Fit and Comfort

Seen above is the right channel of the Effect Audio Axiom IEMs installed into an artificial ear mold, and I am using the size M silicone ear tips included with the IEMs. This is my typical combination for personal use and illustrates the nature of the fit one can achieve with these IEMs. Indeed, I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. The semi-custom design of the shells shaped for ergonomics with the ear concha in mind works out well if you have medium or large ears, and the nozzle shape, insertion depth, and angle help with smaller ears, too. In fact, this is one of the best-fitting IEMs I have tried to date. The soft curves of the shells are continuous contact surfaces for the ear, which adds support and keeps the IEMs in place. The vents on the shells also make for decent passive isolation without affecting the seal too much, and they weigh next to nothing at under ~5 g each, making for no sense of physical fatigue. There is no stock cable, but the Vogue Maestro does the job by not only adding another support point with the ears, but having decently shaped ear hooks, too. That said, notice that the connectors for the recessed 2-pin (CIEM) connectors stick out past the shells and look somewhat ugly while extending the connector further to make the ear hook come off at a steep angle. Angular connector housings would have been nice thus, so keep that in mind if you wish to pair the Axiom with this cable.

Audio Performance

Audio Hardware

There's a lot going on inside the Effect Audio Axiom, with the modular units (MUs) having already been discussed in detail. These add an electronic crossover layer that makes the tuning somewhat customizable too, but the Axiom for now only ships with the base set in both the MMCX and 0.78 mm 2-pin (CIEM) cable connector options. The acoustic chamber is composed of CNC-machined aluminium alloy hosting a 12 mm magnesium alloy diaphragm dynamic driver with a liquid crystalline polymer (LCP) surround, which caters to the low and mid frequencies and aims to be stiff, quick, and with low inertia relative to the usual mylar or coated mylar drivers. There is no mention of the magnets used, but as per usual for this price range, these presumably are Neodymium N52 magnets. The machined titanium nozzle also hosts a twin balanced armature driver setup of a Knowles FK-series dual BA driver handling the high frequencies, likely the TWFK-30017. The crossover between drivers is at 4800 Hz and involves what Effect Audio calls a proprietary RC architecture, which the MUs contribute to.

In fact, I appreciate Effect Audio being transparent about this while clearly stating the linear frequency response of the Axiom is from 20 Hz to 16.8 kHz rather than the usual 20 Hz to 20 kHz everyone talks about. Given the average person listening to these will not hear much past 16 kHz, if anything at all, I am fine with the frequency response range. Driving the hardware is quite easy compared to the average set of IEMs, with a rated 32 Ω impedance at 1 kHz and sensitivity of 112 dB/mW, once again at 1 kHz, presumably measured at the drum reference point. In practice, it gets plenty loud out of a bog-standard 3.5 mm audio jack on a laptop or motherboard without a fancy isolated onboard audio segment. However, realistically, customers purchasing the Axiom will also have a preferred standalone or portable source in mind. A portable hybrid wireless DAC/amp will suit your needs perfectly for when you find yourself without an available 3.5 mm audio jack on the go. The better source, and even a dedicated DAP, may be considerations useful in avoiding potential hissing and clipping with some sensitive IEMs, including the Axiom. If not using them on the go, consider getting a longer cable for laptop or desktop sources to remove the limitation of standard 1.2 m long IEM cables.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature emphasizing a slightly elevated bass and smooth treble range with detailed mids and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the sound card. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. Given the shorter loan period of these IEMs, I opted to skip the testing with the anthropomorphic pinna in place as usual. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the Effect Audio Axiom, or at least the useful part. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are basically identical throughout the entire frequency range. I knew going in that Effect Audio was boasting hand-matched and assembled components, and we see an example of this with the excellent channel matching even past the coupler resonance frequency of ~8 kHz, where it's best taken with a grain of salt. Measurements taken after 30 hours of testing, including with these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable either.


This is the average frequency response for both channels of the Effect Audio Axiom with the stock MUs plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. With the Axiom, Effect Audio is targeting a reference sound that is "non-fatiguing, immersive and balanced." So this is what I am going to judge the Axiom's actual performance by, but note that the Axiom can be customized with different MUs through a crossover. As mentioned before, a newer silver-colored MU aiming to change the tuning further is being tested, but I was not able to test it with the Axiom, which is unfortunate in a few different ways since the few comments I have seen about the new MU were all positive, certainly compared to the stock MUs.

The tuning with the current configuration has issues even outside of any tonality preferences, especially as the company is marketing the Axiom as a reference set that does not color the sound signature too much. Instead, this is clearly an extremely warm set that is V-shaped with an elevated bass and treble, but one that isn't well-executed, either. The bass is elevated ~8–9 dB from the lowest point in the mids at ~900 Hz, with the peak a broad distribution centered at 60 Hz. Sub-bass extension is plenty decent, but distinguishing the hard-hitting EDM beats amid the bloat in the mid-bass is difficult, for example. The Axiom plays very well with some music genres, such as new age rock and pop music, but compromises on detail and technicalities when purely instrumental music is playing—think kick drums where the leading edge doesn't have the impact I expect, and even bass guitars with strumming notes decay erratically. Certainly not a reference set given the ambiguity in how the Axiom will represent and prioritize some music notes over others.

If you primarily listen to music with a mix of vocals and instruments, I can see the Axiom appealing to you. Just be aware that the bass bleed-over is real, and male vocals are very forward-facing. I often found myself lowering the volume when listening to podcasts and movies, but soon realized I simply had to EQ the bass to mids transition down a few dB instead of constantly fiddling with making the Axiom a more pleasant listening experience. The current configuration hurts imaging with a general haze over not only different instrument classes, but also mediocre instrument separation that further affects the likes of R&B and jazz. Soundstage is also nothing to boast about, which has more to do with the physical constraints of the acoustic chamber, and there are greater issues, so how width, depth, and height of the sound field from this small closed-back set reaches your ears wasn't my main worry at all. Notice how Effect Audio aims to address pinna gain, but fails to do so meaningfully, which especially hurts with higher-pitched female vocals, as those feel quite low in volume compared to the booming male ones.

The treble transition happens at the crossover point, with the dynamic driver handing things off to the twinned BA at ~4.8 kHz. This is a smoother transition than the graph makes it seem, with the relative elevation at 5 kHz and onward not coming off overly bright or sibilant, although there's still a shimmer to some string instrument notes that feels off. Timbre is also going to be hit or miss, especially if you are solely accustomed to dynamic driver treble, with the BA timbre making instrument notes seem somewhat metallic. There is a sense of space and air past the higher treble, but the fundamental frequencies are compromised to where the harmonics are more of a bandage over a basic flaw. As expected, the frequency response falls off a cliff past the advertised 16.8 kHz, which I don't mind in itself. Needless to say, this is not a set I would recommend for instrumental music.

Comparisons

Price point and tonality of the Effect Audio Axiom in this state considered, I compared it against three other sets in the $1,000–$2,000 price bracket. The Lime Ears Pneuma is a hybrid set from Poland that costs ~$2,000 and is the most expensive of the lot. It is a set with similar issues that aims to address the bass to mids transition with a physical switch. Otherwise, we again have a warmer tuning with lackluster pinna gain and a dark treble response. The Pneuma handles bass better than the Axiom when it comes to macrodynamics and contrast, and the switch caters to more presence for female vocals and instruments, but I'd pick the Axiom over it for treble presence, and the fit, comfort, and modular nature help, too. The Chinese-made ThieAudio V16 Divinity costs $1,500 and is an all-BA set, but the best-tuned of the four in my opinion. It's also the one I'd go with from among these even though it is on the larger side. The accessories are better, and it is a funner set that is still detailed, and certainly more of a reference set than the Axiom. Making this truly an international comparison is US-based 64 Audio with the $1,200 Duo (review coming soon), which is also a hybrid set with 1 DD and 1 BA and a warmer tuning. But we again see the Duo handle this type of tuning better, so pick the Duo over the Axiom if the semi-open nature is not a deal breaker. In fact, the Axiom is the warmest set because of the aforementioned bloat and has the least pinna gain too, which exacerbates the issue further.