Tanchjim OLA II

A Coaxial Dynamic-and-BA Hybrid IEM With a USB-C DAC/DSP Cable and Tanchjim App PEQ

The OLA II is the first update to Tanchjim’s long-running OLA line in a while — other coverage of the lineup describes the original OLA as one of Tanchjim’s mainstay budget models, and I don’t have a reason to doubt that. It moves to a hybrid driver configuration — a coaxially-mounted dynamic driver and balanced armature working together — and ships with a V-shaped default tuning, which is a change from the more neutral tuning I associate with Tanchjim’s other IEMs.

It’s sold in three cable variants — 3.5mm single-ended, 4.4mm balanced, and the USB-C version reviewed here, which adds a built-in DAC and DSP stage with an eight-band PEQ controllable from the Tanchjim app. I picked the USB-C version specifically for that reason: it turns the OLA II from a fixed-tuning IEM into one you can reshape yourself, using either Tanchjim’s own presets or your own filters, and the OLA II is easy to drive from an ordinary phone or dongle either way.

I’ve had the OLA II for about a week now, provided by Tanchjim for this review. The headline so far: at this price, with this level of driver engineering and a proper PEQ implementation behind it, there’s little to complain about — the only real question is whether you’ll want to touch the EQ at all, since the stock tuning already leans hard into bass. But first, let’s take a look at what’s in the box.

Unboxing and Packaging

The outer sleeve carries Tanchjim’s usual understated branding — a grey textured wrap with the brand’s bird logo — but sliding it off reveals a much more colourful inner box, printed with artwork of Tanchjim’s character mascot wearing the OLA II:

Sliding the inner sleeve open reveals a layered structure, with a smaller white box marked “OLAII” nested inside, and a drawstring pouch tucked into the fold:

The box back is worth a look on its own: alongside the regulatory markings and full specification printout, Tanchjim print their own frequency response curve directly on the packaging:

Lifting the lid off the OLAII compartment shows the two IEM shells seated in a foam cutout, each stamped with its own pull-tab:

Pulling the tray fully open shows both shells nested against the printed handling warning, with the pull-tab card sitting between them:

The cable gets its own separate compartment beneath the earpiece tray, coiled neatly inside:

Once everything is laid out, the accessory count is straightforward: two IEM shells, a detachable cable, six pairs of eartips across two bore sizes, a grey velour carrying pouch, a manual, a quick guide, and a QR code card for the Tanchjim app:

The eartips themselves are worth calling out specifically, since one set is a named Tanchjim product in its own right — the T500, a tapered, dual-hardness silicone tip intended as a “high-frequency acoustic waveguide”:

A second, clear set of tips ships alongside them:

Laid out together, the full eartip selection makes the two-family approach obvious — a set of six black tips in different sizes for a fuller, warmer seal, and a smaller set of clear T500-style tips for a different acoustic character:

A closer look at one pair from each family shows the difference in bore size and tip profile clearly:

Design and Build Quality

The OLA II keeps to a compact, rounded shell built around the dynamic driver at its core — the front housing is resin with a matte smoky-grey finish, nested into a metal rear shell, and the two materials meet with no visible gap. Each shell is clearly marked, with “OLAII” and “TANCHJIM” etched into the faceplate on opposite earpieces:

Looking straight down at the nozzles shows the vent Tanchjim describe in their pressure-relief design — a recessed groove intended to sit clear of the ear rather than getting blocked against it:

A closer look at a single shell shows the internal driver wiring visible through the semi-transparent housing base, along with the side vent connected to the dynamic driver cover:

Side by side, the two shells show the same rounded, driver-centric shaping on both sides:

The nozzle itself is on the thicker side, with an alignment groove that made fitting the supplied tips straightforward, and the metal nozzle collar shows some machining lines under close inspection:

Fit and Comfort

The shell is genuinely compact for a hybrid design, and that shows up directly in wearing comfort — it sits light and doesn’t announce itself the way some larger multi-driver IEMs do. The rounded housing follows the concha cavity rather than filling it, so there’s no digging-in sensation even after extended wear.

Cable and Connections

The included cable on this unit is the USB-C DSP version — a silver-plated copper twisted pair terminating in a USB-C plug with a “TANCHJIM” marking and a small status LED cutout:

Partway down the cable is an inline remote with a single button and a mic port, matching the marketing description of a Goertek microphone and single-button control on this variant:

The Y-split is a metal barrel engraved “OLA II,” with a chin slider fitted just below it:

At the earpiece end, the cable terminates in a detachable two-pin connector, colour-coded red and blue for the two channels:

Coiled up, the cable is thin, light, and shows only slight self-tangling in normal handling:

Features and Performance

The core of the OLA II is Tanchjim’s DMT5 dynamic driver — described as a dual-magnetic-circuit, dual-chamber design intended to increase magnetic flux density and field uniformity within the magnetic gap, while the dual-chamber structure manages the air load on both sides of the diaphragm for more stable diaphragm control. Alongside it sits a second driver Tanchjim call PURE Hi, an independent balanced armature dedicated to extending the ultra-high-frequency range and adding overtones and air, which Tanchjim say lets the main diaphragm focus on lows, mids, and core treble without carrying the extreme top end itself.

What’s more unusual is how the two drivers are arranged: Tanchjim place them in what they call a coaxial acoustic structure, so that different frequency ranges enter the ear canal along a more closely aligned acoustic axis. The claimed benefit is reduced imaging shift from having two physically separate sound sources, more focused imaging, and treble with a higher proportion of direct sound. Internally, Tanchjim also describe a smoother inner acoustic chamber intended to carry the driver’s output into the ear canal with less loss, plus a large Helmholtz-style resonance rear chamber that they say gives the vocal range a more stable foundation.

The USB-C version reviewed here adds a useful practical layer on top of that driver design: a built-in DAC and DSP stage, controllable through the Tanchjim app, with an eight-band parametric EQ where you can set your own frequency and Q values rather than being limited to fixed presets. Because the review sample arrived without any of my own filters applied, I initially cross-checked its default tuning against publicly available measurement sets on squig.link and Crinacles’ graph.hangout.audio, using my own open-source DevicePEQ tool. I’ve since measured the OLA II myself on a 711 clone coupler, and those results are in the Specifications and Measurements section below.

What the app makes obvious is how directly Tanchjim have shaped the default tuning through the same PEQ engine you get to use yourself, rather than baking it into the driver alone. Here’s the default filter set as it ships on the USB-C variant, read straight from the Tanchjim app:

Preamp: -2.0 dB
Filter 1: ON PK Fc    50 Hz Gain  2.0 dB Q 0.5
Filter 2: ON PK Fc   551 Hz Gain  2.0 dB Q 2.3
Filter 3: ON PK Fc   738 Hz Gain  1.2 dB Q 3.6
Filter 4: ON PK Fc  1433 Hz Gain -2.5 dB Q 1.1
Filter 5: ON PK Fc  2943 Hz Gain  3.0 dB Q 3.7
Filter 6: ON PK Fc  3461 Hz Gain -2.0 dB Q 0.7
Filter 7: ON PK Fc  5749 Hz Gain  1.9 dB Q 4.0
Filter 8: ON PK Fc 12400 Hz Gain -5.0 dB Q 3.0

Reading that filter set is a useful shortcut to understanding the default tuning without waiting on a full 711 coupler measurement: the wide, low-Q lift at 50Hz is the broad bass emphasis behind the V-shape described below, the pair of narrower peaks at 551Hz and 738Hz add some lower-midrange body, the dip at 1433Hz pulls back before the ear-gain region, and the peak at 2943Hz adds presence back in. The -5dB cut at 12,400Hz with a fairly tight Q of 3 stands out too — it’s a deliberate reduction right at the top of the audible band rather than a broad treble rolloff, which fits with the controlled, non-fatiguing treble character described in the Sound Impressions section. None of this requires a screwdriver, tissue paper, or third-party PEQ hardware to change — it’s exactly the kind of adjustment the eight-band editor makes trivial, whether you’re starting from Tanchjim’s own default or dialling in something closer to your own preference.

The Tanchjim app itself is worth walking through, because the PEQ editor is only one part of it. The app’s device list shows the OLA II connected as “TANCHJIM-OLA II DSP,” and tapping into it opens a hub showing whichever EQ is currently active alongside shortcuts to Official Presets, Game EQ, and the EQ Forum:

From that hub, Official Presets gives you a longer list of tuning options than most IEM apps bother with — the screen below shows Default, Natural, Theater, Ambient, Pop, Classical, and OST, with further presets including an Instrument mode further down the list — each just a tap away, no manual filter entry required:

Beyond the official presets there’s a Game EQ section with separate profile lists for Phone, PC, and Switch, each with per-title entries for things like Delta Force, PUBG Mobile, Call of Duty Mobile and Genshin Impact, and an EQ Forum where other users publish and share their own filter sets for the OLA II, each with an Apply button and download/like counts:

The custom PEQ editor itself plots the resulting curve live as you adjust frequency, gain, and Q per band, which makes it easy to see exactly what a filter change is doing rather than guessing from numbers alone, and firmware updates are handled from the same app over OTA:

One more thing worth flagging separately, because it isn’t specific to the OLA II shells at all: the USB-C DSP cable terminates in a standard detachable 0.78mm 2-pin connector, so it isn’t locked to this one IEM. I tried the same cable on a CrinEar Project Monolith and loaded a Monolith-specific PEQ profile through Hangout Audio’s browser-based parametric EQ tool, and it worked exactly as it does on the OLA II itself, noticeably pulling back the Monolith’s usual bass excess:

That makes the USB-C cable a useful accessory in its own right for anyone with other 2-pin IEMs, not just a tuning tool tied to the OLA II.

Sound Impressions

I’ve only had the OLA II for about a week, so rather than commit to a full track-by-track breakdown before I’ve spent proper time with it, here’s what has stood out so far from my own listening — across both the analog cable’s tuning and the USB-C cable’s default DSP tuning, since the two are close relatives rather than identical.

Bass

Straight out of the box, the OLA II is bass-heavy — probably the most bass-forward Tanchjim IEM I’m aware of, and warmth is the tuning’s defining character here rather than outright slam. Sub-bass extension is genuinely good, better than the measured curve on its own suggests, and it doesn’t sound sloppy or overblown for the sake of it — it’s just a lot of bass by default, which lines up with the broad 50Hz lift in the default filter set above. If heavy bass isn’t your preference, this is exactly the kind of tuning the onboard PEQ exists to tame.

Midrange

This is where the analog cable and the USB-C default DSP tuning actually part company. On the analog 3.5mm/4.4mm cable the tuning reads as closer to Harman, if noticeably warmer than a typical Harman target, with a vocal-forward midrange presentation. Switch to the USB-C cable’s default DSP tuning and Tanchjim refine that further into something I’d call warm-bright — the midrange opens out toward a more spacious presentation rather than staying vocal-forward. Both variants share the same underlying warmth; the DSP default is simply the more deliberately reshaped of the two, which lines up with the two cables diverging from around 5kHz up in the measurements below.

Treble

Treble on both variants is generally safe — relaxed through the lower treble on the analog cable, with only the upper treble carrying a bit more energy to keep things interesting rather than sounding flat or rolled-off. It’s a treble character closer to Tanchjim’s own JM-1 than to anything aggressively detailed, and the default DSP tuning’s -5dB cut at 12,400Hz in the filter set above is consistent with that restraint rather than a broad rolloff. Neither variant is chasing treble excitement as the way it holds your attention — the warmth and that touch of upper-treble energy are doing that work instead.

Soundstage and Imaging

On the analog cable the stage is contained rather than expansive, with reasonably clear boundaries — which tracks with the coaxial driver arrangement’s stated goal of tight, coherent imaging rather than sheer scale. The USB-C default DSP tuning nudges that outward into something a little more spacious-sounding, consistent with the midrange shift described above and with the two cables diverging above 5kHz in the measurements.

Comparisons

The OLA II sits in an interesting spot in Tanchjim’s own lineup, since the Bunny and the One (DSP) both cover similar USB-C, DSP-equipped territory at nearby price points and with broadly similar shell sizes.

Here it is alongside several of them — the Nora, the One and the Bunny are all in shot:

What the photo shows is how much variation there is in shell format across a single brand’s range, from small capsule shapes to full moulded shells. The honest answer to “which one should I buy” depends heavily on which default tuning you would rather start EQing from.

Outside Tanchjim’s own range, the Truthear lineup is the obvious comparison set at this price — the Gate, Pure, and Zero Blue 2 all compete directly with the OLA II on price and are all IEMs I already have measurement data for. I have not run the OLA II against them on the same coupler, so I am not going to put a graph here and imply otherwise.

Specifications and Measurements

Specifications

Tanchjim print their own frequency response curve directly on the retail box, alongside the full specification listing — a useful reference, though it’s a small printed chart rather than a proper measurement overlay:

Tanchjim also supplied their own distortion measurement, run at 94.2dB with total harmonic distortion sitting around 0.03% through most of the audible band and a couple of resonance-related bumps higher up:

Those are Tanchjim’s own graphs. I’ve since measured the OLA II myself on a clone IEC60318-4 coupler, and the USB-C default tuning tracks closely between channels, sitting a touch below the Harman Adjusted target through the 200Hz–800Hz lower-mid region before the presence peak around 3kHz and the -5dB, high-Q dip near 12kHz called out in the filter set above:

Swapping the USB-C cable for the 3.5mm/4.4mm analog cable version shows a broadly similar shape through the bass and midrange, with the two diverging more from around 5kHz up — worth knowing if you’re deciding between cable variants rather than assuming the DSP is the only thing that changes:

The official presets make a real, measurable difference rather than just relabelling the same curve. Ambient and Natural both pull the stock tuning’s elevated bass shelf back toward the Harman target, while Classical goes the other way and adds even more bass than the default:

Pop and Instrument split the difference, sitting below the bass-heavy default while Classical stays elevated:

And Theatre is the most reduced of the set, cutting bass further than either Ambient or Natural, while Classical remains the outlier on the bass-heavy side:

On its own, the OLA II’s measured default tuning is exactly what the filter set and the sound impressions earlier in this review would predict.

Rating Explanation

The Pragmatic Rating of 5 reflects an IEM that gets the fundamentals right at $52.99, with real engineering behind it rather than just a driver count on a spec sheet — the coaxial dynamic-and-BA arrangement and the dual-chamber DMT5 driver are specific, described design choices, not marketing filler. The default tuning is bass-heavy enough that it won’t suit everyone, but the USB-C version’s onboard PEQ means that’s a preference to dial in rather than a hard limitation of the hardware.

The Price Rating of 5 reflects $52.99 buying a hybrid driver design, a proper detachable cable, two full eartip families, and — on the USB-C variant — a DAC/DSP stage with an eight-band parametric EQ, all of which would be a strong showing at twice the price. The Features Rating of 5 reflects the same USB-C DSP implementation: an app-controlled PEQ with adjustable frequency and Q values is a genuine step up from fixed presets, and it’s exactly the kind of feature that turns a fixed-tuning IEM into one you can shape yourself.

The Measurement Rating of 4 reflects a clean, channel-matched frequency response that broadly tracks the Harman Adjusted target once you account for the deliberately bass-forward default tuning, plus a set of official presets that measurably shift that balance rather than just relabelling the same curve. The OLA II measures well on its own terms; what remains less certain is its competitive position, since I have not run the Bunny, the One (DSP) or the Truthear lineup on the same coupler to place it against them.

On value — what the driver engineering and the PEQ implementation cost you — this is the best midrange Tanchjim IEM I have reviewed. Buy it if you are willing to spend a few minutes in the app; if you want a finished tuning out of the box, the default’s bass weight will decide it for you.

Conclusion

The OLA II is a smaller, more comfortable shell than I expected from a hybrid driver design, with a coaxial dynamic-and-BA arrangement that Tanchjim have clearly put real thought into rather than just bolting a second driver on for the spec sheet. The default tuning is heavier on bass than most Tanchjim IEMs I’m aware of, which will be exactly right for some listeners and a reason to reach for the PEQ for others — either way, the USB-C DSP version means that choice is actually yours to make.

At $52.99 for the USB-C variant, this is an easy recommendation for anyone who wants a well-built, well-engineered IEM and doesn’t mind spending a little time in the Tanchjim app. If you want a warm, bass-forward tuning you can reshape rather than live with, this is the one to buy; if you want a neutral IEM straight out of the box, start somewhere else and come back when you feel like tinkering.