In-Ear MonitorOverreview

Kiwi Ears x Crinacle Singolo

Crinacle's Helmholtz experiment works exactly as advertised. Whether it seals in your ears is the coin flip.

15 sourcesUpdated
$32Typical US price

Score aggregates reviewer opinions across topics.

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Kiwi Ears x Crinacle Singolo

The short version

What to know.

A single-dynamic IEM built around one genuinely novel idea: a folded Helmholtz resonator that lets one driver carry a large sub-bass shelf without letting it reach the midrange. Measurements from three independent rigs agree it works — the low end is lifted roughly 7 to 10 dB below 40 Hz and is back to level by 200 Hz, dipping slightly below it at 250-300 Hz. Sources also broadly agree on the rest: a safe, gently warm tuning with no harshness, a soft upper treble, good isolation, well-finished shells and thoroughly poor accessories. Past that the field splits. Whether the result actually reads as a bass-head set or merely a clean one, whether the midrange is natural or thin and shouty, whether the stage is intimate or reasonably open, whether layering survives busy material, and above all whether the short, wide nozzle seals in your ears all divide reviewers roughly down the middle. Fit is the split that drives the others: most reports of thin bass come from listeners who could not get a seal.

About this product

The single-dynamic Singolo with the KARS Helmholtz resonator — not one of Crinacle's other budget collaborations (the Truthear Zero and Zero: Red, or the 7Hz Zero: 2), which are separate products from separate makers. Launched at $79; the maker's own store now sells it for about a third of that, and almost every review below was written at the launch price.

In early 2024 Kiwi Ears and the measurement-database reviewer Crinacle set out to prove a point with one driver. Until then, an in-ear that delivered a big sub-bass shelf without smearing the vocals above it needed at least two drivers and a crossover to pull it off. The Singolo does it with a single 11 mm liquid-crystal-polymer dynamic driver and a folded tube — a Helmholtz resonator, 3D-printed to micron tolerances behind the driver, which Kiwi Ears sells under the name KARS.

The engineering worked; three independent measurement rigs say so. The reception is another matter. Reviewers praised the trick and then spent two years disagreeing about nearly everything downstream of it, and a large minority never got the earphone to seal at all. Two years on it is sold out in one colour, gone from Amazon US, and discounted to roughly a third of its launch price — which quietly rewrites the one verdict the reviews were most united on.

A good fit for

  • Listeners who specifically want a big, clean sub-bass shelf that stays out of the midrange — the one thing this set genuinely does differently.
  • People who already tip-roll and have a decent cable and a set of longer tips in a drawer.
  • Long, undemanding listening: the soft top end is very hard to fatigue with.
  • Anyone curious about the engineering now that it sells for roughly a third of its launch price.

Think twice if

  • You need something that seals first time out of the box — the short nozzle is the most common complaint by a wide margin.
  • You want air, sparkle and treble extension; the top octave is deliberately quiet.
  • You listen mostly to fast, dense, bass-heavy material, where the low end is slow to clear and layering suffers.
  • Weighty male vocals matter to you — the lower midrange is scooped on purpose.
  • You want the most resolving set at the price; several reviewers rate it merely average against cheaper rivals.

The reviewer consensus

Agreement &
disagreement.

6 / 12topics divide opinion
tonalityisolationtrebledetaildynamicsbuildbassmidssoundstageimagingcomfortvalue
2 Strong agreement4 Mostly agree6 Divided opinions

Common ground7

  • The headline trick is real: the sub-bass is lifted hard below 100 Hz and back to level by 200 Hz, so the shelf never smears the midrange.
  • The overall balance is deliberately safe — gently warm, free of peaks, and hard to make harsh.
  • The upper treble is genuinely soft. Nobody describes this as an airy or analytical set.

Points of contention6

  • Whether it is actually a bass-head set. The shelf measures large, but a third of reviewers hear it as merely clean and modest rather than subwoofer-like.
  • The midrange: clean and uncoloured to one camp, thin in the lower mids and shouty on loud female vocals to the other.
  • The soundstage: half hear a presentation stuck inside the head, half hear a stage that is respectable for the money.

A closer listen.

12 topics · 6 divided
Left: criticalRight: positiveTighter lines: more agreement

Bass

PositiveDivided opinions
Reviewer sentiment9 supporting sources
CriticalNeutralPositive

Band: opinion spread · Dot: weighted average

The reason the set exists, and still an argument. Everyone describes the same low end — deep, clean, and conspicuously free of mid-bass bleed — and then splits on how much of it there is. Two thirds hear a genuine subwoofer shelf; the rest hear something merely tidy and modest. The graph says both are reading the same curve.

Measured

Three independent rigs agree on the shape. Relative to each rig's own 500 Hz level, the shelf measures +7.3 to +10.0 dB at 20 Hz and +7.8 to +8.7 dB at 40 Hz, then falls away steeply — +4.3 to +4.9 dB at 100 Hz, and −0.3 to +0.3 dB by 200 Hz. The minimum sits at 250-300 Hz, 0.5 to 1.3 dB below the 500 Hz reference. Kiwi Ears' claim that the bass is cut at 300 Hz is real; the cut simply completes nearer 200-250 Hz, which is what Headphonesty also found on his own coupler.

vs. listeners — The graph does not settle the argument so much as explain it. The shelf is genuinely large in absolute terms, but the ear-gain peak is almost exactly as large (+8.4 dB at 3.5 kHz), so the set does not read as bass-tilted the way the raw shelf suggests. The second factor is mechanical rather than acoustic: the reports of thin or absent bass cluster among reviewers and owners who also reported a poor seal, and nothing drains a sub-bass shelf faster than a leak.

Where it splits
a real subwoofer shelf — physical, deep, bass-head territory66%

“Some tracks such as Iori Hobby Shop is downright entertaining with Singolo due to the physical sensation of the bass notes.”

nk-tran, In-Ear Gems
clean and deep, but not actually a bassy set34%

“I don’t hear a distinct subwoofer type sound”

Chris Love, Mobile Audiophile
Link to this topic

The hardware

Specifications.

Checked

Design

Type
In-ear monitor
Drivers
1 × 11 mm dynamic (Liquid Crystal Polymer (LCP) diaphragm, paired with the KIWI Acoustic Resonance System (KARS))
Housing
resin shell

Electrical

Impedance
32 Ω
Sensitivity
108 dB/mW≈ 122.9 dB/V
Frequency response
20 Hz – 20 kHz

Connection

Cable
Detachable, 1.2 m
Connector
0.78 mm 2-pin
Plugs supplied
3.5 mm

Manufacturer-published figures, not measurements · from kiwiears.com (archived).

Follow the evidence

Sources 15

1–6 of 15 sources

Read with context

Limitations & method.

As of

What to keep in mind 8

  1. This is a read of where the reviews land as of July 2026, and nearly all of them were written in 2024 at the $79 launch price. The Singolo now sells for about a third of that, which lands squarely on the value argument and on none of the sound ones.

  2. Fit is the thing to settle first. The nozzle is short and wide, and roughly three in five reviewers and owners could not get a comfortable seal — which is also where most of the complaints about thin or missing bass come from.

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