Disclaimer:
I was sent a nickel direct from periodic audio in exchange for my opinions. The unit is mine to keep, but these are my honest opinions. The unit sent to me is also one of their "blemished" versions, so certain thoughts about the build or aesthetics of the unit will reflect that.

About Me:
I have been in this hobby on and off for a number of years now, much more seriously into it recently with a heavy focus on IEMs and portable listening. I am mostly interested in the IEMs themselves and dont put a huge amount of stock into other components really making a large difference in terms of sound quality. I see an hear lots of talk about cables and amps all making these massive improvements, and its just not something I have personally experienced or really put much stock into. And its from that perspective that I approached this item.

About the Nickel:
The nickel is a small headphone amp that retails for $299, or $199 for a blemished version.

Some of the important specs from the periodic website about the nickel:

• THD+N: < 0.005%, 20 Hz to 20 kHz
• Gain: 6.5dB
• Power Output: 250 mW Continuous, 32 Ohms
• Damping Factor: > 100 @ 32 Ohms

While I am not the most studied up on specs and how they affect things. This should be more than enough power to power most headphones thrown at it with the exception of some of the much harder to power headphones.

The unit itself is about the size of a 9 volt battery. Its very small and very portable. Included it comes with a short usb cable for charging and a male to male 3.5 cable to send audio from your source to the nickel. The body is plastic (polycarbonate) and feels solid enough. My particular unit, the connectors (and feels like all the internals) are slightly loose. I can wiggle the usb connection and feel the jacks moving on the other side. However, as mentioned above, this is a blemished unit, and I would expect this not to be an issue on a normal unit, even though I barely register it as an issue now.

The packaging is a relatively plain white box. It is pretty sparse and definitely is not going to satisfy anyone who is into the whole unboxing experience. Here the box is definitely just for packaging and thats all. If you are expecting a fun unboxing experience, look elsewhere.

In Use:
The nickel is extremely easy to use. Plug the cable from your source into the nickel, plug your headphones into the nickel and... listen. Thats it. The nickel automatically senses when both plugs are being used to power itself on. There is no power buttons to mess around with, no volume, no gain switches, none of it. Its plug an play in the best sense of the word. Volume control remains with your source device. There is an indicator light that shows battery levels that also doubles as the charging indicator too.

The 3.5 jacks are extra strong so it may take some extra force to get your cables inserted, but I have read that this was done on purpose with the intent that they are strong enough to support the nickel hanging from your device. In theory thats great, as the nickel itself is lightweight. And while the jacks wont be the source of failure due to their strong lock, if you are using cables that cant hold up, that could potentially be an issue.



Overall, its a slick little package that is very portable and super easy to use. The markings could potentially be a little more clear as to which jack is which. It is fairly obvious that the triangle pointing inwards is the input, while the triangle pointing out is for the headphones. But I could see it getting easily mixed up.

One caveat to the usage though. The order of plugging in the headphones and the input cable are important. Likely it will not do any damage, but if your headphones are plugged in first, plugging and unplugging the input cable can create a loud popping noise that can be very unpleasant.



It does make for a slick little package, especially with periodics IEMs. Slap in a small case like this and you have a nice solution for great quality portable audio.

Sound Quality:
This is likely the most important part and it is a part that I may not necessarily be the best person to review. As stated above, I think most of the quality comes from the headphones themselves with other components only contributing a small amount. And I do not think there are ever really large gains to be had by swapping amps and dacs and all that, unless of course the dac is bad, and the headphones are underpowered.

Of course, for small sensitive IEMs, I think its unlikely that they will be underpowered. However, phones are often not created with audio quality as a priority, so I do think there is likely room for improvement there. And that is exactly what this product is targeted at, phone users who want a little more quality without having to carry around large extra gear.

The nickel is however only an amp. So if your phone has a poor dac already, it will not be able to improve on that, but only on the amp section.

For me, I use a oneplus 5t. It is adequate with its audio output. And when I use my IEMs directly from my phone, its fine. Likely not the best audio quality but more often than not good enough.

And so while I am dubious about the effects of a device like this, I definitely could hear a difference between it and when just using my phone. The sound is ever so slightly cleaner and more detailed with better dynamics. Its not a night and day difference, but the difference is there and it is noticeable.

One major flaw:
The flaw here is not with the device itself. It does exactly what it promises and does it well. And it does it in a really slick, really small and really portable package.

But, in 2019, and likely as we move in to 2020 and continue forward, phones are increasingly not coming with a headphone jack anymore. So I am left wondering exactly who this product is targeting. Those with phones who dont have a headphone jack already have to use a dongle of some sort to use wired headphones. This would just then essentially be a second dongle. And I cant see that being very popular. There are also already some great and very portable usb dacs out there that provide enough power for most portable headphones and IEMs. While the nickel would still likely provide an improvement, I imagine it would be very small.

And for those that use a dedicated dap, chances are the dap itself is already geared in some way towards audio quality. And adding a separate amp might be redundant or again would present very small improvements.

Then there is the price. $299 is not a huge amount in the grand scheme of audio gear, but it does feel like kind of a lot. Even the $199 price for the blemished still feels like a lot for such a portable amp, regardless of the technology included. Perhaps if the device had a built in dac and could plug directly into the usb or lightning port of your phone it could certainly be billed as a higher quality dongle than normal.

Conclusion:
So, it took me a while to really come to terms with this and how I would rate it. It definitely achieves its goal and does it in a really small and slick package that is super easy to use.

But for the price and with phones increasingly losing the 3.5 jack, this is just hard for me to recommend unless it meets your sort of exact specific needs.

Disclaimer:
Dan Wiggins from Periodic Audio contacted me about doing a demo of both the carbon and the nickel. I was provided the carbon in exchange for an honest and unbiased review, and I intend to provide just that.

About Me:
I have been in the audio hobby now on and off for a number of years now, and find myself drawn almost exclusively to IEMs. I really like the portability and quality you can get from a good pair of IEMs. I have gravitated mostly towards smaller single dynamic driver IEMs. Part of that is the bass quantity and quality that a good dynamic driver seems to provide over BAs, but also the coherency a good single dynamic driver can provide. I do not consider myself specifically a basshead, but I also really tend to like a good bassy sound as it is just more rich and full, so long as the bass does not overpower or take over the rest of the signature. I do not consider myself at the top of the audiophile world and often find a lot of the terms thrown about hard to follow. I have a general idea what I like, but at the end of the day, what is most important to me is does it sound good, and is it fun to listen to.

The carbon first came to my attention because of another IEM that I own and love, the Campfire Atlas. I originally had the Vega, and then moved on to the Atlas. And as much as I love the Atlas, they are big and heavy and obviously quite expensive so they are not always a pair I want to take everywhere with me. It is my understanding that with dynamic drivers, the driver material is a large component of what makes the sound signature what it is. Having heard great things about periodic audio, when I found they were also making a Diamond (or diamond like carbon) driver IEM similar to the Atlas, I was immediately interested.

About the Carbon:
In case any of you were wondering or have not seen the product page directly, I will include a bit of info about the IEM itself. The carbon is the newest flagship from periodic audio. It follows a similar design pattern to all the IEMs in their lineup. It is a barrel type IEM with a fixed cable. What differentiates it from their other IEMs is the driver material, being diamond (or carbon) in this case.

Specs:

• Price: $399 USD ($299 for a blemished version)
• Frequency Response: 12 Hz to 38 KHz
• Impedance: 32 Ohms Nominal
• Sensitivity: 98 dB at 1mW in ear
• THD: Less than 0.2% THD at 1mW

Packaging:
Packaging for these is pretty sparse. A relatively plain white box with information printed on it.



There is a flap that opens from the front to show some technical graphs about the IEM as well as more information (that can also be found on the product page on periodics website)



Inside the box is again a fairly sparse affair. A small tin that contains all the accessories, and some plastic to hold and "showcase" the IEMs in the box.



Inside the tin are a couple plug adapters, a 3.5 to 1/4" plug and a dual 3.5 airplane adapter. Eartips, 3 pairs of foam, 3 single flange silicon, and 3 double flange silicon. It is a nice selection of tips, and what you would expect, but it certainly doesn't go above and beyond. The tin is fine for storage, but I would not rely on it personally as it does not stay closed very easily. Perhaps that is due to being part of the blemished kit, but my recommendation would likely be to use a different carrying case.



My initial thoughts were that this is a relatively sparse kit. Its not very showy especially compared to some others I have owned. So first impressions were maybe not the best. But as I came to discover later, a flashy box and presentation here is just not a priority on these. And I actually think thats a very good thing. More on that later.

Build and Fit:
The IEM shells are polycarbonate. After coming from some other IEMs this actually felt a bit cheap at first, after all its just a plastic shell. However, the more I have used these I think its rather a positive. It keeps the carbon very lightweight. One of my major gripes with many other IEMs is that they are just not comfortable, especially for longer listening sessions. I find my ears are very sensitive to pressure points and some IEMs I have used can even cause pain after a short time. So having something lightweight is definitely a plus for me. And after a number of full work day long sessions, I can confirm that for me, these are one of the most comfortable pairs of IEMs I have used. And as Dan from Periodic has explained, polycarbonate is a good material to use as well since the sound does not resonate unnecessarily inside the shells, which should help deliver the sound cleanly.

The cable itself is fixed to the IEM. This seems to be a mixed bag, but one that I would likely file as a negative. At this price point, having the flexibility to change cables is almost a given these days. So it is a bit disappointing. There is the worry that if the cable fails, the whole IEM fails. The reasoning given by Dan at periodic is that current solutions are not great. And while I have never personally had an issue with MMCX or 2 pin connectors, I also do not often switch cables anyways. Plus, I believe there is a 5 year warranty on these, so periodic stands by their products.

The cable has a rubber texture and I have found that it is slightly prone to tangling, though I have never had any trouble with the small tangles I have seen. They have been minor. It does not retain shape at all which is nice, though it may not be ideal for wearing over ear. I personally prefer wearing down. However, this is also the source of my biggest issue with the non removable cable. It is quite microphonic. So I would likely not recommend these for working out. However when sitting still with music playing, its not that noticeable. I also use my IEMs for listening to tv shows and movies as well which often have a lot of quiet parts during dialog, and the microphonics can become very noticeable then even with relatively small head movements. Earhooks, or maybe a shirt clip would have been nice additions to help there for those that feel it necessary.

Overall, for the fixed cable, and build quality, the price seemed maybe a bit high. However, after I started listening, I think I have a better idea what periodic is all about. Sound and comfort.

Sound:
As with any other IEM, fit and seal is important, both for sound and comfort. For these, I landed on using ML Spiral Dot tips. I found they give a great fit for me and the wide open nature of these tips really does not choke off the sound at all, and I found it gave the most air and sparkle in the treble (by small amounts).

I have been listening to these for about 3 weeks now on and off. There was no mention of burn in from the manufacturer, and I personally do not truly believe in burn in. What I do believe in is brain burn in, and being able to have some time to adjust to the sound. So I wanted to make sure I gave myself enough listening time, both for those who do care about burn in, but also just to make sure I felt really comfortable with the sound.

Bass:
These are bassy IEMs. Definitely. They might even push to basshead levels. However after some time listening to them, I do not feel like the bass is too much. This is obviously in part personal preference. But the bass feels very controlled and balanced with the overall signature. These extend deep into the sub bass and have a good amount of rumble and enough oomph to really deliver that rich full sound that I personally crave. However for someone averse to bass, these are likely not the best option. The bass is also nice and tight, not at all sloppy or loose.

Mids:
Mids are presented nicely, if maybe slightly recessed in the mix. I did not find them lacking though and vocals, both male and female were present in the mix and never got lost, and depending on the song could even really take center stage so to speak. Instruments were presented clearly and sounded as they should

Trebles:
Simply from reading the graph, it appears as though there is a big spike at around 5Khz. This may potentially be bothersome to some people, but I guess I am not too sensitive to it. Trebles have a nice sense of air, and come through clear enough. I do not hear any sibilance or anything that causes discomfort, and I would likely characterize the trebles as a bit on the smoother side of things instead of sharp or harsh. Which I believe helps in longer listening sessions to keep these from getting too fatiguing.

Soundstage and Other:
Soundstage is a weird one to me in that I was never really the most attuned to it and could never quite hear what some others described. It also seems like certain BA IEMs can have the edge here. I find it adequate, maybe not the most spacious or open. Not too much front to back depth, but a decent enough left-right separation.

Timbre. An elusive quality thats hard to define... From my understanding its just about how "right" or "wrong" it sounds. And these definitely sound right to me. Instruments have a natural feeling. Nothing sounds too over or under emphasized. They are really a nice sounding pair of IEMs.

Amping:
This is another area I personally think maybe too much emphasis is placed on especially with IEMs that are usually quite sensitive already. Most devices out there (phones included) can provide enough power to these. Regardless, I was provided with a nickel amp as well and have spent most of my time listening through it. I did some a/b ing with it and my phone directly and the sound out of the nickel definitely sounded more full with a bit more sparkle and clarity up top. So it would seem these do respond decently well to some additional amping. But the changes were subtle, and I do not think anyone would feel the carbons are lacking when played directly from a phone.



Comparisons:

Campfire Atlas: The carbon and atlas are obviously in much much different price brackets, with the atlas costing over 3 times as much as the carbon. Regardless, they share the same (or at least similar) driver material and considering it was my driving interest in the carbons it would be wrong not to compare them. The atlas has a stainless steel shell and is quite heavy. The carbon is much more comfortable to me. They seem to share a similar overall sound signature. Bass on the Atlas seems to be a bit more enhanced giving the atlas a slightly fuller sound. Treble on the atlas also seems to extend a bit further giving the atlas a bit more of a feeling of clarity. Atlas still feels like the superior IEM in terms of sound, but overall its relatively close. The atlas does have a more premium feel and premium feeling cable, and obviously the option to swap them out, but again it is over 3 times the price when bought new. And I would say the carbon actually does a decent job holding its own here.

Final Audio E5000: The E5000 is in a slightly different price bracket as well, coming in at about $270. The only real similarity here is that I would classify them as another mid range single DD. But the E5000 does not share the same driver material, and has a significantly smaller DD than the carbon. Before the carbon, the E5000 has been my more affordable DD in my kit. Sound wise, the E5000 is more mid focused than either the atlas or carbon. Bass is still present on the E5000 but it does not seem to extend quite as deep, yet still provides a rich full sound. Trebles seem like they extend well, but there is not as much sparkle or clarity as the carbon. Its a smoother sound. The semi-open design also gives them a slight edge in soundstage and air, but that also means sound leakage and worse isolation. Their small driver and small size also make them lightweight and super comfortable just like the carbon. Unlike the carbon, the cable is removable, and as nice as the stock cable is, it is also quite microphonic like the carbon. But the E5000 does include earhooks which help, and earhooks might have been a nice addition to the carbon package. The E5000 is less sensitive than the carbon and requires quite a bit more power to drive, and may almost require a separate amp or dac/dap to really get the most out of them, making them potentially less portable.

Conclusions and Final Thoughts:
I want to talk about the "blemished" version I received. There are a few small gaps between some of the connectors that might not necessarily be there in the finished version. And a couple small nicks (such as on the backplate) that otherwise might not be there either. But overall, they look quite nice and I do not think anything is really taken away from the quality. They certainly sound wonderful. For those who the price might be a bit high for what is included, the blemished version is $299, which I think represents a great value for these if you can live with the minor aesthetic imperfections.

The right and left shells for all intents and purposes are identical. This can make figuring out which is right and left difficult. The only identifying marks are the grills. Black on the left, and a red grill on the right. I have seen others post that they have added something to the cable to identify them, but this is an area that could certainly be improved. Being able to identify right from left easier without having to look inside the tips would be nice, or even a raised bump on one to differentiate by touch would be nice.



They are also very nice and portable. And fit perfectly in this small case I found way back from amazon, along with the nickel and the audio and charging cables. This has become a very nice and very portable kit for high quality playback out of my phone.

As I mentioned above, first impressions (just on looks and feel) were not the greatest. These are lightweight and feel a bit cheap in the hand. But are supremely comfortable. But sound quality is also really great. And thats the rub, these are unassuming, but focus on the most important things. Comfort and Sound. Periodic seems to have their priorities straight. Who cares about the box or the looks when they are in your ear. Sound quality and comfort are much more important.

So, I land at 4.5 stars here. I think they sound great and are super comfortable. And they likely punch above their price point strictly in terms of sound. But for the price there are a few things that would otherwise be expected, mainly the fixed cable. Its flexible and nice, but quite microphonic, and since its fixed, there are no other options there. The issues mentioned are not necessarily trivial, and at this price point a more premium build with detachable cable might be expected. But I think for the sound, comfort, and portability these provide, they are excellent and I would not hesitate to recommend them to anyone who might be interested in this type of sound signature.