The Tzar of hybrids.

PROS: expanded soundstage, deep analog textured bass, revealing mids/treble supercharged by TIA drivers, custom storage case, quality stock cable.

CONS: price, non-replaceable internal apex, universal-fit only.

The product was provided to me free of charge for the review purpose in exchange for my honest opinion.

Manufacturer website: 64 Audio.  Available for sale directly or retailers like Bloom Audio.

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Intro.

It’s common to see companies release their new flagship IEMs either once a year or every other year because it takes a lot of research and development time for manufacturers to come up with something new and original to make their product stand out from the crowd. Likewise, it usually takes audiophiles longer to research and to compare available flagships before narrowing it down to their next TOTL purchase. On rare occasions, this process can get even more complicated if a manufacturer offers more than one flagship, exactly what happened when 64 Audio revealed new TIA driver tech and introduced two new models: U18 Tzar and TIA Fourte.

One might think, choosing between 18xBA drivers and 4-way hybrid is an easy task, but you will be surprised. After reviewing U18, which still impresses me every day I use it, now it’s time to look at its sibling that shares the same DNA. Though Fourte has a different driver config, it still features TIA drivers, built-in apex module, tubeless design, and acoustic chambers. Since I already shared my thoughts about 64 Audio flagship iem pricing in U18 review, I’m not going to rehash that topic. Instead, I will focus on how Fourte compares to U18 and other flagships, and how it pairs up with different sources (along with unboxing and accessories sections which are partially recycled from U18 review). So, let’s take a closer look!

Unboxing.

Like U18, Fourte arrived in a larger box, bigger than a compact packaging I got used to with other 64 Audio IEMs I have reviewed. Their previous packaging box was about the size of their new custom travel case used with different A/U models. Here, 64 Audio decided to do something different, giving the box more room to showcase a glossy, nearly 3D hi-res image of TIA Fourte shells popping out of the sleeve cover wrapped around the main box. When you flip it over, you get a lot of detailed info about Fourte with a CAD drawing of the inner guts, the philosophy behind the design and the sound, and the spec in thumb images with a corresponding description. Furthermore, there is info about 64 Audio’s TIA technology, covering open balanced armature driver design, and a detailed description of the inner shell, driver placement, and tubeless design. You will also find the info about their new cable and the description of apex tech.

I always say, this is a type of packaging you would expect to see on the shelves of traditional brick-and-mortar shops, reminiscent of the days when people used to go to the actual store to browse the isles, to read what’s on the cover, to learn about the product before making a purchase decision. Obviously, you can’t go to your local Best Buy to pick up a pair of 64 Audio IEMs, but I do appreciate the effort put into the packaging design and can see owners proudly showcasing it on their desk at home.

With a packaging sleeve off, you are looking at a black cardboard box with a magnetic latch front cover which has a glossy 64 Audio logo, also in black. After you flip the cover open, you can read a personal message from Vitaliy Belonozhko, founder and CTO of 64 Audio, with a Thank You note at the end of the message. Inside of the box you have a foam cutout securely housing Fourte shells with an attached cable, 64 Audio custom travel case inside of another secure cutout opening, and a small cardboard tray with 6 pairs of eartips.

Overall, it was a satisfying unboxing experience, and I was able to read about the product without going on manufacturer webpage.

Accessories.

TIA Fourte arrived with a handful of different eartips. Here you will find two sets with 3 pairs (S/M/L) of foam eartips, and 3 pairs (S/M/L) of generic silicone eartips. Choosing the right eartip is a matter of a personal preference which going to affect not only the fit and the comfort, but also the sound. For me personally, I have dozens of other spare eartips and usually take my time to tip roll, to find the right one with the best seal, making sure I get the full doze of the bass! I didn’t find any of the included ones to work well with my ears, so I end up using a pair from my private stash. I do wish 64 Audio would include a better selection of eartips, maybe another set with hybrid silicone tips that have a firmer cap and a longer stem.

Other included accessories were a custom storage case which I’m going to talk about next, 64 Audio round sticker, and a product manual with some useful info about the fit, care & maintenance, handling detachable cable and apex modules, and volume advisory. Inside the storage case you will find a small dehumidifier, cleaning tool, and a shirt clip.

The storage case.

In my previous 64 Audio reviews, I referred to their new case as a “VIP case”. Everything from an easy to handle wide latch to an air valve eliminating build-up of inner case pressure when you close it, individual earpiece storage sections with removable rubber lining to a custom built-in cable winder, a spot to plug right angled headphone connector and to place the included round dehumidifier container, as well as a built-in organizer to hold securely a shirt clip (included), and a cleaning tool (included) – all this was custom tailored and well thought of. There is even enough room if you decide to use a thicker replacement cable. Since this is universal case to accommodate other 64 Audio IEMs, there was also a placeholder for 2 sets of apex modules (M15/M20), but none were included since Fourte’s apex technology is built-in and not replaceable.

When you are placing the order, you can also specify if you want your name to be etched on the top of the storage box to personalize it. While many companies use off the shelf Pelican or Otterbox storage cases with a pre-cut foam inserts, 64 Audio went one step further with their own custom designed case which protects your investment and keeps everything organized inside.

Cables.

Many IEM manufacturers are starting to pay more attention to included cables, and lately I noticed quite a few releases with other than cheap OFC stock cables. Not everybody has a collection of aftermarket cables, and some people don’t realize that a metal conductor can have an influence on the sound of IEM. Just like we go through eartip rolling (with universal IEMs) to finetune the sound, you can do the same with cables. Here 64 Audio did their own homework, testing various wires to settle on a new SPC (silver plated copper) cable they include standard with A/U18 and TIA Fourte. TIA drivers can give you super revealing details which can be masked by OFC cable or turn grainy with silver or other exotic wires. Also, considering all SPC cables are not the same, I found this new 64 Audio cable to have sound characteristic closer to pure copper cable. I will talk more about its sound property in the follow-up aftermarket cable shootout.

As far as the cable goes, it feels very durable and still flexible enough without springy memory effect. It has 4 separate conductors, all inner-twisted, with a tight rubbery black shielding, and no microphonics effect. The headphones plug is a premium gold plated 3.5mm TRS right-angled by Neutrik which has a built-in rubber-boot strain relief. This is a single ended TRS plug, but since you have 4 separate conductors, if you’re up to a challenge you can try to re-terminate it to a balanced connector. The y-splitter is a common heat-shrink tube, nothing fancy, and the chin-slider is a clear oval piece with enough friction to keep it from sliding freely. Toward the earpiece connectors, you have a memory wire which you pre-shape for comfort. I’m not a big fan of memory wires, but this one works fine and felt secure. The 2pin connector is universal which can be used in both surface and recessed 2pin shell sockets, and it’s conveniently color-coded with a Red dot for the Right side and a Blue dot for the Left side.

Aftermarket cables.

I’m a cable believer because I hear the difference, either a subtle or a more pronounced, and I have mentioned in many of my other reviews that intent of my testing with different cables is not to stir up a controversy, but rather to share my experience of what I hear. Feel free to skip this section if the talk about cables offends you. In this test, I analyzed Fourte and compared various cables to 64 Audio stock SPC cable. I did volume match by ear because many of these multi-conductor thicker cables have lower impedance which usually result in a louder sound that could be misleading when analyzing and comparing to a stock cable. Last, but not least, I hear the changes but nothing is night’n’day. Cable doesn’t function like an EQ to drastically change the sound, but I hear a noticeable refinement of the sound, described below.

SPC to 1960 2wire – soundstage is a little wider, close to U18 now, bass is similar, just with a little better definition, and mids are pulled back a little bit, making the sound more balanced, also treble is a little smoother. This is by far my favorite pair up with Fourte since it takes just a little edge off the upper frequencies and balances out the sound.

SPC to 1960 4wire – soundstage is wider, sub-bass has a little less rumble, mids are still a little forward, revealing, micro-detailed, but a touch smoother, and treble is still crisp and airy. Overall sound is a little more coherent, but still on a brighter side.

SPC to Thor II+ – soundstage is a little wider, sub-bass is similar, while mid-bass has a little more impact now, mids are still a little more forward, revealing, but a touch smoother. Treble is the same. Sound sig is a little more balanced now.

SPC to Lionheart Psquare – soundstage is wider, maybe even a touch wider than U18, bass is very similar, and while mids are still a little more forward and as revealing and analytical, they are a touch smoother. Treble is the same.

SPC to TWau – soundstage is a little wider, bass is a little bit tighter, mids are still a little forward, but now also a treble pushed a little forward as well.

SPC to Ref8 – soundstage is a little wider, bass is very similar though has a touch more sub-bass rumble, mids are still a little forward, and treble a little crisper now.

Design.

There are a lot of similarities between Fourte and U18 when it comes to their exterior shell design. Both have a similar shape, machined out of a solid piece of aluminum, slick and durable anodized aluminum shell with rounded corners, a smooth finish, and a copper faceplate with a patina inlay. While U18 shell has a slightly “aged” red shell finish and a faceplate inlay with reddish details, Fourte shell is black with a faceplate inlay that has darker colors with green touches. Though I’m not too picky about IEM colors and faceplate artwork, I know others like to customize their IEM shells. A design with all BA drivers is easier to implement in CIEM, thus U18 is available in A18 custom shell. But I have a feeling that TIA Fourte, with its hybrid design that includes a dynamic driver and internal apex module vented to outside, is more challenging to implement in a custom shell. In my opinion, if 64 Audio could stuff 18 drivers in such a compact shell, I hope that down the road they will figure out how to turn Fourte into CIEM too.

Each shell weighs about 6g, even less than U18 (8g), though in reality that will make a very little difference when you wear it. Don’t expect to be able to put your head with ear down on the pillow, but at the same time – Fourte doesn’t stick out too much. Plus, the nozzle length and the shell depth (nearly identical to U18) enables a comfortable and a secure fit. Unlike U18 where you have a replaceable apex module, a compromise was reached to offer apex module internally to the shell. As a result, it’s not removable and according to Fourte spec with -20dB of isolation – it’s implied to be an equivalent of internal M20 module. Upon closer examination, you can see a larger hole drilled on the bottom of the shell facing forward so it’s not blocked by your ear – this is dynamic low driver back vent, and I can reassure you I never experienced driver-flex with Fourte. There is another smaller pinhole vent, on the back, which is part of internal M20 module. I’m not going into all the details about apex modules since I already covered it in my U18 review, and similar to U6/U12 with Adel modules and U12/U18 with apex modules, TIA Fourte with its built in apex module had a similar fatigue-free listening experience with an open-back like performance and no ear pressure build up.

Inside, we are dealing with a hybrid 4-way design with a single dynamic driver for lows, one TIA BA mid, one BA high/mid, and one TIA high. Balanced Armatures are typically self-enclosed with a single opening port, and usually they are grouped and tubed (in multi-BA IEMs) to be routed to a specific bore in the nozzle. Open BA driver has one of the enclosure walls removed, to enable direct-radiating of the inner diaphragm which no longer has a 4-wall confinement. Inside of the shell, 64 Audio partitioned the space with custom pockets, creating acoustic chambers which allow drivers to be placed without sound tube and allowing to fine tune the driver sound performance. From the diagram on the back of Fourte packaging, I can see a separate acoustic chamber for one of TIA drivers (probably mids), and then dynamic driver pumping the sound into the main part of the inner shell which narrows down to a large single bore acoustic chamber with high/mid BA driver and high TIA driver going into the nozzle which acts as another acoustic chamber where everything gets mixed before going to a mesh covered single bore opening. This last TIA high driver is closer to your earcanal/eardrum and shouldn’t be affected by any artifacts of resonance associated with tubed sound routing.

It looks to me that one of the main challenges with U18 was to position 18 drivers, including TIA, inside of a very compact shell design. Fourte is 4-way hybrid where you have less drivers, but now have other challenges such as dealing with a larger dynamic driver, built in apex, custom acoustic chamber partitioning, etc. 64 Audio met these challenges and were able to use the shell with nearly the same dimensions as U18.

The fit.

Page 2: Sound analysis, Pair up, Comparison, and Conclusion.