Campfire Audio's Polaris

Before I even received these headphones, I reached out to Caleb Rosenau, Campfire Audio’s Vice President, looking to get a little wider perspective into the acoustic and aesthetic design of these headphones. With everything that CA says in terms of marketing (e.g. their T.A.E.C. and Polarity Tuned Chamber), I wanted to have more detail into what those terms actually meant, in terms of both acoustics and physical design. Thankfully, Caleb was very open to this and with me, and I came out having learned a lot about Campfire Audio has done that makes their headphones so, evidently, unique.

I came in with a number of prepared questions, but many of Caleb’s responses covered more than what I asked, so I’ll try to structure this as conducive-to-understanding-ly as I can. The structure will be my questions, followed by Caleb’s responses, almost entirely verbatim.

Can you expand on what the Polarity Tuned Chamber does and how it’s constructed?

“Basically what what we’re doing there is building on some of the ideas we had with the Tuned Acoustic Expansion Chamber. We were using a 3D printed box to tune the high drivers, so by removing the acoustic dampers and paths, and getting the correct volume and space, we were able to achieve better high frequency extension while simultaneously adding a lot more clarity to the high frequencies.

So, building on that concept, we’re doing a lot of 3D printing these days. We wanted to take that similar approach with the dynamic driver, to be able to control the dynamic driver in the same way that we control our balanced armatures. So, this is much the same thing - making this a speaker cabinet-styled design. We’ve got, in the back of the dynamic driver, a volume of air, which has an acoustic damper on the exit. The front is a specific size and shape, which then leads to the nozzle. That combination, the relationship of the front and back space, basically allowed us to get the tuning that we were looking for.”

I’m assuming that, aside from the peakiness, much of that was resonance control and improving your cumulative spectral decays?

“Yeah, right. That’s exactly right. We’re trying to optimize the performance, generally speaking.”

My next question was about your Tuned Acoustic Expansion Chamber - so it is very much the same, in that you remove the complicated system of tubes and dampers and the adjustments of both, in favor of something that is physically… what?

“Yeah, it’s, physically, just a little box. It’s a box that’s adhered to the end of the balanced armature. In the case of the Polaris, it’s printed into the spout of the earphone, so it’s controlling the negative space inside the spout.

In the Andromeda, it’s a 3D printed box that is separate - it's a subassembly. 

It’s really nothing more than that, but the important part here are the factors we’re adjusting for - the volume of air that’s in it and the size of the exit hole. Those are the variables that we’re looking for.

So we’re doing that as opposed to tube length and damper selection, and that kind of stuff.”

When you say “3D printed box”, a lot of the materials that can be printed this exactly with these low tolerances, wouldn’t necessarily be materials that I would assume to be acoustically favorable. Can you speak to the process of choosing a material for this that would simultaneously make the process feasible and allow the acoustic properties that you need for the process to be tenable?

"Yeah, it is still a plastic, but we tried a number of them to get the result that we were looking for. So, yes, you’re right in that in an ideal world the chamber might be made of something more sonically ideal, but we are very happy with the result, and we tried a number of different materials before arriving at something that is as close to ideal as we could get, while still being an improvement over more traditional systems for driver control.”

When you say “emotionally engaging and highly resolving” in reference to the sound signature of the Polaris, can you clarify exactly what that means, from the perspective of Campfire Audio?

“The “emotionally engaging” part is what I typically associate with dynamic drivers, we’re using them for mid- and low-frequencies in the Polaris. Our dynamic driver line - the Vega, the Dorado, the Lyra II - are all using this similar 8.5mm dynamic driver design, although it is implemented in very different ways across each model. I think of BAs as describing low-frequency very well, whereas dynamic drivers help you feel the low-end. That’s, kind of, the emotional part, as opposed to a more analytical sound.

The “resolving” part is using the single high driver to complement the part of the frequency that the dynamic driver covers. I think you’ll find that it’s fairly seamless, as far as hybrid are concerned - the transition from the dynamic to the BA is pretty smooth.

So that’s the resolving part, the T.A.E.C. allows the sparkly highs that people typically associate with high resolution. Your run-of-the-mill earphone that you’re listening to is going to have really rolled-off highs, so when you have that extra sparkle on top, it makes the whole thing pop a bit more, especially when it’s not strident and not, sort of, an ice pick in the ear. If you can hit that right sound, it just sounds really natural.”

Is there anything that you wanted to add, in terms of acoustic or apparent design, that was specifically employed in the development of this product that you feel significantly improved the end result?

“The Polaris is really the culmination of many different things that we’ve been working on and a lot of different ideas that we’ve been experimenting with. We’re constantly developing and improving what we do. What I like about the Polaris is that it’s a fairly balanced sounding earphone - it has a nice low-frequency warmth, it’s a very listenable earphone. It’s also an earphone that plays well with mobile devices, so when people are listening right out of their phones, it’s a little more compatible than some of our other earphones.

For example, the Andromeda, which is our best selling earphone, can show you a lot of what’s going on, and if your source is crummy and your file is crummy, you’ll hear something crummy. The Polaris is a bit more forgiving, without losing the resolution.

I also think that the cool part about it, using the BA and the dynamic, it’s, kind of, the unicorn product. They've both got awesome acoustic properties that are inherent to them, with BAs being highly resolving and dynamic drivers being very powerful and engaging. It’s trying to find a balance, and I feel that, with the Polaris, we've done a really good job - finding a coherent sound signature between the two.

It’s also an interesting price point for us, we’re trying to give really excellent price-to-performance in this product, specifically. So that, when people buy Polaris, they feel good about the value of the earphone that they’re getting.

We’re trying a bunch of new things, and I think that the Polaris is the result of that.”

I want to thank Caleb for taking the time out of his day to answer this many questions at this depth of information; the conversation was very helpful to me in understanding exactly why these headphones are special, from a design perspective.

So, with that out of the way, let's get to what the headphones are actually like, in hand and in ear.

Fit and Form

These headphones have a somewhat polarizing design (pun intended). I'm personally a fan of the two-tone design, although I'll admit that I wasn't until I had them in hand. They're a lot smaller in person than they are on a computer screen and that, combined with the less ostentatious difference betweens colors in person, makes for a pretty good looking pair of headphones. The design isn't for everyone though, but that's just personal preference.

The cable connects to each earphone with a very solid MMCX connector, better than I've seen in the past. Campfire Audio uses beryllium/copper connections here, which isn't necessarily industry standard. They click in well, and don't have the annoying caveat of possibly bending a pin that some of the MMCX connectors I've used in the past have had.

From the earphone connectors, the cable has memory wire wrapped in heat shrink tubing to conserve the user's ear shape and keep the cable tamed around the back of the helix. I had a problem with this, as storage in the included case necessarily bent the cable out of shape, in my use, and the wire itself wasn't responsive enough to properly hold shape well enough that it wasn't somewhat of a hassle to use. I'd love to see more companies move to what Noble has been doing with their cables - wrapping them in a heat shrink tubing that is shaped like the back of the average helix. This requires no adjustment, and has never been uncomfortable or inconvenient for me, which can't be said about this cable, regrettably. Your mileage may vary, though, so I can't claim this as the lynchpin in these headphones because, as I'll get to later, they sound pretty phenomenal.

The cable itself is very supple; it bends easily, doesn't retain kinks or twists, and is, overall, great. It terminates to a TRS 1/8" auxiliary connector with a very sturdy right-angle plug, branded with the Campfire Audio logo on the face.

Included as accessories are a Campfire Audio lapel pin, three sizes of single-flange silicon ear tips, three sizes of foam ear tips, four sizes of SpinFit ear tips, an industry standard IEM cleaning tool, and the carrying case. I gravitated towards the smallest size of SpinFit, as I found that they gave me my most preferred sound and best fit, seal, and isolation. The carrying case is made of textured black leather, with an inside that, kind of, cradles the IEMs. I had no doubt, putting the headphones in this case, that they were safe in travel, and the case is conveniently sized for portable use.

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Sound

The sound of these headphones, I think, would be best characterized as musical. I know I use the term all the time, and it can mean many things, so don't worry, I'll expand. There's a very tangible and noticeable emphasis on bass, but the mids do not lose their clarity or control, and the treble does not lose its sparkle. These play well with almost any genre, although I did encounter some trouble in acoustic and jazz, so for heavy listeners of those genres and none other, these may not be the best purchase.

The soundstage presented by these headphones is about average for closed back IEMs. The imaging, however, is very good, with a great sense for locational accuracy and directionality. The isolation is about average, as the ports for the dynamic driver can let a little bit of sound in, but there is little leakage out. One thing I did encounter when using these on commutes was that wind noise can play through the headphones a bit, but only in very windy environment, and it never really detracted from my experience of the headphones.

Bass

Songs used: Three Ralphs by DJ Shadow, I Never Woke Up in Handcuffs Before by Hans Zimmer, and Quick Musical Doodles & Sex by Two Feet

I'll start at the lowest end: sub-bass extension is phenomenal, with a very competent sense of rumble and shake, without losing control. These headphones do, as Caleb said in the interview, really make you feel the bass - it isn't just described. Thankfully though, this intensity does not come with sloth, the earphones competently kept up with whatever I could throw at them without becoming sloppy or flabby. The texture and detail in this range isn't exemplary though, as I've seen it outclassed by a few other IEMs I have in my possession, namely Periodic Audio's Beryllium and Noble Audio's Kaiser Encore (which sit far below and farther above the price range of the Polaris, respectively). Although I personally prefer a bit more detail in my low-end, this is undeniably a very fun and engaging range - it easily kept my attention.

Key descriptors: prominent, fast, and rounded

Mids

Songs used: Scarlet Town by Chris Thile & Brad Mehldau, Cajon by Daniel Waples & Friends, and While My Guitar Gently Weeps by Jake Shimabukuro

I would expect, given the targeted sound signature, for this range to be the low point of the headphone. Arguably, it is, but the low certainly isn't much lower than the high, if that makes remotely any sense. The mids retain very good naturalness and detail, even when faced with the bass I just described. The bass adds a lot of weight to this range, but vocals and instrumental lines can still hold their own pretty well. I rarely felt the need to turn up the music above what I normally would in order to properly hear the mids, which was a surprise to me. This range holds a lot of detail and clarity, especially when contrasted with the bass. Vocals, both male and female, come across with a great sense of dynamism and detail. Instrumentals fair just as well, with good recordings being almost entirely decoded by these headphones, although I won't say that there aren't headphones that can pull more out of the file.

Key descriptors: detailed, natural, and clear

Treble

Songs used: Ageispolis by Aphex Twin, K.K.P.D. by Christian Scott, and Morphogene by Machinedrum

Campfire Audio aptly described the treble as soaring - their use of the T.A.E.C. really does allow for some tremendously clean, clear, and extensive treble. This added a great sense of space to recordings that very much needed it, and was never offensive. These join the ranks of Noble Audio's Kaiser Encore and Periodic Audio's Beryllium in my list of "IEMs that don't have treble problems," and that is a shockingly rare breed. I never experienced sibilance in my use of these, nor did I ever find them grating, strident, or stress-inducing. Cymbals gain their definition in these headphones from the performance of this range, and that added a very exciting element to genres that extensively employ drums, particularly acoustic metal.

Key descriptors: extensive, detailed, and poignant

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Wrap-Up

Aside from the cable issues that I encountered, I'm a big fan of these headphones. Although they aren't exactly "all-arounders", they do an incredible job with genres that suit this tuning - particularly electronic, dance, hip-hop, and punk/metal. This isn't to say that they are unlistenable with anything, though, as they still make for a very pleasant presentation of almost any genre that I could think to throw at them. Campfire Audio, and the technical innovations and inventions that they've employed in this headphone, have created something very unique in its price point, marketshare, and presentation.

Disclaimers

These headphones were provided to me by Campfire Audio. I am not being paid by anyone to write this review, to endorse the product reviewed, or for the content that I put in the review.

These headphones were powered by an Astell&Kern AK Junior, a Google Pixel, a Neurochrome HP-1, and by whatever soundcard is in the motherboard of my computer.

I have had these headphones for about two weeks, and I have put about 40 hours of analytical listening through them during that period.

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