64 Audio Fourte Blanc vs U18t Comparison Review

64 Audio, Fourte Blanc, U18t, IEM, in-ear monitor

64 Audio Fourte Blanc vs U18t Comparison Review

With 64 Audio’s recent limited edition release of the Fourte Blanc, we’re revisiting another G.O.A.T.’ed release from the company: the 64 Audio U18t. While both feature 64 Audio’s tia design principle of tubeless drivers, they approach it in pretty different ways and have some sonic differences to show for it. As usual, we’ll be getting into the practical and technical sides of these two elite IEMs before we compare the moderate differences in their sound character.

64 Audio, Fourte Blanc, U18t, tia, IEM, in-ear monitor
Box and accessories that come with 64 Audio U18t   

What’s in The Box?

64 Audio’s Forte Blanc comes with an additional 4.4mm silver core cable. The U18t comes with additional m15, m20, and mX apex acoustic nozzle modules. Aside from that, the Fourte Blanc and U18t appear to come with identical accessories:

  • 2 pin to 3.5mm Detachable Premium Cable
  • 6 Pairs of Silicone Ear Tips
  • 3 Pairs of Foam Ear Tips
  • Hard leather carrying case
  • 64 Audio Sticker
  • IEM Cleaning Tool
64 Audio, Fourte Blanc
64 Audio Fourte Blanc

Look and Feel

You can tell from the pictures that 64 Audio’s Fourte Blanc and U18t are openly related to one another. They have the same rounded, crescent shape that ergonomically found support against the back outer rim of my ear. Both are exceptionally lightweight and feature sturdy anodized aluminum builds – though the U18t has a little more shine with its copper patina faceplates. Also common to the two is the fun, colorful, and somewhat sporty aesthetic that’s a little surprising to see on in-ear monitors that have such serious, almost intimidating, reputations.

The U18t and the Fourte Blanc also seem to share a similar nozzle and tip situation: silicone tips that come with both IEMs leave the filter riding up towards their outer rim of the tip, allowing soundwaves to bypass the silicone medium on their way down your ear canal. This is a little hard to explain with just words, so reference the picture below to see what I’m yammering on about here:

Filter is completely exposed and unobstructed by the silicone tip on both units.

With the silicone tips, the fits seem intentionally shallow, comfortable, and non-intrusive. If you prefer a deeper fit, the included foam tips seemed to do the trick. I ended up preferring the foam tips on the U18t and the silicone on the Fourte Blanc, but for reasons that have more to do with balance and imaging that I’ll get into shortly.

64 Audio, U18t, IEM, in-ear monitor
64 Audio U18t

Design and Technical Specs

Both IEMs have rather different approaches to their tubeless driver design principles that 64 Audio calls “tia.” The U18t features an astonishing 18 tia open balanced armatures on left and right sides – 36 drivers total. Only the high driver follows a properly tubeless design. The sound waves from the high driver meet with those from the tubed BA’s before reaching a listeners ear canal due to the tia single bore. Once again, this is a little hard to describe with only words, and I encourage you to take a look at some of the pictures below to get an idea of what I’m describing.

The Fourte Blanc contains a mere four drivers on either side: one dynamic and three armatures. Building on the original Tia Fourte and the Fourte Noir, the Blanc is entirely tubeless, fully utilizing the tia acoustic chambers that U18t reserves for its high driver.

Standard IEM tube design. Tubes carry sound from a driver to the ear canal, each tube has a separate point at which it outputs sound. Tia design does away with these tubes in favor of specially designed acoustic chambers.
Tia single bore design on the U18t. Soundwaves from the drivers exit the IEM together instead of separately.

Sound Stage

I’ll start by saying that both IEMs are spatially rich, incredibly entertaining and precise so that we can move on to focus on their exact differences. I can’t help but suspect that the Fourte Blanc and U18t’s differing implementation of tia design principle is the underlying cause behind the differences in their image. The Fourte Blanc is exceptionally 360, and wrapped fluidly around my head with mono kick drums and vocals frequently feeling like they originated from the back of my head. The U18t, on the other hand, had more of a fractal image that seemed aggressively forward facing. Tracks seemed to originate far from my face and angle past my ears, much like they would if I were listening to some premium studio monitors. In short, the Fourte Blanc is shaped like an astronaut’s helmet, whereas the U18t conveyed the shape of a trapezoid or triangle.


Both the Fourte Blanc and the U18t provide ample and clean low end boosts that show love to their subs. The U18t brings this boost into its mid bass before rolling it off in time for a balanced low mids profile. The Fourte Blanc seems to run with its low end boost at a higher amplitude and wider bandwidth, even roping its low mids into its boosted low end shelf. The rounder, more enveloping image of the Fourte Blanc seemed to go hand-in-hand with the larger waves produced by its massive sub and bass response. The open, airy feeling of the provided silicone tips felt complimentary to these sonic qualities. While the U18t had plenty of subs and rumble, it had a little more mid-bass growl and punch than the Fourte Blanc. This punchier low end coupled with its more insulated and forward-facing image left me preferring the foam ear tips on the U18t.


The main differences between both IEMs center frequency profiles mostly reside in the low mids. As I previously mentioned, the Fourte Blanc is still in the process of cooling off from its widely boosted low end, leaving low mids moderately boosted until find more balanced levels in the center mids. The U18t is already cool and controlled by the time it gets to its low mids, and seemed to have a pretty uniformly balanced sound all throughout its middle frequencies. This difference in mids balance was most noticeable on vocals, and particularly noticeable when listening to spoken word rather than music. The Fourte Blanc seems keen on the warm, low end hum in vocal fundamentals, while the U18t has a very fair and even handed approach through out its lower and center mids. Both IEMs start ramping up again in the high mids, but I’ll be contextualizing that boost with the general high end in the next section.


This seems to be where the two IEMs have the most in common. The higher end of vocalists’ harmonic profiles find a lot of extra power and shine. Though this is a feature that owners of 64 Audio’s tia IEMs seem to treasure, it’s probably the most controversial decision that was made in both units’ tuning. Some listeners may find this high-mid to high peak somewhat grating, but I personally appreciate headphones and IEMs that make bold moves in their treble. Further up in the treble region, there’s a more universally appealing boost present in both units that breathes air into vocals and gives hi-hats some extra snap and sizzle. My favorite part about these boosts that occur in the highest of the highs is how much detail gets revealed in short and long reverbs alike, which further enhances the highly spatial characteristics present in both IEMs.


If you’ve been lucky enough to try just one of these IEMs, you have a pretty decent reference for what the other one sounds like. Of course, there are some key differences that can be plainly stated here. Relative to the Blanc, the U18t is a more analytical IEM. Though plenty wide and spatial, most of its layering and distinction is a result of its meticulous balance. The Fourte Blanc, while still distinct and clear in its balance, is more about delivering layers of energy than the U18t, and performs more of its layering in its image. I usually like to be honest in these comparison reviews and disclose where my personal preferences lie, but this time I’ll be honest when I say that both of these IEMs are modern legends that I just felt lucky to have in my ears. 64 Audio’s Fourte Blanc and U18t are both mammoth contenders in the high end IEM market. It’s hard to make a “wrong” choice here.

64 Audio’s Fourte Blanc and U18t are available at Audio46.

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