The U18s shell follows a traditional 64 Audio design shape, but to my surprise it was a little taller than U18t. In theory the have the same number of drivers, the same apex cavity, and tia driver in the nozzle. LID tech was added and maybe internal design and driver placement was optimized that resulted in a slightly taller shell, but it was still very comfortable to wear and had a very durable build with a shell machined from a solid piece of aluminum and all black matte stealth finish. It also features a non-recessed universal 2pin socket and a matching metal nozzle with a mesh at the tip to keep elements away from tia driver.
But what really stands out here is an all-new faceplate design. You will not find a traditional 64 Audio faceplate with an inlay insert like in previous releases of U18t, Fourte/Noir, U12t/Trio, and Nio. U18s features all metal faceplate with a cool 3D fractured pattern and sort of a dark gunmetal finish. And this pattern looks truly 3D, achieved with a shinier top surface and black filled pattern cavities. I tried to capture it in pictures, but pictures don’t do it justice. The faceplate look is enhanced further with a branded apex module.
Inside the shell you have all BA design featuring 18 drivers with a 4-way passive crossover partitioning 8 lows, 8 mids, 1 high-mid, and 1 tia high drivers. Balanced Armatures (BA) are typically self-enclosed with a single opening port, while you can think of tia as an open BA driver where one of the enclosure walls is removed, to enable direct-radiating of the inner diaphragm which no longer has a 4-wall confinement. Tia driver is usually positioned in the nozzle, next to the grill since it has to be closer to your earcanal. As a result, U18s doesn’t have sound tube bores going to the nozzle, and instead has a mesh cover to protect from wax build up.
Another tech included with U18s, that wasn’t previously available in original U18t, is their Linear Impedance Design (LID) crossover where despite a low impedance (8ohm), U18s should be compatible and have the same signature when paired up with different sources, regardless of their output impedance. Of course, the tonality of the source will affect the pair up synergy and the sound you hear, but variation in output impedance is no longer a variable in U18s design.
And I’m sure by now everybody is familiar with 64 Audio apex (Air Pressure Exchange) modules, but just in case if you have been living under a rock, it is the interchangeable venting system that releases air pressure sealed in the ear canal for fatigue free listening. The included apex modules have a fixed sound isolation, based on the model number: MX (-10dB, black module), M15 (-15db, dark grey module), and M20 (-20dB, aluminum color module)
As I mentioned in the intro, I did receive A18s CIEM at first, and if you decide to take that route, especially if you prefer custom fit or want to customize the look of your IEM, 64 Audio has a very comprehensive tool to design your monitors. The one in my original CIEM had a transparent shell with an exotic wooden faceplate, and I decided to include pictures of it here in the review so people can appreciate the layout and placement of all these drivers inside of a compact shell.