Custom Knowles · enhanced bass BA drivers

FIIO collaborated closely with Knowles to create a custom bass BA driver. By improving the airflow throughput of this driver, we enhance its overall energy. Additionally, the FA19 uses four of these custom drivers per channel, further ensuring there are enough drivers to produce detailed and powerful bass. The result is truly robust, impactful bass.

Negative feedback bass enhancement system

With four custom enhanced bass balanced armature drivers per channel developed by FIIO in collaboration with Knowles, the FA19 boasts ample bass. Engineers creatively made use of the precise DLP 3D printing technology to create a shell that helps to guide this low-frequency energy into the earphone’s rear cavity, effectively lowering the resonant frequency there – essentially a negative feedback bass enhancement system. The result is a bass that reaches extremely deep, uncommon among IEMs of its class.

Mid-frequency notch filter

A smooth mid-frequency curve not only stems from the core unit’s quality but also results from meticulous tuning by professional acousticians. The FA19 employs two classic Knowles ED mid BA drivers, known for their high resolution and favored by demanding listeners. However, if not implemented properly they can sometimes exhibit sibilance which negatively affects the overall listening experience. To address this, engineers have specially designed a mid-frequency notch filter at the bottom of these two mid BA drivers.

Upgrade 1: Enhanced mids

Measurements show that the mid-frequency notch filter increases the sound pressure level between 1kHz and 3kHz in the FA19, avoiding a “hole” in the mids. This ensures not only that the highly detailed nature of a BA driver continues to come through, but also that the mids sound lusher and more realistic, as if the singer really was in front of you.

Upgrade 2: Sibilance eliminated

The mid-frequency notch filter effectively filters out the 8kHz peak of the mid-frequency BA driver. Doing so reduces the overlap in frequency response range between the mid and treble BAs, eliminating sibilance and enhancing overall clarity.

Upgrade 3: Refined treble

Additionally, the mid-frequency notch filter shifts the crossover point between multiple drivers to 3.5kHz. By establishing a clean separation between the mid and treble drivers, both sets of drivers properly work to their maximum potential within their designated frequency ranges without any interference.

Rubycon audiophile-grade crossover capacitors

Truly be immersed with each striking musical note thanks to a precise crossover. The FA19 employs audiophile-grade film capacitors as its electronic crossover components, which boast exceptional precision. While typical resistors used for crossovers have an error tolerance of around 1%, the FA19’s resistors have an impressively low error tolerance of 0.1%. Thus, compared to ordinary ceramic capacitors, the FA19 not only attains more accurate crossover points but also features enhanced high-frequency resolution without sacrificing tonal finesse.