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In the world of audio, drivers aren’t people behind steering wheels, they’re the tiny objects that physically produce sound. These tiny speakers come in many forms, from piston-like dynamic drivers you’d recognize as miniature speaker cones to more advanced forms of, essentially, magnetically moving a diaphragm in the air to create sound waves.
In my time as an audio reviewer, dozens of companies have claimed to have the best, cleanest, most perfect driver technology ever. Some of it has sounded really great, but fundamentally every model I've tried was still operating on the same technology available to us when Jimmy Hendrix was window-shopping for Fender Stratocasters (9/10, WIRED Recommends): magnets and metals.
In the mid-2020s, headphones are finally headed to solid state. Thanks to innovations from xMEMS, a California startup that wants to print headphone drivers the same way one typically makes microchips, we’re closer than ever to headphones that sound utterly perfect in all environments, even if you accidentally put them through the wash.
With major manufacturers like Creative Labs on board to add these drivers to next-gen wireless earbuds, and a few high-end products already on the market, the future of portable sound is finally peeking around the corner.
The future of headphones, it turns out, may have been in our pockets for about a decade. MEMS technology (the acronym stands for “micro-electromechanical systems”) uses the piezoelectric effect and silicon chips to, in the case of many cell phones, capture audio from the outside world as a microphone. These MEMS-based mics are easy to manufacture, don't require much calibration, and are extremely consistent, but they don't exactly sound fantastic.
The folks at xMEMS have spent the past few years working with new materials developed in 2015, essentially reversing microphone technology to make it a speaker. The end result is a driver that is among the flattest and most responsive of any I’ve ever heard, and one that can be made en masse entirely without human sorting—previously impossible in headphone land.
It’s very rare that a product lives entirely up to the hype that’s presented, but xMEMS’ Montera drivers, as tested inside a pair of $1,500 Singularity Industries Oni headphones, via a special $1,100 iFi xMEMS amp, sound like nothing I’ve ever heard before.
For one thing, the earbuds have an utterly flat frequency response down to about 20 Hz. That means every part of the mix is able to stand on its own, with nothing becoming too prominent due to the headphones alone. But the secret sauce the xMEMS drivers bring to the table isn’t just near-linear frequency response, it's in their speed. Unlike traditional membrane-based drivers, the piezoelectric effect utilized by MEMS technology is sub-millisecond fast (about 150X faster than older driver technology), which means each note comes through more clearly.
Imagine jumping on a trampoline to create sound: The MEMS drivers aren’t jumping very high, while traditional dynamic drivers are bouncing to the ceiling before they can reset to their original shape.
Such speed means remarkable separation between instruments and a soundstage where bassier songs don’t lose mid or upper range. It’s like looking through crystal clear glass where you previously could see smudges.
Well-produced mixes sound great, especially ones that might sound a bit muddy or dark on other systems. On Loudon Wainwright III’s acoustic rhapsody “Hollywood Hopeful,” you can hear the strings of the guitar rattle near the microphone clearly on the right side of the soundstage, with his speech-song vocals biting at the entire middle of your consciousness. The separation between instruments and sense of musical space is speaker-like. The next thing that pops up on my playlist is NRQB’s “Magnet.” The electric bass is propellant, like a tiny set of wheels that push the music forward, fully in earshot because of the excellent low-frequency response of the xMEMS drivers.
It’s the low end that I find most enthralling about these new drivers. It’s extremely present and clean; you can hear every note in the bass. Unlike with dynamic drivers, there isn’t the same eardrum-pumping feeling down low you’d expect with bass this apparent and separated in the mix. Some companies are reportedly experimenting with adding a dynamic or balanced armature driver to the earbuds for punch. At least in these earbuds, it’s not needed.
The best way I can describe the xMEMS experience is that it is one of absolute, unabashed clarity. You hear exactly what everything sounds like in a mix, with virtually no color from the drivers themselves. It’s utterly liberating, but it can make bad mixes—anything with an unbalanced midrange, weird panning, or too much high end—immediately stand out. You might hate how some favorite old records translate to a set of headphones with this much clarity. I found a few mixes shockingly awful through such a clear window.
Obviously the drivers’ characteristics, their speed and separation, are exaggerated to the highest degree inside this pair of custom-milled titanium earbuds and the purpose-built amp. The scary thing for hi-fi nerds is that I have also demoed preproduction sample units of much more affordable earbuds with the xMEMS drivers inside, and they sound very close to this good. The drivers are naturally flat up to the high-end of the frequency spectrum, which means that they can be easily tuned by manufacturers using EQ and acoustic design.
xMEMS headphones don’t require more power than traditional earbud drivers, so they’d essentially fit inside any existing pair on the market as long as form factor and impedance allow. (These headphones run on an inverse impedance curve compared to normal drivers, and the iFi amp has a special DC bias to power them.) It’s a small change, a trade-off for such excellent and repeatable sound, and one that can, the folks at xMEMS assure me, be easily designed into earbuds and dongles given existing power restrictions. The company makes a tiny 1.9 mm x 1.9 mm chip that can easily power its drivers.
The robustness of the drivers is another big plus. These can be treated like utter crap and still sound great, according to the company. The masochists at xMEMS proudly claim they’ve gotten them really hot, cold, and wet, and ran them through a full wash and dry cycle, and the drivers still come back perfectly in spec. The joys of solid state.
The best part about xMEMS’ driver tech? It doesn’t appear to be a mirage on the horizon so much as a plane that’s rapidly coming in for landing. Creative, a brand that has long been at the forefront of audio technology and itself made some pretty decent wireless earbuds, will have two pairs of xMEMS-based headphones for under $200 on the market before the end of the year.
Singularity's high-end earbuds (the ones I’m listening to) already exist and are for sale, as are another pair from Soranik ($1,200). The company continues to innovate and create new and better drivers, such as the new Cypress it announced recently. I expect that many brands, especially at the higher end of earbuds, will follow suit as soon as they spend time with the technology.
The new drivers might not be substantially cheaper than previous dynamic or balanced armature options (the company claims they are more expensive than dynamic drivers, about the same as high-end balanced armature drivers), but they make up for that in ease of manufacturing, the fact that they don’t have to be sorted by humans or matched, and, of course, the fact that they create such incredible sound. The folks at xMEMS point out that MEMS microphone technology is still slightly more expensive than the previous technology used in cell phones, yet it's still the market leader due to the many benefits it offers in a macro sense.
Between innovations like this new solid-state driver technology and the latest Qualcomm chipsets for wireless earbuds meaning lossless audio transmission and Wi-Fi-based streaming, it’s gearing up to be a very exciting decade for earbuds. In 10 years, we might listen back to the original AirPods (7/10, WIRED review) and think they sound like AM radio. As someone who loves to make music as much as I love to listen to it, I can't wait for everyone else to experience such true-to-life musical performance at attainable prices.
