises me most about FX15 is the panel design. Different from FiiO’s previous panel patterns, this time the hollow ginkgo leaf pattern has an oriental charm.
The earbuds adopts a replaceable cable design, and the FiiO FX15 is equipped with an 8 strands 224 wires high-putity silver cable. Silver cable has higher conductive efficiency, thereby reducing energy loss during signal transmission and maintaining the original quality of audio signals. A special point is that the transmission in the high frequency part is more stable and accurate – treble details can be restored more clearly.
In addition, according to FiiO’s official promotion, the litz structure of the headphone cable can also reduce uneven signal transmission caused by the skin effect. So I think FiiO chose silver cable because of its advantages in audio transmission, especially its excellent high-frequency performance and resolution.
The accessories of FiiO FX15 are really rich. There are 19 pairs of different types of eartips, which can be replaced according to personal preference. Also, there are carrying case, magnetic clip, cleaning brush, MMCX quick release tool and 3.5/4.4mm interchangeable plugs.
The key to hybrid driving is balance
There are three different types of driver units configured in FiiO FX15 – 4EST+1DD+1BA driver combination. Although the earbuds use hybrid drivers, the purpose of FX15 is to let everyone experience the charm of electrostatic drivers. Compared with dynamic drivers and balanced armature drivers, the sensitivity of electrostatic driver is usually lower. This means that under the same power, the volume produced by electrostatic driver headphones will be relatively small.
Although the solution of using FiiO FX15 with 4 electrostatic drivers seems simple, making these three different types of drivers work together is the biggest difficulty. The frequency response characteristics of these three types of drivers are all different, and certain peaks and valleys will inevitably appear near the crossover point. In addition, the rated impedance of FX15 is only 24Ω, which will also have some impact on frequency response linearity.
FiiO’s approach is to design the sensitivity as low as 103dB, and lower the output response of the dynamic driver and armature driver to match the response curve of the electrostatic driver – thereby achieving sound pressure balance and preventing the sound of electrostatic driver from being masked. This design idea can be said to reflect FiiO’s experience and technical strength in tuning.
FiiO FX15 is not easy to drive
FiiO FX15 adopts a low-impedance and low-sensitivity design, which means that the earphones need to be paired with a sound source device with the larger output power to achieve optimal performance. The iPhone audio adapter or ordinary headphone amplifier is no longer able to drive the FX15 to its best performance.
I think the best way to use FiiO FX15 is to choose a 4.4mm balanced interface with HiFi player, or a device with a certain output power.
During my listening process, the advantages of FX15’s low-sensitivity design were fully verified. I was deeply impressed by the texture and airiness that the earphones displayed when playing high-frequency delicate music. The knowles armature driver is used for the mid-high frequency, and the transition effect between low-frequency and high-frequency is very good. The mid-frequency performance is natural and moist. The low-frequency dynamic driver uses DLC dome, which has fast transient response. The control and detail of the low-frequency are excellent, which is most obvious when performing some cello music.
I used the combination of FiiO M15S + FiiO FX15 for listening. The output power of FiiO M15S can fully meet the needs of low-sensitivity headphones. When I listen to classical music with this combination, the timbres of different instruments are more clearly distinguished, and the overtones of the violin are rich and delicate. The tone of the mid-low frequency part is also very textured. It can be clearly felt that the strong driving force of FiiO M15S allows FX15 to exert its extremely high performance, and the potential of the earphones is well released.
In general, the three types of drivers of FiiO FX15 have a clear division of labor and coordinate with each other. The mid-frequency and low-frequency is smooth and natural, and the high-frequency is rich in details.
FiiO FX15 also has a toggle switch that can turn on/off the electrostatic driver with one click. Considering that the electrostatic driver is the biggest highlight of FX15, there should be no one who will take the initiative to close it. I think the greater significance of this switch is to compare the sound effects of electrostatic driver.
FiiO FX15 boldly uses 4 electrostatic drivers, combined with low-resistance and low-sensitivity tuning, to successfully balance the energy output ratio of different types of driver units, greatly improving the layering and details of the sound. If you want to experience the delicate sound brought by hybrid electrostatic drivers, FiiO FX15 is definitely worth trying.