TRN Bax EST Review 6 e1659268237400

TRN Bax EST Review

TRN Bax EST Review – A True Flagship

Announced in March, TRN’s flagship model Bax comes with two Electrostatic drivers from Sonion, one BA driver from Knowles, and one 10mm dual magnetic in-house dynamic driver.

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The shells are made from aluminium-magnesium alloy, but the faceplates of the IEM are made from 304 stainless steel. TRN Bax has a semi-open design with openings on the faceplate.

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TRN Bax also comes with 16-core silver plated cable in the box which has a swappable audio jack design, but you can only select one type of connector when ordering the IEM. The cable is very soft, handles, and feels amazing on hands (I prefer soft cables yes).

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In its hybrid configuration, TRN Bax handles the mid-frequencies with custom tunes Knowles 29689 BA driver. The lows are handled with a third-generation 10mm dual magnetic dynamic driver whose magnetic density has been increased by 15% compared to the previous generation. The high frequencies are handled with two Sonion EST drivers.

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Comfort levels are important of course and the TRN Bax presents no problems far as creating sore spots because all the edges on the backside are non-protruding and everything is rounded. Their weight is somewhat noticeable, and the IEMs are somewhat chubby you feel them in your ear, but the comfort level is acceptable enough for a couple of hours at least.

Isolation is also common and again mostly depends on the choice of tips and the seal they form. For me, Moondrop’s Spring tips worked the best both for sealing and comfort.

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Although the price seems high, especially for an IEM made by TRN, the Bax is the cheapest IEM on the market with Sonion EST drivers. The closest contender costs 180$ more with the same driver configuration. Let’s find out how the TRN Bax holds up.

What’s in the box


Impedance: 22Ω
Sensitivity: 118dB/mW
Frequency range: 7-40000Hz
Connection: 2-pin 0.78
Price: 312$
I would like to thank TRN and Hifigo for providing me with the review sample of TRN Bax.


TRN Bax vs Dunu EST

TRN Bax is the most sensitive IEM that I have come across, tested both with Shanling UA3 and Cayin RU6, and I never had volume levels so low in any IEM. Even though I like listening mostly at high volume levels, %20 of the scale was more than enough, from a 4.4mm balanced output.


Summarizing the overall sound from the get-go, TRN Bax has a delicate and calm V-shaped sound signature. Bax’s lows are something special. It desires a linear bass reproduction all while retaining the meant and dynamics. Lows are soothing with moderate tightness and punchiness. However, the bass is tightened up only to the point of having them kept tidy and doesn’t get rock-solid. In other words, lows sound better than I expected from TRN. Tender enough to make them feel organic but not loosened. With a well-established body, the bass maintains a very consistent flow throughout the low range. The reverbs are carefully controlled without degrading the natural dynamics but only keep the boominess calmed down.

The bass quantity is just about the same as other mildly v-shaped IEMs. Lows show neutral depth and thickness in color. The ultra-low extension is quite decent considering its calm nature yet not too ponderous in emphasis. The bass in general keeps its presentation in the lowland, offering a stable foundation for the upper ends to build the headroom.

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Mids are very well connected with the lows, perhaps the most seamless and natural transition achieved from a hybrid (and tribrid) IEM from TRN. Vocals are well highlighted by taking a slight step forward but not detached from the lows. Taking this small step forward in vocal is done so carefully that mids sound more like they’re on top of the lows instead of feeling pulled up close. The thickness is neutral with a touch of extra meat, performing ideally on both male and female vocals.

If TRN Bax sounding too “soft” or boring for an EST tribrid IEM is your concern, no worries. Vocals are meticulously worked in tonality which I’d imagine being a nightmare acquiring this tuning from scratch. Mids show a natural tone that also hints at some mild shine and crisp lushness brought from the EST driver. I love this impression of “being unique and familiar at the same time” vibe going on with TRN Bax’s tonality. It’s just wonderfully balanced between reference and fun. Vocals also carry subtle strength and coolness without getting shouty or wacky in tone.

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The EST drivers of course have to be another fun factor of TRN Bax. Trebles are smoothly transitioned from the upper mids and offer a comfortable open-field environment. The texture of EST trebles varies by different IEMs from soft to roast crisp. As for Bax, the Spring tips towards the crisp side but only to the extent of securing a good tightness. Highs are analytical as expected from EST drivers with tonality and brightness that blends coherently with lows and mids.

Because of that, highs don’t necessarily highlight extreme quantity or brightness. It makes sense since Bax is tuned for consistency and neatness. Carried with airiness, highs are articulated that expose fine grains and upper-end layerings but always under one circumstance: keeping things smooth. When you give it a listen, the trebles may come across to be calmer than expected. But then again, you would soon notice that it was the TRN Bax that the drivers were so carefully and seamlessly fused. Highs show clear EST characteristics yet are carefully integrated with the rest.

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Soundstage – Imaging

The headroom is delicate and elaborate. I would like to use the word “pretty” but trying to refrain as TRN Bax doesn’t get too miniature and cute in its presentation. The size of the headroom is slightly above moderate, not being so grand or narrow. The separation is nicely done as expected yet doesn’t get too crazy in sensitivity to maintain Bax’s wholeness. The instruments are appropriately divided and pronounced – it’s just that they don’t fly away or get aggressive in separating.

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Let’s be honest, releasing the Bax is a very bold move from TRN. Yes, they may have been inspired both in design and tuning by some competitors but that’s not the point. The thing is that they have accomplished giving customers the cheapest Hybrid IEM which has legit Sonion EST drivers in it, and with amazing sound performance in my opinion. The Bax has the best treble performance that I have heard in any IEM. This is another level compared to dynamic and balanced armature drivers. Has great extension but is also very smooth without any sharp edges.

Some may say that these EST drivers may have the potential for better tuning but even this level makes a treble-head like me feel in total joy listening to the Bax. Now I understand why people are buying expensive TOTL IEMs with Sonion EST drivers in them and this justifies the price of TRN Bax with golden stars. One of the best IEMs in the 300$ price range, easy.