It just shows with dynamic drivers, bigger is better.
Got confirmation the Zen has a large 13.5mm driver.
It's not only the size that matters, but the motion of the dome portion!
Let's actually explain what we mean. We've had 13.5 mm drivers in a bunch of our past/current products: DK-3001, DK-4001, DK-3001 PRO, DK-2001, 17th Anniversary model. LUNA was an exception at 10 mm because it was a truly bespoke driver designed from the ground up, whereas the aforementioned models were all somewhat similar. ZEN's driver size was chosen because it was originally supposed to use the 17th Anniversary model's driver. Once LUNA came into the picture, we knew we had to redesign the driver and develop our ECLIPSƎ platform so that more of our models could enjoy the superior macrodynamics and speed of our patented composite driver design. The shells of the ZEN had already been designed, and so we wanted to preserve the 13.5 mm diameter and retrofit the new platform into the existing shell shape.
The following is a pictorial description of the benefits of ECLIPSƎ driver construction techniques for driver control and dynamic sound excursion. By using a fully composite driver design, we can choose highly disparate materials for the dome and surround, in this case Mg-Al alloy (coated with ta-C) for the dome, and a very soft thermoplastic polymer for the surround. The softness of the surround allows for better driver excursion without needing to resort to dedicating a large proportion of the surface area to the surround. We can push the dome portion (most important for directional sound) out as wide as we can, also allowing for wider attachment points for the voice coil. The wider diameter the voice coil, the better control it can exert over the diaphragm, as it exerts a greater angular moment over each point of the dome. For a conventionally thermoformed, one-piece driver to possess similar properties, it'd have to be substantially larger in diameter. Of course, when it comes to gluing and damping, we also put in a few more tricks into the ECLIPSƎ platform that help with linearity of excursion, but these techniques are fully proprietary and we won't discuss them here.
Lastly, with this design, we can also play with the dimensions of the voice coil and air gap more freely. With the introduction of our external 1.8T ring-type magnet, we can more confidently control the driver. With such large pole pieces, we had to make the housings of the ZEN more thick, but thus far we haven't heard of any issues with comfort.
For a fuller (but still on a layman's level) explanation of why a very stiff dome and a soft surround are desired in speaker design, please refer to Oratory1990's explanation here:
https://www.reddit.com/r/headphones/comments/bacd37/duck_duck_goose/ekaxsri/
