Campfire Audio
Astrolith IEMs
£2,199 RRP
Planar magnetic IEMs have been around for a long time, popularised by Chi-Fi brands such as Letshuoer, 7Hz, and more. Normally, though, the 2-way types are paired with dynamic drivers. Campfire Audio’s new Astrolith is a pure planar magnetic dual-driver design, however, which really piqued my interest. StereoNET had the opportunity to try this for about three weeks before it was officially announced, so let’s talk about this unique product.
It is classic Campfire Audio but with a new, so-called Additive Acoustic Optical Inclusion housing introduced on this model. The shell has built-in acoustic-shaping geometries to enhance the dual planar magnetic drivers’ output. These acoustic chambers are patented by the manufacturer and can be found in many of its IEMs. The company says the ones in the Astrolith are engineered to “create precisely controlled acoustic volumes” for better sound.
The translucent shell appears jet black from a distance but becomes slightly translucent when picked up and viewed. It’s not a completely transparent IEM that allows for viewing the drivers and crossovers, but it’s a nice touch all the same. The shell is coated with a bio-compatible clear lacquer, with the internal surfaces of the polymer shell dyed black for a semi-transparent effect. The faceplate is machined from a stainless steel billet, and the metal is hand-polished to a high mirror finish. The MMCX rings and nozzles are also made of the same stainless steel material.
UP CLOSE
The Astrolith comes with a nice array of accessories, including different sizes of foam and silicone ear tips, a cleaning tool, Campfire Audio’s iconic enamel pin, a polishing cloth for the stainless steel faceplate, and a choice of mesh and leather carrying pouches. I personally preferred using the foam tips for comfort, although it does impact the sound a little, which we’ll touch on later.
Two sets of Time Stream Metal silver-plated copper cables are supplied, one terminating in a 3.5mm single-ended plug and the other a 4.4mm balanced plug, which I used for the entirety of the testing period. I am fond of this cable’s flat design, which results in fewer tangles and knots even if you casually roll it up and put it into a bag. There’s no cable memory or microphonics, nor is there any stiff memory wire, so it’s extremely comfortable for bespectacled users like myself.
The Astrolith’s most unique feature is its new dual planar magnetic drivers. One 14.2mm unit is used for bass and midrange frequencies, plus a tiny 6mm unit is used for high frequencies. The design is crossover-less, and Campfire Audio claims that the new planar magnetic drivers are superior in all measurable metrics compared to other existing technologies.
The benefit of planar magnetic drivers is, of course, their very light weight, which in turn means they have excellent transient response because they can move very quickly. The 6mm tweeter is said to have been particularly challenging for Campfire Audio’s engineering team, with new mating acoustic parts needed to be developed, along with new acoustic geometry designed for high frequencies.
Even though the impedance is low, planar magnetic equipment usually requires a decent amount of power for optimal performance. With a rated sensitivity of 94dB at 1kHz, I paired the Astrolith with the Astell&Kern SP3000 flagship DAP for testing, with the audio player providing more than enough power to bring out the best in this pair of IEMs. Campfire Audio quotes a very low 7.1 ohm impedance at 1kHz, with less than 0.3% Total Harmonic Distortion, by the way.
The Astrolith is a comfortable IEM to wear, although the shape of the shell provides a less-than-ideal seal than some of the more sculpted resin-shelled rivals do. Thanks to that, however, there’s no feeling of congestion in the ear, even after long periods of wear.
THE LISTENING
This pair of in-ear monitors sounds incredible – everything I expected, and more. The first thing you notice when listening to a complicated piece of music is how effortlessly the Astrolith brings out every detail when needed. Whether it’s the slight tinkle of a bell or a tiny hum in the background, it is present without needing to strain to hear it. Thanks to the nature of the planar magnetic drivers inside, this design is very quick and punchy while retaining accuracy.
Campfire Audio doesn’t have one specific voicing and instead opts to tune its IEMs differently for varying tastes, but the Astrolith feels like it has been built for a pure reference sound. There’s next-to-no added warmth, letting the listener enjoy the song as close as possible to how the artist intended.
Bass response is excellent, with fast transients and great decay, and thanks to that speed, I found myself really enjoying electronic dance and house music. You don’t get that same rumble or slam that you would out of a dynamic driver, but this is sublime for people who value accuracy and tightness in the bass over sheer power. For example, the bass guitar in the first chorus of Attention by Charlie Puth had more of an impact thanks to the Astrolith’s transient speed and clarity.
The midrange is prominent and clear, with guitars, snares and the like having a sharp attack that resolves phenomenally with plenty of detail. Listening to Joni Mitchell‘s Carey, the guitar plucks and strums were accurately placed, with lead and backing vocals crisp and slightly more forward. B.Y.O.B by System of a Down cleverly showcased how well this pair of IEMs deals with something a little more complicated. The incredibly fast guitar riffs, energetic drum beats and erratic rhythmic changes were all deftly handled.
Treble performance is also excellent, although it was dampened slightly by my choice of foam tips. There’s a good amount of sparkle and energy, with enough air between instruments and a hint of shimmer. The 6mm driver here certainly provides a nice boost to the treble that was lacking a little in Campfire Audio’s previous planar magnetic offerings. Korean singer IU‘s Good Day was rendered beautifully with the Astrolith, making her three high notes in the fifth octave sound even more impressive. Soundstaging is great too, with instruments located in the right place with plenty of spaciousness around them.
THE VERDICT
While we’re used to Campfire Audio’s high prices, the Astrolith’s cost somehow feels quite palatable considering its performance. It is, without doubt, one of the most expensive planar magnetic IEMs around, but you’re not only paying for the technology here but also for the build quality and sound. Campfire Audio’s founder, Ken Ball, told StereoNET that it took the company eight months to develop the Astrolith, and all I can say is that it was time well spent.