FiiO FF5 Flat-Head Dynamic Driver Earbud

The FiiO FF5 is a flat-head earbud, the classic open style that rests in the outer ear rather than sealing the ear canal, rethought with a large 14.2mm dynamic driver and a carbon-based diaphragm. FiiO tuned it especially for female vocals, with a diffuse open back and acoustic resistance pipes for cleaner, more extended bass than earbuds usually manage. The CNC aluminium shells weigh just 3.4g, and unusually for an earbud the cable detaches, with swappable 3.5mm and 4.4mm balanced plugs.

Tuned for female vocals

As Joseph, chief engineer of FiiO’s IEM R&D centre, explains: the female voice spans roughly 160Hz to 1.2kHz, and the FF5 was designed to focus on it rather than on heavy bass. The team controlled the resonance at 127Hz so vocals don’t sound muddy or boomy, and lifted 2kHz–4kHz slightly to make female voices clearer, more transparent and more prominent. The light carbon diaphragm gives excellent treble, so the overtones of voices, guitars, cymbals and violins come through with nuance and layering.

A large 14.2mm carbon-based driver

Breaking with earbud tradition, the FF5 uses a specially developed 14.2mm dynamic driver with a carbon-based diaphragm and a PU surround, both light and very rigid. Unwanted movement is kept in check, minimising non-linear distortion, for quick transients and excellent treble resolution.

A diffuse open back, like a flower in bloom

Inspired by the layers of a flower’s petals, the FF5’s diffuse open design uses an acoustic damping device that lets some of the air pressure inside the earbud escape. That reduces internal reflections and standing waves, for a purer sound and better bass.

Acoustic resistance pipes for extended bass

Earbuds need more care than in-ear monitors to sound great, and after much experimentation FiiO developed acoustic resistance pipes for the FF5. As the diaphragm moves, the air pressure is diverted into the pipes, reducing low-frequency resonance, so the bass is more extended and better textured.

Light aluminium, with anti-slip rings

The shells are aluminium alloy, as used in many high-end earphones, light yet durable: each earbud weighs only about 3.4g, so it almost disappears in your ear. Some listeners prefer silicone rings on earbuds, so as well as three types of foam cover, FiiO includes six moulded anti-slip silicone rings in two sizes. They give a better seal for more extended bass while keeping the resolution elsewhere.

A 392-wire cable you can detach

Few earbuds have detachable cables, which makes them hard to keep using if the cable fails. The FF5 uses expanded MMCX connectors, so you can replace the cable or try others. The included cable is high-purity silver-plated monocrystalline copper: 14 wires braided into a small strand, seven small strands into a large one, and four large strands in all, 392 wires. The extra cross-section and Litz braiding improve conductivity and treble resolution. Swappable 3.5mm and 4.4mm balanced plugs (a design licensed from FABRILOUS) let you match your source.

Good to know

• Earbuds don’t seal like in-ear monitors, so they let in more of the world around you but feel very natural to wear. Swap between the bass, balanced and treble foam covers and the silicone rings to change the bass, fit and grip.
• FiiO ships either the new or the older design of interchangeable plug; both are genuine and the cable is the same.
• In the box: FF5, cable with 3.5mm and 4.4mm plugs, MMCX tool, HB1 carry case, anti-slip silicone rings (3 pairs medium black, 3 pairs large clear), foam covers (6 pairs each of treble, bass and balanced) and manual.
• FiiO’s beryllium-plated earbud is the FiiO FF1.