The FiiO JT7 planar magnetic headphones are available for less than $200. These headphones utilize planar magnetic technology, differing from traditional dynamic drivers. Dynamic drivers use a coil attached to a small part of the diaphragm, while planar magnetic drivers feature a conductive trace spread across most of the diaphragm, placed between two rows of magnets.
These headphones utilize planar magnetic technology, differing from traditional dynamic drivers.
Planar Magnetic vs. Dynamic Drivers
Planar magnetic drivers offer advantages due to their lighter, thinner diaphragms (e.g., the JT7's 95x86mm diaphragm is 3 micrometers thick), allowing for highly responsive movement.
Unlike dynamic drivers, which can act electrically like an inductor and introduce resonances, planar magnetic headphones have negligible inductance, making them less susceptible to signal impacts from source devices.
This negligible inductance makes them less prone to signal impacts from source devices, a common issue with traditional dynamic drivers that can introduce resonances due to their electrical properties.
FiiO JT7 Specifications and Design
The FiiO JT7 headphones are passive, wired, over-ear, and open-back models. They weigh 329.6 grams, have an impedance of 18 ohms, and a sensitivity of 92dB (1mW@1kHz). The frequency response ranges from 7 to 40,000 hertz.
The open-back design contributes to an open, airy sound but offers minimal noise isolation and allows sound to escape.
For comfort, the headphones feature padded earcups, significant swivel, and adjustment. Structural components include spring metal and high-strength fiberglass material for hinges, with durability tested over 10,000 times.
Two 1.5-meter cables are included: one with a 3.5mm stereo TRS plug (and a 6.25mm adapter) and another with a 4.4mm balanced TRRRS plug for compatible high-end audio devices. The cables are easily replaceable.
The headphones are Hi-Res Audio certified, indicating a measured frequency response up to at least 40kHz.
Output Impedance Considerations
The performance of headphones can be influenced by the output impedance of the source device. A high output impedance can lead to several issues:
- Reduced voltage and power delivered to low-impedance headphones like the JT7 (18 ohms).
- Frequency response variations, particularly with dynamic headphones, due to impedance fluctuations across the frequency range.
- Reduced control over diaphragm movement, potentially impacting sound quality.
The FiiO JT7's low impedance means some devices, suchs as certain home theater receivers or laptops with high output impedance (e.g., a Lenovo Yoga at 69 ohms), may struggle to produce adequate volume.
However, devices with low output impedance (e.g., MacBook Air M4 at 0.3 ohms) or external DACs (e.g., AudioQuest Dragonfly Red) can drive them effectively.
Due to their planar magnetic design, the JT7 headphones exhibited less than 0.1dB variation in voltage across the audio range, demonstrating immunity to frequency balance shifts caused by varying output impedance.
Listening Experience
Testing with various high-quality audio equipment, including FiiO digital audio players and dedicated headphone amplifiers, showed strong performance. The headphones reproduced bass frequencies accurately and maintained clarity during complex musical passages.
They displayed a slightly prominent upper midrange, which could reveal recording details but also highlight imperfections.
Compared to higher-priced headphones, the FiiO JT7 headphones offer a significant portion of high-end audio performance at a lower cost, making them a suitable option for those seeking quality sound.