KZ Castor (Standard/Harman-Neutral Version)

KZ Castor

I was contacted by KZ recently and invited to review the Castor IEM (Harman Target Version). This product was provided at no cost by Kate, the representative at the company.
Product link:
https://www.kztws.com/products/kz-castor

Knowledge Zenith (KZ) is known for producing excellent value high-performing earphones, including the popular ED range of dynamic driver IEMs and the hybrid series beginning with the ZST. The company has recently taken a new direction in design and tuning and this is reflected in the nomenclature with some newer products given names rather than alphanumeric titles. The Castor, named after one of the twins of Greek legend, is a dual dynamic model with tuning switches and retails for around £20.

The Castor is presented in a compact white rectangular box, as we have been accustomed to seeing from KZ. The front of the box bears a line drawing of the IEMs and the rear features the specifications. Removing the slip cover reveals a white plastic tray with the IEMs inside, below which is a white card box containing the accessories. The contents comprise:

● Castor IEMs
● 2-pin silver-plated copper cable
● Three pairs "Starline" silicone ear tips
● One pair foam ear tips (pre-fitted)
● 2-pin silver-plated copper cable
● Tuning lever
● Documentation

The model tested here is the Harman Target version and it is finished in a silver colour with the name "Castor" printed in black in a freestyle font on the faceplate. The lower half of the earpiece is transparent allowing the inner workings to be seen. There is a large vent on the lower edge of the earpiece similar to that on the Krila hybrid IEM and the four tuning switches are mounted on the rear of the shell. The raised clear plastic 2-pin sockets are fixed to the top of the unit. Due to the stacked design of the drivers, the earpieces are fairly chunky and do protrude a little beyond the ears. The build quality is excellent.

The cable is a silver plated copper type with a 2-pin 0.78mm connector and a gold plated 90° angled 3.5mm plug. The sheath is transparent, revealing the copper wire within. The cable is not as prone to tangling as previous KZ designs but there is still no chin slider.

Internally, the Castor employs two dynamic drivers in a stacked configuration. Bass duties are handled by a 10mm unit dealing with the frequency range up to 200 Hz while the midrange and upper frequencies are covered by an 8mm driver.

The four tuning switches enable the user to adjust the bass, mid and treble as follows:

Switch 1: increases bass by 1dB
Switch 1 + 2: increases bass by 2dB
Switch 3: increases mid/treble by 1dB
Switch 3 + 4: increases mid/treble by 2dB

I discovered that the profile became increasingly V-shaped as the switches were engaged and affected the Castor's neutral balance which I preferred. The mids became recessed and I also felt that the staging was affected, becoming narrower and more shallow. Therefore, during testing, all four switches were set in the off position.

The Castor was tested with Xduoo X20 and Hidizs AP80 Pro X DAPs. A smartphone, via a USB-C dongle, and a digital radio were also used. The IEMs were subjected to a burn-in period of 100 hours before evaluation.

Sound Quality
The Castor was immediately impressive in its presentation with a lively, full tonality, precise transient attack, bright extended treble and a spacious soundstage. It majors on technicalities, and the overall profile was well balanced with a moderate emphasis in the high frequencies and an unexpectedly forward midrange considering that it was designed to follow the Harman Target. The bass reached well into the lower octaves with good impact, the mids were clear with a natural timbre and treble detail was abundant. It was astonishing to hear what can be obtained for just £20. A few years ago this level of quality would have only been available at a much higher price.

Bass
The bass showed fine texture and resolution with good extension. It did not dominate the rest of the frequency range, but remained in balance with the midrange and treble. There was plenty of weight and impact when present in the recording and I did not find it necessary to increase the level by using the switches or applying EQ. The delivery was clean, displaying good speed and a natural timbre.

"Nuvole a Colori" comes from the album "Stagioni de Venezia" by Rondo Veneziano. The track is a fusion of synthesisers and baroque violin, supplemented by electronic percussion. It begins with powerful synth strings and deep bass playing a descending motif in the minor key. Dramatic diminished chords are accompanied by violin arpeggios and the Castor really made the most of the arrangement here with a focused, weighty bass showing fine resolution, detail and texture. There was no boominess or overhang and the delivery was clean and precise. The bass driver's character resembled a BA in its speed and impact yet possessed the natural timbre more associated with a dynamic unit.

Malcolm Arnold's suite of "Four Cornish Dances" composed in 1966, reflects the landscape, people and traditions of the county with a dash of humour added for effect. The third movement is inspired by marching bands and Methodism. The piece begins with a bold theme from the brass section underpinned by a sustained bass drum accompaniment. The Castor dealt with this very well with a healthy rumble and fine rendition of the tuba bass line. The piece rises to a climax and, after a spirited section featuring a solo tambourine, it concludes with a triumphant chord with the full orchestra which was handled thrillingly.

Mids
Although based on the Harman profile, the Castor's midrange was not recessed, and in fact was a little brighter and more forward than expected. There was a wealth of detail, a clean and airy character and excellent separation. The tonality might be described as bright/neutral with an attractive immediacy and never strayed into harshness.

I have always found cello and piano to be good indicators of midrange quality in a transducer. Venezuelan composer Reynaldo Hahn's "A Chloris" is a homage to Bach. In the version by Julian Lloyd Webber and John Lenehan, the Castor's delivery was clean and accurate. The two instruments displayed a natural timbre while the ambience of the recording venue was reproduced authentically, taking the listener direct to the performance. The incisive nature of the bowing brought out a clear depiction of the "rosin" whilst the piano's overtones were equally well rendered, adding to the realism.

Bob Dylan's "Farewell Angelina", performed by Joan Baez, showed what the Castor was capable of with vocals. Accompanied simply by double bass and guitar, Baez's voice retained all its character with her diction reproduced cleanly and precisely. The balance with the accompaniment was well rendered and the emotion of the performance was captured with perfect clarity.

Treble
The Castor's treble was very extended and somewhat brighter than neutral. There was plenty of detail and lively transients, with notes starting and stopping with precision and upper frequencies displaying excellent detail. The presentation was quite forward with some extra brightness at higher volumes occasionally dominating proceedings.

Zimbabwean multi-instrumentalist Hennie Bekker has produced a large catalogue of music in various genres including jazz, film music and New Age. "Summer Dawn" from his album "Summer Breeze" features banks of Synclavier strings, woodwind samples and electronic embellishments. The texture and extension of the treble was a joy to hear and blended perfectly with the solo woodwind samples. Bright synth percussion elements danced across the stage and created a colourful panorama of sound with exceptional clarity.

Lavinia Meijer is a Dutch harpist and has recorded many albums of classical transcriptions and other genres. Claude Debussy's "The Girl with the Flaxen Hair" comes from her 2015 album "Voyage". She has a light and gentle touch and the Castor's reproduction stayed true with a delicate and detailed rendition of the piece. Being a more gentle piece, the treble remained smooth and clean. The fine detail did not escape the Castor's attention with the feeling of the piece taking centre stage and revealing an impressively pure quality of tone.

Soundstage
The Castor produced a spacious, open and atmospheric stage with precise imaging, layering and separation. The effect extended beyond the ears with good depth and height. Movement of elements within the image was reproduced effectively with the location of instruments easy to discern.

Kevin Braheny is an electronic music artist who pioneered the use of analog synths in the early days of the genre, developing "The Mighty Serge," a modular analogue system that he still uses in his music. His output also features the Steiner EWI (Electronic Wind Instrument). These elements come to the fore in "Desert Walkabout" which appears on the compilation album "Western Spaces".

The music is described as "a celebration of the sense of freedom inspired by the timeless beauty of arid vistas" and the Castor certainly managed to convey that impression, with a palpable sense of openness and space. Delicate percussive elements manifested in a cavernous acoustic while the solo EWI soared above the accompaniment in impressive fashion. There was a particularly good portrayal of depth with subtle sounds appearing to emanate from a distance, adding to the atmosphere and emphasising the feeling of isolation.

Anatoly Liadov's beautiful tone poem "The Enchanted Lake" received a wonderful interpretation from the Philharmonic Symphony Orchestra of London under the baton of Charles Gerhardt. This is a particularly fine recording and the Castor did not disappoint. The introduction features bassoons, horns and harp and all their different locations were pinpointed in impressive fashion with a real sense of space and perspective. The bass drum deep in the image, the attractive layering of the strings and the interplay between the various sections of the orchestra were presented in a realistic way, producing a satisfying experience.

Comparisons
Lindy Cromo IEM-75
The Cromo, like the Castor, is a dual dynamic IEM. The bass driver is 15mm in diameter and the treble unit has a 6mm diaphragm. The two drivers are in a dual concentric configuration. The cable is fixed and the large aluminium housing is very comfortable.

The Cromo has a warm and inviting profile with an easy going musical character. The timbre is natural although slightly coloured. The Castor is brighter, more detailed and has a better transient attack and is superior in technicalities. With a comfortable fit and cable down wearing style, it is possible to listen to the Cromo for long periods without fatigue, whereas the Castor's assertive delivery can become tiring after extensive listening. The Castor has a better build quality and detachable cables. The two IEMs are very different animals and are more complementary than rivals, it being a choice between the technical and the musical.

Audio Dynamix Euphony
Audio Dynamix was a company producing high quality Bluetooth speakers and ventured into the IEM market with an ambitious design for the time. The Euphony is again a dual dynamic design also in a stacked configuration, with a 10mm bass driver and a 6mm unit covering the mid/high frequencies. The diaphragm is a Mylar type 6 microns thick. The earpieces are crafted from aluminium and they have a T2 interface which is similar to MMCX but smaller in size. This connection is used by Westone and Etymotic.

The Euphony is quite similar in tonality to the Castor but a little more "laid back" in its presentation. It still possesses a strong and entertaining delivery but is a little more V-shaped in nature. The midrange is only moderately recessed but detail is very good, in fact similar to the Castor but with a somewhat softer quality. Bass goes a bit deeper than the Castor but it has a more "rounded" tonality whereas the Castor is faster and more incisive. Treble and soundstage are similar but the Castor's treble extension is superior.

KZ Krila
KZ's recent Krila is a dual hybrid model featuring the second generation Xun dynamic driver with a 10mm diaphragm, paired with an updated version of the long-running 30095 BA. Housed in a similar shaped earpiece to the Castor, it too, is well made. It has the same 2-pin cable as the Castor.

The Krila sounds different from the Castor, being more V-shaped in profile. Its detail retrieval is on a par with the newer model, but the Castor's midrange presents vocals in a more immediate fashion. In the bass, the Krila's Xun driver is preferable with more weight, rumble and impact, although of course the Castor's bass switches can be used here if more bass is required. The treble is similarly extended but brighter, occasionally straying into slight hardness which sometimes happens with BAs. The Castor is smoother here, with better separation. The Krila and Castor are both excellent models in their price range.

Conclusion
Technology has moved on very quickly in the world of IEMs. In the last few years things have advanced and manufacturers have responded to customer feedback regarding tuning. The Castor is an example of that. To be able to experience this at such a low cost brings high fidelity sound within the reach of everyone.

With a crowd-pleasing profile based on the Harman curve, the Castor also possesses a notable immediacy, presenting music in a lively assertive manner. The four tuning switches allow some adjustment, but at times, I would have liked a function to lower the levels rather than increase them, especially in the treble, which can be a bit over enthusiastic. Lengthy listening did result in a little fatigue but the resolution and detail available here was remarkable. The Castor is definitely one of KZ's best models and is a bargain at the modest asking price.

Disclaimer:

• - I don’t read FR graphs. I only use my ears, as how earphones should be used.
• - KZ sent this unit to me in an exchange for an honest, unbiased review. Rest assured that this review will do its best to devoid from any bias/es as much as possible.
• - The following remarks and observations shall be made and owned only by me.
• - No monetary compensation is/was involved before, during, and after the period of creation of this review.
• - Your mileage may (and always, will) vary.
• - Burn-in time: 4-8 hours per day, 5 days.

Source/s used:

• - Non-HiFi smartphone (Infinix Note 12 G96), PC.
• - Fosi Audio DS1.
• - Sony Xperia X Compact
• - Local Files via Foobar, YouTube Music, Deezer, and Qobuz with UAPP.

IEM/Earbud/Setup configuration: stock medium eartips, any form of EQ or MSEB off, DSP/USB-C plug, 40-60% volume.

(We'll start this review with all of the switches flipped on, as it is the "stock" configuration of the KZ Castor out of the box.)

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Sound signature:

• - The KZ Castor (Neutral) quite resembles the overall sound characteristic that the KZ EDA (Balanced) had, but greatly improved. It is still a “harman” or mild-u-shaped sounding set, but managed to balance both tonality and technicalities for its price greatly, in terms of quality.

Lows:

• - This region isn't the Castor neutral's strong suit because it isn't the most raised or textured in this IEM. It's punchy and somewhat raised, with a fast attack and decay, yet it can get boring on certain tracks. When compared to the EDA Balanced, it is noticeably thicker and has better decay for most genres, including bassy ones. However, the Castor Bass version is the one to choose if you want a bassy sound while still preserving the Castor naming scheme.

Mids:

• - Now we are at the highlight of this IEM, in my humble opinion. Sure, it is slightly more recessed than the other frequencies, as are most u-shaped IEMs, but it is quite open, clear, and detailed for the price. Male vocal fans may find the thickness of the male vocals missing, but it is usually insignificant and has the details when needed. Upper frequencies are slightly raised, clean, airy, and contain a lot of sparkle. This region will sound "peaky" to sensitive hearing on badly recorded or particularly sibilant tracks, but it will never be sibilant or piercing. Overall, I like the mids of the KZ Castor Neutral and probably it’s their best rendition of their signature mids among all of their products I have auditioned.

Highs:

• - This set's treble is nicely extended and somewhat raised. It's neither sibilant or fatiguing at all, while still retaining the necessary presence of this region. Detail retrieval is average, nothing new or something to write home about. It still has most of the details needed for casual music listening sessions.

Soundstage, Imaging, and separation:

• - Just like the EDA Balanced, the Castor Neutral quite has the balance in terms of technical and tonal performance. The soundstage is better on this set in terms of depth and height, layering and separation is also a bit better but nothing too significant and may struggle on very busy tracks compared to their recently released IEMs. Imaging and separation is very good and very good for listening to live performances and fps games.

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Switch configurations in a nutshell!

• Just like the first KZ to do the tunable switch feature, the switches here in the KZ Castor exhibits the “add/subtract” type of mechanism. One switch flip equates to a 1db elevation in the low/high frequencies.

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Other IEM comparisons!

VS CVJ KE-S

• - The KE-S is definitely warmer, smoother, but suffers less treble extension, air, and detail. Technical performance is also better on the Castor Neutral.

VS Tanchjim Zero

• - The Zero is literally dead flat, neutral, and prioritizes the technical performance more than the tonality. The Castor Neutral is a bit behind on the layering, but is on par on all technical aspects when compared. It is also easier to drive when compared.

VS CCA Duo

• - The CCA Duo is a brighter, more peaky IEM. It edges out the Castor Neutral on the detail retrieval and layering, but the rest both IEMs are on par. The Castor Neutral does not suffer in any form of harshness though. It is cheaper as well.

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Pros:

• - For the nth time, their “best” IEM is under 30 USD yet!
• - The usual, “neutral” sound signature (subjective).
• - Well-balanced sound quality in terms of technical and tonal performance.
• - Well-controlled, smooth bass bass response.
• - Open, detailed mids.
• - Non-fatiguing yet airy upper frequencies.
• - Very good technical performance under 25 USD.
• - Versatile, “KZ-signature” tuning switch.
• - Very good fit, comfort, and isolation.
• - Smooth, sleek “fluid” design! (subjective).
• - Easy to drive.
• - Relatively cheap!

Cons:

• - Due to two existing versions of this IEM, the switch feature is quite pointless or a gimmick (subjective).
• - Bass may sound monotonous at times (subjective).
• - Sound isn't good when all switches are turned off/ some of the switches are turned off.
• - Despite not being sibilant or harsh in any way, people with sensitive ears may prefer the bass version more or look for something else due to its “clean-neutral” sound approach (highly subjective).
• - Barebone accessories.

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In a very good, positive way, there is nothing significantly new about KZ's current lineup. All of their products are really good, refined, and very capable of sounding great on casual music listening sessions. This KZ Castor Neutral version, in KZ manner, is by far, their best yet and their “for the masses” IEM yet! However, I do find its switch feature rather pointless and definitely a useless gimmick due to the Castor’s dedicated “bass” version. Despite the said gimmick, the KZ Castor is definitely on the top of my budget recommendations if you are looking for a neutral-sounding set, well done!

Pairing recommendation/s:

• - Eartips: The eartips are alright and enough for the most part. You may always use your preferred eartips.
• - Source: This IEM is easy to drive, but benefits well on a Hi-Fi dongle or USB DAC.
• - Cable: is already good as what it is, but you may use what you prefer.

Thank you for reading!

Non-affiliated product link here!: https://shopee.ph/KZ-Castor-In-Ear-...fIJWA6f8eBiyXfzFUMMcik8JNlpFRICgZdEAtVwdYsx30

Additional Photos Here: