Fosi Audio i5 Open-Back Planar Magnetic Headphones

The Fosi Audio i5 is an open-back planar magnetic headphone designed to deliver reference-level clarity, low distortion, and long-term comfort. Developed through extensive in-house acoustic tuning, it combines large-scale planar drivers with carefully engineered materials to achieve a natural, spacious presentation.

With a focus on precision, comfort, and refined craftsmanship, the i5 is suited for critical listening, studio work, and immersive home audio setups when paired with a capable headphone amplifier.

Features

• Open-back planar magnetic headphone design for an expansive, accurate soundstage
• Nano-thin diaphragm engineered for fast transient response and low distortion
• Ultra-large 97 mm planar driver designed to reveal fine detail and layered sound
• Symmetrically arranged high-strength magnetic matrix for precise diaphragm control
• Silver-coated diaphragm using sputtered coating technology for refined, consistent performance
• Acoustically transparent rear mesh to support open sound and controlled damping
• Studio-oriented tuning aimed at natural timbre and reference accuracy
• Memory metal headband designed to maintain shape while reducing pressure
• Dual-axis earcup arms for improved fit across different head shapes
• Stepless silicone adjustment system for precise, smooth headband sizing
• Breathable, skin-friendly earpads with memory foam for extended listening comfort
• Handcrafted walnut wood earcups paired with a CNC-machined aluminum frame

Specifications

• Transducer type: Planar magnetic
• Driver size: 97 mm
• Diaphragm thickness: 2 μm
• Frequency response: 10 Hz – 50,000 Hz
• Sensitivity: 98 dB/mW @ 1 kHz
• Nominal impedance: 28 Ω
• Maximum SPL: ≥ 120 dB SPL
• Total harmonic distortion: < 1% @ 100 dB SPL
• Recommended amplifier power: ≥ 500 mW

What’s in the box

• Fosi Audio i5 headphones
• 3.5 mm headphone cable
• 6.35 mm adapter
• User manual