Preamble:
Knowledge Zenith, in short “KZ”, is a Chinese manufacturer of very inexpensive in-ears and headphones that usually offer a really good value, sound and build quality for the little money they cost. Sure, you can’t expect the sound of $100 headphones from earphones that usually cost around $10, but many of the KZ earphones offer a sound (and build) quality that can compete with $30-$50 headphones easily (I have also heard some worse $30-50 IEMs than most $10 KZ’s).
After I had already bought many models of the KZ range from the KZ Official Flagship Store (
http://aliexpress.com/store/1358152), they kindly provided me with a sample of the ZS1 (
http://aliexpress.com/store/product/KZ-ZS1-Independent-Dual-Driver-Monitoring-In-Ear-Headphones-HiFi-Earphone-With-Microphone/1358152_32478361300.html, ~ $20) for review.
Please note that (as always) I am not affiliated with Knowledge Zenith or any of their stores in any way and that this review reflects my actual thoughts on the product. (As always,) I don’t gain any financial benefits from writing this review.
Technical Specifications:
Drivers: dynamic, Dual-Driver (8 & 6.8 mm)
Impedance: 18 Ohms
Sensitivity: 108 dB
Colours: unicolour
Delivery Content:
The ZS1 arrives in a black cardboard box with a purple KZ logo on the top and the technical specifications on the back.
Inside is another black box that contains the in-ears as well as silicone tips.
Note that I received a sample unit, so your retail unit’s accessories may vary.
Looks, Feels, Build Quality:
The ZS1 looks like the ZN1, but does not include the in-line amplifier/EQ-box and has got additional ear guides. The cable is very flexible, appears sturdy and has got proper strain relief – other IEM manufacturers could learn a lesson from KZ in this regard. A chin-slider is unfortunately missing, which is an issue with all Knowledge Zenith in-ears I know.
Taking a closer look at the ZS1, it becomes obvious that they slightly differ from the ZN1 on the inside: there is a gold-coloured metal ring-shaped element in the ZS1’s nozzle that narrows it, and the crossovers sit on the high-frequency drivers and cover their rear vents.
Comfort, Isolation:
The ZS1 are intended to be worn around the ears, which is also my preferred style with all of my in-ears, as it reduces microphonics and improves fit as well as comfort.
The shape of the plastic bodies is ideal for me and just as comfortable as Westone’s and Shure’s in-ears.
Personally, I like the ear guides, as they somewhat compensate for the lack of a chin-slider and hold the cable in place well when leaning back. Though, I would still have appreciated an additional chin-slider.
Isolation is definitely better than just mediocre and the IEMs block out ambient noise quite effectively.
Sound:
The sound was mainly evaluated with the iBasso DX80, DX90 and the LH Labs Geek Out IEM 100. The music files were stored in FLAC format, but I also used some MP3s. I used the application “Sine Gen” as sine generator on the computer (with the Geek Out as DAC/Amp).
(Just in case,) the in-ears were burnt in for at least 50 hours before I started listening.
The sound was evaluated with the large, black stock silicone tips.
Tonality:
One could think that these IEMs sound exactly like the ZN1, but they do not (for some of the reasons I stated above (different nozzle diameter, tweeter not back-vented)).
The ZS1 is a very bassy earphone with an emphasis that mainly concentrates on the sub- and mid-bass (~ 13 dB), but is also present in the ground-tone. From sub-bass on, level starts evenly decreasing up to ~ 300 Hz, but has got a narrow dip at 550 Hz (it is not obtrusive with music, but subjectively lets the bass appear less coherent – it seems like the transition of both drivers has somehow failed a bit).
There is also an emphasis at 850 Hz which makes voices sound warm and full-bodied.
The treble is clearly in the background, especially the middle highs, wherefore overall sound is warm, bassy and dark as well. Although there is a peak in the upper treble, it is still below the ground-line and too little to brighten the sound.
Compared to the ZN1, the bass emphasis of the ZS1 starts extending deeper, wherefore the middle and lower ground-tone are a bit less present. The ZN1 has got a successful (and inaudible/invisible) transition between both drivers, wherefore it has got the better coherence (and its bass doesn’t sound slightly disconnected, unlike with the ZS1).
The ZN1’s mids are much better made, as its voices are tonally correct and solely gain a little warmth by the ground-tone – the ZS1 however has got some kind of peak at 850 Hz which makes voices warmer.
The ZN1 has got a very consistent treble without dips and has even got an evenly raising emphasis in the upper treble – the ZS1’s treble is clearly more in the background and darker.
Especially in the area between 300 and 1000 Hz, the ZN1 is tonally superior.
Resolution:
For the price, the resolution is good, but also not breath-taking. The mids and treble seem (regarding the price) well resolving, but there is some sort of veil on vocals. The treble and mids definitely benefit from the two-way configuration, especially with fast music, where the IEMs still maintain good control.
Just as with the ZN1, the bass is however very soft and also boomy, bloated – a lesser emphasis would have been better for the drivers.
The ZN1 has got the better resolution in the mids and does not appear veiled in this area.
Soundstage:
The ZN1 has got a huge (!) soundstage, the ZS1 does not – why that? Well, just as written above, the amp-less ZS1 has got a crossover on the back of the tweeter vent, wherefore it is closed, unlike the ZN1’s, which sounds audibly more open and spacious.
The ZS1’s width is minimally wider than average and gas got a fair amount of depth as well, although a bit less than width. The instrument rendering is quite precise, just as the layering.
Though, it sad that the ZS1 do not deliver that feeling of spaciousness as the ZN1 do (they don’t only sound roomier but also have got the slightly better layering and instrument separation).
Conclusion:
The ZS1 offer a good build quality and a great comfort, but have got a slightly failed transition between both drivers as well as a peak in the lower mids and a quite soft bass. Resolution is okay, but not extraordinary – some cheaper KZ IEMs are a bit better here. Though, for less than $20, you get a quite solid performance, but the ZN1 (with turned off amp module) is the better choice.
All in all, I give the ZS1 3.25 (rounded 3.5) out of 5 stars.