The Fosi Audio i5 is an open-back planar magnetic headphone built around a large driver and a combination of metal and wood construction. Its open acoustic design and planar magnetic transducer are engineered for detailed reproduction and an expansive presentation.
The 97 mm diaphragm is only 2 μm thick and operates with 44 N50 neodymium magnets, while nominal impedance is 28 ohms and sensitivity is 98 dB/mW at 1 kHz. The specified frequency response extends from 10 Hz to 50 kHz, with at least 500 mW of recommended driving power.
The i5 combines a CNC-machined aluminum frame with walnut elements, multi-axis earcup pivots and an adjustable headband system. This construction provides a rigid platform for the large planar driver while supporting a controlled and adaptable fit.