Kiwi Ears Quartet

Kiwi Ears Quartet - lets talk about Tilt

The Kiwi Ears Quartet is a versatile IEM offering am excellent set of tuning switches which provide actual useful changes to the frequency response. These switches are what makes the Quartet an interesting IEM and one that should deserve your attention.

While I love both the Kiwi Ears Orchestra Lite and KE4 for completely different reasons, the Quartet I think adds an interesting layer of customizability to the IEM experience and can easily be appreciated as a complimentary IEM to those excellent IEMs.

Currently, the Kiwi Ears Quartet retails for $109 but there are a huge amount of customisation options available with many faceplate and shell colour options as well as UIEM and CIEM options.

But before giving you an idea of what you can expect from the Quartet and explore the various sound signatures the Quartet’s offers, I want to expand on something that is being an often neglected when people talk about personalisation of a sound signature and that is ’tilt'.

An overview of Tilt

In my recent review of the Kiwi Ears KE4 here I was very impressed with the almost perfect ’tilted’ ’new meta’ response that the KE4 provided and explained a little about the audio science behind speakers in a room and a tilted response.

But a crucial aspect of the measurements of that Tilt in speakers that it is a preference every bit as important as bass and treble. We are starting to see this represented more in measurements graphs for example, Crinacle graph database now includes tilt as an important aspect of the visualisation.

But, I think an annotated diagram of my actual measurements of the Quartet might explain what is sort of special with the tuning switches and how they affect the sound - though as this is not a compensated graph:

So relative to the treble the tuning switches allow you to have both more or less bass but also tilt the midrange, allowing you to get various sound profiles. For example, you can get a V-shaped sound indicated with the “green” arrow as the Bass is boosted but since the midrange is recessed. Or you can get a reference sound either “orange” or “blue” (depending on how much treble you want with your ‘reference’) or finally you can have a mid-forward sound indicated the “red” line (logically the opposite of the V-shaped). While this solution is not as flexible as a software EQ implementation it is a very nice implementation of tuning switches and probably the best I have heard in an IEM.

But there are other “aspects” of the sound profile and frequency response that I will get into later that hold the Quartet back from being exceptional.

But first, lets see what you get with the Quartet:

Unboxing Experience and Box Contents

The Kiwi Ears Quartet comes in sleek, modern packaging very similar to other Kiwi Ear products:

The back of the box unusually doesn’t include much useful information:

Sliding the cover off the packaging reveals the internals:

Opening this box finally reveals the Quartet shells:

Taking out everything out of the box:

Within the carry case you get the ear tips and the cable.

So everything provided with all the essentials included:

• Kiwi Ears Quartet IEMs
• Detachable 0.78mm 2-pin cable
• Multiple sets of ear tips (various sizes)
• Carry case
• User manual and warranty card

The detachable cable is of good quality, with minimal microphonics and has good quality connectors on either end:

The carrying case is compact and protective, making it easy to transport the Quartet.

Design and Comfort

The Quartet features a comfortable though large, ergonomic design that provides a secure fit for most users.

The shells are well-shaped to sit naturally within the ear canal, offering effective passive noise isolation, which enhances sound quality by reducing external noise.

Here is are 2 little videos comparing the shells to some other IEMs in my collection, the Kiwi Ears the purple ones, and you can hopefully get an idea of the shape and size of the Quartet from these videos::

Here are the Quartet compared with the KE4 and the Truthear Zero Red, all three have fairly large IEM shells:

The Quartet’s standout feature is its dual tuning switches, located on each IEM, allowing users to adjust the frequency response tilt. This flexibility is ideal for listeners who appreciate control over their listening experience and want to tailor the IEMs’ sound to different genres or preferences.

Sound Signature

So since you are effectively getting 4 very different sound signatures with the Quartet this section is a little difficult to describe and not get too confusing, but I will provide where I feel are the main changes the tuning switches provide the sound:

Bass

The bass on the Quartet is tight and controlled, with good extension and impact. When the bass tilt switch is activated, the low end gains depth and punch, which works well for genres like electronic and hip-hop. Bass-heavy tracks like “Royals” by Lorde feel impactful without overpowering the other frequencies.

Midrange

The midrange is clear and natural, making vocals and instruments sound engaging. One of the most interesting aspects of the tuning switches are that the midrange can be tweaked with the 2nd tuning switches. This preference is really where this ’tilt’ relative to the bass is adjusted and subjectively this gave me 4 different flavours. My favourite setting for this was a more relax midrange with the down / down switch configuration, but your preference may well be different and it so easy to change I would encourage anyone interested in understand what their preference is to get a Quartet to play with these switches.

Treble

The treble is smooth yet detailed, with no harshness or sibilance at least for me. While the treble is changed with the tuning switches, it is effectively since if you lower both the bass and midrange you are effectively raise the treble and adding a bit of brightness, enhancing detail and air. This adjustment is ideal for classical and jazz, where the Quartet can bring out the nuances of cymbals and high-pitched instruments. Though possible this might lead to a more fatiguing experience that when the bass is enhanced.

Soundstage and Imaging

The soundstage on the Quartet is moderately wide for an IEM, with good depth and layering. Imaging is precise, allowing listeners to locate instruments within the sound field with ease. The tuning switches slightly affect soundstage perception, with the midrange tilt down setting giving the impression of a wider stage due to increased clarity and air.

Comparisons

Versus the Kiwi Ears KE4

While the Kiwi Ears KE4 offers a flat and neutral frequency response that is ideal for technical listening, the Quartet’s tuning switches provide more versatility. The KE4 may be preferable for those who prioritize an analytical sound, but the Quartet’s tilt adjustments give it an edge in adaptability, allowing it to perform well across a wider range of genres and preferences.

Versus Aful Explorer

While the Aful Explorer focuses on a meticulously tuned single signature that combines balanced sound with excellent technical performance, relying on its hybrid driver configuration and acoustic design for refinement rather than user-adjustable switches. While the Quartet offers adaptability for varying preferences, the Explorer delivers a polished, out-of-the-box experience aimed at those who value simplicity and consistency

Specifications and Measurements

•	Drivers: 4-driver hybrid (2 dynamic, 2 balanced armature)
•	Frequency Response: 20Hz - 20kHz
•	Impedance: 16Ω
•	Sensitivity: 106dB/mW
•	Connector: 0.78mm 2-pin
•	Cable Plug: Gold-plated 3.5mm stereo plug

The Quartet’s frequency response is adaptable, with each tilt setting providing a slightly different slope, allowing it to achieve a balance that suits both technical and casual listening. The low impedance and high sensitivity make it easy to drive with most portable devices, though the quality of the output can be further enhanced with a dedicated DAC/amp.

Measurements

First with the Frequency Response:

Frequency Response

The Quartet shows excellent channel balance, but you can see that warm mid-bass boost and the dark treble.

Adding all 4 tuning options to the graph shows that those 2 aspects of the frequency response are not really modified by the tuning switches: This graphb also highlight a possible treble peak in the 9K region - this area will be very dependent on your own ears and may not be a peak as beyond 8K these measurements are less representative of what each person’s hears.

Here is another way to look at it as a tilted frequency response using Crinacle graph database (this is his teams measurements of his Quartet): I have highlight those 2 areas I mentioned earlier and Crinacles Quartet also seems to show some treble peaks.

Distortion

Its distortion is very low, resulting in a clean, distortion-free sound across all tuning settings:

As a percentage it also looks great well below 1% even though this was measured at over 90 dbSPL:

Rating

The Kiwi Ears Quartet earns a 4-star pragmatic rating for its combination of versatile tuning, sound quality, and ergonomic design. The only drawback are that the warm mid-bass region and the slightly dark treble aren’t manipulated with the tuning switches. So the overall tone is less analytical and detailed than it might have been, but if you are interested in a more analytical sound get the Kiwiears KE4 instead. I would love to see Kiwi Ears add similar effective tuning switches to the KE4, that would be a very impressive IEM.

Conclusion

The Kiwi Ears Quartet is a highly versatile IEM that offers users control over the sound signature through innovative tilt adjustments. Whether you prefer a balanced, room-like sound or a V-shaped signature for a more energetic experience, the Quartet delivers excellent performance across all settings. With a solid build, comfortable fit, and engaging sound quality, it’s an ideal choice for audiophiles who appreciate flexibility and high-quality audio in an affordable package.