A4Tech B20 – TWS headphones with hybrid diaphragm

A4Tech B20 - TWS headphones with hybrid diaphragm

A4Tech B20 (Mint Green) is a compact TWS headphone in an unusual color scheme and a transparent charging case design. In addition, there is good battery life, Bluetooth v5.2 support, and the M.O.C.I. hybrid aperture. What does the latter give the user, and what else is interesting about the new product? Let’s take a closer look.


The box in which the model is delivered is made of cardboard, and the design combines a matte panel, a considerable number of glossy embossing elements, and a noticeable blister window on the rear wall. The latter, by the way, allows the user to familiarize himself with the design of the product quite well without even taking it out of the box, which is convenient in its own way.

Of course, the box from a product is something that is usually sent for recycling immediately (or almost immediately) after unpacking the product. And even if the A4Tech B20 packaging suffers a similar fate, I still advise you to take a few minutes to study the data on the walls, because there is a lot of really useful information, which will help you get many answers to questions about the model’s capabilities. This is what we will do next.

Information from the box walls

What I particularly liked about the design of A4Tech B20 is the color of the headphones. This is my first “meeting” with Mint Green, although I have reviewed a lot of competitors from different brands before the “twenty”.

If you want to stand out in the crowd with the color of your TWS, B20 is a very good solution in this regard, and the illustration of the product on the front of the box emphasizes this. In addition to it, there is also the brand logo, model name, battery life, and other interesting “stuff”.

The back wall will attract attention with a note about the presence of a 2-barrel hybrid aperture on board and a small illustration of the same.

The side panels provide comprehensive information about the model’s autonomy and key features and capabilities.

And finally, at the bottom, there is the labeling, information about the supplier in Ukraine, and a lot of other useful data. In short, it’s worth a look.

After that, let’s proceed to unpacking.

The package contents

As for the package, the situation is as follows. Inside, in addition to, of course, the product itself – the A4Tech B20 TWS headphones, the user will find a short USB/USB Type-C cable, as well as a quick start guide and a warranty card.

Specifications of A4Tech B20

  • The speaker size is 13 mm;
  • Frequency response – 20 Hz-20 kHz;
  • Headphone sensitivity – 102 dB at -10 dB full scale;
  • Microphone sensitivity – 42 dB at 1 kHz/Pa;
  • Headphone resistance – 32 ohms;
  • Bluetooth version – v5.2;
  • Working distance – 10 m;
  • Headphone battery type – lithium battery (40 mAh);
  • Charging case battery type – lithium battery (380 mAh);
  • Charging power – 5 V = 500 mA;
  • Headphone charging time – <1.5 hours (from low battery to full charge);
  • Case charging time – <1.5 hours (from low charge to full charge);
  • Music playback time without charging ≈5 hours (50% volume);
  • Playback time from the charging case: ≈20 hours (50% volume);
  • Headphone weight: 4 g;
  • Weight – 39 g;
  • Dimensions of one headphone: 20x34x6 mm;
  • Charging case dimensions: 52x63x26 mm.


The A4Tech B20 case is an excellent combination of really high-quality polycarbonate and some metal. You can see how the latter is used in the illustrations to the review. As for the plastic, at first glance, we can conclude that we are dealing with a one-piece case. And although in fact it is not so – if you look closely, you can notice tiny seams, they do not affect the build quality in any way. However, all the details about this are in the next section. Don’t switch to the next section.

Impressions on the build quality

First, let’s talk about the “part” of the product that I didn’t mention in the previous section – the charging case. In it, the manufacturer also combines metal and polycarbonate.

An interesting feature of the lid, which, by the way, I personally see for the first time, is its transparency. At the very least, it looks very unusual. In short, if you wanted to stand out with this “touch”, the “format”, in my opinion, was chosen more than successfully.

As for the build quality, there are no questions here either – the level of fit of parts to each other, the quality of the hinge, the organization of the USB Type-C port – in short, everything is as it should be, including in models of the highest price segment.

The headphones are protected according to the IPX4 standard, and therefore there can be no questions about their build quality by default. As for what the IPX4 standard means and why headphone case protection is so cool, read on.

IPX4 protection

IPX4 is the protection of a product’s case from water splashes from any direction. So, you’re walking down the street, listening to music, and it’s raining. You don’t need to take off your headphones in a hurry and hide them immediately – the product is protected from such weather tricks.

Other outdoor activities will not be a problem either. In short, it is designed to lead an active lifestyle, or to stimulate it in one way or another. Of course, against the background of a considerable number of competitors’ offers, such protection is not a unique feature, but the very fact of its presence is a plus.


As for me, A4Tech B20 (Mint Green) is interesting in terms of design because of its color – the unusual Mint Green color attracts the eye from the first minutes of meeting. It’s an interesting way to stand out by emphasizing your commitment to something new. Are you no longer interested in purple, or classics in white or black? Then it’s time for new “discoveries”.

This model is unusually light for your ears. It fits securely, however, it will require a little adaptation – after all, these “tiny” earbuds have to fit properly into the auricles. This is the key to the fact that the music will be a pleasure and nothing else.

How well was the control format organized? Personally, I was satisfied, but all the details on this matter are below.


First of all, what is worth knowing about the charging case in this regard. It has a USB Type-C port for recharging, as well as a small LED that indicates the charge level of the built-in battery/charging status. For example, a slow blinking red light indicates a charging level of 0% to 30%, a yellow light indicates a charging level of 30% to 70%, and a green light indicates a charging level of 70% to 100%. It is also worth remembering that at 15% of the remaining charge, a corresponding sound warning will sound. Let’s talk about the charging process separately.

The only touch-sensitive headphone control panel is located just below the diode on the outside of the case – I will also discuss its capabilities separately. In addition to the button, the 2Drumtek name is also placed here – we will also return to it later.

The contact plane for recharging is placed classically – you won’t get it wrong.

The part of the headphone that is inserted into the ear during operation is somewhat unusual in shape, and at first glance it does not look interesting. However, in fact it is not so, and having tried it at least once, you will agree with me.

First connection and setup

There are no problems with connection as such – I tried it on more than 10 different sources, so I can say this with confidence. Bluetooth v5.2 is something that speaks for itself.

After the first connection, all subsequent connections are automatic, as soon as you take the headphones out of the case.

The connection is stable, adjusted for the declared features.


Here’s a brief note. Both the headphones and the charging case have lithium batteries. The capacity of the batteries in the headphones is 40 mAh each, in the case – 380 mAh.

Battery life

The manufacturer claims 20 hours of total battery life. These are excellent results.
In my case, it took a little over an hour to restore the battery level, which is not really noticeable.


The first thing worth noting here is that these headphones are autonomous from each other. That is, you can fully listen to music even through one headphone, leaving the other one on charge at the same time.

As for the controls, the vast majority of functionality is duplicated, which also speaks in favor of working without being “tethered” to each other. However, full-fledged volume control is possible only on two headphones – the left one – downward, the right one – upward. A single press pauses/resumes playback or answers an incoming call. Double-click to skip to the previous track, triple-click to call the voice assistant. Is it complicated? Personally, I don’t think so.

Sound quality

I frankly liked the sound. At the very least, it is not worse than any of the competitors in this price division, although personally, as a user who is quite familiar with A4Tech B20 competitors, it seems to me that thanks to the M.O.C.I. diaphragm (it was created on the basis of advanced biotechnology with mycelium and carbon fiber), this model of the popular brand is able to “bypass” many models of its price level. Clear high and medium frequencies are combined with deep and equally pleasant bass. As a result, there is no need for any special settings – just put it on and enjoy.

A4Tech B20

Conclusions and summary

A4Tech B20 is a model worthy of attention in all key respects. In particular, the Mint Green color is something new for our market (or I just haven’t seen any competitors in this color, which is unlikely, but it could be). This color is a great feature to stand out in the crowd, to emphasize your unconventionality and even to some extent uniqueness.

The statement about a somewhat strange shape of the headphone and, as a result, inconvenience is just a myth, and I personally dispelled it in the first minutes of testing.
And finally, the hybrid M.O.C.I. diaphragm with the corresponding high-quality sound output is not so much a feature of the model as a “business card” of the brand, which frankly declares that “the user of A4Tech headphones with this diaphragm will not be disappointed with what he hears”.


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