NXEars Opera Earphones

REVIEW
by Steven Stone
Jan 05, 2022

NXEars are a new entrant in the in-ears marketplace. And while the name is new, the principals have been involved in earphone design for some time, as the primary acoustic design team for NuForce and Erato earphones. Together, they’ve won over 25 international audio awards and produced more than one million earphones. NXEars debuts with three universal-fit in-ear models in its lineup: the Sonata ($199) with one balanced armature driver (BA), the Basso ($499) with four BA drivers, and the Opera ($799) with eight BA drivers. We will look at the Opera in detail.

What makes NXEars unique is its primary focus on alleviating the negative aural effects of something it calls “the occlusion effect,” which is the pressure build-up in a listener’s ear canals caused by low frequencies. All NXEars employ a new and proprietary acoustic/mechanical innovation called “aperiodic ground loading” (AGL) to correct the problem. AGL operates at below 10Hz and is asynchronous to the frequency response of earphones. According to NXEars, “this innovation greatly benefits hearing health and reduces listening fatigue. It also removes the self-distortion of the inner ear, resulting in a pristine, distortion-free, delicate, and revealing musical experience.” Let’s see if AGL and the reduction of the occlusion effect combine to make for a better listening experience than more conventional designs.

Tech Tour

At first glance, the NXEars Opera universal-fit in-ears appear to be much like other in-ears, with their kidney-shaped, translucent, 3D-printed shells, but the reality is different, starting with the material itself. Instead of the usual ABS plastic resins used in most shells, Opera employs the same material as high-end custom hearing aids. This hypo-allergenic bio-compatible resin has been engineered for long-term contact with the skin. Its self-damping acoustical properties also make it ideal for high-end audio applications.

Inside each Opera earpiece you will find eight Knowles balanced-armature drivers in an array consisting of two bass drivers, four midrange drivers, and two upper-frequency drivers. Obviously, using this number of drivers successfully requires a well-designed crossover to eliminate all the potential issues with group delay, phase shift, and impedance variations. Common solutions range from no crossovers (letting each driver roll-off naturally) to complex ones that require sharp slopes and filters. NXEars relies on a variety of advanced computer-modeling tools that allow it to run dozens of multi-variant simulations to determine optimal crossover networks. Its efforts have taken the form of a linear-phase/time-coherent crossover. This advanced modeling has also enabled NXEars to construct crossovers using a minimum number of components, with a headphone-friendly electrical impedance throughout the entire audio-frequency range.

Occlusion is a pretty fancy word for a complete seal. And a complete seal is absolutely necessary on the vast majority of in-ears, because without a complete seal you will not hear the earphones’ true frequency response due to low-frequency loss and leakage. But the same environment that makes it possible to create good bass also introduces the possibility of fatigue, and in extreme cases even pain as a result of the pressure build-up created by low frequencies in the sealed environment of your ear canal. The NX series of in-ears are the first to devise a patent-pending solution to these problems.

Ergonomics and Use

The NXEars Opera comes with a complete accessories package that includes six pairs of eartips, a hardshell travel case with belt clip, a cleaning tool, a cable clip, a Velcro cable tie, and a removable, monocrystal 6N-copper cable. The eartips come in three sizes of silicone and three sizes of malleable foam, similar to Comply eartips. Cable swapping has become quite common among in-ear users, but given the quality of the supplied cable, which is both flexible and non-microphonic with high-quality termination hardware, I suspect that most users will not need to hunt for alternative cabling options.

Many travel cases that come with in-ears are virtually useless, except for providing a place to put your earphones when they’re not in your ears. The NXEars case is much better, being a hardshell, so it provides some protection. Inside the case is a foam block into which you can place each earpiece, so it doesn’t roll around inside the case. This is important because the primary reason that balanced armatures eventually fail is trauma that knocks the internal elements out of alignment. This foam block is a design detail that should heighten Opera’s longevity and that all BA in-ear cases should employ, though few do.

The Opera has a sensitivity rating of 100dB with 18-ohm average impedance, which places it among the easy-to-drive but not most-sensitive category of in-ears. In comparison, the most-sensitive CIEMs in my collection, the Empire Ears Zeus, have a 115dB sensitivity. While custom in-ears, such as the Zeus, offer multiple colors and finishes, currently the Opera comes in only one color, an attractive “Stardust” blue, which is translucent enough to let you see inside, but dark enough so that the Opera doesn’t resemble a 3-D schematic. The dark blue is punctuated by metallic sparkles, so it brings to mind Vincent Van Gogh’s “Starry Night.”

The Opera comes with a large pair of silicon tips already installed. I used these for the first couple of hours before I grew tired of having to re-seat the left earpiece on a far too regular basis. I tried all the other tips before I settled on the large Comply type, which remained in my ears without readjustment for entire listening sessions.

I mentioned the cable earlier. It deserves a bit more discussion. It excels in all the areas where a cable should. It is soft and flexible with a geometric weave that is strong enough and long enough to allow you to put your player in a thigh-high pocket. All the junctions have strain-relief, so if you don’t have a locking headphone connection (which is a terrible addition to any headphone amplifier) the connections will give way before any damage to the cable itself.

One of the principal reasons for choosing an in-ear rather than an on- or over-ear headphone is because the isolation capabilities of an in-ear are greater. I used to attend a local, well-attended gym for workouts three times a week, which gave me an ideal location to see how well a pair of earphones isolated me from extraneous noise. Since I work out at home now, I checked isolation by playing music from one of my room-based systems, inserting the Operas, and checking how much isolation they delivered. With the foam tips isolation was around 10dB, which is not close to the 30dB+ I get from custom in-ears. With silicon tips the isolation was a bit better.

My longest listening session with the Operas was several hours. During that time, I had no sense of pressure build-ups from low frequencies, which is something I have noticed with some in-ears. In my experience, the Opera’s stated goal of eliminating “the occlusion effect” is successful. I used a variety of headphone amplifiers and sources including the Sony NW-WM1Z, Astell & Kern SP2000, Schiit Magnius, Apple iPhone 8 with AudioQuest Dragonfly Carbon dongle, and Sony TAZ-H1ES. Even the iPhone rig had ample power to drive the Opera.

Sound

Most earphones that use balanced drivers use Knowles BAs. You would think that balanced-armature earphones might share a similar “house sound” due to the common use of these Knowles drivers, but that is definitely not the case. In my experience the other technical details in a BA-earphone design have a far greater effect on the overall sound than the basic Knowles components themselves.

Earphones can be and are “voiced” in a myriad of ways. Some are designed to adhere to something called “the Harman Curve,” which is a frequency-response curve that differs from a “flat” frequency response. Sean Olive, from Harman’s research division, developed this EQ curve after extensive testing, using both experienced and inexperienced headphone users. In Olive’s tests, respondents preferred the Harman curve to a flat frequency response. Some reviewers claim that any variations from the Harman curve are wrong and must be corrected by user-supplied equalization to be deemed acceptable. I take a more liberal approach: There is more than one way to voice a pair of earphones. To expect all manufacturers to adhere to one particular frequency-response curve is like expecting all brands of chocolate ice cream to taste exactly like your favorite brand. Some users would prefer it sweeter; some want a deeper, darker chocolate taste. Same with earphones…there is no one curve that I have found that is so superior to all others in every situation that I consider it the only way to voice earphones. Personal taste matters in personal audio. A lot.

So how do the Opera earphones sound? First thing I noticed was how well they imaged. The soundstage was large without sounding stretched out. Instruments and lead vocals were placed precisely. Pop vocals, which often feature multiple lead vocal tracks overlaid upon each other, were replicated and elucidated with excellent spatial accuracy. This kind of specific imaging is often sacrificed in multi-driver in-ears in favor of a bigger, wider, but less precise soundstage, so kudos to the crossover design. The Opera was seamless and retained spatial cues.

The Opera’s harmonic balance to my ears was essentially neutral, with well-defined but underwhelming mid-and-low bass impact and level. I suspect that other listeners with somewhat larger ear canals will get more bass extension and dynamics than I did. This is not necessarily due to any shortcomings in the Opera’s native frequency response, but all about the fit. As I harp on, again and again, when it comes to earphones, especially universal in-ears, the fit will often be the most important aspect of the headphone’s performance.

The Opera in-ears have a somewhat larger-than-average barrel circumference, which for me meant that I could not get the tip ends as deeply as needed into my narrower-than-average ear canals for optimal bass response, even though I had a completely occluded seal. For someone with a slightly larger ear-canal opening this will be less of an issue, and they will get more bass. I confirmed this by pressing the Opera’s tips slightly into my ears, whereupon the bass output level and dynamics improved, but my comfort level decreased.

Summary

On paper the NXEars Opera compete with universal and custom in-ears costing almost twice as much. But when it comes to earphones, there’s on-paper and there’s in-your-ear. The Opera in-ears succeeded in most performance areas with exemplary soundstaging abilities. They are well constructed with premium components, amply accessorized, and carefully engineered to minimize listener fatigue. For me, their fit was not optimal, but that was for me, not you. Also, the bass dynamics and extension may not be sufficient for pop music fans.

I would still recommend trying out the NXEars Opera earphones if you are seeking a top-tier universal in-ear solution. They could very well be just right for you.