Perfect Seal Deca


Sound impressions
Before listening, I always let the iem burn for at least 100 hours to ensure the cable and crossover components are run in properly. Impressions were done with the Lotoo Paw Gold.

Mike tuned Deca with the diffuse field equalization as a starting point, while further fine-tuning it by ear. Diffuse field is a tuning philosophy with its own approach on recreating natural sound, resulting from researching the average overlap of sound waves from different directions. This manifests in a relatively flat tuning in the bass and midrange, followed by a bump in the upper midrange and a slight dip in the lower/mid treble. And Deca does sound natural. Better yet, it is one of the most natural sounding ciems I’ve heard to date. Its tonality comes very close to neutral, being neither warm, nor bright. Overall, Deca is defined by a natural, clear and relatively uncolored sound, with an accurate instrument timbre.

Its presentation is neither forward nor distant, and overall notes are neutral in size. However, due to the upper midrange peak, the lower and center midrange are relatively less prominent. So while the midrange isn’t recessed by any means, the lower end of the midrange is not very full, and as a result the sound isn’t overly dense or thick. The AR6 manifested itself with uniquely open stage, due to a lean mid-bass presentation. Deca adds some more mid-bass to the mix, which consequentially tightens the stage a bit in comparison. It isn’t intimate by any means, it just has normal stage dimensions: an average rectangular shape with good width, height and depth. While the Deca has a bit more mid-bass in comparison to the AR6, this still isn’t a bassy monitor by anybody’s means. This keeps the stage clean and airy, and the combination with good stage dimensions provides good instrument separation.


The Deca has good sub-bass extension, with tight and well-controlled hits. The mid-bass takes a neutral approach. I’ve mentioned Deca has relatively more mid-bass than the AR6, but make no mistake – this is still more of an ‘audiophile’ neutral; a bass to listen to rather than feel. In sheer impact, it falls slightly behind the iem average. More often than not, iems tend to be tuned with relatively more (sub)bass impact, to compensate for the lack of bodily feel you’d get from speakers. So while the Deca’s bass has good qualitative properties, in quantity it is lighter than neutral, although I wouldn’t call it light all together. If you’re looking for a sub-bass rumble with solid impact, the Deca won’t give you that. It’s more of an audiophile rather than ‘fun’ tuning. The mid-bass has good resolution; while bass-lines aren’t overly pronounced, they are well defined, while displaying good speed.

The midrange has a neutral positioning, being neither forward nor distant. The midrange is primarily characterized by a peak in the upper midrange around 5 KHz. This gives it a very clear and open sound, there’s a certain lightness to it – very similar to Lime Ears’ Aether. It’s tonality balances perfectly between sounding warm or analytical; it simply sounds natural, clean, and tonally accurate. The upper midrange bump gives a boost to its transparency, and really helps instruments like violins and guitars to shine. But due to the relative prominence of the upper compared to the lower midrange, the midrange itself does not carry a lot of weight. It isn’t recessed by any means, and has good size. But deep male vocals will not sound very dense, although they sound clear. Iconic singers like Elvis or Sinatra might lack just a bit of power, where you’d want to feel the sound coming from deep behind the throat. Female vocals however really seem to shine, truly portraying an angelic quality. There’s a certain sweetness, a purity, that really makes magic happen. So while the instrument tonality and transparency really helps to make the music sound beautiful, it might miss a bit of fill in the lower end of the midrange for heavier rock or male vocals.

Due to the use of the popular TWFK drivers, a lot of iems are tuned with a 7 KHz peak – it’s an inherent property of the driver. It gives a brittle, brighter type of treble response, with a focus on clarity at the expense of naturalness. While Mike also used the TWFK drivers, he managed to shift the peak towards 5 KHz – creating a less bright treble response, resulting in an overall more natural timbre. The treble has good detail, certainly isn’t laidback, but also never gives that artificial, icy cold type of response that can be harsh or fatuiging. Another advantage is that the Deca retains a safe margin when it comes to sibilance. The overall naturalness of the sound is also the result of a slight dip in the mid treble region between 6-9 KHz. This gives notes a softer attack, the focus isn’t on analytical precision you might get with a brighter tuned iem. The downside is that the imaging misses a bit of that pinpoint precision you’ll find with iems like the EarSonics S-EM9 or Jomo Samba. Clearly, there’s a tradeoff off of smooth musical flow and naturalness, for that final bit of analytical precision. Deca’s treble displays a good bit of sparkle. Cymbals have a beautiful crash, although the more peripheral treble relying on the higher frequencies can be more of a musical sidenote – it’s part of the flow, just less prominent.

Page 3: Comparisons and concluding thoughts

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About Author

Nic is currently in pursuit of a PhD degree in social neuropsychology, while trying not to get too distracted by this hobby. In pursuit of theoretical knowledge by day, and audiophile excellence at night. Luckily for him, both activities are not mutually exclusive which helps to lighten the workload. Always on the go, Nic's enthusiasm for hi-fi is focused on all chains of the portable system: iems, cables and daps.

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