Closer Examination

The cable that now ships with the 64 Audio U18t is the biggest improvement of the recent updates. The previous cable had one of the worst memory-wire formations I have seen to date, coupled with an excessively large plug housing. This new cable is thankfully much better in pretty much every regard, and more befitting of a flagship-class IEM product. This new cable, aptly titled "premium cable," costs $199 by itself and starts with a straight 3.5 mm TRS connector for your source, and the housing is all aluminium with the 64 Audio logo on it. The conductor is silver-plated OCC (Ohno Continuous Cast) high-purity copper in 26 AWG thickness, braided into four strands that employ a 7x7 multi-twist each. It's a predominantly black cable down to the branded cable splitter and cinch, which works beautifully in containing the two split lengths at any specific point owing to the tapered structure. There is a section of translucent plastic sheathing over the cable closer to the other end, which is formed well into hooks that go over the ears. Angled connector housings come marked L/R for the left and right channels respectively. The physical connectors are standard 0.78 mm 2-pin plugs, and these are gold-plated for oxidation resistance. Modular plugs on the source end would have been nice at this price, or even black nickel-coating instead of gold for a stealthy black look, but this remains an excellent cable with a rated net impedance of 0.23 Ω and measured electrical resistance of just under 0.30 Ω from end to end. I have seen plenty of better behaving and looking cables for the money though, including from the likes of DUNU and ThieAudio that only only do modular plugs but also are easy to shape and don't kink at all, so it is not one that I would buy separately.


The 64 Audio U18t is not the only set of IEMs covered on TechPowerUp that employ a large number of balanced armature drivers—the CCA CA24 has 12 BA drivers per side, and the upcoming ThieAudio V16 Divinity goes with 16 drivers each. What I was most impressed by is how small the 18t is, so much so that I immediately had to look up the inner composition to find out how the company was able to stuff 18 drivers into what are relatively small IEM shells even for single-driver units! These also get a very distinctive finish that makes use of anodized CNC-machined aluminium for the shells and face plate frame, with a patinated copper inlay fit into the face plate. This design language is shared with the even more expensive Fourté UIEMs, and the shape is consistent across the entire range of 64 Audio UIEMs.


We get a closer look at the inlay composition and design of the face plates, with the copper patina making for a unique outcome each time. I never had both samples of the U18t at the same time for a group photo, but one thing I did notice is that the older set has a duller look on even the shells. The newer one has a more vibrant finish, which may also be a result of updated production techniques in addition to age. The inlay comes with the truncated 64 Audio logo on one side and "tia" on the other, indicating the use of the company's tia technology we will get into over the course of this review. Note the circular recess towards the bottom of the face plate, which is currently filled out by what 64 Audio refers to as an Apex module. This gray-colored metal module is the m15 Apex module that has rubber O-rings on the outside for a good seal. It is named such because it provides ~15 dB of noise isolation compared to having nothing in the recess. Removing them allows for a closer look at the entire family of m20 (silver colored, 20 dB isolation), m15, and mX (black colored, 10 dB isolation) modules. The way these modules work is via deliberately designed ambient ports and internals for the controlled release of air pressure from the ear canal, which makes for a comfortable fit over longer periods of time. These three modules comprise the company's Apex technology and sell for $99 per pair, and there is even a set of m26 solid plugs that are used in 64 Audio's custom-fit earplugs. Removing them is easy enough given the notches finger nails fit into easily, and installing them is as easy as pushing them in place, which has the O-rings securing them.


With the Apex technology accounted for, we can move on to the rest of the IEMs, and their side profile confirms the use of a two-piece aluminium shell with the top in orange folded over to meet the bottom in red. The bottom shell also has a cutout to accommodate a daughter PCB that has the 0.78 mm 2-pin connectors coming out flush with the shells that rise up to make it so, which also results in a cleaner look from all other sides. L/R markings on the inner side touching the ear concha indicate the left and right channels respectively, and the serial number is found here too. The ear tips go over a relatively thin and long nozzle shaped so very deliberately for reasons we will get to soon, and there is barely a notch on either end to keep the ear tips in place once installed. The nozzle also isn't very aggressively angled inward, but its length should help with the fit. A metal mesh filter placed on the nozzle opening prevents contaminants from entering the acoustic chamber, and given the uncommon size, I would have liked 64 Audio to provide some replacement filters in the box.


Fitting the ear tips is easy because of the relatively small diameter nozzle that is ~5 mm at the widest point, which the ear-tip bores push through easily enough. Seen above are the foam and two silicone ear tips in size M, installed on one of the IEMs to show the length and form factor of each. The all-black silicone tips turned out to be my favorite of the set overall, and we can see how the nozzle is nearly flush with the bore opening there as well. You may want to try different ear tips to get the best-possible fit, and perhaps affect the sound signature with the foam tips as opposed to silicone. Certainly also try out different sizes to ensure you have them on properly, and do not feel as though both ears necessarily need the same-sized ear tips, either.


Regardless of which tips you go with, the next step is to connect the cable by carefully pushing the connectors in place, which are then held there by friction alone. The 3.5 mm TRS connector then goes to your source. I know there are many who prefer to use IEMs throughout, but I like to use over-ear headphones when sitting down and IEMs/TWS earbuds on the go. I paired the 64 Audio U18t with all the tested portable DAC/amps to date and personally like the cleaner profile and handy EQ options of the Qudelix-5K as the source, in turn paired to my phone or laptop.