Periodic Audio Carbon (C) In-Ear Monitor


Diamonds are formed of carbon (C) atoms that have been placed under extremely high temperatures and pressures that exist naturally very deep beneath the earth’s surface. This natural process from carbon to diamond takes an incredibly long time—about 2 billion years.

Although widely prized for their beauty as jewelry and treasured since BC, they possess other qualities such as extraordinary hardness that are ideal for various industrial applications including audio, such as diamond styli for phono cartridges. They also, under normal everyday conditions, will last forever. Fortunately, scientists can mimic the process in the laboratory, ‘growing’ diamonds in a matter of weeks. These lab-grown diamonds have essentially the same chemical, physical, and optical properties as the natural ones—but still are expensive.

Periodic Audio just released a new in-ear-monitor (IEM) named Carbon (C), and in their own words, ‘The C IEM utilizes a lab-grown diamond layer (8 microns) on our own proprietary high-temperature polymer substrate’. With a clever twist on the famous slogan used by De Beers Jewelers, ‘A Diamond is Forever’, the motto for the C is ‘Made From Diamond Because Music Is Forever’.

Two years ago I reviewed their other three IEM models all at one go, Magnesium (Mg) ($99), Titanium (Ti) ($199) , and Beryllium (Be) ($299) and was sufficiently impressed to now check out the C, which I review here. At $399 it is now their highest level model. Many thanks to Sue Toscano, Toscano Communications, for offering a chance to review them and so quickly ensuring their arrival.

When I queried Dan Wiggins, Periodic Audio Co-Founder, about what is the advantage of using diamond in the IEM, he said that it was a combination of things:

Young’s modulus (a measure of stiffness)– it simply doesn’t break up/resonate, meaning diaphragm-based distortion doesn’t happen.

High speed of sound–equivalent to Beryllium, makes sure the entire diaphragm moves together, cohesively.

Higher mass– counterintuitive, but this lowers the resonant frequency of the transducer, and provides for an even fuller sub-bass experience

The C has a trim looking all-black (carbon color) construction, and the right (R) channel is the one with a red-colored grill inside the earbud. A black 1.5m cable with a solid gold-over-nickel plated brass 3.5mm plug is permanently connected, but comes with both an airplane and a 1/4” adaptor, as well as a variety of earbuds of different sizes.

I must say that the C fit my ears so snugly and sealed them in so well that they served as the best earplugs for keeping out external sound that I have ever experienced—if I could, I would use them to sleep at night. (I might ask Wiggins to make me a special pair for that purpose.)

Some further specifications of the C

Frequency Response: 12 Hz to 38kHz 

Impedance: 32 Ohms nominal

Sensitivity: 98dB SPL @ 1 mW, in ear 

Power Handling: 200 mW continuous 

THD: Less than 0.2% at 1 mW

Peak SPL: 121 dB 

Warranty: 5 years

Note: Although diamonds are forever, if you are of the foppish type, these are not for you; don’t expect to show off sparkling diamond to your friends and loved ones with these IEMs; Periodic Audio has a different philosophy:

We make portable audio products. Those are products you can quickly and easily tuck into a pocket.

We do not make jewelry. We don’t care about elevating your social status because you are seen with our products. We do not court sports-stars or media-darlings to be a fashion brand.

We just care about music. And that it should move you.


I used the C with Periodic Audio’s superb tiny Nickel headphone amplifier ($299) throughout with an iPhone and Macbook Air. I streamed using Qobuz and Tidal. As the main comparison, I used the Periodic Audio Be. (The Be and C have the same frequency response.) What was immediate was the increase in body and richness, and the bass was deep but with more clarity, transparency and with less distortion. The Be sounded somewhat thin and crispy by comparison. Together, with that tight earbud seal, the C certainly reminded me of the sound quality one is likely to expect from closed over the ear headphones; but the C can fit in the pocket of a T-shirt.

In their online promotion, they write ‘Carbon is unique. Lab grown diamond meets Neil Diamond.’ So what better way to have started my listening than with Neil Diamond—which I did. While most people probably think of `Red Red Wine' as a reggae song by UB40 (1983), it was written by Neil Diamond who recorded it in 1967 (non-reggae, of course). He sings about a lost love, and explains how the only way he could get over her was to drown his sorrows by drinking red wine:

Red, red wine
Go to my head
Make me forget that I still need her so.

It is a sad song. Through the C, Neil Diamond’s slow and deliberate version was rendered spot on; it made me feel the need to grab a glass (or bottle) of red wine and join in his sorrow out of sympathy. The festive UB40 version really showed off how well the C handles bass and integrates it with higher frequencies; it made me want to drink margaritas at a party—joining in some fun. Although, UB40 retains some of the original lyrics, they add some of their own which turns its original meaning on its head:

Red red wine, you make me feel so fine
You keep me rockin’ all of the time
Red red wine, you make me feel so grand
I feel a million dollar when you’re just in my hand....

Progressive rock band King Crimson recently released their music to be streamed at 24 bit high-resolution. As a long-time fan of them particularly when with drummer Bill Bruford, I tried out the albums Larks’ Tongues in Aspic (1973), Red (1974) and Three of a Perfect Pair (1984). I have all three on vinyl, too, and had blasted my stereo system with them and three of their other LPs on Fathers Day last month which had brought back many fond memories. (To ensure I was getting true 24 bit play while streaming here, I used only the MacBook Air utilizing its 3.5mm output, as opposed to the iPhone 8’s Lightening output.)

The C handled them with aplomb, and since I am the only one in my household who appreciates such genre of music at high volumes, I could listen at any time—in private. For a hilarious spoof on a Barber Shop Quartet style (no instruments here only singing), check out the track ‘The King Crimson Barber Shop’ from Three of a Perfect Pair, where the unique vocals of Levin, Bruford, Fripp and Belew are captured so succinctly by the C.

I also tried other genres of music such as the album Temptation by Holly Cole (as a tribute album to Tom Waits), with tracks ‘Train Song’ and ‘Jersey Girl’; a fantastic recording which shows off the C’s ability to capture a beautiful female voice intermixed with bass and fascinating delicate percussion.

Enjoy the C, I sure did. Highly recommended at such a price of $399 given their surprisingly fine sound quality for an IEM and ability to block out external sound. Coupled with the Nickel amp they make three of a perfect pair.

Further information: Periodic Audio