The development of the A series began with establishing a new sound evaluation method by analyzing the relationship between sound quality and physical characteristics. The results came to fruition with the A8000, and the sound evaluation method evolved further with the A4000. Final listen to music recorded at various qualities at various sound levels. However, conventional evaluation methods generally entail a subjective evaluation under the fixed conditions such as constant sound pressure level and an evaluation method that takes into account the various practical listening conditions that could actually occur when users evaluate the sound of various products of earphones that didn’t exist. Final believe that researching a sound evaluation method that made it possible to arrive at a realistic evaluation even under various listening conditions made it possible to bring a product that can be said to be the new standard for this price range.
In order to achieve sound quality impossible at this price range, Final newly developed 6mmφ [f-Core DU] dynamic driver unit from scratch. To realize the brand new driver, Final established a new production facility overseas and newly designed parts for the driver unit such as diaphragm, voice coil, magnet, magnetic circuits, adhesives, and the production machinery used in the manufacturing process. As the material for the driver front housing, rather than the traditional aluminum, we used brass, a material that is both highly resistant to the effects of magnetism and also boasts a high specific gravity. In order to increase the time response characteristic of the diaphragm, the voice coil employs a 30μ ultrathin CCAW, and a minimum of adhesive is used for assembly to thoroughly lighten the moving parts. Moreover, the diaphragms are neatly pressed in small lots of roughly 1/3 the normal size in order to constrain pressure deviation to a minimum and realize uniformly shaped diaphragm with no deformation.
Based on the chassis design that serves as an ideal solution for the IEM that become established during the development of the B Series, the A4000 realizes a superior sense of fit. Whether or not earphones offer a superior sensation of fit is determined by the sensation of oppression. While at first glance it may seem correct to select an ergonomic shape and hold it in place with the elasticity of silicone, this always places pressure on the ear, which creates an unwary burden and leads to the accumulation of fatigue. By limiting the area that comes in contact with the ear in contrast to an ergonomic shape that comes in contact with a large area of the ear, this product aims to achieve a sense of fit with no feeling of oppression. The green section of the diagram below (earpiece) is the 1st position, the blue section (Tragus) is the 2nd position, and the pink-colored section (cavity of the concha) is the 3rd position which contributes to the ultimate stability and fitting. For that reason, it is suitable for the ears of many different people. To the extent that there is no feeling of oppression at any of the points of contact, that makes for such a comfortable, superior feeling of a customized earphone fit.
The 2-Pin connector is a high precision part that was developed in-house. The plug employs the highest versatility φ0.78 standard. The cable employs soft, supple coating material designed with consideration to touch noise and bends flexibly when used in conjunction with an ear hook to achieve a good fit.