KBEar is the new in-house brand for the popular audio retailer, Keep Hifi. For now, KBEar is focusing on value-oriented IEMs, aiming to provide the maximum amount of performance for the lowest cost to the consumer. To that end, the KB02, the subject of today’s review, crams a full-sized 10mm dynamic driver and a bone-conduction driver into a single $40 package. I have historically been skeptical of booku-buck “tribrid” and “quadbrid” IEMs featuring BC drivers, but the barrier of entry for this hybrid is low-enough to justify an assessment. Lets get into the details!

You can find the KB02 for sale here on Keep-Hifi, and here on their Amazon storefront. As of writing, the KB02 has a 30%-off coupon live on Amazon, bringing its total price to a mere $28.

About My Preferences: This review is a subjective assessment and is therefore tinged by my personal preferences. While I try to mitigate this as much as possible during my review process, I’d be lying if I said my biases are completely erased. So for you, my readers, keep this in mind:

• My ideal sound signature would be one with competent sub-bass, a textured mid-bass, a slightly warm midrange, and an extended treble.
• I have mild treble sensitivity.

Testing equipment and standards can be found here.

The Big Picture​

Pros:

• Excellent sound stage and directionality
• Clean, articulate sound signature
• Textured midrange
• Sub-bass extension
• Excellent price-to-performance ratio

Cons:

• No case included
• Bone-conduction driver resonates at higher volumes
• Spring-loaded echo sensation when handling IEM
• Lacking in bass speed
• Average sources are insufficient for proper powering

Tech Specs​

• Driver: 1x 10mm Dynamic, 1x Bone-Conduction
• Impedance: 40 ohms
• Shells: 3D-printed Resin
• Cable Standard: 0.78mm 2-pin
• Cable Termination: 3.5mm

Sound Signature​

Sonic Overview:​

The KB02 features a clean, detail-oriented sound signature that prioritizes transparency. Its midrange is slightly recessed, but neutrally-toned. Its treble is forward without being sharp, and its bass picks up steam at around 200hz and continues on well past 50Hz with a surprising amount of resilience. These properties form an overall V-shaped sonic profile aimed at broad appeal.

Sonic Breakdown:​

Treble: Songs used: In One Ear, Midnight City, Outlands, Satisfy, Little One, Show Me How To Live (Live at the Quart Festival), Bittersweet Symphony

It is remarkable how much treble performance KBEar crammed into a $40 IEM. I frequently write about how impressive budget earphones are these days, but the KB02 ups the ante. Its treble is slightly forward, but remarkably clear. Proper amping is key here, as insufficiently-powered sources will reduce the KB02’s treble clarity.

High-hats, cymbals, and other percussive instrumentation resolve cleanly and fade out organically. In One Ear’s highly-textured cymbals crash into existence with force and precision, then wilt away into the background with minimal clipping. The KB02 captures treble-bound textures very well, only dropping very subtle impulses from busy segments of songs.

Speaking of busy songs, the KB02 performed remarkably well during Bittersweet Symphony. Each of the major instrumental layers, most of which live in the upper register, resolved clearly. The KB02 staged the various instruments with a surprising degree of air and space, something I find many budget IEMs struggle with on this particular track.

Midrange: Songs used: Flagpole Sitta, Jacked Up, I Am The Highway, Dreams, Too Close, Little Black Submarines, Bohemian Rhapsody, Cash Machine, Chasm

The KB02’s midrange is clean, flexible, and all-around articulate. It features particularly intelligible vocals — a selling point you don’t always get on budget dynamic-driver-based IEMs. Male and female vocals sound great, with the KB02 showing a minor partiality to higher-pitch vocals. Deeper male vocals are neutrally-toned, but could stand for a hint of added warmth for additional weight.

I’ve used the word “clean” a number of times already, but that really is one of the best ways to describe the way that the KB02 sounds. Instrumentation is well-articulated across the entire midrange, with the KB02 doing a great job of layering multiple instruments against each-other (and the vocals). Further, the KB02 captures an above-average amount of texture in its midrange.

Bass: Songs used: Moth, Gold Dust, In For The Kill (Skream Remix), War Pigs (Celldweller Remix)

KBEar writes quite a bit about the KB02’s BC driver and its subwoofer-like nature. But based on my listening, the KB02 isn’t really a “basshead” or “bass-centric IEM”. Sure, its bass is forward, but not beyond anything you’d hear in a normal V-shaped IEM. That said, I do appreciate the tactile nature of the KB02’s bass. It feels much more “real” than its peers, likely owing to the BC driver’s unique psychoacoustic properties.

The KB02’s bass is generally articulate, with its dynamic driver doing most of the “shape” work and its bone conduction driver lending extra weight and rumble to the mix. And while I do generally enjoy the KB02’s take on bass, I wish it had a more cohesive cross-over from its midbass to sub-bass. It is impressive what KBEar achieved for $40 — but it’s clear to me that BC drivers are not end-all-be-all replacements for the multi-DD configurations often found in pricier IEMs (Cappucinno MK II, Trifecta).

Packaging / Unboxing​

The KB02’s packaging is minimalistic. The unboxing experience is better than I expected given it’s price, but overall fairly average.

Build​

Construction Quality​

KBEar really nailed the KB02’s shells. They are made from resin, but feature beautiful hand-polished faceplates that, not even 7 years ago, would only be found on far more expensive IEMs.


The top of the KB02’s shells house its 0.78mm 2-pin sockets. They are molded flush to the shell’s surface. Beside the sockets lies a driver vent — Its position isn’t problematic per-se, but it does expose the vent to buildup of hand-oils as it sits right where you grab the shell to insert or remove it from your ears. I’d avoid handling the KB02 with anything other than clean, dry hands for this reason.


The KB02’s nozzles are made from cleanly-cut metal. This is a must for longevity. The cost is well worth it, as plastic/resin nozzles are a major failure point and often cripple an IEMs ability to go the distance. KBEar gets major credit here, as a lot of ChiFi brands cheap out in this price-segment.



Moving on to the KB02’s cable, we can see that it is a sturdy, utilitarian cable. It has virtually zero body, meaning it can be coiled without introducing kinks or deformities. It is so pliable that I was able to easily fit it, plus a USB-C dongle, in my smallest carrying case — a major achievement for an IEM with such large shells.

The cable uses plastic bits for the 3.5mm shell, Y-splitter, and 2-pin shell. They each feature strain relief components, so I am confident in the cable’s longevity. It is, however somewhat thin. From an aesthetic perspective, you may want something a little chunkier. For those who do, the KB02 is widely compatible with aftermarket 2-pin cables such as the Tripowin Zonnie.

It is worth mentioning that the KB02’s use of a “Bone Conduction Driver”(BCD) is a bit of a misnomer. Yes, it utilizes a driver that makes use of the same underlying technology as proper bone conduction drivers, but the KB02 doesn’t actually use bone-conduction. It’s a lot closer to a two-driver IEM where one driver is a full-range speaker and the other is a dedicated subwoofer. In the KB02’s case, its “BCD” is the subwoofer. As those who’ve used BC IEMs may already know, these drivers have an internal resonance inherent to their physical design. This means that they impart a… unique spring-loaded/echo sensation to the IEM that you feel while handling the IEM. If you get a strong seal with them, even the act of swallowing can trigger resonance within the BC driver. I can tolerate this, but my wife absolutely hates it. You don’t usually hear it while listening to music, aside for when certain bass queues trigger its resonance point at higher volumes.

Comfort​

Disclaimer: comfort is a highly individual metric — no two people will have the same experience.

The KB02 is on the larger side, but it is more comfortable for me than many of its peers. I was able to get a strong, comfortable seal with the included eartips (though with different sizes on each ear). I can listen to the KB02 indefinitely, though I always recommend you rest your ears at least once every hour for the sake of your ear health.

Accessories​

Inside the box you’ll find:


Note: the left-most eartips are white and were colored by ambient lighting

• 3x sets of silicone eartips
• 1x 3.5mm cable

This is a sparse accessory package, but for $40 (or $28 with the sale), you can’t really ask for much more. Sure, a baggie or carrying case would be welcomed, but virtually every cheap ($5-$10) pocket-sized case on Amazon/AliExpress will easily fit the IEMs.

Comparisons​

1: 7hz Eula ($30)

The Eula is another budget ChiFi IEM that aims to bring subwoofer-like sound to its listeners. The Eula, however, uses a dual dynamic-driver setup. Both the Eula and KB02 have “enhanced” sub-bass, though these bonuses manifest in different ways. The Eula has less extension, but a more familiar sub-bass timbre. Its sub-bass attack and decay speeds feel a little faster than the KB02. The KB02, on the other hand, has deeper and vastly more tactile bass. Its bone-conduction driver generates a much more “real” physical sensation.

The Eula has sharper, more pronounced upper-midrange. This manifests itself as sounding less natural, though with slightly better micro details. The Eula is a good IEM, but considering both IEMs set out to achieve similar goals, I prefer the KB02’s approach. From sound to physical design, the small $10 price-bump makes a big difference in the KB02’s favor.

2: Tripowin Vivace ($30)

The Viviace is 25% cheaper than the KB02. It has a thicker, heavier cable with an all-around similar shell texture. The KB02’s shells, however, are larger and have a richer design. They also benefit tremendously from having metal nozzles, as compared to the Vivace’s plastic. I found that KB02 sealed better in my ears and provided a greater degree of noise insulation.

As for sound quality, the Viviace has a number of similarities to the KB02. Both IEMs have clear, intelligible midranges. Both have a forward and clean treble. The Vivace, however, has a less-recessed lower midrange and comes across as slightly warmer. Its mid-bass is less pronounced and quicker. The KB02 has a more emphasized mid-bass and sub-bass, with far greater lower-register extension.

Neither IEM come with a carrying case, though the Vivace gets more of a pass for that than the KB02 due to its reduced price. In terms of which IEM is “better”, you’ll have to defer to your personal preferences. Sure, the KB02 has (subjectively) prettier shells and metal nozzles, but if you’re looking for gently V-shaped / bright sound signatures, you’re going to enjoy listening to the Viviace a lot more. If you’re seeking out bassier, full-bodied sound, then the $10 premium for the KB02 probably won’t bother you one bit.

3: BQEYZ BQ-10 ($30)

The BQ-10 is also 25% cheaper than the KB02, and comes with a case. That said, I found myself consistently reaching for the KB02 over the BQ-10. It has a cleaner sound signature, better-extended sub-bass, and vastly superior ergonomics.

But, personal preferences and ergonomics aside, there are still scenarios where I can see someone opting for the BQ-10. It has a warmer, more boisterous lower-midrange and mid-bass, giving it broader impact in bass-heavy music. Its shallow-fit profile will likely fit better for people with typical Asian ear shapes (BQEYZ’s main audience). It is also much easier to drive, making it a more practical choice for those with limited options for sources.

Conclusion​

I adore the KB02. It is beautifully crafted, comfortable, and articulate. Its unique blend of clean instrumentation and subwoofer-like bass makes it a top-tier contender in the budget IEM space. For $40, it’s a steal. For $28, it is nearly peerless, at least for those who enjoy V-shaped IEMs. While it would be nice to have an included carrying case, I can give the KBEar a pass — the KB02 is a compelling package as it stands and requires no tweaking to give buyers great value for their hard-earned cash.

Who This is For​

• Bass lovers who want a well-tamed, articulate lower-register
• V-shaped IEM enthusiasts
• Listeners who don’t mind using a higher-powered source

Who This isn’t For​

• Bassheads who want a bass-centric sound signature
• Listeners who are sensitive to the “bone-conduction driver echo”

As always, happy listening!