Moondrop debuted in 2015 with its first product, the VX earbud and released its first IEM, the IX some time later. Since then the well-regarded Kanas, Starfield, Aria and Kato models followed, which were tuned to Moondrop’s own VDSF curve, a variation on the Harman tuning.
The Chu is a new affordable IEM with a 10mm dynamic driver and fixed cable. It retails for around $20.
The Chu is attractively packaged in a small square box with a clear plastic cover. A full-colour card bears an illustration of a waifu figure and there are two apertures revealing the earpieces. Inside the IEMs are nestled in a foam insert. A long black box contains a set of three “Spring” eartips (S, M, L) and a pair of earhooks. Under the foam you will find the black fabric carrying pouch (which is not very spacious) and documentation.
Build and Design
The compact earpieces are solidly built from zinc alloy and are a flat oval shape. They are finished in a matt black with a bamboo leaf design in a rose-gold colour on the faceplate. Channel identification is provided by L and R markings on the top side of the earpieces which have some heft to them and are smoothly contoured.
There are two small pinhole vents on the inner surface. Inside there is a 10mm dynamic driver with a titanium coated diaphragm, N52 magnet, composite cavity and waveguide and a CCAW voice coil. The Chu has been tuned to Moondrop’s VDSF curve and a frequency response of 10Hz-35kHz is specified.
The non-detachable cable is rubbery and is reminiscent of those on early KZ single DDs like the ED3. It tends to tangle easily and there is no strain relief where it exits the earpieces. There is a disc-shaped Y split with Moondrop branding and the cable terminates in a right-angled gold plated 3.5mm plastic plug. There is no chin slider.
The Spring tips come in three sizes, but they are very small; the largest I would describe as a “medium”. They are quite shiny and do not afford much grip.
Fit and Isolation
Fitted with the largest of the tips, the Chu was very comfortable. I obtained quite a deep insertion with the earpieces fitting snugly inside the ear and remaining generally secure. However, the cable facing forwards was a slight concern, tending to loosen a little over time resulting in the cable falling off the ears.
I therefore made use of the included ear hooks which provided extra stability and improved the seal, thereby improving the bass. Isolation in this configuration was very good, with few external sounds being audible while music was playing.
The Moondrop Chu was principally auditioned with a Hidizs AP80 Pro X DAP but a smartphone and a CD player were also used. Adequate volume was obtained with all sources but I did find the sound improved with the volume set at a higher than usual level. A burn in period of 100 hours was carried out.
The Moondrop Chu acquitted itself very well indeed with a neutral bass, somewhat forward midrange and a bright and detailed treble. The staging was fairly intimate but the excellent imaging and separation gave the impression of a larger stage.
There was a linear bass profile with good extension. The tonality was on the warm side of neutral and the transient attack was just a little soft with leading edges somewhat blunted. This affected the texture and resolution, where a little more definition would have been welcome. There was some rumble in the sub bass but the level was reduced resulting in a “distant” effect.
Mid bass was also neutral and light in nature with no evidence of bleeding into the midrange. Drums and bass guitars displayed good timbre but lacked impact and weight. Overall though, the bass response was nicely balanced with the rest of the frequency range and was in some ways preferable to a V-shaped profile with a recessed midrange.
The midrange was perhaps the Chu’s best feature. It was clear, well-defined and open with very good detail and separation. Imaging was also of a high standard. The only minor issue was the depth of the staging due to the forward nature of the presentation. The timbre was largely natural, especially in the lower range, where cellos and male vocals displayed a little attractive warmth.
Female vocals were well projected and clear. Brightness gradually increased with frequency and in the upper region, there was occasionally some sharpness of tonality and a slightly thin quality to the sound which affected high woodwind and strings, giving them a somewhat metallic quality, but otherwise the midrange was very good indeed.
The treble continued where the midrange left off with a bright tonality, good detail and separation. Sibilance was well controlled, only appearing when present in the recording. The timbre was brighter than neutral, sometimes straying into sharpness but displaying good extension.
There was a rise in the lower region, a dip which avoided harshness and a higher peak which added some air and fine detail, after which it rolled off. Instruments sounded fairly natural, but again there was a general thinness of tone. Overall detail retrieval was excellent for the price and there was a good sense of space with the clarity of the reproduction adding to the effect.
Soundstage and Imaging
The Chu’s soundstage showed good width and height, but the forward nature of the midrange reduced the impression of depth. The width extended just beyond the ears and height was also well rendered. Imaging was of a high standard with positioning cues easy to hear, especially laterally, where stereo effects were notable.
Layering was impacted by the shallow staging and there was a flattening of perspective in climaxes, but due to the clean, detailed nature of the Chu, separation was very well portrayed. In general, the staging came over as a little more intimate than ideal, and I found myself wishing for a bit more space in the presentation.
Change of tips
I suspected that the supplied Spring tips may not be best suited as I switched to a pair of KZ Starlines and the above problems were much reduced. The extra grip helped with the fit and the narrower bore seemed to improve the treble and expand the staging. This of course will depend on ear anatomy but it is worth bearing in mind that tip rolling may be beneficial.
Fiio JD3 ($20)
The JD3, like the Moondrop Chu, is a fixed cable IEM. It features a stainless steel “bullet” style housing containing a 9.2mm dynamic driver, a powerful neodymium magnet assembly, a CCAW voice coil and dual cavity construction. It also has a sound reflection absorbing device. The earpieces are vented to increase the soundstage and the build quality is excellent as expected from Fiio.
The JD3 has a fairly standard V shaping with a powerful and rather dominant bass with some bleed into the midrange which is a little recessed. There is good timbre as befits a dynamic driver and the treble is generally smooth with an emphasis in the lower presence region and a roll-off in the upper frequencies.
This tuning helps to avoid undue harshness and sibilance. The soundstage is average in dimension. Overall, it displays a warm, easy-going, amenable sound suiting many genres. The Chu is much brighter in tonality, with a lighter but faster bass and a more open midrange. The treble is more incisive and extended with better levels of detail.
It is more immediate and dynamic in nature and is more suited to vocal music with its excellent projection, whereas the JD3 is more relaxing. The JD3 and Chu are complementary in character and would appeal to different tastes.
Moondrop Aria ($80)
The Aria employs a 10mm dynamic driver with a liquid crystal polymer (LCP) diaphragm. It has a solid metal build and detachable 2-pin cable.
It has an open, clean and lively sound which is very engaging. There is a gentle W or U profile with a moderate sub bass emphasis. The rest of the bass region is tight and well textured, the midrange, although a little recessed, is clear and expressive and there is a moderate lift in the treble which is detailed and extended.
There is a good balance between the technical and the musical and the general impression is relaxed with a good deal of refinement, making it eminently suitable for long-term listening. Occasionally one would wish for a little more excitement but its easy-going nature should appeal to the majority of listeners.
The Aria is particularly impressive with classical music and possesses an attractive musicality which encourages further listening. It therefore must be considered amongst the top choices in its price bracket. Although tuned to the same in-house VDSF curve as the Aria, the Chu sounds quite different, being leaner in the bass, more forward in the midrange and brighter in the treble.
It does not have the same level of refinement as the Aria, occasionally displaying some sharpness of tonality and the soundstage is not as extensive. However, at around a quarter of the price of the Aria, it turns in an excellent performance, at times being more exciting to listen to, although extended listening can become slightly fatiguing.
HZ Sound Heart Mirror ($45)
The Heart Mirror has a 10mm dynamic driver with a carbon nanometer diaphragm and powerful iron-boron magnet. It is clothed in a zinc alloy housing with a reflective finish. The connection is 2-pin. It has remarkable transparency and clarity deriving from low distortion and a lack of colouration.
The tonality is brighter than neutral and it excels in technicalities. Detail retrieval is excellent. Bass, including sub-bass, shows very good resolution and texture, but reduced a little in level.
There is no mid bass emphasis which allows the mids to breathe, and the transition into the midrange is seamless. Treble is bright and clear with no harshness or peaks and is very extended, only occasionally flirting with sharpness. There is a natural timbre, high quality staging and a clean and bright tonality with lots of detail. The overall sound of the Chu is broadly similar, but not as adept technically.
The bass is quite similar and the midrange is also forward in nature, and the treble is also bright but lacks the refinement and micro detail of the Heart Mirror. It does not have the same level of transparency or quality of timbre, but acquits itself very well at around half the price.
The Chu impressed in many areas. The packaging and accessories are excellent at the price and the IEMs themselves are solidly built. With a bright, clear and immediate sound and an overall well balanced profile, it engages the listener in a lively entertaining way and it is testament to the progress in technology today that such a sound can be obtained for such a low price.
It is not perfect; it is somewhat bass-shy and could benefit from a little more resolution in the low frequencies, there is a slightly thin quality to the tonality in the upper midrange and treble and the rubbery, fixed cable is not ideal. It is also worth experimenting with alternative tips as I noticed a marked improvement in these areas with a change of tips.
All considered, when the price is taken into consideration, all these criticisms largely disappear and the Chu essentially recommends itself as one of the best value IEMs in its price sector.
Moondrop Chu Specifications
- Material: Zinc alloy
- Driver: 10mm high-performance dynamic driver
- Diaphragm material: Titanium-coated
- Sound coil: 0.035mm ultra-fine black CCAW
- Magnetic circuit: N52 neodymium
- Sensitivity: 120dB/Vrms(@1KHz)
- Impedance: 28 Ω 土15% (@1khz)
- THD: THD@1KHz≤1%
- Frequency range: 10Hz-35kHz (IEC61094, Free Field)
- Effective frequency response: 20Hz -20kHz (IEC60318-4, -3dB)