Review: FIR Audio Electron 12

Select comparisons

Sennheiser IE900 ($1,299). I thought it made sense to first compare e12 with another single dynamic driver IEM in a more-or-less similar pricing ballpark (not exactly, but the closest I could get from what I have at hand). Sennheiser’s IE900 happens to be my all-time favourite single DD IEM, and also my favourite Sennheiser product (I say that as a long-time HD800 owner and admirer). 

Its bass presentation is nothing short of spectacular, with a deep, guttural sub-bass emphasis and plenty of punch and impact further up too. It also has clarity in spades, but with a smoother, more relaxed presentation overall that doesn’t shout or pierce even at higher volumes thanks to a tasteful and very effective 6KHz dip.

In many ways, e12 is the polar opposite. It shares some bass characteristics, like texture and nuance, but lacks the elevation and sheer impact of IE900’s bass. Considering e12’s driver is almost twice the size (12mm vs IE900’s 7mm), that’s purely a case of FIR wanting to tune the driver a particular way, rather than a limitation of the driver itself. 

Midrange is where e12 has an upper hand, at least if you favour clarity and resolution. While IE900 has excellent mids for my taste, there’s no question e12 is the better technical performer here, extracting more detail and revealing more layering in the same tracks back-to-back. That said, I much prefer IE900 for female vocals, with its relaxed upper midrange and lower treble dip giving me a more gentle, sweet presentation compared to e12’s forward and sometimes shouty alternative. IE900 sounds more analogue and organic, while e12 leans more cool and digital. 

Treble is also more relaxed on IE900, though you’d swear that wasn’t the case from some reviews that call it bright and overbearing. I don’t hear it that way at all, and in fact if there’s any overabundance of treble energy to be had, it’s with e12. Both offer treble detail in spades, so it really comes down to how you prefer your music replayed, and whether or not the peaks in each monitor trigger tour sensitivities. 

Technically I do find e12 pulls ahead, which probably justifies its loftier price for those who find the tonality agreeable. It’s for sure more resolving than IE900, and the stage, while not being bigger, is better structured and layered, with pinpoint imaging. e12 is perhaps a bit less cohesive, with bass and mids/treble almost seeming to come from different driver types, while IE900 is the epitome of cohesive single dynamic sound. 

Lastly, from a build and ergonomic perspective, you have here two supremely well-made IEMs. IE900 easily wins on comfort, but that’s for my small ears and narrow ear canals; others may prefer the surer, larger fit of e12’s more ‘normally-sized’ shells and nozzles. IE900 is also much smaller and lighter, and one of the few IEMs I can fully insert into my ears without any discomfort and lie flat on my side without issue. Don’t try that with e12.   

Campfire Audio Cascara ($499). At the other end of the budget scale, I’ve only recently received Cascara from the great guys at Campfire Audio, and will have a review coming soon (watch this space). As part of the new Chromatic Series, Cascara shares the same large but surprisingly comfortable shell as its universal siblings like Supermoon and Bonneville. It towers over e12 in dimensions, but is oddly more comfortable in ear, at least for me. 

Tonally, I hear Cascara with more, bigger and also looser bass that e12. It’s CFA’s signature bombastic but well-controlled bass (they’ve debuted a new dual magnet dynamic driver for Cascara and Bonneville that’s really paying off), whereas e12 leans more towards tight, textured, nuanced, but not nearly as elevated bass as Cascara. e12 is more articulate, Cascara is more fun, with a harder punch and more rumble. Cascara is closer to basshead, whereas e12 won’t satisfy most bassheads. 

In the mids, e12 is cleaner, with a darker background, While Cascara isn’t noisy, per se, it’s also not as clean and clear, and there’s less space between instruments, vocals and other elements. Imaging and separation on e12 is therefore a step or two ahead of Cascara. ⁠e12 stage is also comfortably wider and deeper, where Cascara has nice height but is otherwise comparatively flat and smaller in all dimensions. 

Cascara has some rawness in the treble that leaves it less resolving and more smeared in the finer details, which isn’t helped (or rather covered up) by its bigger, more elevated bass. E12 is more energetic here, and while I do find treble occasionally peaky on both, e12 is definitely the more refined.  

Overall, I’d rate Cascara as an outstanding entry in the sub-$500 segment, with a sound that should resonate with those wanting a fuller, warmer, bass-first presentation without worrying too much about technical performance. e12 is in a different league technically, but its more balanced, digital-leaning sound might not win favour with those who naturally gravitate to Cascara. Price aside, Cascara is raw and emotive, e12 is technically energetic hi-fi; take your pick.  

FIR Audio Radon 6 ($3,299). The only reason I’m including Rn6 here is because e12 shares a lot of its DNA, and I sometimes get ‘Rn6 vibes’ when listening to certain types of music with the smaller sibling (my Rn6 is custom, and as you can see from the photo below, e12 is by far the ‘smaller’ sibling). 

Tonally Rn6’s sound is fuller, larger, and more analogue, even though it still has plenty of detail, nuance and clarity. Bass delivery is actually closer than you might think, with e12’s Tactile Bass coming very close to replicating the depth and detail of Radon’s Kinetic Bass, especially when using the ‘least-bassy’ and more detailed red module. You can tell there’s a Belonozhko behind the bass tuning in both, with Rn6 being a natural evolution of e12’s bass tech.  

Midrange delivery on both is tuned for clarity, though Rn6 has fuller lower mids and a more earthy sound to the midrange overall, with less elevation than e12 in the upper midrange too. e12 by comparison is crisper and more revealing, with a possible edge in imaging and layering as a result of the tonal balance rather than driver performance. e12 is also more elevated and sometimes peaky up top, but with less upper treble air and resolution than Rn6. 

Technically the two monitors are very close, which is a testament to the quality of e12’s driver and tuning, considering Rn6 has six drivers, including an e-stat, to work with. Stage is larger and wider on Rn6, but maybe a fraction deeper on e12. Both resolve very similarly, though Rn6 sounds more dynamic and definitely more refined across the board. 

Unless you find e12’s particular sound profile exactly to your liking, I’d say Rn6 is an almost direct upgrade. That said, since Rn6 will soon be discontinued, if it hasn’t been already, and only 100 Radon customs were said to be made, Rn6 might be quite difficult to find, so the upgrade path may not be so easy to follow. 

Select pairings

I mentioned earlier that I found e12 to be quite sensitive to source pairing, and I’ll qualify that here by adding that it’s mainly to do with treble emphasis. Because I’m particularly sensitive to certain treble peaks, and generally find upper midrange forwardness offensive, I tend to gravitate to sources the de-emphasise these areas, especially in certain IEMs.

e12 is one such IEM, if that wasn’t obvious by now. My listening journey started with HiBy’s new R8 II (reviewed here), and while I consider that to be a fairly neutral source with a hint of warmth, it does tend to spotlight some of the midrange forwardness and mid-treble peaks e12 brings to the mix. 

Switching to HiBy’s co-flagship, RS8 (reviewed here), immediately takes down the upper midrange heat, and also balances out some of the treble peaks by virtue of RS8’s bigger midbass bump (over R8 II). With its inherently analogue-sounding R2R DAC, I also find RS8 adds some meat to the midrange bones, giving e12 a slightly fuller presentation and tilting its sometimes-digital sound more towards analogue tonality (though it still sounds less analogue with RS8 than other monitors by comparison).

By negating some of the more obvious tonal issues, RS8 shifts the focus to e12’s technical performance. RS8 is one of the better technical performers in the high-end DAP space today, and makes the most of e12’s technical proficiency. e12’s resolution, imaging and layering ability is at peak when combined with a DAP like RS8, and while technicals get a slightly bigger bump with R8 II, tonally I find RS8 the better match.

Ironically, my favourite DAP pairing with e12 is an old-timer, ths Sony WM1Z. The ‘gold brick’ is known for its warm, full, analogue sound that’s resplendent with detail, a massive stage, and plenty of refinement, and it brings all these elements together in what I consider the best-sounding version of e12 I’ve heard to date. 

Gone are (most of) the mid-treble peaks, replaced by silky smoothness and a delightful lower treble sparkle. Midrange is kept even-keeled, with less of an upper midrange bump and a touch of lower midrange fullness. And midbass is given a small lift, complementing e12’s excellent quality down low. 

I wouldn’t necessarily seek out a mint WM1Z just to pair with e12, but if you’re already a lucky owner of one of these fine pieces of discontinued audio art, you might find that e12 makes an excellent addition to your collection.  

Continue to closing thoughts…    



Picture of Guy Lerner

Guy Lerner

An avid photographer and writer 'in real life', Guy's passion for music and technology created the perfect storm for his love of portable audio. When he's not playing with the latest and greatest head-fi gear, he prefers to spend time away from the hobby with his two (almost) grown kids and wife in the breathtaking city of Cape Town, and traveling around his native South Africa.


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