The Fosi Audio i5 planar magnetic open-back headphones offer a unique listening experience, currently available through Kickstarter at a discounted price. This review delves into the i5's performance, comfort, and build quality, comparing it to established competitors like the Meze Audio 105 AR and Hifiman HE400i. We'll examine its sound signature, highlighting both its strengths and weaknesses, including its surprisingly warm mid-range and upper bass, contrasted with a noticeable treble peak and a weaker-than-expected sub-bass response. The i5 boasts a robust walnut and aluminum chassis, comfortable earcups, and a premium suede headband, but its stiff adjustment mechanism is a minor drawback.This in-depth review explores the Fosi Audio i5's objective measurements, including impedance and sensitivity, as well as subjective impressions of its soundstage and overall listening experience. We'll assess whether its unique sonic characteristics, including the potentially problematic treble peak and lack of sub-bass, outweigh its comfortable fit and impressive clarity in the mid-range. Ultimately, we determine whether the Fosi Audio i5 is a worthwhile investment for audiophiles seeking a distinctive planar headphone experience within its price range.
Pros And Cons
- Uses real walnut and CNC-milled aluminum, feels strong and well-made
- Robust hinges and no rattles
- Real suede strap
- Comfortable for long periods of time due to plush padding
- Good glasses comfort
- Large pads distribute pressure well, reducing clampy feeling despite high clamp force (630g)
- Warm and lush sound presentation, especially good for acoustics and vocals
- Clear and detailed sound
- Smooth sound signature
- Weak sub-bass due to Velcro-mounted pads creating a leaky seal
- Noticeable 10,000-10,500 Hz peak can make some songs sound sharp
- Modal issues with the driver cause rises and dips in frequency response, especially in upper midrange and low treble (although not always noticeable in listening)
- Vocals sound slightly distant
- Cable has a fabric material that can be prone to microphonics, although the reviewer did not experience this issue.
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Pricing and Packaging
The Fosi Audio i5 planar magnetic open-back headphones are currently available through Kickstarter at a discounted price, ranging from just under $400 to under $500 for the deluxe package. The deluxe package includes extra earpads, a balanced cable, and an adapter for XLR connectivity. Once the Kickstarter ends, the retail price is expected to be closer to $550-$600, although tariffs could impact this further.
The packaging is quite simple; you get the headphones and at least one cable. There's no carrying case included, just foam padding for protection. Considering its size, this minimalist approach is somewhat understandable.
Technical Specifications and Build Quality
The i5 boasts a 98dB sensitivity and a 28-ohm impedance (measured at 30 ohms by the reviewer). The impedance is linear, minimizing the impact of high-output impedance tube amps on frequency response. The clamp force, measured at 630g, places it in the middle range for headphones in this price bracket.
The headphones feature a robust build with a real walnut and CNC-milled aluminum chassis. The hinges are strong, and the suede strap feels premium; however, the strap adjustment mechanism is somewhat stiff. The large earcups (nearly 30mm thick) use a combination of leatherette and breathable fabric, making them comfortable for extended use.
Sound Quality and Frequency Response
Objective measurements reveal a peak around 80Hz, followed by a dramatic falloff, likely due to the Velcro-mounted earpads which create a less-than-ideal seal. This affects the sub-bass response, making it weaker than expected for a planar magnetic driver.
Subjectively, the mid-range and upper bass sound warm, a characteristic enhanced by the relaxed mid-range. However, the upper treble comes in noticeably stronger, with a significant peak around 10,000-10,500Hz, which can be quite sharp on certain tracks. The overall sound is lush and sultry on many tracks, but the lack of sub-bass and the treble peak might not appeal to all listeners.
Comparison with Other Headphones
Compared to the Meze Audio 105 AR, the Fosi Audio i5 offers better clarity and resolution but less sub-bass. The i5's warmer tuning is similar to the 105 AR's, though the 105 AR has a more punchy bass.
Against the Hifiman HE400i, the i5 showcases better comfort and a smoother presentation. While the HE400i boasts impressive technical performance and detail, the i5 offers a warmer and more balanced sound signature. The Arya Stealth offers incredible technical capabilities, stage and detail but might be more expensive than the i5.
Conclusion
The Fosi Audio i5 offers a unique listening experience with a warm, lush sound signature. However, its lack of sub-bass (though potentially fixable with the provided mod kit) and prominent treble peak might be dealbreakers for some.
Its comfortable, well-built design, and impressive clarity in the mid-range make it a compelling option for those seeking a different planar headphone. While not perfect, its strong points, especially its comfortable fit and unique sound profile, are enough to make it a worthwhile consideration within its price range.