I’ve been listening to 1964EARS’ custom IEMs since December of 2010 when I received my 1964-T, a triple-driver monitor from the company’s first-generation lineup. Since then, I’ve had a chance to also try the mid-range 1964-V3 model and the higher-end V6-Stage. In both cases I was impressed by the performance and especially value for money when comparing them to similarly-priced sets from other brands, foreign and domestic.
Now, 1964 is finishing up work on a new flagship – the A12. The A12 is notable not only for being the most advanced (and pricy) product in 1964EARS’ history, but also for utilizing a technology developed by Asius Technologies known as ADEL (which stands for Ambrose Diaphonic Ear Lens, after its inventor and Asius CEO, Stephen Ambrose). The main idea behind ADEL is that the operating principle of in-ear monitors – having the earpieces sealed inside the ear canal, creating a closed system with driver and ear drum – is unnatural as far as sound reproduction goes when compared to live sound, speakers, and even unsealed headphones, and can even be potentially damaging to the ear in the long run.
I first read about ADEL and the potential issue of over-pressurization of the ear drum when using in-ear monitors back in 2011, when the original ADEL concept was unveiled. I don’t remember which article it was that I read – probably this one from Sound & Vision – but the “inflatable balloon” concept left an impression. I thought the idea interesting but likely impractical as far as the inflatable balloon goes, and put it out of mind until 1964EARS launched a Kickstarter campaign for a new earphone lineup developed in collaboration with Stephen and Asius Technologies earlier this year. This meant that the latest crop of 1964EARS monitors would be using a variant of the ADEL technology.
In its current iteration the desired effect of reducing or eliminating the unnatural pressures inside the ear is achieved with a membrane placed inside the earphones (in its own separate sound tube) that acts as a “second eardrum” and is meant to absorb pressures that would otherwise be pushed against both the user’s eardrum and the driver of the earphone – neither of which is a good thing for audio fidelity, according to the creators. The membrane is adjustable and can be made tighter and looser, as needed, and can also be bypassed (or rather disabled) completely by sealing the chamber behind it, which prevents membrane excursion. All this is done with a rotating knob located somewhere on the earpiece.
Those interested in the current implementation of the ADEL technology can read more about it on the above Kickstarter page – as usual, I am interested primarily in the sound of the earphones. The A12 beta unit I received was a last-minute arrangement – I had glanced over the aforementioned Kickstarter when it first launched and even shared it on The Headphone List’s Facebook page, but certainly didn’t expect to be able to try it until Vitaliy from 1964EARS got in touch and asked if I wanted to give the A12 a listen. Fast forward a week and a half and I had a set of beta A12s in hand and ear.
First the basics – aside from a watch-style rotary knob at the bottom end of the faceplate, the A12 looks and fits like any other of the half-dozen or so clear acrylic custom IEMs in my collection. It utilizes a standard 2-pin detachable cable.
The A12 uses 12 balanced armature drivers per earpiece in a three-way, 4 low/4 mid/4 high configuration, with each set having its own sound tube. There is one additional sound tube for the ADEL module, so the configuration can be considered quad-bore. The internals look quite complex, but still not as messy as the 5-way Spiral Ear SE-5. The image below (from the Kickstarter page) shows it better than my own could:
The ADEL module of the A12 is removable – it can be extracted quite easily by pulling on the knob. It is small – less than 5mm in diameter and about 8mm long with the knob. Removing it leaves a gaping hole in the housings and doesn’t do the sound any favors, completely dropping out the low end as expected with an unsealed balanced armature IEM.
1964EARS 1964 ADEL A12
Base Price: $1999 | Manufacturer’s page
SQ score range: 9.9-10 (final score still TBD)
As mentioned above, the unit I have here is a beta test sample. From what I understand, the configuration of the A12 earphone itself is final whereas the ADEL modules might still undergo some revision. The purpose of this post is not to verify the science behind the technology – I have neither the background nor a particularly strong interest in doing that. As usual, I will leave discussing the science and tech to those more well-versed than I. All I care about is the end result – i.e. the sound – so what I wanted to do was compare the A12 with the ADEL technology to a couple of the other high-end custom IEMs in my possession.
The source used in my listening is primarily an OPPO HA-1, a full-size DAC/amp with surprisingly low output impedance at the headphone jack.
First a general note on the sound – the A12 can be characterized as a smooth and neutral earphone with a very slight perceived warm tilt. I actually found it to be spot-on neutral for my own preference, falling in the midst of all of my other “neutral” in-ears. Coincidentally, taking out the ADEL modules and sealing the holes where they used to be increases bass quantity, but also introduces some bass “boom”. I can see a sealed A12 appealing to some people and it will go toe-to-toe with some of the warmer custom IEMs out there, such as the Westone ES50 and Heir Audio 8.A.
The general sound performance of the A12 has a couple of notable strengths, the first being balance across the spectrum and a very natural tonal character all around. Another is smoothness – I’m not among those who are greatly bothered by mild treble unevenness, but it’s something I do notice. The A12 has none that I’ve heard so far, easily beating my 1964 V3 and V6-Stage in that regard. The final one is the presentation, which is nice and airy – more so than any of the sets I’ve managed to round up for comparisons so far.
InEar StageDiver SD-2 ($450)
To start off, I pitted the A12 against a high-end universal in-ear monitor. I selected the InEar StageDiver SD-2, which I consider to be a straight-shot upgrade from some very popular mid-range in-ears and an excellent-sounding product for the price. The SD-2 has a very smooth sound signature slightly on the warm/dark side of neutral, with excellent end-to-end extension. The bass of the SD-2 is rather flat, but compared to the A12 there is a boomy character, almost like a resonance, that’s audible at the low end. The A12 sounds cleaner and tighter, and more natural as a result. Likewise, in the midrange the A12 has fantastic clarity that the SD-2 trails. The A12 is not a bright earphone, but the slightly dark tonality of the SD-2 is also very apparent in comparison. The biggest difference, however, was in the way the sonic space is presented. The SD-2 is a very competent earphone, but with its darker sound and slightly boomier bass, it can’t hold a candle to the open presentation of the A12. The soundstage is smaller all around and appears enclosed – even congested – in comparison. On the whole, the A12 sounds more spacious, more refined, and somehow more “delicate” – a very potent combination.
1964EARS V6-Stage ($699)
The V6-Stage is probably my favorite monitor in its price range – it didn’t replace the more expensive JH13 Pro as my CIEM reference, but in everyday listening I quite like its slightly v-shaped sound and well-extended bass. The biggest complaint with the V6-Stage for me has always been treble smoothness – the peak (or two) present at the top end are more noticeable with some records than others, and on occasion can point out sibilance in a rather aggressive way. No such danger with the A12 – the top end there is smoother and significantly more refined, making the highs of the V6-Stage sound a little shimmery, almost metallic in comparison. The A12 also sounds more full-bodied, and yet at the same time clearer than the leaner V6-Stage. The V6-Stage does dig a little deeper in terms of bass and occasionally derives some additional perceived clarity from its brighter, sharper highs, but in the sense of being more transparent and less congested-sounding, the A12 still wins out.
Noble 4S ($999)
Noble’s quad-driver, silicone-shelled 4S is also a rather balanced and neutral-sounding in-ear, but its signature leans in the opposite direction from the slightly v-shaped V6-Stage and JH13 Pro. The 4S is more mid-centric, with slight bass roll-off and relaxed, almost smoothed-over treble. Next to the A12, its bass sounds a little gutless and lacking in depth – pretty much the opposite of the V6-Stage. The A12 appears more dynamic, and its low end has better definition. The 4S is a little more vague and not as clear overall despite sounding a bit leaner. The A12 sounds more rich without being in the least bit “bassy” in the conventional sense. The A12 is also a little more crisp and focused in the treble region where the 4S tends to be more smoothed-over, and sounds more natural as a result.
Unique Melody Miracle ($1049)
Unlike the majority of audio and consumer electronics products, the UM Miracle has appreciated in price over the years – an odd development considering how much more competition there is today than in 2010 when it was first introduced. Next to the 1964 ADEL A12, the Miracle is lacking mostly in clarity and openness. Its midrange sounds more distant and somewhat muffled compared to the more prominent mids of the A12. Treble quantity is similar between the two but the Miracle is just a bit less smooth. The A12 is also clearer, and this clarity also seems to carry over to the presentation, where the A12 is a bit more spacious, but more importantly has better imaging with more distance/separation between instruments.
JH Audio JH13 Pro Freqphase ($1099)
The JH13 has been one of my IEM benchmarks since first listen. Several of the custom IEMs I’ve heard since have given the JH13 a run for the money in this way or that, but I think the A12 does the most convincing and complete job of it. The JH13 follows a balanced, slightly v-shaped sound sig with some bass emphasis and strong treble. Thanks to the slight bass hump, its low end is more powerful than that of the A12, and a bit more boomy as well. The bass of the A12 still has good impact, but better quality. The A12 sounds a touch clearer on occasion and has a more full-bodied, less “analytical” sound than the JH13. It’s smoother and more natural than the JH13 up top, too, making the JH Audio set sounds a little harsh/edgy in comparison. The A12 even has a slightly more 3-dimensional and spacious sound presentation compared to the more forward and aggressive JH Audio unit.
Custom Art Harmony 8 Pro ($1100)
The Harmony 8 Pro from Poland-based Custom Art is a silicone-shelled, 8-driver CIEM that I’ve been using quite a lot lately. To me it sounds like a slightly brighter V6-Stage with slightly less bass and a bit more clarity, which makes for a solid reference earphone when it comes to listening for fine detail. It is thinner than the A12, and of course is tonally brighter and more “analytical” in presentation. Clarity is about on-par but the warmer, more full-bodied A12 sounds smoother, more natural, and more spacious, and even carries a bit more impact in the bass than the H8P.
Hidition NT 6 ($1200)
The NT 6 from Korea-based Hidition is a bright, hyper-detailed 4-way earphone on the performance level of the JH13 and Harmony 8 Pro. Clarity is similar between the ADEL A12 and the Hidition unit, but the NT 6 derives some of its clarity from its brightness. It’s actually quite impressive that the A12 can keep up in clarity considering its warmer and more full-bodied sound. The NT 6 has a cooler tonal character and its treble sounds more splashy/not as smooth. The A12 is also a bit more spacious with better soundstage depth and layering.
I recently picked up a new reference in full-size headphones, finally retiring my trusty Sennheiser HD600, and now I feel that the 1964 ADEL A12 may be able to do the same to my favorite in-ear monitors. The price puts it in a class of its own compared to my other CIEMs, but in my listening thus far its has the fewest concessions of any top-tier CIEM I’ve tried. Balanced with a very mild warm tilt, it can be described as refined and extremely “comfortable”-sounding, remaining smooth, natural, and un-congested even at louder volumes. More time will need to be spent to see if I’m getting the best possible performance out of the A12, but it is deserving of a full review down the line. Even ignoring the stated potential benefits of the less-than-fully-sealed IEM design to long-term ear health, reduction in listening fatigue, etc. (some of them potentially more important to stage musicians than audiophiles), the A12 is shaping up to be a great earphone.