Headphones Hands-On: Periodic Audio Carbon IEMs & Nickel Amp

Periodic Audio is a company focused on producing IEMs (in-ear monitors) that perform at a high level for their price point. The company offers four models, all virtually identical save for the material used to create the full-range dynamic drivers. Until recently, the Periodic Audio Beryllium ($299) held the top slot in the Periodic hierarchy, but now there is the flagship Periodic Audio Carbon ($399). And in this case the carbon takes the form of… diamond. Other models in the company lineup are the Magnesium ($99) and Titanium ($199).

In addition to the earphones, Periodic Audio sent me it’s ultra-simple, ultraportable amplifier, the Nickel ($299). There’s practically nothing to it, and the idea is it provides 6.5 dB of transparent gain to give your phone a helping hand. It’s an old-school, analog solution for listeners who like some extra oomph in their portable playback.

Features and Specifications

Periodic Audio Carbon IEM

Carbon is an IEM with lab-grown diamond drivers. The company claims to know of no other IEM with lower distortion… and fundamentally, the key to audio transparency is the absence of distortion.

The driver’s diamond layer measures a mere 8 µm (microns) and are proprietary to Periodic Audio. The driver is housed in a black polycarbonate body that is all business and will draw attention to you as you walk down the street.

Rated frequency responses 12 Hz to 38 kHz and nominal impedance is 32 ohms. Sensitivity is rated as 98 dB with 1 mW of input, measured in-ear and maximum power handling is 200 mW continuous, allowing for a peak SPL of 121 dB. With 1 mW of input power, it keeps total harmonic distortion to below 0.2%, according to Periodic Audio.

The permanently attached, tangle resistant cable measures 1.5 m. A small tin is provided with replacement eartips in silicone as well as foam, and in various sizes. Also included is a quarter-inch adapter as well as an airplane adapter. These IEM’s are assembled in the USA and warrantied for 5 years.

One feature of Periodic Audio is the company insistently only spends money where it matters for the sake of performance. Therefore, the packaging for its products is as minimalist as it gets. The company maintains a FAQ where it is totally transparent about its philosophy and decision-making process, including the packaging: “Simply put: YOU DON’T LISTEN TO THE BOX.” I’m all for this performance-first attitude but I think it’s important to alert prospective buyers that you will not have the “unboxing experience” that some other products offer.

Periodic Audio skips the fancy packaging, spends the money on engineering and materials.

Nickel Amp

50mm long, 30mm wide, 18mm thick. 20 grams. Yep, it’s tiny and super light. Nickel is a polycarbonate-body “pocket amp” that charges in 30 minutes or less and provides 8 hours of amplification (6.5 dB fixed gain) with 8 Hz to 80 kHz response and <0.005% THD from 20 Hz to 20 kHz. Power output is rated at 250 mW continuous into a 32-ohm load and almost double that into 16 or 8 ohms. In other words, it’s powerful and transparent, which is why it costs $300 despite being a tiny plastic box with no “functions” aside from amplifying the audio you feed it from your cell phone.

Nickel has a micro-USB port for charging and an LED that shows charge status. Aside from that, it’s defining feature is a pair of 3.5mm jacks that have an extra-firm grip so your cables don’t come unplugged. One is the input, the other is the output, and that’s all there is to it.

Hands-On Impressions

Okay, this is crazy… I’ve got an $700 IEM rig that is free of bling. No fancy packaging, no fancy cables, and the Nickel is made of plastic. I bring this up right away because I suspect some consumers have a totally different expectation regarding what their money gets when they buy headphones, versus where Periodic Audio is coming from. Here, you are paying for audio fidelity. And, you’re paying for audio fidelity. Plus, you are paying for audio fidelity. Not weird, magical, quantum-whatever fidelity, but rather the performance that diamond drivers deliver.

Amusingly, this is the 30th anniversary of when I got my first $500 pair of diamond driver earphones. It was early August 1989 and my friends and I were traveling in Europe, when in Paris I saw a Sony boutique that was selling “Diamond Fontopia” earbuds. Being that I was willing to starve for good audio, no matter what my situation, I spent a large chunk of my discretionary travel funds on that pair of headphones and plugged them into my Sony Walkman. The result, I literally could not believe that IEM’s sounded better than any full-sized headphones that I owned, or for that matter had ever heard. Sadly, I only got year’s use out of those before a roommate stepped on them and they broke.

Fast forward to today, and I can say that practically nothing has changed: If you make IEM’s with diamond drivers, and engineer them properly, the resulting fidelity is hard to beat. I had already settled on the Periodic Audio Beryllium as my favorite (corded) IEMs, but Carbon is… even better. There’s no mystery why, diamond is the hardest material and therefore the most resistant to distortions—it’s the ideal material for a full-range dynamic driver.

The very first moments listening to Carbon, plugged directly into my Galaxy Note 9 (no Nickel) told me a lot. For one, these IEMs get plenty loud with no added amplification. Second, the great fit and inner-ear seal that I experienced with the Beryllium model (and the Magnesium and the Titanium too… they are the same size, shape, etc.) was present in the Carbon. That provided good passive noise isolation plus  allowed for excellent bass extension, which complemented the clean, detailed presentation.

Forgive me for not getting into specifics of how this or that song sounded, is basically I’m going to say that they all sounded great and the bass was awesome and the soundstage was very clear, although basically trapped inside my head (as is the case with any IEMs) unless the mix itself accounts for it (some mixes genuinely sound like they are “bigger” than your head, it definitely depends on the production approach.

As for the Nickel amp… It may be tough to understand why it commends a $299 MSRP for a device that’s restricted to analog 3.5mm input with no controls and no options. I don’t wish to sound critical but in terms of look, feel and features it comes across as something that should cost $19.95 on Amazon, not three hundred bucks. On the plus side, it’s as simple as can be and small and lightweight and best I can tell, transparent. The 6 dB boost it provides allowed my Galaxy Note 9 to power the Carbon IEMs to levels beyond what I need, but I could also get that volume level out of my phone by turning up the volume.

Having said all that, the Nickel works with other, harder to drive headphones. I plugged in full-size cans (KLH Ultimate One, B&W PX) that can easily handle more power than my phone provides. The Nickel’s 6 dB boost allowed me to back off a couple notches on the phone volume while enjoying a few extra dBs of output and the punchier dynamics that come with it. If you can stomach the price of the Nickel, it is the smallest, lightest, simplest way to ensure you can power just about any headphones properly while using your phone as the source. But make no mistake, when you look at it and hold it, the price is not exactly going to make “sense” so you’ll just have to decide for yourself if the performance justifies the cost.


Periodic Audio has scored a home run in terms of delivering the absolute smallest, lightest high-end audio rig I’ve ever had the pleasure of putting in my pocket. Whether this is the right approach to audio bliss for you is a personal decision. This kit is strictly for folks who appreciate a minimalist, no-nonsense “performance first” approach to sound. It is not for anyone who cherished unboxing, fancy packaging, or “luxurious” fit and finish.

Thanks to a laser-like focus on fidelity, the Periodic Audio Carbon is an obvious Top Choice selection for IEMs. As for the Nickel amp, I can recommend it conditionally: If you specifically want 6.5 dB of clean gain that slips into your pocket and does its job with zero fuss, then give it a look.

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