Review: Beyerdynamic Custom One Pro Headphone

When I attend trade shows, I’m always reluctant to ask for a review sample of a new product. ’Cause who knows if I’ll see something cooler around the corner? But when I saw the Custom One Pro at the recent Rocky Mountain Audio Fest in Denver, I asked Beyerdynamic’s Pete Carini to send me a sample ASAP. After a quick listen to the Custom One Pro, I knew there was no way I’d find a more interesting headphone that weekend.

The $199 Custom One Pro has a lot going for it, but first and foremost has to be its custom sound sliders — two four-position vents, one near the bottom of each earpiece, that let you tune the sound to your taste. At the bottom setting, the vents are fully closed for maximum bass power and maximum isolation from outside sounds. At the top setting, the vents are open for a more spacious sound with less bass.

There’s more custom about the Custom One Pro than just the sound, though. Perhaps taking a cue from V-Moda, it also has removable side panels that let you customize the look. Beyerdynamic offers a variety of panels on its website. The company also plans to offer headbands and cables in different colors, as well as an optional cable with an inline microphone. “We wrote a book, but we’re still adding chapters,” Carini told me at RMAF.

Each of the Custom One Pro’s metal earpieces houses one of the company’s new Velocity dynamic drivers, a 16-ohm design intended for use with smartphones, laptops, and other sources that tend to have wimpy headphone amps. Driver size isn’t specified but it appears to be 40mm.

Great? Or gimmick?

Sometimes in audio, freedom to customize the sound really means freedom to mess it up—to impose your own fleeting and questionable preferences on a product that’s already professionally tuned for optimal performance. (Disagree? Rent a car and check out the way the last guy set the tone controls. Case closed.) My brief listen at RMAF suggested that the sound sliders are an exception, a tuning technology that really does provide useful and appealing options. But would it stand up to a longer listen?

To find out, I gave the Custom One Pro a couple of weeks of use, then called in our West Coast headphone listening panel: L.A. voice actress Lauren Dragan and jazz musician Will Huff. Because the Custom One Pro’s designed for use with portable products, we did most of our listening from iOS and Android smartphones. We also used my Rane HC6S professional headphone amp for direct comparisons with other headphones.

“The adjustable vents are brilliant,” Will raved. “It’s not a high-tech solution, but it lets you change the balance and dynamics easily.” For most recordings, he set the controls to the mostly closed (not fully closed) setting, which he found to be “almost the perfect sound for me.” He particularly complimented the Custom One Pro’s sound with jazz percussion. “It really gets that ‘salty’ sound of a brushed snare just right,” he said. Lauren wasn’t so enthused, though. She liked the way the controls work, but complained about distortion in vocals — something I heard when she demonstrated it for me with her music, but something I didn’t encounter in my own listening. (As you can see in the measurements, distortion is somewhat high, but only in the bass.)

Personally, I found the sound sliders addictive: super-useful, super-easy to set. Two of my favorite test tracks — Steely Dan’s “Aja” and Mötley Crüe’s “Kickstart My Heart” — clearly demonstrated the sliders’ efficacy.

“Aja” sounded just right with the sliders set to full open. The bass sounded fairly precise and tuneful, in perfect balance with the piano, guitar, voices, and percussion. The sound was also appropriately delicate and airy — no match for the spaciousness of a full open-back model like Beyerdynamic’s own DT-990 or the HiFiMan HE-400, but more open than I’m used to hearing in a $199 headphone. When I switched to the closed or mostly closed positions, the bass became overwhelming and the tonal balance seemed dull.

But it was just the opposite with “Kickstart My Heart,” which sounded emasculated with the sliders in the open and mostly open positions, but just right in the mostly closed position, where the bass and kick drum sounded powerful but not overwhelming. The fully closed position? Overwhelming for me, but that guy who rented that car before I did might find it just right.

The Custom One Pro can also make ridiculously bass-heavy mixes more listenable. Case in point: 9th Wonder’s “Loyalty.” To me, this tune sounds crazily bass-heavy through many headphones, but with the Custom One Pro in the mostly open position, the subtle, laid-back groove was much easier to appreciate.

All that said, the Custom One Pro isn’t what you’d call an audiophile headphone. While the overall tonal balance can easily be made as flat and neutral as an audiophile headphone’s, the Custom One Pro’s mids and highs aren’t as lush or refined. Voices sounded smoother and simply more real through my V-Moda M-80, a compact, $229 headphone that’s a favorite among aficionados.


To measure the Custom One Pro’s performance, I used a G.R.A.S.43AG ear/cheek simulator, a Clio FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-Can headphone amplifier. I experimented with various positions of the Custom One Pro’s earpads on the ear/cheek simulator and settled on the positions that gave the most representative results.

The Custom One Pro’s frequency response varies a lot below 1 kHz depending on the sound slider setting. In all settings, the headphone shows a strong response peak at 2.4 kHz and a broader peak between 6 and 8 kHz; most headphones that deliver a subjectively flat response have similar peaks. Obviously, the closed setting delivers the strongest bass. What’s surprising is that the mostly open setting delivers the flattest bass response. The fully open setting produces less deep bass, but a strong bass peak at 130 Hz.

Impedance is fairly flat, running between 17 and 27 ohms, and it varies only slightly with changes in the sound slider setting. Adding 70 ohms output impedance to the V-Can’s 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp boosts the bass by an average of +2 dB below 200 Hz.

Total harmonic distortion (THD) at 100 dBA is modest below 100 Hz, but there’s an unusual distortion peak at 70 Hz, which might be audible with certain material. Distortion below 100 Hz is pretty high in open mode, running between 7% and 20%. Isolation is typical for an over-ear design; using the closed mode improves isolation by about -15 dB between 150 and 400 Hz.

Average sensitivity with a 1 mW signal at 16 ohms rated impedance is 91.8 dB in fully closed mode, 93.3 dB in fully open mode from 300 Hz to 10 kHz, 93.0/94.7 dB from 300 Hz to 6 kHz. That’s not particularly high sensitivity; I often had to set my iPod touch to full volume or just one click down to get satisfying sound.

Bottom Line

Because opinions of headphones vary so much, it’s always hard for us to recommend one unconditionally. A tonal balance that’s absurdly bass-heavy for one listener may be perfect for another. But with the Custom One Pro, you’re pretty much assured of getting not only the right tonal balance for your taste, but also the appropriate tonal balance for the music you’re listening to. We hope Beyerdynamic extends the sound slider concept into more models, because it is definitely a winner.